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Sample records for biocontrol agents electronic

  1. Toxorhynchites as biocontrol agents.

    Science.gov (United States)

    Focks, Dana A

    2007-01-01

    Toxorhynchites is an unusual and interesting genus of large, non-biting mosquitoes. In spite of their size, they are--like many species of mosquitoes--completely harmless to man. The larvae are predaceous on other mosquitoes and aquatic organisms that inhabit both natural and artificial containers. Because this habitat is the source of several medically important species of mosquitoes, there is warrant for evaluating the potential of Toxorhynchites as a biological control agent under various conditions. Toxorhynchites is not seen as a panacea for the control of all container-inhabiting mosquitoes. However, it has demonstrated practical potential in certain restricted but important situations.

  2. Biocontrol agents in signalling resistance

    NARCIS (Netherlands)

    Loon, L.C. van; Pieterse, C.M.J.

    2002-01-01

    The mechanisms by which biological control agents suppress disease comprise competition for nutrients, notably iron, production of antibiotics, and secretion of lytic enzymes, as well as inducing resistance in the plant. The former three mechanisms act primarily on the pathogen by decreasing its

  3. Recent taxonomy changes and their impact on biocontrol agents

    Science.gov (United States)

    The revolution in DNA sequencing technology has led to and improved understanding of genetics and taxonomy of biocontrol agents. Our lab recently reported the genomes of some important Bacillus bacterial biocontrol agents, which in turn resulted in a change of taxonomy for these commercially importa...

  4. Biocontrol Agents for Take-all.

    NARCIS (Netherlands)

    Raaijmakers, J.M.; Weller, D.M.; Thomashow, L.S.; Cook, R.J.

    1997-01-01

    Fluorescent Pseudomonas spp. are described which are effective for the control of diseases caused by the soil-borne fungus, Gaeumannomyces graminis (Gg), such as take-all, in small grain crops or turf grass. The subject biocontrol strains have a unique genotype as shown by a characteristic banding

  5. Potential biocontrol agents for biofouling on artificial structures.

    Science.gov (United States)

    Atalah, Javier; Newcombe, Emma M; Hopkins, Grant A; Forrest, Barrie M

    2014-09-01

    The accumulation of biofouling on coastal structures can lead to operational impacts and may harbour problematic organisms, including non-indigenous species. Benthic predators and grazers that can supress biofouling, and which are able to be artificially enhanced, have potential value as augmentative biocontrol agents. The ability of New Zealand native invertebrates to control biofouling on marina pontoons and wharf piles was tested. Caging experiments evaluated the ability of biocontrol to mitigate established biofouling, and to prevent fouling accumulation on defouled surfaces. On pontoons, the gastropods Haliotis iris and Cookia sulcata reduced established biofouling cover by >55% and largely prevented the accumulation of new biofouling over three months. On wharf piles C. sulcata removed 65% of biofouling biomass and reduced its cover by 73%. C. sulcata also had better retention and survival rates than other agents. Augmentative biocontrol has the potential to be an effective method to mitigate biofouling on marine structures.

  6. Dragonflies are biocontrol agents in Wisconsin cranberry marshes

    Science.gov (United States)

    Dragonflies (Order Odonata) are abundant predators that emerge in large hatch events each summer in Wisconsin cranberry marshes. They seem to be a potential group of biocontrol agents for pest management that may be influenced by the diversity found on the marsh. In fact, our evidence shows that dra...

  7. Screening of biocontrol agents for control of foliar diseases

    NARCIS (Netherlands)

    Köhl, J.

    2009-01-01

    Candidate antagonists for the development of biocontrol agents have to fulfill many criteria. The criterion often investigated first in detail is the antagonistic potential of candidates against the target pathogen. However, candidates must also have high ecological competence, must be suitable for

  8. Use of phylloplane fungi as biocontrol agent against Colletotrichum ...

    African Journals Online (AJOL)

    Phylloplane fungi were used as biocontrol agent against Colletotrichum leaf disease of rubber (Hevea brasiliensis Muell. Arg.). Aspergillus sp. lysed the cytoplasm of Colletotrichum gloeosporioides on Potato Dextrose Agar. Trichophyton sp. and Gliocladium sp. antagonised C. gloeosporioides by overgrowing on it.

  9. Allelopathic potential of some biocontrol agents for the control of ...

    African Journals Online (AJOL)

    The adverse effect of synthetic pesticides on human health and the natural ecosystem necessitate the need to explore natural mechanisms of disease control in plants. This study evaluated the allelopathic potential of five biocontrol agents: Trichoderma longibrachiatum, Trichoderma asperellum, Bacillus subtilis, Bacillus ...

  10. Bioprospection of yeasts as biocontrol agents against phytopathogenic molds

    Directory of Open Access Journals (Sweden)

    Márcia Maria Rosa-Magri

    2011-02-01

    Full Text Available Yeasts isolated from sugar cane and maize rhizosphere, leaves and stalks were screened against the phytopathogenic molds Colletotrichum sublineolum and Colletotrichum graminicola, both causal agents of the anthracnose disease in sorghum and maize, respectively. Strains identified as Torulaspora globosa and Candida intermedia were able to inhibit the mold growth, with the first species also exhibiting killer activity. No previous report on the application and potentiality of these yeasts as biocontrol agents were found neither the killer phenotype in Torulaspora globosa.

  11. A numerical study of combined use of two biocontrol agents with different biocontrol mechanisms in controlling foliar pathogens.

    Science.gov (United States)

    Xu, X-M; Jeffries, P; Pautasso, M; Jeger, M J

    2011-09-01

    Effective use of biocontrol agents is an important component of sustainable agriculture. A previous numerical study of a generic model showed that biocontrol efficacy was greatest for a single biocontrol agent (BCA) combining competition with mycoparasitism or antibiosis. This study uses the same mathematical model to investigate whether the biocontrol efficacy of combined use of two BCAs with different biocontrol mechanisms is greater than that of a single BCA with either or both of the two mechanisms, assuming that two BCAs occupy the same host tissue as the pathogen. Within the parameter values considered, a BCA with two biocontrol mechanisms always outperformed the combined use of two BCAs with a single but different biocontrol mechanism. Similarly, combined use of two BCAs with a single but different biocontrol mechanism is shown to be far less effective than that of a single BCA with both mechanisms. Disease suppression from combined use of two BCAs was very similar to that achieved by the more efficacious one. As expected, a higher BCA introduction rate led to increased disease suppression. Incorporation of interactions between two BCAs did not greatly affect the disease dynamics except when a mycoparasitic and, to a lesser extent, an antibiotic-producing BCA was involved. Increasing the competitiveness of a mycoparasitic BCA over a BCA whose biocontrol mechanism is either competition or antibiosis may lead to improved biocontrol initially and reduced fluctuations in disease dynamics. The present study suggests that, under the model assumptions, combined use of two BCAs with different biocontrol mechanisms in most cases only results in control efficacies similar to using the more efficacious one alone. These predictions are consistent with published experimental results, suggesting that combined use of BCAs should not be recommended without clear understanding of their main biocontrol mechanisms and relative competitiveness, and experimental evaluation.

  12. Desirable Traits of a Good Biocontrol Agent against Verticillium Wilt.

    Science.gov (United States)

    Deketelaere, Silke; Tyvaert, Lien; França, Soraya C; Höfte, Monica

    2017-01-01

    The soil-borne fungus Verticillium causes serious vascular disease in a wide variety of annual crops and woody perennials. Verticillium wilt is notoriously difficult to control by conventional methods, so there is great potential for biocontrol to manage this disease. In this study we aimed to review the research about Verticillium biocontrol to get a better understanding of characteristics that are desirable in a biocontrol agent (BCA) against Verticillium wilt. We only considered studies in which the BCAs were tested on plants. Most biocontrol studies were focused on plants of the Solanaceae, Malvaceae , and Brassicaceae and within these families eggplant, cotton, and oilseed rape were the most studied crops. The list of bacterial BCAs with potential against Verticillium was dominated by endophytic Bacillus and Pseudomonas isolates, while non-pathogenic xylem-colonizing Verticillium and Fusarium isolates topped the fungal list. Predominant modes of action involved in biocontrol were inhibition of primary inoculum germination, plant growth promotion, competition and induced resistance. Many BCAs showed in vitro antibiosis and mycoparasitism but these traits were not correlated with activity in vivo and there is no evidence that they play a role in planta . Good BCAs were obtained from soils suppressive to Verticillium wilt, disease suppressive composts, and healthy plants in infested fields. Desirable characteristics in a BCA against Verticillium are the ability to (1) affect the survival or germination of microsclerotia, (2) colonize the xylem and/or cortex and compete with the pathogen for nutrients and/or space, (3) induce resistance responses in the plant and/or (4) promote plant growth. Potential BCAs should be screened in conditions that resemble the field situation to increase the chance of successful use in practice. Furthermore, issues such as large scale production, formulation, preservation conditions, shelf life, and application methods should be

  13. Desirable Traits of a Good Biocontrol Agent against Verticillium Wilt

    Directory of Open Access Journals (Sweden)

    Silke Deketelaere

    2017-07-01

    Full Text Available The soil-borne fungus Verticillium causes serious vascular disease in a wide variety of annual crops and woody perennials. Verticillium wilt is notoriously difficult to control by conventional methods, so there is great potential for biocontrol to manage this disease. In this study we aimed to review the research about Verticillium biocontrol to get a better understanding of characteristics that are desirable in a biocontrol agent (BCA against Verticillium wilt. We only considered studies in which the BCAs were tested on plants. Most biocontrol studies were focused on plants of the Solanaceae, Malvaceae, and Brassicaceae and within these families eggplant, cotton, and oilseed rape were the most studied crops. The list of bacterial BCAs with potential against Verticillium was dominated by endophytic Bacillus and Pseudomonas isolates, while non-pathogenic xylem-colonizing Verticillium and Fusarium isolates topped the fungal list. Predominant modes of action involved in biocontrol were inhibition of primary inoculum germination, plant growth promotion, competition and induced resistance. Many BCAs showed in vitro antibiosis and mycoparasitism but these traits were not correlated with activity in vivo and there is no evidence that they play a role in planta. Good BCAs were obtained from soils suppressive to Verticillium wilt, disease suppressive composts, and healthy plants in infested fields. Desirable characteristics in a BCA against Verticillium are the ability to (1 affect the survival or germination of microsclerotia, (2 colonize the xylem and/or cortex and compete with the pathogen for nutrients and/or space, (3 induce resistance responses in the plant and/or (4 promote plant growth. Potential BCAs should be screened in conditions that resemble the field situation to increase the chance of successful use in practice. Furthermore, issues such as large scale production, formulation, preservation conditions, shelf life, and application methods

  14. Responses of Yeast Biocontrol Agents to Environmental Stress

    Science.gov (United States)

    Sui, Yuan; Wisniewski, Michael; Droby, Samir

    2015-01-01

    Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeast species, is a research topic that has received considerable attention in the literature over the past 30 years. In principle, it represents a promising alternative to chemical fungicides for the management of postharvest decay of fruits, vegetables, and grains. A yeast-based biocontrol system is composed of a tritrophic interaction between a host (commodity), a pathogen, and a yeast species, all of which are affected by environmental factors such as temperature, pH, and UV light as well as osmotic and oxidative stresses. Additionally, during the production process, biocontrol agents encounter various severe abiotic stresses that also impact their viability. Therefore, understanding the ecological fitness of the potential yeast biocontrol agents and developing strategies to enhance their stress tolerance are essential to their efficacy and commercial application. The current review provides an overview of the responses of antagonistic yeast species to various environmental stresses, the methods that can be used to improve stress tolerance and efficacy, and the related mechanisms associated with improved stress tolerance. PMID:25710368

  15. Modulation of Human Immune Response by Fungal Biocontrol Agents

    Science.gov (United States)

    Konstantinovas, Cibele; de Oliveira Mendes, Tiago A.; Vannier-Santos, Marcos A.; Lima-Santos, Jane

    2017-01-01

    Although the vast majority of biological control agents is generally regarded as safe for humans and environment, the increased exposure of agriculture workers, and consumer population to fungal substances may affect the immune system. Those compounds may be associated with both intense stimulation, resulting in IgE-mediated allergy and immune downmodulation induced by molecules such as cyclosporin A and mycotoxins. This review discusses the potential effects of biocontrol fungal components on human immune responses, possibly associated to infectious, inflammatory diseases, and defective defenses. PMID:28217107

  16. Biocontrol of fouling pests: Effect of diversity, identity and density of control agents.

    Science.gov (United States)

    Atalah, Javier; Newcombe, Emma M; Zaiko, Anastasija

    2016-04-01

    Augmentative biocontrol, using native natural enemies, has been suggested as a promising tool to control marine biofouling pests on artificial structures. However, there are still important knowledge gaps to be addressed before biocontrol can be considered as a management tool. In a field experiment on floating marine structures we examined intra- and interspecific consumer interactions among biocontrol agents on different surface orientations. We tested the effect of identity, density and diversity of three invertebrates (the 11-arm seastar Coscinasterias muricata, the sea urchin Evechinus chloroticus and the gastropod Cook's turban Cookia sulcata) to reduce established biofouling and to prevent fouling growth on defouled surfaces. High densities of biocontrol agents were not more effective at fouling control (cover and biomass) than low densities. Nor did multi-species treatments function more effectively than mono-specific ones. However, biocontrol agent identity was important, with the 11-arm seastar and Cook's turban being the most effective at fouling reduction and prevention, respectively. Surface orientation had a strong effect on the effectiveness of control agents, with the best results obtained on vertical compared to diagonal and underside surfaces. This study confirmed the potential of biocontrol as a management tool for marine pest, indicating that identity is more important than richness and density of control agents. It also highlighted the limitations of this approach on diagonal and underside surfaces, where control agents have limited retention ability. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes

    Science.gov (United States)

    Odedina, Grace Fiyinfoluwa; Vongkamjan, Kitiya; Voravuthikunchai, Supayang Piyawan

    2015-01-01

    Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination. PMID:26371033

  18. Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Grace Fiyinfoluwa Odedina

    2015-09-01

    Full Text Available Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination.

  19. Vibrio vulnificus bacteriophage SSP002 as a possible biocontrol agent.

    Science.gov (United States)

    Lee, Hyun Sung; Choi, Slae; Shin, Hakdong; Lee, Ju-Hoon; Choi, Sang Ho

    2014-01-01

    A novel Vibrio vulnificus-infecting bacteriophage, SSP002, belonging to the Siphoviridae family, was isolated from the coastal area of the Yellow Sea of South Korea. Host range analysis revealed that the growth inhibition of phage SSP002 is relatively specific to V. vulnificus strains from both clinical and environmental samples. In addition, a one-step growth curve analysis and a bacteriophage stability test revealed a latent period of 65 min, a burst size of 23 ± 2 PFU, as well as broad temperature (20°C to 60°C) and pH stability (pH 3 to 12) ranges. A Tn5 random transposon mutation of V. vulnificus and partial DNA sequencing of the inserted Tn5 regions revealed that the flhA, flhB, fliF, and fleQ mutants are resistant to SSP002 phage infection, suggesting that the flagellum may be the host receptor for infection. The subsequent construction of specific gene-inactivated mutants (flhA, flhB, fliF, and fleQ) and complementation experiments substantiated this. Previously, the genome of phage SSP002 was completely sequenced and analyzed. Comparative genomic analysis of phage SSP002 and Vibrio parahaemolyticus phage vB_VpaS_MAR10 showed differences among their tail-related genes, supporting different host ranges at the species level, even though their genome sequences are highly similar. An additional mouse survival test showed that the administration of phage SSP002 at a multiplicity of infection of 1,000 significantly protects mice from infection by V. vulnificus for up to 2 months, suggesting that this phage may be a good candidate for the development of biocontrol agents against V. vulnificus infection.

  20. Environmental factors affect the activity of biocontrol agents against ochratoxigenic Aspergillus carbonarius on wine grape.

    Science.gov (United States)

    De Curtis, F; de Felice, D V; Ianiri, G; De Cicco, V; Castoria, R

    2012-09-17

    The influence of temperature and relative humidity (RH) on the activity of three biocontrol agents-the yeast Metschnikowia pulcherrima LS16 and two strains of the yeast-like fungus Aureobasidium pullulans LS30 and AU34-2-against infection by A. carbonarius and ochratoxin A (OTA) accumulation in wine grape berries was investigated in lab-scale experiments. The presence of wounds on grape skin dramatically favored infection of berries by A. carbonarius strain A1102, since unwounded berries showed very low levels of infection at all conditions of RH and temperature tested. Artificially wounded berries pre-treated with the biocontrol agents were inoculated with the ochratoxigenic A. carbonarius strain A1102 and were incubated for 5 days at two levels of RH (60% and 100%) and three different temperatures (20, 25 and 30 °C). The three biocontrol agents were able to prevent infections at 60% RH and 20 °C. At 60% RH and 25 °C only strain AU34-2 achieved some protection on day 5, whereas at 30 °C a limited biocontrol efficacy was evident only up to day 2. At 100% RH, LS16, LS30 and AU34-2 showed effective protection of grape berries at 20 °C until the 5th day of incubation. The three biocontrol agents achieved significant protection at higher temperatures only until the 2nd day after the beginning of the experiment: all three strains at 25 °C, and only strain LS16 at 30 °C. After 5 days, the three biocontrol agents were able to significantly reduce the level of OTA in berries at all the conditions tested. This occurred even when protection from infection was not significant, except at 30 °C and 100% of RH for all the three strains, and at 25 °C and 100% of RH for strain LS16. The biocontrol agents displayed a higher rate of colonization on grape berries at 20 and 25 °C than at 30 °C. The higher value of RH (100%) appeared to increase the rate of colonization, in particular at 20 and 25 °C. Taken together, our results emphasize the significant influence of

  1. Utilization of winery wastes for Trichoderma viride biocontrol agent production by solid state fermentation.

    Science.gov (United States)

    Bai, Zhihui; Jin, Bo; Li, Yuejie; Chen, Jian; Li, Zuming

    2008-01-01

    Biocontrol agents are safe and environmental friendly alternatives for pesticides in agriculture application. Trichoderma viride WEBL0703 performed a high level of antagonistic activity toward a broad spectrum of phytopathogens and was determined as a biocontrol agent, which was produced by solid state fermentation using grape marc and wine lees. The maximum yield of T. viride conidia was up to 6.65 x 10(9) CFU/g initial dry substrate (IDS) after 10 d fermentation. As important enzymes for protecting plants from disease, chitinase, beta-glucanase, and pectinase yields were 47.8 U/g IDS, 8.32 U/g IDS and 9.83 U/g IDS, respectively. These results show that it is feasible to convert winery wastes to a value-added and environmental friendly biocontrol agent.

  2. Characterization of effective bio-control agent Bacillus sp. SRB 27 ...

    African Journals Online (AJOL)

    Rhizoctonia solani and Alternaria solani was obtained from forest soil sample by carrying out in vitro and in vivo screening techniques. This study reports the identification and characterization of a Bacillus sp. SRB 27 that may be used as a bio-control agent against the plant diseases in crop plants. It was identified as ...

  3. Evaluation of potential bio-control agents on root-knot nematode ...

    African Journals Online (AJOL)

    Tuoyo Aghomotsegin

    2016-05-11

    May 11, 2016 ... nematode, Meloidogyne incognita and Fusarium oxysporum f.sp. conglutinans in vitro. Cell free ... are manifested by the formation of root galls accompanied by stunted growth, chlorosis and loss of viability of the plant (Babu et al., 1999). Fusarium wilt is ... effective bio-control agent on Meloidogyne spp. on.

  4. Cucumber rhizosphere microbial community response to biocontrol agent Bacillus subtilis B068150

    Science.gov (United States)

    Gram-positive bacteria Bacillus subtilis B068150 has been used as a biocontrol agent against the pathogen Fusarium oxysporum f. sp. Cucumerinum. However, their survival ability in cucumber rhizosphere and non-rhizosphere as well as their influence on native microbial communities has not been fully i...

  5. Isolation and identification of actinomycetes from a compost-amended soils biocontrol agents

    Energy Technology Data Exchange (ETDEWEB)

    Garcia de la Fuente, R.; Cuesta, G.; Fornes, F.; Abad, M.

    2009-07-01

    Compost capability to suppress soil-borne plant pathogens has become an interesting subject as a strategy for reducing the adverse effects of massive fungicides application in the environmental. In this context, actinomycetes have received considerable attention as biocontrol agents, particularly Streptomyces species. (Author)

  6. Genomic Analysis of Bacillus sp. Strain B25, a Biocontrol Agent of Maize Pathogen Fusarium verticillioides.

    Science.gov (United States)

    Douriet-Gámez, Nadia R; Maldonado-Mendoza, Ignacio E; Ibarra-Laclette, Enrique; Blom, Jochen; Calderón-Vázquez, Carlos L

    2018-03-01

    Bacillus sp. B25 is an effective biocontrol agent against the maize pathogenic fungus Fusarium verticillioides (Fv). Previous in vitro assays have shown that B25 has protease, glucanase, and chitinase activities and siderophores production; however, specific mechanisms by which B25 controls Fv are still unknown. To determine the genetic traits involved in biocontrol, B25 genome was sequenced and analyzed. B25 genome is composed of 5,113,413 bp and 5251 coding genes. A multilocus phylogenetic analysis (MLPA) suggests that B25 is closely related to the Bacillus cereus group and a high percentage (70-75%) of the genetic information is conserved between B25 and related strains, which include most of the genes associated to fungal antagonism. Some of these genes are shared with some biocontrol agents of the Bacillus genus and less with Pseudomonas and Serratia strains. We performed a genomic comparison between B25 and five Bacillus spp., Pseudomonas and Serratia strains. B25 contains genes involved in a wide variety of antagonistic mechanisms including chitinases, glycoside hydrolases, siderophores, antibiotics, and biofilm production that could be implicated in root colonization. Also, 24 genomic islands and 3 CRISPR sequences were identified in the B25 genome. This is the first comparative genome analysis between strains belonging to the B. cereus group and biocontrol agents of phytopathogenic fungi. These results are the starting point for further studies on B25 gene expression during its interaction with Fv.

  7. Identification of Biocontrol Agents to Control the Fungal Pathogen, Geomyces destructans, in Bats

    Science.gov (United States)

    Braunstein, S.; Cheng, T.

    2013-12-01

    The fungal pathogen Geomyces destructans (Gd) causes the disease White-nose Syndrome (WNS) in bats and is estimated to have killed millions of bats since its emergence in North America in 2006. Gd is predicted to cause the local extinction of at least three bat species if rates of decline continue unabated. Given the devastating impacts of Gd to bat populations, identifying a viable method for controlling the pathogen is pertinent for conservation of affected bat species. Our work focuses on identifying naturally-occurring skin bacteria on bats that are antagonistic to Gd that could potentially be used as a biocontrol. We cultured bacteria from skin swabs taken from wild bats (Myotis lucifugus, Eptesicus fuscus, Myotis sodalis, Perimyotis subflavus). We conducted challenge experiments to identify bacterial strains that inhibited Gd growth. Bacteria that exhibited antifungal properties were identified using 16S and gyrB markers. Our methods identified several bacteria in the Pseudomonas fluorescens complex as potential biocontrol agents. Future work will continue to test the viability of these bacteria as biocontrol agents via experimental treatments with live captive bats. The failure of previous non-biocontrol methods highlights the importance of developing these bacteria as a biologically-friendly method for controlling Gd. A bat infected with Geomyces destructans. Photo by West Virginia Division of Natural Resources Bacterial culture from the swab of a bat's wings

  8. Conjunctively screening of biocontrol agents (BCAs) against fusarium root rot and fusarium head blight caused by Fusarium graminearum.

    Science.gov (United States)

    Wang, Lu-Yao; Xie, Yue-Shen; Cui, Yuan-Yu; Xu, Jianjun; He, Wei; Chen, Huai-Gu; Guo, Jian-Hua

    2015-08-01

    Fusarium root-rot and fusarium head blight are plant diseases caused by Fusarium sp. in different growth periods of wheat, bring heavy losses to crop production in China. This research is aiming to screen biocontrol agents conjunctively for controlling these two diseases at the same time, as well as evaluate our previous BCAs (Biological Control Agents) screening strategies in more complex situation, considering biocontrol is well concerned as an environmental-friendly plant disease controlling method. Totally 966 bacterial isolates were screened from different parts of wheat tissues, of which potential biocontrol values were detected according to their abilities in antagonism inhibition and secreting extracellular hydrolytic enzyme. Biocontrol tests against fusarium root rot and fusarium head blight were carried out on 37 bacterial isolates with potential biocontrol capacity after pre-selection through ARDRA- and BOX-PCR analysis on strains with high assessment points. We acquired 10 BCAs with obvious biocontrol efficacy (more than 40%) in greenhouse and field tests. Pseudomonas fluorescens LY1-8 performed well in both two tests (biocontrol efficacy: 44.62% and 58.31%), respectively. Overall, correlation coefficient is 0.720 between assessment values of 37 tested BCA strains and their biocontrol efficacy in trails against fusarium root rot; correlation coefficient is 0.806 between their assessment values and biocontrol efficacy in trails against fusarium head blight. We acquired 10 well-performed potential BCAs, especially P. fluorescens LY1-8 displayed good biocontrol capacity against two different diseases on wheat. Biocontrol efficacies results in both greenhouse and field tests showed high positive correlation with assessment values (0.720 and 0.806), suggesting that the BCAs screening and assessing strategy previously developed in our lab is also adaptable for conjunctively screening BCAs for controlling both root and shoot diseases on wheat caused by same

  9. Inability to Find Consistent Bacterial Biocontrol Agents of Pythium aphanidermatum in Cucumber Using Screens Based on Ecophysiological Traits

    NARCIS (Netherlands)

    Folman, L.B.; Postma, J.; Veen, van J.A.

    2003-01-01

    A collection of 821 rhizobacteria from cucumber, originating from different root locations and stages of plant development, was screened for potential biocontrol agents of Pythium aphanidermatum (Edson) Fitzp. The screening procedure exploited carbon source utilization profiles and growth rates of

  10. Genomic characterization of key bacteriophages to formulate the potential biocontrol agent to combat enteric pathogenic bacteria.

    Science.gov (United States)

    Parmar, Krupa M; Dafale, Nishant A; Tikariha, Hitesh; Purohit, Hemant J

    2018-01-12

    Combating bacterial pathogens has become a global concern especially when the antibiotics and chemical agents are failing to control the spread due to its resistance. Bacteriophages act as a safe biocontrol agent by selectively lysing the bacterial pathogens without affecting the natural beneficial microflora. The present study describes the screening of prominent enteric pathogens NDK1, NDK2, NDK3, and NDK4 (Escherichia, Klebsiella, Enterobacter, and Serratia) mostly observed in domestic wastewater; against which KNP1, KNP2, KNP3, and KNP4 phages were isolated. To analyze their potential role in eradicating enteric pathogens and toxicity issue, these bacteriophages were sequenced using next-generation sequencing and characterized based on its genomic content. The isolated bacteriophages were homologous to Escherichia phage (KNP1), Klebsiella phage (KNP2), Enterobacter phage (KNP3), Serratia phage (KNP4), and belonged to Myoviridae family of Caudovirales except for the unclassified KNP4 phage. Draft genome analysis revealed the presence of lytic enzymes such as holing and lysozyme in KNP1 phage, endolysin in KNP2 phage, and endopeptidase with holin in KNP3 phage. The absence of any lysogenic and virulent genes makes this bacteriophage suitable candidate for preparation of phage cocktail to combat the pathogens present in wastewater. However, KNP4 contained a virulent gene rendering it unsuitable to be used as a biocontrol agent. These findings make the phages (KNP1-KNP3) as a promising alternative for the biocontrol of pathogens in wastewater which is the main culprit to spread these dominated pathogens in different natural water bodies. This study also necessitates for genomic screening of bacteriophages for lysogenic and virulence genes prior to its use as a biocontrol agent.

  11. A combination of biocontrol agents improves the management of dry root rot (Macrophomina phaseolina in greengram

    Directory of Open Access Journals (Sweden)

    R. Thilagavathi

    2007-08-01

    Full Text Available The biocontrol agents Trichoderma viride (strains Tv1 and Tv13, Pseudomonas fluorescens (Pf1 and Py15 and Bacillus subtilis (Bs16 were tested individually and in combination for their effectiveness against root rot of greengram caused by Macrophomina phaseolina. As regards the compatibility of the biocontrol agents with each other, T. viride strains were not compatible with B. subtilis (Bs16, but P. fluorescens strains were compatible with B. subtilis and T. viride. Of the biocontrol agents tested in vitro against M. phaseolina, combinations of P. fluorescens+T. viride (Pf1+Tv1, Pf1+Tv13 and Py15+Tv1 inhibited mycelial growth of the pathogen and they also promoted the growth of the greengram seedlings. A combination of Pf1+Tv1 was most effective in reducing root rot incidence under glass-house and field conditions as compared with other single or combined treatments or the untreated control. The activity of the defense-related enzymes peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase was significantly greater in greengram plants treated with a talc based formulation containing Pf1+Tv1 followed by Pf1+Tv13 and Py15+Tv1, than in plants receiving other treatments or the untreated control. Moreover, a combination of Pf1+Tv1 followed by Pf1+Tv13 and Py15+Tv1 significantly increased yield under glass house and field conditions.

  12. Microencapsulation Technique with Organic Additives for Biocontrol Agents

    Directory of Open Access Journals (Sweden)

    Szczech Magdalena

    2016-06-01

    Full Text Available The aim of these studies was to develop an effective formulation for microbial strains active in plant protection. Emulsification technique in oil was used to produce alginate microcapsules supplemented with organic additives to improve production process and stability of the preparations during storage. The release of microorganisms from the capsules in soil and their effectiveness in biocontrol of Fusarium wilt were evaluated. Three bacterial strains Burkholderia cepacia strain CAT5, Bacillus spp. strains PZ9 and SZ61, and fungus Trichoderma virens TRS106 were immobilized separately in calcium alginate supplemented with chitosan, peat powder, or skim milk. The productivity of microcapsules was enhanced by 60% when peat was added to the alginate matrix. Peat reduced also contamination of the capsules during storage, significantly enhancing their quality. By contrast, the addition of skim milk reduced quality of the microcapsules. The additives did not influence the viability of entrapped microorganisms and their release in soil. The survival of the microbial cells was mainly related to the kind of microorganism used, and the highest viability showed Bacillus sp. PZ9 and Trichoderma TRS106. Lyophilization of the microcapsules appeared to be unfavorable by reducing microbial viability in the capsules and in the soil after application. The best properties: good storage ability and sufficient microbial release in the soil, exhibited wet microcapsules amended with peat. These capsules were used to control Fusarium wilt in tomato plants. The protective effect was obtained when the microcapsule-entrapped bacteria PZ9 were used. The effectiveness of this bacterium was comparable with fungicide. Peat-amended microcapsules entrapping Bacillus PZ9 showed the best quality and may have potential for commercial use.

  13. Releasing biocontrol agents: Risk assessment and overdue reform

    Science.gov (United States)

    Bob Peterson; Sharlene Sing

    2007-01-01

    Although the need for universally instituting formal risk assessment (RA) in the screening and approval process for non-native biological control (BC) agent releases has been widely acknowledged for the past several years, little seems to have been accomplished in terms of codifying this practice within a regulatory framework. Given the low success rate of classical BC...

  14. The Potential ofStreptomycesas Biocontrol Agents against the Rice Blast Fungus,Magnaporthe oryzae(Pyricularia oryzae).

    Science.gov (United States)

    Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

    2017-01-01

    Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae ). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10-30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyce s bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae . The ability of various S treptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae . In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents.

  15. Biocontrol agents promote growth of potato pathogens, depending on environmental conditions.

    Science.gov (United States)

    Cray, Jonathan A; Connor, Mairéad C; Stevenson, Andrew; Houghton, Jonathan D R; Rangel, Drauzio E N; Cooke, Louise R; Hallsworth, John E

    2016-05-01

    There is a pressing need to understand and optimize biological control so as to avoid over-reliance on the synthetic chemical pesticides that can damage environmental and human health. This study focused on interactions between a novel biocontrol-strain, Bacillus sp. JC12GB43, and potato-pathogenic Phytophthora and Fusarium species. In assays carried out in vitro and on the potato tuber, the bacterium was capable of near-complete inhibition of pathogens. This Bacillus was sufficiently xerotolerant (water activity limit for growth = 0.928) to out-perform Phytophthora infestans (~0.960) and challenge Fusarium coeruleum (~0.847) and Fusarium sambucinum (~0.860) towards the lower limits of their growth windows. Under some conditions, however, strain JC12GB43 stimulated proliferation of the pathogens: for instance, Fusarium coeruleum growth-rate was increased under chaotropic conditions in vitro (132 mM urea) by >100% and on tubers (2-M glycerol) by up to 570%. Culture-based assays involving macromolecule-stabilizing (kosmotropic) compatible solutes provided proof-of-principle that the Bacillus may provide kosmotropic metabolites to the plant pathogen under conditions that destabilize macromolecular systems of the fungal cell. Whilst unprecedented, this finding is consistent with earlier reports that fungi can utilize metabolites derived from bacterial cells. Unless the antimicrobial activities of candidate biocontrol strains are assayed over a full range of field-relevant parameters, biocontrol agents may promote plant pathogen infections and thereby reduce crop yields. These findings indicate that biocontrol activity, therefore, ought to be regarded as a mode-of-behaviour (dependent on prevailing conditions) rather than an inherent property of a bacterial strain. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  16. [Optimization of biocontrol agent Burkholderia pyrrocinia strain JK-SH007 fermentation by response surface methodology].

    Science.gov (United States)

    Li, Hao; Ren, Jiahong; Ye, Jianren

    2013-02-01

    In order to improve ferment efficiency of biocontrol agent Burkholderia pyrrocinia JK-SH007, the fermentation conditions of this strain were optimized. The optimal fermentation conditions were corn steep liquor (13.88 g/L) and glucose (3.37 g/L) by screening test, steepest ascent experiments and response surface analysis. The results showed that the cell density of JK-SH007 (1.18 x 10(9) CFU/mL) increased 1.35 times than before, and there was a 28.84% increase in antifungal activity.

  17. The fungal biocontrol agent Coniothyrium minitans: production by solid-state fermentation, application and marketing.

    Science.gov (United States)

    de Vrije, T; Antoine, N; Buitelaar, R M; Bruckner, S; Dissevelt, M; Durand, A; Gerlagh, M; Jones, E E; Lüth, P; Oostra, J; Ravensberg, W J; Renaud, R; Rinzema, A; Weber, F J; Whipps, J M

    2001-07-01

    Biological control agents (BCAs) are potential alternatives for the chemical fungicides presently used in agriculture to fight plant diseases. Coniothyrium minitans is an example of a promising fungal BCA. It is a naturally occurring parasite of the fungus Sclerotinia sclerotiorum, a wide-spread pathogen which substantially reduces the yield of many crops. This review describes, exemplified by C. minitans, the studies that need to be carried out before a fungal BCA is successfully introduced into the market. The main aspects considered are the biology of C. minitans, the development of a product by mass production of spores using solid-state fermentation technology, its biocontrol activity and marketing of the final product.

  18. The biocontrol agent Pseudomonas chlororaphis PA23 primes Brassica napus defenses through distinct gene networks.

    Science.gov (United States)

    Duke, Kelly A; Becker, Michael G; Girard, Ian J; Millar, Jenna L; Dilantha Fernando, W G; Belmonte, Mark F; de Kievit, Teresa R

    2017-06-19

    The biological control agent Pseudomonas chlororaphis PA23 is capable of protecting Brassica napus (canola) from the necrotrophic fungus Sclerotinia sclerotiorum via direct antagonism. While we have elucidated bacterial genes and gene products responsible biocontrol, little is known about how the host plant responds to bacterial priming on the leaf surface, including global changes in gene activity in the presence and absence of S. sclerotiorum. Application of PA23 to the aerial surfaces of canola plants reduced the number of S. sclerotiorum lesion-forming petals by 91.1%. RNA sequencing of the host pathogen interface showed that pretreatment with PA23 reduced the number of genes upregulated in response to S. sclerotiorum by 16-fold. By itself, PA23 activated unique defense networks indicative of defense priming. Genes encoding MAMP-triggered immunity receptors detecting flagellin and peptidoglycan were downregulated in PA23 only-treated plants, consistent with post-stimulus desensitization. Downstream, we observed reactive oxygen species (ROS) production involving low levels of H 2 O 2 and overexpression of genes associated with glycerol-3-phosphate (G3P)-mediated systemic acquired resistance (SAR). Leaf chloroplasts exhibited increased thylakoid membrane structures and chlorophyll content, while lipid metabolic processes were upregulated. In addition to directly antagonizing S. sclerotiorum, PA23 primes the plant defense response through induction of unique local and systemic defense networks. This study provides novel insight into the effects of biocontrol agents applied to the plant phyllosphere. Understanding these interactions will aid in the development of biocontrol systems as an alternative to chemical pesticides for protection of important crop systems.

  19. Solid state fermentation of broiler litter for production of biocontrol agents.

    Science.gov (United States)

    Adams, T T; Eiteman, M A; Hanel, B M

    2002-03-01

    Several varieties of heat-sterilized broiler litter with 60% (wet basis, wb) moisture content were substrate in solid-state fermentations to produce biocontrol agents. Litter varieties included litter produced by one flock of broilers from medicated and non-medicated controlled rations, and litter produced by two flocks and four flocks on a single application of bedding material from medicated commercial sources. Litter preparations were inoculated with monocultures of Bacillus thuringiensis serovar japonensis strain Buibui, a pathogen of Japanese beetle larvae (Popillia japonica), or Pseudomonas fluorescens 2-79. B. thuringiensis did not grow in unextracted 1-flock litter nor in water extracted litter, but grew in methanol extracted litter to 5 x 10(10) cell forming units (CFU)/g litter (dry weight, dw) and a spore count of 1 x 10(10) CFU/g litter (dw). B. thuringiensis also grew in unprocessed 2-flock and 4-flock litter, achieving cell counts of 3 x 10(9) and 1 x 10(9) CFU/g litter (dw), respectively, and spore counts of 1 x 10(9) CFU/g litter (dw). P. fluorescens grew in medicated 1-flock litter with no extraction to a cell density greater than 4 x 10(11) CFU/g litter (dw). Bioassays in soil containing over 0.5% (db) litter fermented with B. thuringiensis resulted in over 90% mortality in 21 days for first instars of Japanese beetle when compared to a control treatment using compost without fermented litter. The investigations demonstrate that bacterial biocontrol agents produced via solid substrate fermentations using broiler poultry litter have potential in biocontrol applications in the soil environment.

  20. Development of a biocontrol agent for plant disease control with special emphasis on the near commercial fungal antagonist Clonostachys rosea strain "IK726"

    DEFF Research Database (Denmark)

    Jensen, Dan Funck; Knudsen, Inge M.B.; Lübeck, Mette

    2007-01-01

    . Among the success stories for control of seed- and soilborne diseases are fungal biocontrol agents based on Trichoderma harzianum, Clonostachys rosea and Conithyrium minitans, and bacterial biocontrol agents based on strains of Agrobacterium, Pseudomonas and Streptomyces. We have developed C. rosea...

  1. Benefits of pre-release population genetics: a case study using Psyttalia lounsburyi, a biocontrol agent of the olive fruit fly in California

    Science.gov (United States)

    From a pest management perspective, limited knowledge on the genetics of released biocontrol agents has been repeatedly considered as one possible cause of failures in classical biological control. Introduced biocontrol agents are expected to experience a loss in genetic diversity as the result of s...

  2. Should the biofilm mode of life be taken into consideration for microbial biocontrol agents?

    Science.gov (United States)

    Pandin, Caroline; Le Coq, Dominique; Canette, Alexis; Aymerich, Stéphane; Briandet, Romain

    2017-07-01

    Almost one-third of crop yields are lost every year due to microbial alterations and diseases. The main control strategy to limit these losses is the use of an array of chemicals active against spoilage and unwanted pathogenic microorganisms. Their massive use has led to extensive environmental pollution, human poisoning and a variety of diseases. An emerging alternative to this chemical approach is the use of microbial biocontrol agents. Biopesticides have been used with success in several fields, but a better understanding of their mode of action is necessary to better control their activity and increase their use. Very few studies have considered that biofilms are the preferred mode of life of microorganisms in the target agricultural biotopes. Increasing evidence shows that the spatial organization of microbial communities on crop surfaces may drive important bioprotection mechanisms. The aim of this review is to summarize the evidence of biofilm formation by biocontrol agents on crops and discuss how this surface-associated mode of life may influence their biology and interactions with other microorganisms and the host and, finally, their overall beneficial activity. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  3. Effectors involved in fungal-fungal interaction lead to a rare phenomenon of hyperbiotrophy in the tritrophic system biocontrol agent-powdery mildew-plant.

    Science.gov (United States)

    Laur, Joan; Ramakrishnan, Gowsica Bojarajan; Labbé, Caroline; Lefebvre, François; Spanu, Pietro D; Bélanger, Richard R

    2018-01-01

    Tritrophic interactions involving a biocontrol agent, a pathogen and a plant have been analyzed predominantly from the perspective of the biocontrol agent. We have conducted the first comprehensive transcriptomic analysis of all three organisms in an effort to understand the elusive properties of Pseudozyma flocculosa in the context of its biocontrol activity against Blumeria graminis f.sp. hordei as it parasitizes Hordeum vulgare. After inoculation of P. flocculosa, the tripartite interaction was monitored over time and samples collected for scanning electron microscopy and RNA sequencing. Based on our observations, P. flocculosa indirectly parasitizes barley, albeit transiently, by diverting nutrients extracted by B. graminis from barley leaves through a process involving unique effectors. This brings novel evidence that such molecules can also influence fungal-fungal interactions. Their release is synchronized with a higher expression of powdery mildew haustorial effectors, a sharp decline in the photosynthetic machinery of barley and a developmental peak in P. flocculosa. The interaction culminates with a collapse of B. graminis haustoria, thereby stopping P. flocculosa growth, as barley plants show higher metabolic activity. To conclude, our study has uncovered a complex and intricate phenomenon, described here as hyperbiotrophy, only achievable through the conjugated action of the three protagonists. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  4. Plant growth-promoting rhizobacteria (PGPR: their potential as antagonists and biocontrol agents

    Directory of Open Access Journals (Sweden)

    Anelise Beneduzi

    2012-01-01

    Full Text Available Bacteria that colonize plant roots and promote plant growth are referred to as plant growth-promoting rhizobacteria (PGPR. PGPR are highly diverse and in this review we focus on rhizobacteria as biocontrol agents. Their effects can occur via local antagonism to soil-borne pathogens or by induction of systemic resistance against pathogens throughout the entire plant. Several substances produced by antagonistic rhizobacteria have been related to pathogen control and indirect promotion of growth in many plants, such as siderophores and antibiotics. Induced systemic resistance (ISR in plants resembles pathogen-induced systemic acquired resistance (SAR under conditions where the inducing bacteria and the challenging pathogen remain spatially separated. Both types of induced resistance render uninfected plant parts more resistant to pathogens in several plant species. Rhizobacteria induce resistance through the salicylic acid-dependent SAR pathway, or require jasmonic acid and ethylene perception from the plant for ISR. Rhizobacteria belonging to the genera Pseudomonas and Bacillus are well known for their antagonistic effects and their ability to trigger ISR. Resistance-inducing and antagonistic rhizobacteria might be useful in formulating new inoculants with combinations of different mechanisms of action, leading to a more efficient use for biocontrol strategies to improve cropping systems.

  5. Phaeobacter inhibens as biocontrol agent against Vibrio vulnificus in oyster models

    DEFF Research Database (Denmark)

    Porsby, Cisse Hedegaard; Gram, Lone

    2016-01-01

    acid (TDA), inhibited V. vulnificus as did pure TDA (MIC of 1-3.9 μM). P. inhibens DSM 17395 (at 106 cfu/ml) eradicated 105 cfu/ml V. vulnificus CMCP6 (a rifampicin resistant variant) from a co-culture oyster model system (oyster juice) whereas the pathogen grew to 107 cfu/ml when co......, the presence of P. inhibens could not prevent subsequently added V. vulnificus from entering the live animals, likely because of too low levels of the biocontrol strain. Whilst the oyster model studies provided indication that P. inhibens DSM 17395 could be a good candidate as biocontrol agent against V...

  6. Integrated effect of gamma radiation and biocontrol agent on quality parameters of apple fruit: An innovative commercial preservation method

    International Nuclear Information System (INIS)

    Ahari Mostafavi, Hossein; Mahyar Mirmajlessi, Seyed; Fathollahi, Hadi; Shahbazi, Samira; Mohammad Mirjalili, Seyed

    2013-01-01

    Effects of gamma irradiation and biocontrol agent (Pseudomonas fluorescens) on the physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Golden Delicious apples were investigated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 200, 400, 600 and 800 Gy and then inoculated with P. fluorescens suspension. Samples were evaluated at 3 month intervals. The results demonstrated a clear link between antioxidant activity and phenolic content, so that dose range of 200–400 Gy significantly increased phenolic content and antioxidant activity. Effect of P. fluorescens was similar to irradiation at 200 and 400 Gy that could prevent lesion diameter in pathogen-treated apples. As dose and storage time increased firmness decreased but, combination of P. fluorescens as well as irradiation (at 200–400 Gy) could decrease softening apple fruits during storage. In all parameters, P. fluorescens (as biocontrol agent) inhibited P. expansum similar to irradiation at 200–400 Gy. So, integrated treatment of irradiation and biocontrol agent explored the potential dual benefit of low doses (200 and 400 Gy) as a suitable method to sustain physico-chemical quality and conclusively reduce apple fruits losses during post-harvest preservation. - Highlights: • A suitable method to reduce apple quality losses during 9 month storage period. • Effects of γ radiation in combination with biocontrol agent on physico-chemical parameters of the apple fruits during cold storage. • The potential dual benefit of low irradiation dose combined with biocontrol agent. • Radiation dose determination for Penicillium expansum (postharvest pathogen) control

  7. Non-aflatoxigenic Aspergillus flavus as potential biocontrol agents to reduce aflatoxin contamination in peanuts harvested in Northern Argentina.

    Science.gov (United States)

    Alaniz Zanon, María Silvina; Barros, Germán Gustavo; Chulze, Sofía Noemí

    2016-08-16

    Biological control is one of the most promising strategies for preventing aflatoxin contamination in peanuts at field stage. A population of 46 native Aspergillus flavus nonaflatoxin producers were analysed based on phenotypic, physiological and genetic characteristics. Thirty-three isolates were characterized as L strain morphotype, 3 isolates as S strain morphotype, and 10 isolates did not produce sclerotia. Only 11 of 46 non-aflatoxigenic isolates did not produce cyclopiazonic acid. The vegetative compatibility group (VCG) diversity index for the population was 0.37. For field trials we selected the non-aflatoxigenic A. flavus AR27, AR100G and AFCHG2 strains. The efficacy of single and mixed inocula as potential biocontrol agents in Northern Argentina was evaluated through a 2-year study (2014-2015). During the 2014 peanut growing season, most of the treatments reduced the incidence of aflatoxigenic strains in both soil and peanut kernel samples, and no aflatoxin was detected in kernels. During the 2015 growing season, there was a reduction of aflatoxigenic strains in kernel samples from the plots treated with the potential biocontrol agents. Reductions of aflatoxin contamination between 78.36% and 89.55% were observed in treated plots in comparison with the un-inoculated control plots. This study provides the first data on aflatoxin biocontrol based on competitive exclusion in the peanut growing region of Northern Argentina, and proposes bioproducts with potential use as biocontrol agents. Copyright © 2016. Published by Elsevier B.V.

  8. Unsuccessful introduced biocontrol agents can act as pollinators of invasive weeds: Bitou Bush (Chrysanthemoides moniliferassp.rotundata) as an example.

    Science.gov (United States)

    Gross, Caroline L; Whitehead, Joshua D; Silveira de Souza, Camila; Mackay, David

    2017-10-01

    The extent of self-compatibility and reliance on pollinators for seed set are critical determinants of reproductive success in invasive plant species. Seed herbivores are commonly used as biocontrol agents but may also act as flower visitors, potentially resulting in pollination. However, such contrasting or potentially counterproductive interaction effects are rarely considered or evaluated for biological control programs. We investigated the breeding system and pollinators of Bitou Bush ( Chrysanthemoides monilifera ssp. rotundata ), an invasive species in Australia that has been the subject of biocontrol programs since 1987. We found the species to be obligate outcrossing in all six populations tested. From 150 video hours, we found 21 species of potential pollinators, including Mesoclanis polana , the Bitou Seedfly, native to South Africa and released in Australia as a biocontrol agent in 1996. Mesoclanis polana transferred pollen to stigmas and was the most common pollinator (52% of pollinator visits), followed by the syrphid fly Simosyrphus grandicornis (9%) and introduced honeybee, Apis mellifera (6.5%). Fruit-to-flower ratios ranged from 0.12 to 0.45 and were highest in the population with the greatest proportion of Mesoclanis polana visits. In an experimental trial, outside the naturalized range, the native bee Homalictus sphecodoides and the native syrphid Melangyna viridiceps were the primary pollinators, and fruit-to-flower ratios were 0.35, indicating that Bitou Bush would have ready pollinators if its range expanded inland. Synthesis . Invasive Bitou Bush requires pollinators, and this is effected by a range of generalist pollinators in eastern Australia including the Bitou Seedfly, introduced as a biocontrol agent, and the major pollinator detected in this study. Fruit-to-flower ratios were highest when the Bitou Seedfly was in high abundance. This study underscores the importance of evaluating the pollination biology of invasive species in their

  9. Endophytic Streptomyces spp. as Biocontrol Agents of Rice Bacterial Leaf Blight Pathogen (Xanthomonas oryzae pv. oryzae

    Directory of Open Access Journals (Sweden)

    RATIH DEWI HASTUTI

    2012-12-01

    Full Text Available Xanthomonas oryzae pv. oryzae (Xoo, a causal agent of bacterial leaf blight (BLB, is one of the most important pathogens of rice. The effectiveness of ten Streptomyces spp. isolates in suppressing Xoo disease was assessed in planta and in vitro. In planta experiments were carried out in a greenhouse and arranged in a randomized completely block design (RCBD with three replications. Twenty treatments were tested which included plants inoculated with both Streptomyces spp. and Xoo, and plants inoculated with only Streptomyces spp. Plants inoculated with Xoo and sprayed with a chemical bactericide, and plants inoculated with only Xoo served as positive controls, whereas plants not inoculated with either Streptomyces spp. or Xoo were used as negative controls. The results showed that the effect of endophytic Streptomyces spp. on BLB disease expressed as area under disease progress curve (AUDPC was not significantly different to that on control plants (P > 0.05. However, plants inoculated with endophytic Streptomyces spp. were significantly taller and produced higher tiller number than control plants (P < 0.05. Streptomyces spp. isolate AB131-1 gave the highest plant height. In vitro studies on biocontrol mechanisms of selected Streptomyces spp. isolates showed that isolate LBR02 gave the highest inhibition activity on Xoo growth, followed by AB131-1 and AB131-2. Two isolates (AB131-1 and LBR02 were able to produce chitinase, phosphatase, and siderophore which included biocontrol characteristics. Morphological and colonization studies under SEM and light microscopy confirmed that the three isolates were endophytic Streptomyces spp. from different species. These studies found that the paddy plant which was inoculated with endophytic Streptomyces spp. AB131-1 and infected by Xoo could increase the height of plant and number of tillers.

  10. Antibiosis and bmyB Gene Presence As Prevalent Traits for the Selection of Efficient Bacillus Biocontrol Agents against Crown Gall Disease

    Directory of Open Access Journals (Sweden)

    Olfa Frikha-Gargouri

    2017-08-01

    Full Text Available This study aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall disease. The relationship between the strain biocontrol ability and their in vitro studied traits was investigated to identify the most important factors to be considered for the selection of effective biocontrol agents. In fact, previous selection procedure relying only on in vitro antibacterial activity was shown to be not suitable in some cases. A direct plant-protection strategy was performed to screen the 32 Bacillus biocontrol agent candidates. Moreover, potential in vitro biocontrol traits were investigated including biofilm formation, motility, hemolytic activity, detection of lipopeptide biosynthetic genes (sfp, ituC and bmyB and production of antibacterial compounds. The obtained results indicated high correlations of the efficiency of the biocontrol with the reduction of gall weight (p = 0.000 and the antibacterial activity in vitro (p = 0.000. Moreover, there was strong correlations of the efficiency of the biocontrol (p = 0.004 and the reduction in gall weight (p = 0.000 with the presence of the bmyB gene. This gene directs the synthesis of the lipopeptide bacillomycin belonging to the iturinic family of lipopeptides. These results were also confirmed by the two-way hierarchical cluster analysis and the correspondence analysis showing the relatedness of these four variables. According to the obtained results a new screening procedure of Bacillus biocontrol agents against crown gall disease could be advanced consisting on two step selection procedure. The first consists on selecting strains with high antibacterial activity in vitro or those harbouring the bmyB gene. Further selection has to be performed on tomato plants in vivo. Moreover, based on the results of the biocontrol assay, five potent strains exhibiting high biocontrol abilities were selected. They were identified as Bacillus subtilis or Bacillus

  11. Potencialidade de um actinomiceto de rizosfera de tomateiro como agente de biocontrole de doenças Potenciality of an actinomycete from tomato rhizosphere as a biocontrol agent for tomato diseases

    Directory of Open Access Journals (Sweden)

    Renato Carrer Filho

    2009-09-01

    Full Text Available Um actinomiceto (Streptomyces setonii, isolado 'UFV-RD1', obtido de rizosfera de planta sadia de tomateiro, foi selecionado dentre outros 117, como promissor agente de biocontrole de enfermidades da cultura. Em testes de antagonismo in vitro contra patógenos do tomateiro, o isolado 'UFV-RD1' foi incapaz de inibir o crescimento de bactérias (Pseudomonas syringae pv. tomato, Ralstonia solanacearum, Pectobacterium carotovorum subsp. carotovorum, Xanthomonas campestris pv. vesicatoria mas inibiu a germinação de conídios de alguns fungos (Alternaria solani, Phytophthora infestans, Corynespora cassiicola, Stemphylium solani. Em ensaios de biocontrole experimental in vivo, em casa de vegetação, o actinomiceto foi efetivo em reduzir a severidade de sintomas no caso de patógenos fúngicos e bacterianos testados como desafiantes. A campo, quando A. solani e P. infestans ocorreram naturalmente, as plantas originárias de sementes microbiolizadas com propágulos da estirpe 'UFV-RD1' exibiram sintomas menos severos que as plantas controle para o caso da pinta preta. O agente de biocontrole é promissor para futuros protocolos de manejo integrado, como forma de reduzir a quantidade de defensivos utilizados.An actinomycete (Streptomyces setonii, isolate 'UFV-RD1', isolated from the rhizosphere of a healthy tomato plant was selected out of 117 as a promising biocontrol agent for tomato diseases. In in vitro antagonism tests against tomato pathogens, the isolate 'UFV-RD1' was unable to inhibit growth of bacterial pathogens (Pseudomonas syringae pv. tomato, Ralstonia solanacearum, Pectobacterium carotovorum subsp. carotovorum, Xanthomonas campestris pv. vesicatoria but inhibited conidium germination of fungi (Alternaria solani, Phytophthora infestans, Corynespora cassiicola, Stemphylium solani. Experimental biocontrol assays in a greenhouse indicated that the actinomycete was effective for reducing symptom severity in the case of bacteria and fungi tested

  12. Effect of seed pelleting with biocontrol agents on growth and colonisation of roots of mungbean by root-infecting fungi.

    Science.gov (United States)

    Ramzan, Nadia; Noreen, Nayara; Perveen, Zahida; Shahzad, Saleem

    2016-08-01

    Mungbean (Vigna radiata (L.) Wilczek) is a leguminous pulse crop that is a major source of proteins, vitamins and minerals. Root-infecting fungi produce severe plant diseases like root rot, charcoal rot, damping-off and stem rot. The soil-borne pathogens can be controlled by chemicals, but these chemicals have several negative effects. Use of microbial antagonist such as fungi and bacteria is a safe, effective and eco-friendly method for the control of many soil-borne pathogens. Biological control agents promote plant growth and develop disease resistance. Application of bacteria and fungi as seed dressing suppressed the root-infecting fungi on leguminous crops. Seeds of mungbean were pelleted with different biocontrol agents to determine their effect on plant growth and colonisation of roots by root-infecting fungi, viz. Fusarium solani, Macrophomina phaseolina, Pythium aphanidermatum, Rhizoctonia solani and Sclerotium rolfsii. Treatment of mungbean seeds with fungal antagonists showed more shoot and root length as compared to bacterial antagonists, whereas seed treated with bacterial antagonists showed maximum shoot and root weight. Trichoderma harzianum and Bacillus subtilis were the best among all the biocontrol agents since they provided the highest plant growth and greater reduction in root colonisation by all root-infecting fungi. Bacillus cereus, Trichoderma virens, Pseudomonas fluorescens and Micrococcus varians were also effective against root-infecting fungi but to a lesser extent. T. harzianum, T. virens, B. subtilis and P. fluorescens were found to be best among all biocontrol agents. The root-infecting fungi can be controlled by pelleting seeds with biocontrol agents as it is safe and effective method. Additionally, plant growth was promoted more by this method. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  13. Optimization of a protective medium for freeze-dried Pichia membranifaciens and application of this biocontrol agent on citrus fruit.

    Science.gov (United States)

    Niu, X; Deng, L; Zhou, Y; Wang, W; Yao, S; Zeng, K

    2016-07-01

    To optimize a protective medium for freeze-dried Pichia membranifaciens and to evaluate biocontrol efficacies of agents against blue and green mould and anthracnose in citrus fruit. Based on the screening assays of saccharides and antioxidants, response surface methodology was used to optimize sucrose, sodium glutamate and skim milk to improve viability of freeze-dried Pi. membranifaciens. Biocontrol assays were conducted between fresh and freeze-dried Pi. membranifaciens against Penicillium italicum, Penicillium digitatum and Colletotrichum gloeosporioides in citrus fruit. Solving the regression equation indicated that the optimal protective medium was 6·06% (w/v) sucrose combined with 3·40% (w/v) sodium glutamate and 5·43% (w/v) skim milk. Pi. membranifaciens freeze-dried in the optimal protective medium showed 76·80% viability, and retained biocontrol efficacy against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit. The optimal protective medium showed more effective protective properties than each of the three protectants used alone. The viability of freeze-dried Pi. membranifaciens finally reached 76·80%. Meanwhile, the biocontrol efficacies showed no significant difference between fresh and freeze-dried yeast against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit. The results showed the potential value of Pi. membranifaciens CICC 32259 for commercialization. © 2016 The Society for Applied Microbiology.

  14. Peptaibol, Secondary‐Metabolite, and Hydrophobin Pattern of Commercial Biocontrol Agents Formulated with Species of the Trichoderma harzianum Complex

    DEFF Research Database (Denmark)

    Degenkolb, Thomas; Nielsen, Kristian Fog; Dieckmann, Ralf

    2015-01-01

    in plant‐protective Trichoderma species, which are successfully used against economically relevant bacterial and fungal plant pathogens, certainly contributes to a better understanding of these complex antagonistic interactions. We analyzed five commercial biocontrol agents (BCAs), namely Canna®, Trichosan...... metabolites, were detected, the latter being known for their antifungal, siderophore, or plant‐growth‐promoting activities. Notably, none of the isolates produced low‐molecular weight mycotoxins....

  15. In vitro evaluation of biocontrol agents and fungicides on wood decay fungiganoderma associated with mortality of tree legumes

    Directory of Open Access Journals (Sweden)

    M Bhadra

    2016-12-01

    Full Text Available An experiment was conducted to isolate a number of biocontrol agent- Trichoderma spp. from infected spawn packets of oyster mushroom at National Mushroom Development and Extension Centre, Savar, Dhaka, Bangladesh. These bio-control agents were used as antagonist against four wild wood decay fungi of Ganoderma, viz., G. lucidum-1, G. lucidum-2, G. lucidum-3, G. applanatum and two cultivated G. lucidum-4, G.lucidum-6 under in vitro condition. An in vitro trial of Trichoderma spp. against Ganoderma were performed by dual culture, by treating with volatile, non-volatile and naturally untreated metabolites of bio-control agents. In dual culture, all the Trichoderma species showed 70- 100% mycelia inhibition of G. lucidum-1 and G. lucidum-2, 55.6-100% inhibition of G. lucidum-3, 20-66.7% of G. applanatum, 100% of G. lucidum-5, 75-100% of G. lucidum-6. Effects of heat killed extracts of Trichoderma spp. on growth of G. lucidum-2 (wild and G. lucidum-6 (cultivated were also evaluated. Fungicides Bavistin and Dithane M-45 were also used to investigate the mycelial growth inhibition of Ganoderma spp.

  16. Integrated effect of gamma radiation and biocontrol agent on quality parameters of apple fruit: An innovative commercial preservation method

    Science.gov (United States)

    Ahari Mostafavi, Hossein; Mahyar Mirmajlessi, Seyed; Fathollahi, Hadi; Shahbazi, Samira; Mohammad Mirjalili, Seyed

    2013-10-01

    Effects of gamma irradiation and biocontrol agent (Pseudomonas fluorescens) on the physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Golden Delicious apples were investigated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 200, 400, 600 and 800 Gy and then inoculated with P. fluorescens suspension. Samples were evaluated at 3 month intervals. The results demonstrated a clear link between antioxidant activity and phenolic content, so that dose range of 200-400 Gy significantly increased phenolic content and antioxidant activity. Effect of P. fluorescens was similar to irradiation at 200 and 400 Gy that could prevent lesion diameter in pathogen-treated apples. As dose and storage time increased firmness decreased but, combination of P. fluorescens as well as irradiation (at 200-400 Gy) could decrease softening apple fruits during storage. In all parameters, P. fluorescens (as biocontrol agent) inhibited P. expansum similar to irradiation at 200-400 Gy. So, integrated treatment of irradiation and biocontrol agent explored the potential dual benefit of low doses (200 and 400 Gy) as a suitable method to sustain physico-chemical quality and conclusively reduce apple fruits losses during post-harvest preservation.

  17. Development of biocontrol agents from food microbial isolates for controlling post-harvest peach brown rot caused by Monilinia fructicola.

    Science.gov (United States)

    Zhou, Ting; Schneider, Karin E; Li, Xiu-Zhen

    2008-08-15

    An unconventional strategy of screening food microbes for biocontrol activity was used to develop biocontrol agents for controlling post-harvest peach brown rot caused by Monilinia fructicola. Forty-four microbial isolates were first screened for their biocontrol activity on apple fruit. Compared with the pathogen-only check, seven of the 44 isolates reduced brown rot incidence by >50%, including four bacteria: Bacillus sp. C06, Lactobacillus sp. C03-b and Bacillus sp. T03-c, Lactobacillus sp. P02 and three yeasts: Saccharomyces delbrueckii A50, S. cerevisiae YE-5 and S. cerevisiae A41. Eight microbial isolates were selected for testing on peaches by wound co-inoculation with mixtures of individual microbial cultures and conidial suspension of M. fructicola. Only two of them showed significant biocontrol activity after five days of incubation at 22 degrees C. Bacillus sp. C06 suppressed brown rot incidence by 92% and reduced lesion diameter by 88% compared to the pathogen-only check. Bacillus sp.T03-c reduced incidence and lesion diameter by 40% and 62%, respectively. The two isolates were compared with Pseudomonas syringae MA-4, a biocontrol agent for post-harvest peach diseases, by immersing peaches in an aliquot containing individual microbial isolates and the pathogen conidia. Treatments with isolates MA-4, C06 and T03-c significantly controlled brown rot by 91, 100, and 100% respectively. However, only isolates MA-4 and C06 significantly reduced brown rot by 80% and 15%, respectively when bacterial cells alone were applied. On naturally infected peaches, both the bacterial culture and its cell-free filtrate of the isolate C06 significantly controlled peach decay resulting in 77 and 90% reduction, respectively, whereas the treatment using only the bacterial cells generally had no effect. Isolate C06 is a single colony isolate obtained from a mesophilic cheese starter, and has been identified belonging to Bacillus amyloliquefaciens. The results have clearly

  18. First Record of Biocontrol Agent Torymus sinensis (Hymenoptera; Torymidae in Bosnia and Herzegovina

    Directory of Open Access Journals (Sweden)

    Dinka Matošević

    2017-01-01

    Full Text Available Background and Purpose: Dryocosmus kuriphilus is an invasive insect species of sweet chestnut (Castanea spp. originating from China, and the only effective control measure against this pest is classical biological control with introduced parasitoid Torymus sinensis. This parasitoid has been widely released in many European countries, but it also has the ability to rapidly spread naturally. No official releases have been done in Bosnia and Herzegovina. Material and Methods: D. kuriphilus galls were collected in July 2017 on 6 localities in forest district Unsko (Una Sana canton in Bosnia and Herzegovina. Presence and parasitism rates of T. sinensis were recorded in the entomological laboratory, Croatian Forest Research Institute. T. sinensis larvae were identified morphologically and by being compared with the voucher specimens. Results and Discussion: Torymus sinensis larvae were positively identified in the examined D. kuriphilus galls from all localities in Bosnia and Herzegovina. Parasitism rates ranged from 44.83 to 74%. Occurrence and high parasitism rates in Bosnia and Herzegovina observed in this study are not results of biocontrol releases of T. sinensis, but can be attributed to natural spread from Croatia. High parasitism rates observed in this study can indicate that the parasitoid was present in Bosnia and Herzegovina in 2016. Conclusions: This study presents the first record of Torymus sinensis in Bosnia and Herzegovina. We predict that the parasitoid will continue its spread over Bosnia and Herzegovina in sweet chestnut forests and orchards and that it will act as effective biological control agent against D. kuriphilus.

  19. Selection and Characterization of Endophytic Bacteria as Biocontrol Agents of Tomato Bacterial Wilt Disease

    Directory of Open Access Journals (Sweden)

    ABDJAD ASIH NAWANGSIH

    2011-06-01

    Full Text Available Biological control of bacterial wilt pathogen (Ralstonia solanacearum of tomato using endophytic bacteria is one of the alternative control methods to support sustainable agriculture. This study was conducted to select and characterize endophytic bacteria isolated from healthy tomato stems and to test their ability to promote plant growth and suppress bacterial wilt disease. Among 49 isolates successfully isolated, 41 were non-plant pathogenic. Green house test on six selected isolates based on antagonistic effect on R. solanacearum or ability to suppress R. solanacearum population in dual culture assays obtained BC4 and BL10 isolates as promising biocontrol agents. At six weeks after transplanting, plants treated with BC4 isolate showed significantly lower disease incidence (33% than that of control (83%. Plants height was not significantly affected by endophytic bacterial treatments. Based on 16S rRNA sequence, BC4 isolate had 97% similarity with Staphylococcus epidermidis (accession number EU834240.1, while isolate BL10 had 98% similarity with Bacillus amyloliquefaciens strain JK-SD002 (accession number AB547229.1.

  20. OPTIMIZATION AND EVALUATION OF MICROBE FORTIFIED COMPOSTS AS BIOCONTROL AGENTS AGAINST PHYTOPATHOGENIC FUNGI

    Directory of Open Access Journals (Sweden)

    Ajinath S. Dukare

    2013-04-01

    Full Text Available A set of bacterial (B1-10 and cyanobacterial strains (C1-C14 were evaluated for their fungicidal activity against selected phytopathogenic fungi - Fusarium solani, Fusarium oxysporum, Fusarium oxysporum lycopersici, Fusarium moniliforme, Pythium debaryanum and Rhizoctonia solani. Further, they were used to amend rice straw compost and the filtrates were evaluated against the selected fungi after 10 and 20 days of incubation. Six promising strains, including three bacterial and three cyanobacterial strains were selected and characterised in terms of activity of hydrolytic enzymes. Interestingly, C12 strain (Anabaena spp. showed highest activity of cellulase, chitosanase and β 1, 3 glucanase. These strains were then evaluated by optimization of inoculum levels (1-5% in the rice straw compost. The strains B3, B5, C8 and C12 were observed to be most promising as they exhibited inhibition and significantly higher activity of microbiological parameters and hydrolytic enzymes at 1-2% level of inoculum in the compost. Further investigations are being undertaken to scale up the development of compost based biocontrol agents using these strains for evaluation at field level.

  1. Cucumber Rhizosphere Microbial Community Response to Biocontrol Agent Bacillus subtilis B068150

    Directory of Open Access Journals (Sweden)

    Lihua Li

    2015-12-01

    Full Text Available Gram-positive bacteria Bacillus subtilis B068150 has been used as a biocontrol agent against the pathogen Fusarium oxysporum cucumerinum. Cucumber was grown in three soils with strain B068150 inoculated in a greenhouse for 90 days, and the colonization ability of strain B068150 in cucumber rhizosphere and non-rhizosphere soils was determined. Changes in total bacteria and fungi community composition and structures using denaturing gradient gel electrophoresis (DGGE and sequencing were determined. Colony counts showed that B068150 colonization in the rhizosphere was significantly higher (p < 0.001 than in non-rhizosphere soils. Based on our data, the introduction of B. bacillus B068150 did not change the diversity of microbial communities significantly in the rhizosphere of three soils. Our data showed that population density of B068150 in clay soil had a significant negative correlation on bacterial diversity in cucumber rhizosphere in comparison to loam and sandy soils, suggesting that the impact of B068150 might be soil specific.

  2. Probiotics as potential alternative biocontrol agents in the agriculture and food industries: A review.

    Science.gov (United States)

    Hossain, Md Iqbal; Sadekuzzaman, Mohammad; Ha, Sang-Do

    2017-10-01

    Pathogenic microorganisms are a potential threat to the agriculture and food industries. Food contamination can be happened in the production levels at any point in the chain by pathogenic microorganisms. Conventional methods, such as those involving antibiotics, disinfectants, and physical methods, are commonly used as microbial control strategies. Owing to the limitations of these methods, such as emergence of resistance, low effectiveness, high cost, and detrimental effects on food, health, and the environment, many countries have adopted laws and regulations restricting their use. To overcome these problems, an environmentally friendly, cost-effective alternative approach is urgently needed. Probiotics are live microorganisms that offer health benefits to the host, when consumed in adequate amounts, by providing pathogen protective action and nutritional benefits. From a food microbiological point of view, to use probiotics in animals, there is a reduction of zoonotic pathogens in the gastro-intestinal tract (GIT) among animals which prevent the transmission of these pathogens through food. Therefore, probiotics have been proposed as an alternative antimicrobial means to protect against pathogenic microorganisms for better healthcare and food safety. In this review, we discuss probiotics, their selection criteria, mechanisms of action, and their prospects as alternative biocontrol agents, with special emphasis on the agriculture (livestock and aquaculture sectors), and food industries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Use of wild yeasts as a biocontrol agent against toxigenic fungi and OTA production

    Directory of Open Access Journals (Sweden)

    Mariana Lino Souza

    2017-05-01

    Full Text Available This study evaluated the antagonistic potential of 32 wild yeast isolates from coffee and cocoa bean fermentation. These yeasts were inoculated in co-cultivation with Aspergillus carbonarius (CCDCA 10608 and CCDCA 10408 and Aspergillus ochraceus (CCDCA 10612 isolated from grapes and coffee beans. The mycelial growth and ochratoxin A (OTA production were evaluated, and the spores were counted after cultivation at 28°C for seven days. The yeasts presented higher inhibitory effects (53% in relation to the control over the mycelial growth of the isolated A. ochraceus (CCDCA10612. Pichia anomala CCMA0148 and Saccharomyces cerevisiae CCMA0159 provided the greatest inhibition of the growth of all fungal strains. All Pichia species presented the highest inhibitory effects on the production of spores, and S. cerevisiae CCMA 0159 at concentrations of both 104 and 107 mL-1 cells inhibited the production of spores by 100%. Rhodotorula mucilaginosa was effective at inhibiting OTA production by the three isolates of Aspergillus. S. cerevisiae CCMA0159 and Pichia anomala CCMA0148 showed high potential as biocontrol agents in the conditions tested.

  4. Closed Genome Sequence of Phytopathogen Biocontrol Agent Bacillus velezensis Strain AGVL-005, Isolated from Soybean.

    Science.gov (United States)

    Pylro, Victor Satler; Dias, Armando Cavalcante Franco; Andreote, Fernando Dini; Morais, Daniel Kumazawa; Varani, Alessandro de Mello; Andreote, Cristiane Cipolla Fasanella; Bernardo, Eduardo Roberto de Almeida; Zucchi, Tiago

    2018-02-15

    We report here the closed and near-complete genome sequence and annotation of Bacillus velezensis strain AGVL-005, a bacterium isolated from soybean seeds in Brazil and used for phytopathogen biocontrol. Copyright © 2018 Pylro et al.

  5. Staurosporine from the endophytic Streptomyces sp. strain CNS-42 acts as a potential biocontrol agent and growth elicitor in cucumber.

    Science.gov (United States)

    Li, Xiaolin; Huang, Pei; Wang, Qian; Xiao, Lie; Liu, Miaomiao; Bolla, Krishna; Zhang, Bo; Zheng, Linyong; Gan, Bingcheng; Liu, Xueting; Zhang, Lixin; Zhang, Xiaoping

    2014-09-01

    Chinese medicinal plants and their surrounding rhizospheric soil serve as promising sources of actinobacteria. A total of 180 actinobacteria strains were isolated from the rhizosphere soil, leaves, stems, and roots of nine selected plants and have been identified as potential biocontrol agents against Fusarium oxysporum f. sp. cucumerinum. An endophytic strain CNS-42 isolated from Alisma orientale showed the largest zone of inhibition demonstrating a potent effect against F. oxysporum f. sp. cucumerinum and a broad antimicrobial activity against bacteria, yeasts, and other pathogenic fungi. The in vivo biocontrol assays showed that the disease severity index was significantly reduced (P plant shoot fresh weight and height increased greatly (P plant growth promoting activities and the latter property of staurosporine is reported for the first time. The in vivo assay was further performed and indicated that staurosporine showed good growth promoting effect on the plant shoot biomass of cucumber. This is the first critical evidence identifying CNS-42 as a biocontrol agent for the soil borne pathogen, F. oxysporum f. sp. cucumerinum.

  6. Stenotrophomonas maltophilia: a new potential biocontrol agent of Ralstonia solanacearum, causal agent of potato brown rot

    NARCIS (Netherlands)

    Messiha, N.A.S.; Diepeningen, van A.D.; Farag, N.S.; Abdallah, S.A.; Janse, J.D.; Bruggen, van A.H.C.

    2007-01-01

    Stenotrophomonas maltophilia was isolated from the rhizosphere of eggplant in the Nile Delta of Egypt, and its antagonistic potential against Ralstonia solanacearum race 3 biovar 2, the causal agent of potato brown rot, was in vitro evaluated on KB agar medium and in vivo on potato plants. In vitro,

  7. Integrated management of foot rot of lentil using biocontrol agents under field condition.

    Science.gov (United States)

    Hannan, M A; Hasan, M M; Hossain, I; Rahman, S M E; Ismail, Alhazmi Mohammed; Oh, Deog-Hwan

    2012-07-01

    The efficacy of cowdung, Bangladesh Institute of Nuclear Agriculture (BINA)-biofertilizer, and Bangladesh Agricultural University (BAU)-biofungicide, alone or in combination, was evaluated for controlling foot rot disease of lentil. The results exhibited that BINA-biofertilizer and BAUbiofungicide (peat soil-based Rhizobium leguminosarum and black gram bran-based Trichoderma harzianum) are compatible and have combined effects in controlling the pathogenic fungi Fusarium oxysporum and Sclerotium rolfsii, which cause the root rot of lentil. Cowdung mixing with soil (at 5 t/ha) during final land preparation and seed coating with BINA-biofertilizer and BAU-biofungicide (at 2.5% of seed weight) before sowing recorded 81.50% field emergence of lentil, which showed up to 19.85% higher field emergence over the control. Post-emergence deaths of plants due to foot rot disease were significantly reduced after combined seed treatment with BINA-biofertilizer and BAU-biofungicide. Among the treatments used, only BAU-biofungicide as the seed treating agent resulted in higher plant stand (84.82%). Use of BINA-biofertilizer and BAU-biofungicide as seed treating biocontrol agents and application of cowdung in the soil as an organic source of nutrient resulted in higher shoot and root lengths, and dry shoot and root weights of lentil. BINA-biofertilizer significantly increased the number of nodules per plant and nodules weight of lentil. Seeds treating with BAUbiofungicide and BINA-biofertilizer and soil amendment with cowdung increased the biomass production of lentil up to 75.56% over the control.

  8. Potential of Microbispora sp. V2 as biocontrol agent against Sclerotium rolfsii, the causative agent of southern blight of Zea mays L (Baby corn)--in vitro studies.

    Science.gov (United States)

    Patil, N N; Waghmode, M S; Gaikwad, P S; Gajbhiye, M H; Gunjal, A B; Nawani, N N; Kapadnis, B P

    2014-11-01

    The study was undertaken with the aim of exploring novel and beneficial agro activities of rare actinomycetes like Microbispora sp. V2. The antagonistic activity of Microbispora sp. V2 was evaluated as a biocontrol agents against Sclerotium rolfsii, a soil-borne fungal plant pathogen. The methodology performed for evaluation of biocontrol agent was in vitro evaluation assay which comprised of three tests viz., cellophane overlay technique, seed germination test and Thiram (fungicide) tolerance of Microbispora sp. V2. The isolate was found to inhibit the fungal pathogen Sclerotium rolfsii to 91.43% in cellophane assay. In seed germination assay, Microbispora sp. V2 treated seeds resulted in 25.75% increased germination efficiency, as compared to seeds infected by Sclerotium rolfsii. The isolate Microbispora sp. V2 could tolerate 1000 microg mL(-1) of Thiram (fungicide). The in vitro assay studies proved that Microbispora sp. V2 can be used as antifungal antagonist and thus posses' great potential as biocontrol agent against southern blight caused by Sclerotium rolfsii in Zea mays L (Baby corn) which causes large economical losses.

  9. Selection rhizosphere-competent microbes for development of microbial products as biocontrol agents

    Science.gov (United States)

    Mashinistova, A. V.; Elchin, A. A.; Gorbunova, N. V.; Muratov, V. S.; Kydralieva, K. A.; Khudaibergenova, B. M.; Shabaev, V. P.; Jorobekova, Sh. J.

    2009-04-01

    Rhizosphere-borne microorganisms reintroduced to the soil-root interface can establish without inducing permanent disturbance in the microbial balance and effectively colonise the rhizosphere due to carbon sources of plant root exudates. A challenge for future development of microbial products for use in agriculture will be selection of rhizosphere-competent microbes that both protect the plant from pathogens and improve crop establishment and persistence. In this study screening, collection, identification and expression of stable and technological microbial strains living in soils and in the rhizosphere of abundant weed - couch-grass Elytrigia repens L. Nevski were conducted. A total of 98 bacteria isolated from the rhizosphere were assessed for biocontrol activity in vitro against phytopathogenic fungi including Fusarium culmorum, Fusarium heterosporum, Fusarium oxysporum, Drechslera teres, Bipolaris sorokiniana, Piricularia oryzae, Botrytis cinerea, Colletothrichum atramentarium and Cladosporium sp., Stagonospora nodorum. Biocontrol activity were performed by the following methods: radial and parallel streaks, "host - pathogen" on the cuts of wheat leaves. A culture collection comprising 64 potential biocontrol agents (BCA) against wheat and barley root diseases has been established. Of these, the most effective were 8 isolates inhibitory to at least 4 out of 5 phytopathogenic fungi tested. The remaining isolates inhibited at least 1 of 5 fungi tested. Growth stimulating activity of proposed rhizobacteria-based preparations was estimated using seedling and vegetative pot techniques. Seeds-inoculation and the tests in laboratory and field conditions were conducted for different agricultural crops - wheat and barley. Intact cells, liquid culture filtrates and crude extracts of the four beneficial bacterial strains isolated from the rhizosphere of weed were studied to stimulate plant growth. As a result, four bacterial strains selected from rhizosphere of weed

  10. Unusual acylation of chloramphenicol in Lysobacter enzymogenes, a biocontrol agent with intrinsic resistance to multiple antibiotics.

    Science.gov (United States)

    Zhang, Wei; Huffman, Justin; Li, Shengying; Shen, Yuemao; Du, Liangcheng

    2017-07-04

    The environmental gliding bacteria Lysobacter are emerging as a new group of biocontrol agents due to their prolific production of lytic enzymes and potent antibiotic natural products. These bacteria are intrinsically resistant to many antibiotics, but the mechanisms behind the antibiotic resistance have not been investigated. Previously, we have used chloramphenicol acetyltransferase gene (cat) as a selection marker in genetic manipulation of natural product biosynthetic genes in Lysobacter, because chloramphenicol is one of the two common antibiotics that Lysobacter are susceptible to. Here, we found L. enzymogenes, the most studied species of this genus, could still grow in the presence of a low concentration of chloramphenicol. Three chloramphenicol derivatives (1-3) with an unusual acylation pattern were identified in a cat-containing mutant of L. enzymogenes and in the wild type. The compounds included chloramphenicol 3'-isobutyrate (1), a new compound chloramphenicol 1'-isobutyrate (2), and a rare chloramphenicol 3'-isovalerate (3). Furthermore, a mutation of a global regulator gene (clp) or a Gcn5-related N-acetyltransferase (GNAT) gene in L. enzymogenes led to nearly no growth in media containing chloramphenicol, whereas a complementation of clp restored the chloramphenicol acylation as well as antibiotic HSAF production in the clp mutant. The results indicated that L. enzymogenes contains a pool of unusual acyl donors for enzymatic modification of chloramphenicol that confers the resistance, which may involve the Clp-GNAT regulatory system. Because Lysobacter are ubiquitous inhabitants of soil and water, the finding may have important implications in understanding microbial competitions and bioactive natural product regulation.

  11. Detection and quantification by PCR assay of the biocontrol agent Pantoea agglomerans CPA-2 on apples.

    Science.gov (United States)

    Soto-Muñoz, Lourdes; Teixidó, Neus; Usall, Josep; Viñas, Inmaculada; Torres, Rosario

    2014-04-03

    The registration of biological control agents requires the development of monitoring systems to detect and quantify the agent in the environment. Pantoea agglomerans CPA-2 is an effective biocontrol agent for postharvest diseases of citrus and pome fruits. The monitoring of CPA-2 in postharvest semi-commercial trials was evaluated by Rodac impression plates and the colonies isolated were confirmed by conventional PCR using the SCAR primers PAGA1 and PAGB1. Samples were taken from different surfaces that had contact with CPA-2, the surrounding environment and working clothes worn by handlers. Moreover, population dynamics of the strain CPA-2 were determined on apple surfaces using both the classical plating technique and real-time quantitative PCR (qPCR). A qPCR assay using a 3'-minor groove-binding (MGB) probe was developed for the specific detection and quantification of P. agglomerans strain CPA-2. Based on the nucleotide sequence of a SCAR fragment of CPA-2, one primer set and TaqMan MGB probe were designed. The primers SP2-F/SP2-R and the TaqMan MGB probe showed a specific detection of strain CPA-2 on apple surfaces, which was verified tested against purified DNA from 17 strains of P. agglomerans, 4 related Pantoea species, and 21 bacterial strains from other genera isolated from whole and also freshly-cut fruit and vegetables. The detection level was approximately 10(3) cells per reaction, and the standard curve was linear within a range of 5log units. Results from semi-commercial trials showed that CPA-2 had a low impact. The maximum persistence of P. agglomerans CPA-2 was not longer than 5days in plastic boxes stored at 0°C. Significant differences in CPA-2 population level dynamics were observed in results obtained by qPCR and dilution plating. These differences may indicate the presence of non-degraded DNA from non-viable cells. In conclusion, qPCR is a novel potential tool to quickly and specifically monitor recent surface colonisation by CPA-2

  12. Isolation and Characterization of phiLLS, a Novel Phage with Potential Biocontrol Agent against Multidrug-Resistant Escherichia coli

    Directory of Open Access Journals (Sweden)

    Luis Amarillas

    2017-07-01

    Full Text Available Foodborne diseases are a serious and growing problem, and the incidence and prevalence of antimicrobial resistance among foodborne pathogens is reported to have increased. The emergence of antibiotic-resistant bacterial strains demands novel strategies to counteract this epidemic. In this regard, lytic bacteriophages have reemerged as an alternative for the control of pathogenic bacteria. However, the effective use of phages relies on appropriate biological and genomic characterization. In this study, we present the isolation and characterization of a novel bacteriophage named phiLLS, which has shown strong lytic activity against generic and multidrug-resistant Escherichia coli strains. Transmission electron microscopy of phiLLS morphology revealed that it belongs to the Siphoviridae family. Furthermore, this phage exhibited a relatively large burst size of 176 plaque-forming units per infected cell. Phage phiLLS significantly reduced the growth of E. coli under laboratory conditions. Analyses of restriction profiles showed the presence of submolar fragments, confirming that phiLLS is a pac-type phage. Phylogenetic analysis based on the amino acid sequence of large terminase subunits confirmed that this phage uses a headful packaging strategy to package their genome. Genomic sequencing and bioinformatic analysis showed that phiLLS is a novel bacteriophage that is most closely related to T5-like phages. In silico analysis indicated that the phiLLS genome consists of 107,263 bp (39.0 % GC content encoding 160 putative ORFs, 16 tRNAs, several potential promoters and transcriptional terminators. Genome analysis suggests that the phage phiLLS is strictly lytic without carrying genes associated with virulence factors and/or potential immunoreactive allergen proteins. The bacteriophage isolated in this study has shown promising results in the biocontrol of bacterial growth under in vitro conditions, suggesting that it may prove useful as an alternative

  13. Wonder world of phages: potential biocontrol agents safeguarding biosphere and health of animals and humans- current scenario and perspectives.

    Science.gov (United States)

    Tiwari, Ruchi; Chakraborty, Sandip; Dhama, Kuldeep; Wani, Mohd Yaqoob; Kumar, Amit; Kapoor, Sanjay

    2014-02-01

    Darwin's theory of natural selection and concept of survival of fittest of Wallace is a universal truth which derives the force of life among all live entities on this biosphere. Issues regarding food safety along with increased drug resistance and emerging zoonotic infections have proved that multidisciplinary efforts are in demand for human and animal welfare. This has led to development of various novel therapies the list of which remains incomplete without mentioning about phages. Homologous and non-homologous recombination along with point mutation and addition of new genes play role in their evolution. The rapid emergence of the antibiotic resistant strains of bacteria have created keen interest in finding necessary alternatives to check microbial infections and there comes the importance of phages. Phages kill the bacteria either by lysis or by releasing holins. Bacteriophages; the viruses that live on bacteria are nowadays considered as the best biocontrol agents. They are used as replacers of antibiotics; food industry promoter; guard of aquatic life as well as of plants; pre-slaughter treatment agents; Generally Recognized As Safe (GRAS) food additives; Typing agent of bacteria; active tool of super bug therapy; in post harvest crops and food and during post infection and also to combat intracellular pathogens viz. Mycobacteria and Mycoplasma. Cyanophages/phycophages are particularly useful in controlling blooms produced by various genera of algae and cyanobacteria. By performing centrifugation studies and based on electron microscopy certain virus like particles containing ds RNA have been confirmed as mycophages. They are well proven as threat to pathogenic fungi (both fungal hyphae and yeast). Those that infect yeasts are called zymophages. Virophages have exquisite specificity for their viral host, hence can extensively be used for genetic studies and can also act as evolutionary link. After the discovery of very first virophage till now, a total of 3

  14. Tolerance of triazole-based fungicides by biocontrol agents used to control Fusarium head blight in wheat in Argentina.

    Science.gov (United States)

    Palazzini, J M; Torres, A M; Chulze, S N

    2018-02-25

    Fusarium head blight (FHB) caused by Fusarium graminearum species complex is a devastating disease that causes extensive yield and quality losses to wheat around the world. Fungicide application and breeding for resistance are among the most important tools to counteract FHB. Biological control is an additional tool that can be used as part of an integrated management of FHB. Bacillus velezensis RC 218, Brevibacillus sp. RC 263 and Streptomyces sp. RC 87B were selected by their potential to control FHB and deoxynivalenol production. The aim of this work was to test the tolerance of these biocontrol agents to triazole-based fungicides such as Prothioconazole, tebuconazole and metconazole. Bacterial growth was evaluated in Petri dishes using the spread plating technique containing the different fungicides. Bacillus velezensis RC 218 and Streptomyces sp. RC 87B showed better tolerance to fungicides than Brevibacillus sp. RC 263. Complete growth inhibition was observed at concentrations of 20 μg ml -1 for metconazole, 40 μg ml -1 for tebuconazole and 80 μg ml -1 for prothioconazole. The results obtained indicate the possibility of using these biocontrol agents in combination with fungicides as part of an integrated management to control FHB of wheat. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  15. Teste de especificidade hospedeira de Phaedon confinis (Coleoptera, Chrysomelidae, um potencial agente de biocontrole de Senecio brasiliensis (Asteraceae.

    Directory of Open Access Journals (Sweden)

    Julianne Milléo

    2011-07-01

    Abstract. Senecio brasiliensis (Spreng. Less when ingested by cattle and horses, the plant causes seneciosis, a serious poisoning. Due to the great financial losses to cattle ranchers, controlling the plant using insects has become attractive. Systematic survey efforts have revealed that Phaedon confinis Klug causes serious damage to the plant, and may be a great biocontrol agent. The object was to extend the tests of host specificity to 52 plants using 1st larval instar and adult chrysomelid bettles. The insects were submitted to “no-choice” and “multiple-choice” tests. The following results were obtained: “NO-CHOICE” L1 – 52 plants tested: null 90.39%; negligible damage 5.77%; light 1.92%; and normal in only S. brasiliensis 1.92%, where 31.67% of larvae obtained an adult phase. “NO-CHOICE” ADULTS – 46 plants. Null damage was recorded in 82.60%; 13.04% showed negligible damage; 2.17% light; 2.17% normal in S. brasiliensis. The chysomelids oviposited during observation days only on S. brasiliensis leaves. 615 eggs were oviposited with 73.01% viability. “MULTIPLE CHOICE” LARVAE – nine plants tested. 66.67% null; 11.11% weak; 11.11% negligible damage; and 11.11% normal in S. brasiliensis. The results indicate that the normal diet, oviposition, survival and development of P. confinis is restricted to S. brasiliensis and corroborates its potential as a biocontrol agent.

  16. Isolation and selection of coliphages as potential biocontrol agents of enterohemorrhagic and Shiga toxin-producing E. coli (EHEC and STEC) in cattle.

    Science.gov (United States)

    Dini, C; De Urraza, P J

    2010-09-01

    To isolate, characterize and select phages as potential biocontrol agents of enterohemorrhagic and Shiga toxin-producing Escherichia coli (EHEC and STEC) in cattle. Sixteen STEC and EHEC coliphages were isolated from bovine minced meat and stool samples and characterized with respect to their host range against STEC, EHEC and other Gram-negative pathogens; their morphology by electron microscopy; the presence of the stx1, stx2 and cI genes by means of PCR; RAPD and rep-PCR profiles; plaque formation; and acid resistance. Six isolates belonged to the Myoviridae and 10 to the Podoviridae families. The phages negative for stx and cI that formed large, well-defined plaques were all isolated using EHEC O157:H7 as host. Among them, only CA911 was a myophage and, together with CA933P, had the broadest host range for STEC and EHEC; the latter phage also infected Shigella and Pseudomonas. Isolates CA911, MFA933P and MFA45D differed in particle morphology and amplification patterns by RAPD and rep-PCR and showed the highest acidity tolerance. Myophage CA911 and podophages CA933P, MFA933P and MFA45D were chosen as the best candidates for biocontrol of STEC and EHEC in cattle. This work employs steps for a rational selection and characterization of bacteriophages as therapeutic agents. This report constitutes the first documentation of STEC and EHEC phages isolated in Argentina and proposes for the first time the use of rep-PCR as a complement of RAPD on DNA fingerprinting of phages. © 2010 The Authors. Journal compilation © 2010 The Society for Applied Microbiology.

  17. Complete genome sequence of Bacillus velezensis M75, a biocontrol agent against fungal plant pathogens, isolated from cotton waste.

    Science.gov (United States)

    Kim, Sang Yoon; Lee, Sang Yeob; Weon, Hang-Yeon; Sang, Mee Kyung; Song, Jaekyeong

    2017-01-10

    Bacillus species have been widely used as biological control agents in agricultural fields due to their ability to suppress plant pathogens. Bacillus velezensis M75 was isolated from cotton waste used for mushroom cultivation in Korea, and was found to be antagonistic to fungal plant pathogens. Here, we report the complete genome sequence of the M75 strain, which has a 4,007,450-bp single circular chromosome with 3921 genes and a G+C content of 46.60%. The genome contained operons encoding various non-ribosomal peptide synthetases and polyketide synthases, which are responsible for the biosynthesis of secondary metabolites. Our results will provide a better understanding of the genome of B. velezensis strains for their application as biocontrol agents against fungal plant pathogens in agricultural fields. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Bioprospecting endophytic diazotrophicLysinibacillus sphaericusas biocontrol agents of rice sheath blight disease.

    Science.gov (United States)

    Shabanamol, S; Sreekumar, J; Jisha, M S

    2017-10-01

    The present study tried to explore the possible in vitro biocontrol mechanisms of Lysinibacillus sphaericus , a diazotrophic endophyte from rice against the rice sheath blight pathogen Rhizoctonia solani. The in vivo biocontrol potential of the isolate and the induction of systemic resistance under greenhouse conditions have also been experimented employing different treatments with positive control carbendazim, the chemical fungicide. The endophytic isolate showed 100% growth inhibition of the fungal pathogen via volatile organic compound production and was positive for the production of siderophores, biosurfactants, HCN, and ammonia. Under greenhouse conditions, foliar and soil application of L. sphaericus significantly decreased the percentage of disease incidence. All bacterized treatments are superior to chemical fungicide treatment. Application of L. sphaericus in single and combination treatments induces systemic resistance as evident from the significant accumulation of defense enzymes such as peroxides, polyphenol oxides and phenylalanine ammonia in addition to the increase of phenolic compounds. The results biologically prospect endophytic diazotroph L. sphaericus as a potent plant growth promoter with excellent biocontrol efficiency.

  19. Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent.

    Science.gov (United States)

    Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

    2016-01-01

    Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China's Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent.

  20. Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent.

    Directory of Open Access Journals (Sweden)

    Beibei Ge

    Full Text Available Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1 from the rare dormant volcanic soils of Changbai Mountain in China's Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%, seedling length (12.5%, and root length (57.7% compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%, stem diameter (12.7%, crown width (16.3%, and maximum fruit diameter (11.5%. These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent.

  1. Potential of a new strain of Bacillus amyloliquefaciens BUZ-14 as a biocontrol agent of postharvest fruit diseases.

    Science.gov (United States)

    Calvo, H; Marco, P; Blanco, D; Oria, R; Venturini, M E

    2017-05-01

    The biocontrol potential of the Bacillus amyloliquefaciens strain BUZ-14 was tested against the main postharvest diseases of orange, apple, grape and stone fruit. After characterizing the temperature and pH growth curves of strain BUZ-14, its in vitro antifungal activity was determined against Botrytis cinerea, Monilinia fructicola, M. laxa, Penicillium digitatum, P. expansum and P. italicum. Subsequently, in vivo activity was tested against these pathogens by treating fruit with cells, endospores and cell-free supernatants. The in vitro results showed that BUZ-14 inhibited the growth of all the pathogens tested corresponding to the least susceptible species, P. italicum, and the most susceptible, M. laxa. In vivo tests corroborated these results as most of the treatments decreased the incidence of brown rot in stone fruit from 100% to 0%, establishing 10 7  CFU mL -1 as the minimum inhibitory concentration. For the Penicillium species a preventive treatment inhibited P. digitatum and P. italicum growth in oranges and reduced P. expansum incidence in apples from 100% to 20%. Finally, it has been demonstrated that BUZ-14 was able to survive and to control brown rot in peaches stored at cool temperatures, making it a very suitable biocontrol agent for application during the post-harvest storage and marketing of horticultural products. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. EndophyticTrichoderma gamsiiYIM PH30019: a promising biocontrol agent with hyperosmolar, mycoparasitism, and antagonistic activities of induced volatile organic compounds on root-rot pathogenic fungi ofPanax notoginseng.

    Science.gov (United States)

    Chen, Jin-Lian; Sun, Shi-Zhong; Miao, Cui-Ping; Wu, Kai; Chen, You-Wei; Xu, Li-Hua; Guan, Hui-Lin; Zhao, Li-Xing

    2016-10-01

    Biocontrol agents are regarded as promising and environmental friendly approaches as agrochemicals for phytodiseases that cause serious environmental and health problems. Trichoderma species have been widely used in suppression of soil-borne pathogens. In this study, an endophytic fungus, Trichoderma gamsii YIM PH30019, from healthy Panax notoginseng root was investigated for its biocontrol potential. In vitro detached healthy roots, and pot and field experiments were used to investigate the pathogenicity and biocontrol efficacy of T. gamsii YIM PH30019 to the host plant. The antagonistic mechanisms against test phytopathogens were analyzed using dual culture, scanning electron microscopy, and volatile organic compounds (VOCs). Tolerance to chemical fertilizers was also tested in a series of concentrations. The results indicated that T. gamsii YIM PH30019 was nonpathogenic to the host, presented appreciable biocontrol efficacy, and could tolerate chemical fertilizer concentrations of up to 20%. T. gamsii YIM PH30019 displayed antagonistic activities against the pathogenic fungi of P . notoginseng via production of VOCs. On the basis of gas chromatography-mass spectrometry, VOCs were identified as dimethyl disulfide, dibenzofuran, methanethiol, ketones, etc., which are effective ingredients for antagonistic activity. T. gamsii YIM PH30019 was able to improve the seedlings' emergence and protect P. notoginseng plants from soil-borne disease in the continuous cropping field tests. The results suggest that the endophytic fungus T. gamsii YIM PH30019 may have a good potential as a biological control agent against notoginseng phytodiseases and can provide a clue to further illuminate the interactions between Trichoderma and phytopathogens.

  3. The complete genome sequence of Bacillus velezensis 9912D reveals its biocontrol mechanism as a novel commercial biological fungicide agent.

    Science.gov (United States)

    Pan, Hua-Qi; Li, Qing-Lian; Hu, Jiang-Chun

    2017-04-10

    A Bacillus sp. 9912 mutant, 9912D, was approved as a new biological fungicide agent by the Ministry of Agriculture of the People's Republic of China in 2016 owing to its excellent inhibitory effect on various plant pathogens and being environment-friendly. Here, we present the genome of 9912D with a circular chromosome having 4436 coding DNA sequences (CDSs), and a circular plasmid encoding 59 CDSs. This strain was finally designated as Bacillus velezensis based on phylogenomic analyses. Genome analysis revealed a total of 19 candidate gene clusters involved in secondary metabolite biosynthesis, including potential new type II lantibiotics. The absence of fengycin biosynthetic gene cluster is noteworthy. Our data offer insights into the genetic, biological and physiological characteristics of this strain and aid in deeper understanding of its biocontrol mechanism. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Structural characterization of antibiotic self-immunity tRNA synthetase in plant tumour biocontrol agent.

    Science.gov (United States)

    Chopra, Shaileja; Palencia, Andrés; Virus, Cornelia; Schulwitz, Sarah; Temple, Brenda R; Cusack, Stephen; Reader, John

    2016-10-07

    Antibiotic-producing microbes evolved self-resistance mechanisms to avoid suicide. The biocontrol Agrobacterium radiobacter K84 secretes the Trojan Horse antibiotic agrocin 84 that is selectively transported into the plant pathogen A. tumefaciens and processed into the toxin TM84. We previously showed that TM84 employs a unique tRNA-dependent mechanism to inhibit leucyl-tRNA synthetase (LeuRS), while the TM84-producer prevents self-poisoning by expressing a resistant LeuRS AgnB2. We now identify a mechanism by which the antibiotic-producing microbe resists its own toxin. Using a combination of structural, biochemical and biophysical approaches, we show that AgnB2 evolved structural changes so as to resist the antibiotic by eliminating the tRNA-dependence of TM84 binding. Mutagenesis of key resistance determinants results in mutants adopting an antibiotic-sensitive phenotype. This study illuminates the evolution of resistance in self-immunity genes and provides mechanistic insights into a fascinating tRNA-dependent antibiotic with applications for the development of anti-infectives and the prevention of biocontrol emasculation.

  5. Inhibition coefficient and molecular diversity of multi stress tolerant Trichoderma as potential biocontrol agent against Sclerotium rolfsii Sacc.

    Science.gov (United States)

    Hirpara, Darshna G; Gajera, H P; Hirapara, Jaydeep G; Golakiya, B A

    2017-11-01

    Trichoderma is one of the most exploited biocontrol agent for the management of plant diseases. Twenty strains of Trichoderma (six of T. harzianum, four of T. viride, three of T. virens, three of T. koningii, each one of T. hamatum, T. reesei, T. parceramosum and Trichoderma spp.) subjected to in vitro antagonism up to 12days after inoculation against Sclerotium rolfsii Sacc. causing stem rot in groundnut. A new concept was developed to determine inhibition coefficient representing pathogen biology and biocontrol related biophysical variables. Results explained differential inhibition coefficient of test pathogen by Trichoderma antagonists. The inhibition coefficient of test pathogen was examined highest (91.13%) by T. virens NBAII Tvs12 followed by T. virens MTCC 794 (89.33%) and T. koningii MTCC 796 (62.39%). Microscopic study confirmed biocontrol mechanism as mycoparasitism for Tvs12 and antibiosis for T. koningii MTCC 796. The sclerotial biogenesis of test pathogen was elevated during weak antagonism and diminished in interactions with strong antagonists. The inhibition coefficient of S. rolfsii was significantly negatively correlated with sclerotia formation and lipid peroxidation during the antagonism. Trichoderma strains were screened for fungicides (carbendazim and tebuconazole, thiram and mancozeb) and abiotic stress (drought and salt) tolerance. Results indicated that T. koningii MTCC 796 efficiently grew better than the other strains with maximum radial growth under adverse conditions. The genetic variability among the Trichoderma was determined using 34 gene specific markers which amplified 146 alleles. The SSR similarities explained substantial diversity (15 to 87%) across Trichoderma strains and pathogen S. rolfsii. Principal coordinates analysis (PCA) were comparable to the cluster analysis and first three most informative PC components explained 64.45% of the total variation. In PCA, potent antagonists appear to be distinct from other strains. Five

  6. Genome Sequencing and Comparative Analysis of the Biocontrol Agent Trichoderma harzianum sensu stricto TR274

    Energy Technology Data Exchange (ETDEWEB)

    Steindorff, Andrei S.; Noronha, Elilane F.; Ulhoa, Cirano J.; Kuo, Alan; Salamov, Asaf A.; Haridas, Sajeet; Riley, Robert W.; Druzhinina, Irina S.; Kubicek, Christian P.; Grigoriev, Igor V.

    2015-03-17

    Biological control is a complex process which requires many mechanisms and a high diversity of biochemical pathways. The species of Trichoderma harzianum are well known for their biocontrol activity against many plant pathogens. To gain new insights into the biocontrol mechanism used by T. harzianum, we sequenced the isolate TR274 genome using Illumina. The assembly was performed using AllPaths-LG with a maximum coverage of 100x. The assembly resulted in 2282 contigs with a N50 of 37033bp. The genome size generated was 40.8 Mb and the GC content was 47.7%, similar to other Trichoderma genomes. Using the JGI Annotation Pipeline we predicted 13,932 genes with a high transcriptome support. CEGMA tests suggested 100% genome completeness and 97.9% of RNA-SEQ reads were mapped to the genome. The phylogenetic comparison using orthologous proteins with all Trichoderma genomes sequenced at JGI, corroborates the Trichoderma (T. asperellum and T. atroviride), Longibrachiatum (T. reesei and T. longibrachiatum) and Pachibasium (T. harzianum and T. virens) section division described previously. The comparison between two Trichoderma harzianum species suggests a high genome similarity but some strain-specific expansions. Analyses of the secondary metabolites, CAZymes, transporters, proteases, transcription factors were performed. The Pachybasium section expanded virtually all categories analyzed compared with the other sections, specially Longibrachiatum section, that shows a clear contraction. These results suggests that these proteins families have an important role in their respective phenotypes. Future analysis will improve the understanding of this complex genus and give some insights about its lifestyle and the interactions with the environment.

  7. RNA Interference of Endochitinases in the Sugarcane Endophyte Trichoderma virens 223 Reduces Its Fitness as a Biocontrol Agent of Pineapple Disease

    Science.gov (United States)

    Romão-Dumaresq, Aline S.; de Araújo, Welington Luiz; Talbot, Nicholas J.; Thornton, Christopher R.

    2012-01-01

    The sugarcane root endophyte Trichoderma virens 223 holds enormous potential as a sustainable alternative to chemical pesticides in the control of sugarcane diseases. Its efficacy as a biocontrol agent is thought to be associated with its production of chitinase enzymes, including N-acetyl-ß-D-glucosaminidases, chitobiosidases and endochitinases. We used targeted gene deletion and RNA-dependent gene silencing strategies to disrupt N-acetyl-ß-D-glucosaminidase and endochitinase activities of the fungus, and to determine their roles in the biocontrol of soil-borne plant pathogens. The loss of N-acetyl-ß-D-glucosaminidase activities was dispensable for biocontrol of the plurivorous damping-off pathogens Rhizoctonia solani and Sclerotinia sclerotiorum, and of the sugarcane pathogen Ceratocystis paradoxa, the causal agent of pineapple disease. Similarly, suppression of endochitinase activities had no effect on R. solani and S. sclerotiorum disease control, but had a pronounced effect on the ability of T. virens 223 to control pineapple disease. Our work demonstrates a critical requirement for T. virens 223 endochitinase activity in the biocontrol of C. paradoxa sugarcane disease, but not for general antagonism of other soil pathogens. This may reflect its lifestyle as a sugarcane root endophyte. PMID:23110120

  8. A Three-Way Transcriptomic Interaction Study of a Biocontrol Agent (Clonostachys rosea), a Fungal Pathogen (Helminthosporium solani), and a Potato Host (Solanum tuberosum).

    Science.gov (United States)

    Lysøe, Erik; Dees, Merete W; Brurberg, May Bente

    2017-08-01

    Helminthosporium solani causes silver scurf, which affects the quality of potato. The biocontrol agent Clonostachys rosea greatly limited the severity of silver scurf symptoms and amount of H. solani genomic DNA in laboratory experiments. Transcriptomic analysis during interaction showed that H. solani gene expression was highly reduced when coinoculated with the biocontrol agent C. rosea, whereas gene expression of C. rosea was clearly boosted as a response to the pathogen. The most notable upregulated C. rosea genes were those encoding proteins involved in cellular response to oxidative stress, proteases, G-protein signaling, and the methyltransferase LaeA. The most notable potato response to both fungi was downregulation of defense-related genes and mitogen-activated protein kinase kinase kinases. At a later stage, this shifted, and most potato defense genes were turned on, especially those involved in terpenoid biosynthesis when H. solani was present. Some biocontrol-activated defense-related genes in potato were upregulated during early interaction with C. rosea alone that were not triggered by H. solani alone. Our results indicate that the reductions of silver scurf using C. rosea are probably due to a combination of mechanisms, including mycoparasitism, biocontrol-activated stimulation of plant defense mechanisms, microbial competition for nutrients, space, and antibiosis.

  9. Screening of freeze-dried protective agents for the formulation of biocontrol strains, Bacillus cereus AR156, Burkholderia vietnamiensis B418 and Pantoea agglomerans 2Re40.

    Science.gov (United States)

    Zhan, Y; Xu, Q; Yang, M-M; Yang, H-T; Liu, H-X; Wang, Y-P; Guo, J-H

    2012-01-01

    The effects of different freeze-drying protective agents on the viabilities of biocontrol strains Bacillus cereus AR156, Burkholderia vietnamiensis B418 and Pantoea agglomerans 2Re40 were investigated. Several concentrations of protective and rehydration media were tested to improve the survival of biocontrol agents after freeze-drying. The subsequent survival rates during storage and rehydration media of freeze-dried biocontrol strains were also examined. The results indicated that cellobiose (5%) and d-galactose (5%) gave maximum viability of strains Bu. vietnamiensis B418 and P. agglomerans 2Re40 (98 and 54·3% respectively) while the perfect one (100%) of strain B. cereus AR156 was obtained with sucrose (5%) during freeze-drying, and the highest survival of the three strains was reached when they were rehydrated with 10% nonfat skim milk. In the following storage, the survival rates showed that B. cereus AR156 could still reach 50% after 12 months. This study showed that freeze-drying could be used to stabilize cells of these three biocontrol strains. Further studies should focus on the scale-up possibilities and formulation development. © Nanjing Agricultural University. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

  10. RNA interference of endochitinases in the sugarcane endophyte Trichoderma virens 223 reduces its fitness as a biocontrol agent of pineapple disease.

    Directory of Open Access Journals (Sweden)

    Aline S Romão-Dumaresq

    Full Text Available The sugarcane root endophyte Trichoderma virens 223 holds enormous potential as a sustainable alternative to chemical pesticides in the control of sugarcane diseases. Its efficacy as a biocontrol agent is thought to be associated with its production of chitinase enzymes, including N-acetyl-ß-D-glucosaminidases, chitobiosidases and endochitinases. We used targeted gene deletion and RNA-dependent gene silencing strategies to disrupt N-acetyl-ß-D-glucosaminidase and endochitinase activities of the fungus, and to determine their roles in the biocontrol of soil-borne plant pathogens. The loss of N-acetyl-ß-D-glucosaminidase activities was dispensable for biocontrol of the plurivorous damping-off pathogens Rhizoctonia solani and Sclerotinia sclerotiorum, and of the sugarcane pathogen Ceratocystis paradoxa, the causal agent of pineapple disease. Similarly, suppression of endochitinase activities had no effect on R. solani and S. sclerotiorum disease control, but had a pronounced effect on the ability of T. virens 223 to control pineapple disease. Our work demonstrates a critical requirement for T. virens 223 endochitinase activity in the biocontrol of C. paradoxa sugarcane disease, but not for general antagonism of other soil pathogens. This may reflect its lifestyle as a sugarcane root endophyte.

  11. Fusarium oxysporum strains as biocontrol agents against Fusarium wilt: effects on soil microbial biomass and activity Linhagens de Fusarium oxysporum como agentes de biocontrole da murcha-de-Fusarium: efeitos na biomassa e atividade microbiana do solo

    Directory of Open Access Journals (Sweden)

    Raquel Ghini

    2000-01-01

    Full Text Available Before planning the large-scale use of nonpathogenic strains of Fusarium oxysporum as biocontrol agents of Fusarium wilt, their behaviour and potential impact on soil ecosystems should be carefully studied as part of risk assessment. The aim of this work was to evaluate the effects of antagonistic F. oxysporum strains, genetically manipulated (T26/6 or not (233/1, on soil microbial biomass and activity. The effects were evaluated, in North-western Italy, in two soils from different sites at Albenga, one natural and the other previously solarized, and in a third soil obtained from a 10-year-old poplar stand (Popolus sp., near Carignano. There were no detectable effects on ATP, fluorescein diacetate hydrolysis, and biomass P that could be attributed to the introduction of the antagonists. A transient increase of carbon dioxide evolution and biomass C was observed in response to the added inoculum. Although the results showed only some transient alterations, further studies are required to evaluate effects on specific microorganism populations.Antes do uso em larga escala de linhagens não-patogênicas de Fusarium oxysporum como agentes de biocontrole da murcha-de-Fusarium, o seu comportamento e seus impactos potenciais no solo devem ser estudados como parte da avaliação de riscos. O objetivo do presente trabalho foi avaliar os efeitos de linhagens antagonistas de F. oxysporum, geneticamente manipuladas (T26/6 ou não (233/1, na biomassa e atividade microbiana do solo. Os efeitos foram avaliados no noroeste da Itália em dois solos de Albenga, sendo um natural e outro previamente solarizado, e em um terceiro solo obtido numa plantação de 10 anos de Popolus sp., em Carignano. Não foram observados efeitos significativos na quantidade de ATP, hidrólise de diacetato de fluoresceina e biomassa P, após a introdução dos antagonistas. Um aumento transitório foi observado na evolução de dióxido de carbono e no carbono da biomassa em resposta

  12. Bacillus amyloliquefaciens subsp. plantarum GR53, a potent biocontrol agent resists Rhizoctonia disease on Chinese cabbage through hormonal and antioxidants regulation.

    Science.gov (United States)

    Kang, Sang-Mo; Radhakrishnan, Ramalingam; Lee, In-Jung

    2015-10-01

    The fungus Rhizoctonia solani is one of the causal agents of numerous diseases that affect crop growth and yield. The aim of this present investigation was to identify a biocontrol agent that acts against R. solani and to determine the agent's protective effect through phytohormones and antioxidant regulation in experimentally infected Chinese cabbage plants. Four rhizospheric soil bacterial isolates GR53, GR169, GR786, and GR320 were tested for their antagonistic activity against R. solani. Among these isolates, GR53 significantly suppressed fungal growth. GR53 was identified as Bacillus amyloliquefaciens subsp. plantarum by phylogenetic analysis of the 16S rDNA sequence. The biocontrol activity of B. amyloliquefaciens subsp. plantarum GR53 was tested in Chinese cabbage plants under controlled conditions. Results showed that R. solani inhibited plant growth (length, width, fresh and dry weight of leaves) by reducing chlorophyll and total phenolic content, as well as by increasing the levels of salicylic acid, jasmonic acid, abscisic acid, and DPPH scavenging activity. By regulating the levels of these compounds, the co-inoculation of B. amyloliquefaciens subsp. plantarum GR53 heightened induced systemic resistance in infected Chinese cabbage, effectively mitigating R. solani-induced damaging effects and improving plant growth. The results obtained from this study suggest that B. amyloliquefaciens subsp. plantarum GR53 is an effective biocontrol agent to prevent the damage caused by R. solani in Chinese cabbage plants.

  13. A case of ecological specialization in ladybirds: Iberorhyzobius rondensis (Coleoptera: Coccinellidae), potential biocontrol agent of Matsucoccus feytaudi (Hemiptera: Matsucoccidae).

    Science.gov (United States)

    Tavares, C; Jactel, H; van Halder, I; Mendel, Z; Branco, M

    2014-06-01

    Specialization is an important attribute of a biological control agent. The maritime pine bast scale, Matsucoccus feytaudi Ducasse (Hemiptera Matsucoccidae), is an invasive species in Southeast France and the North of Italy. Iberorhyzobius rondensis Eizaguirre (Coleoptera: Coccinellidae), is a recently described ladybird species. Both adults and larvae are predaceous, feeding on egg masses of M. feytaudi, and are strongly attracted to M. feytaudi's sex pheromone. To evaluate the potential of I. rondensis as a biocontrol agent of the scale, we studied its niche breadth and prey range with emphasis on pine forests and hemipterans as tested prey. In this study, I. rondensis was found to achieve complete development only when fed on M. feytaudi egg masses (92.9% survival) and an artificial prey: eggs of Ephestia kuehniella Zeller (27.6% survival). From the 2nd instar onwards, complete development could be achieved using other prey species, although larvae had significantly higher mortality and slower development. In choice tests, M. feytaudi was the preferred prey. Surveys of the ladybird populations in the Iberian Peninsula revealed that it was found exclusively on Pinus pinaster Aiton, the sole host of M. feytaudi. The unusual specialization of I. rondensis, among other predaceous ladybirds, makes it an appropriate candidate for classical biological control of M. feytaudi.

  14. Plant tumour biocontrol agent employs a tRNA-dependent mechanism to inhibit leucyl-tRNA synthetase.

    Science.gov (United States)

    Chopra, Shaileja; Palencia, Andrés; Virus, Cornelia; Tripathy, Ashutosh; Temple, Brenda R; Velazquez-Campoy, Adrian; Cusack, Stephen; Reader, John S

    2013-01-01

    Leucyl-tRNA synthetases (LeuRSs) have an essential role in translation and are promising targets for antibiotic development. Agrocin 84 is a LeuRS inhibitor produced by the biocontrol agent Agrobacterium radiobacter K84 that targets pathogenic strains of A. tumefaciens, the causative agent of plant tumours. Agrocin 84 acts as a molecular Trojan horse and is processed inside the pathogen into a toxic moiety (TM84). Here we show using crystal structure, thermodynamic and kinetic analyses, that this natural antibiotic employs a unique and previously undescribed mechanism to inhibit LeuRS. TM84 requires tRNA(Leu) for tight binding to the LeuRS synthetic active site, unlike any previously reported inhibitors. TM84 traps the enzyme-tRNA complex in a novel 'aminoacylation-like' conformation, forming novel interactions with the KMSKS loop and the tRNA 3'-end. Our findings reveal an intriguing tRNA-dependent inhibition mechanism that may confer a distinct evolutionary advantage in vivo and inform future rational antibiotic design.

  15. Fungal pathogens of Euphorbia heterophylla and E. hirta in Brazil and their potential as weed biocontrol agents.

    Science.gov (United States)

    Barreto, R W; Evans, H C

    1998-01-01

    A two-year survey of the fungi associated with two important congeneric pantropical weeds, Euphorbia heterophylla and E. hirta, was conducted in part of their native range in southern Brazil. Sampling was concentrated mainly in Rio de Janeiro State and ten species were identified as pathogens of these weeds. Two taxa, Botrytis ricini and Uromyces euphorbiae, were common to both weed hosts. Alternaria euphorbiicola, Bipolaris euphorbiae, Melampsora sp., Oidium sp. and Sphaceloma poinsettiae were recorded only from E. heterophylla, whereas Colletotrichum gloeosporioides, Sphaceloma sp. and Sphaerotheca fuliginea were restricted to E. hirta. Botrytis ricini and Colletotrichum gloeosporioides are new records for E. hirta, and Alternaria euphorbiicola and Sphaerotheca fuliginea are new host records for Brazil. Bipolaris euphorbiae, previously identified as Helminthosporium sp., is considered to be the correct name for the causal agent of a major disease of E. heterophyllum in Brazil. The potential of these pathogens as biocontrol agents is discussed and the mycobiota associated with both these weeds worldwide is reviewed.

  16. Host-Range Dynamics of Cochliobolus lunatus: From a Biocontrol Agent to a Severe Environmental Threat

    Directory of Open Access Journals (Sweden)

    Bengyella Louis

    2014-01-01

    Full Text Available We undertook an investigation to advance understanding of the host-range dynamics and biocontrol implications of Cochliobolus lunatus in the past decade. Potato (Solanum tuberosum L farms were routinely surveyed for brown-to-black leaf spot disease caused by C. lunatus. A biphasic gene data set was assembled and databases were mined for reported hosts of C. lunatus in the last decade. The placement of five virulent strains of C. lunatus causing foliar necrosis of potato was studied with microscopic and phylogenetic tools. Analysis of morphology showed intraspecific variations in stromatic tissues among the virulent strains causing foliar necrosis of potato. A maximum likelihood inference based on GPDH locus separated C. lunatus strains into subclusters and revealed the emergence of unclustered strains. The evolving nutritional requirement of C. lunatus in the last decade is exhibited by the invasion of vertebrates, invertebrates, dicots, and monocots. Our results contribute towards a better understanding of the host-range dynamics of C. lunatus and provide useful implications on the threat posed to the environment when C. lunatus is used as a mycoherbicide.

  17. Managing Phytophthora crown and root rot on tomato by pre-plant treatments with biocontrol agents, resistance inducers, organic and mineral fertilizers under nursery conditions

    Directory of Open Access Journals (Sweden)

    Giovanna GILARDI

    2014-09-01

    Full Text Available Five trials were carried out under greenhouse conditions to test the efficacy of spray programmes based on biocontrol agents, phosphite-based fertilizers and a chemical inducer of resistance (acibenzolar-S-methyl, phosethyl-Al to control crown and root rot of tomato incited by Phytophthora nicotianae. The best disease control, under high disease pressure resulting from artificial inoculation, was obtained with three pre-plant leaf sprays at 7 d intervals with acibenzolar-S-methyl and with two mineral phosphite-based fertilizers. The disease reduction achieved was similar to that obtained with a single application of azoxystrobin and metalaxyl-M. Phosetyl-Al and the biocontrol agents Glomus spp. + Bacillus megaterium + Trichoderma, B. subtilis QST713, B. velezensis IT45 and the mixture T. asperellum ICC012 + T. gamsii ICC080 provided a partial disease control. Brassica carinata pellets did not control the disease.

  18. Plot- and landscape-level changes in climate and vegetation following defoliation of exotic saltcedar (Tamarix sp.) from the biocontrol agent Diorhabda carinulata along a stream in the Mojave Desert (USA)

    Science.gov (United States)

    Bateman, H.L.; Nagler, P.L.; Glenn, E.P.

    2013-01-01

    The biocontrol agent, northern tamarisk beetle (Diorhabda carinulata), has been used to defoliate non-native saltcedar (Tamarix spp.) in USA western riparian systems since 2001. Biocontrol has the potential to impact biotic communities and climatic conditions in affected riparian areas. To determine the relationships between biocontrol establishment and effects on vegetation and climate at the plot and landscape scales, we measured temperature, relative humidity, foliage canopy, solar radiation, and used satellite imagery to assess saltcedar defoliation and evapotranspiration (ET) along the Virgin River in the Mojave Desert. Following defoliation solar radiation increased, daily humidity decreased, and maximum daily temperatures tended to increase. MODIS and Landsat satellite imagery showed defoliation was widespread, resulting in reductions in ET and vegetation indices. Because biocontrol beetles are spreading into new saltcedar habitats on arid western rivers, and the eventual equilibrium between beetles and saltcedar is unknown, it is necessary to monitor trends for ecosystem functions and higher trophic-level responses in habitats impacted by biocontrol.

  19. Evaluation of yeasts obtained from Antarctic soil samples as biocontrol agents for the management of postharvest diseases of apple (Malus × domestica).

    Science.gov (United States)

    Vero, Silvana; Garmendia, Gabriela; González, M Belén; Bentancur, Oscar; Wisniewski, Michael

    2013-03-01

    Psychrotrophic yeasts were isolated from Antarctic soils, selected based on their ability to grow in apple juice at low temperatures, and were evaluated as potential biocontrol agents for the management of postharvest diseases of apple during cold storage. Among the species recovered, an isolate of Leucosporidium scottii, designated At17, was identified as a good biocontrol agent for blue and gray mold of two apple cultivars. The selected isolate produced soluble and volatile antifungal substances that were inhibitory to apple pathogens. Siderophore production was also demonstrated, but it did not appear to play a role in pathogen inhibition. The selected yeast had the capacity to form a biofilm when grown in apple juice, which is considered an important attribute of postharvest antagonists to successfully colonize wounds and intact fruit surfaces. At17 was resistant to commonly used postharvest fungicides, so application of a combination of low-dose fungicide along with the biocontrol agent could be used as an integrated management practice. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  20. Influence of diluent and sample processing methods on the recovery of the biocontrol agent Pantoea agglomerans CPA-2 from different fruit surfaces.

    Science.gov (United States)

    Torres, R; Viñas, I; Usall, J; Remón, D; Teixidó, N

    2012-08-01

    Determining the populations of biocontrol agents applied as a postharvest treatment on fruit surfaces is fundamental to the assessment of the microorganisms' ability to colonise and persist on fruit. To obtain maximum recovery, we must develop a methodology that involves both diluent and processing methods and that does not affect the viability of the microorganisms. The effect of diluent composition was evaluated using three diluents: phosphate buffer, peptone saline and buffered peptone saline. An additional study was performed to compare three processing methods (shaking plus sonication, stomaching and shaking plus centrifugation) on the recovery efficiency of Pantoea agglomerans strain CPA-2 from apples, oranges, nectarines and peaches treated with this biocontrol agent. Overall, slight differences occurred among diluents, although the phosphate buffer maintained the most ideal pH for CPA-2 growth (between 5.2 and 6.2). Stomaching, using the phosphate buffer as diluent, was the best procedure for recovering and enumerating the biocontrol agent; this fact suggested that no lethal effects from naturally occurring antimicrobial compounds present on the fruit skins and/or produced when the tissues were disrupted affected the recovery of the CPA-2 cells, regardless of fruit type. The growth pattern of CPA-2 on fruits maintained at 20°C and under cold conditions was similar to that obtained in previous studies, which confirms the excellent adaptation of this strain to conditions commonly used for fruit storage. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Environmental fate and behaviour of the biocontrol agent Bacillus amyloliquefaciens CPA-8 after preharvest application to stone fruit.

    Science.gov (United States)

    Vilanova, Laura; Teixidó, Neus; Usall, Josep; Balsells-Llauradó, Marta; Gotor-Vila, Amparo; Torres, Rosario

    2018-02-01

    Bacillus amyloliquefaciens strain CPA-8 has been described as an effective biocontrol agent to control brown rot in stone fruit for both preharvest and postharvest applications. However, no information about the environmental fate and behaviour of this strain under field conditions is available. The dispersion of the CPA-8 application was evaluated using water-sensitive papers, and complete coverage was observed on the leaves of treated trees, while treatment. On non-treated trees, CPA-8 was detected on leaves until 180 days after treatment, and on weeds, the CPA-8 population was dependent on the distance from the treated trees. A high persistence of CPA-8 was detected on inert materials, such as clothes and gloves worn by handlers and plastic harvesting boxes. More than 99% of the samples with a CPA-8 phenotype were confirmed as CPA-8 using polymerase chain reaction (PCR). This work demonstrated a good distribution, persistence and adaptation of the CPA-8 strain to field and postharvest conditions. Monitoring of dispersion and persistence is an excellent tool to determine the time of application and provides valuable information for registering issues. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  2. Effectiveness of Lysiphlebus testaceïpes Cresson as biocontrol agent of Aphis gossypii Glover infesting pepper plants

    Directory of Open Access Journals (Sweden)

    M. Ben Halima Kamel

    2011-12-01

    Full Text Available In Tunisia, greenhouse crops are damaged by Aphis gossypii Glover and Myzus persicae Sulzer (Ben Halima Kamel 1991; Ben Halima Kamel and Ben Hamouda 1993, 1998. These aphids are considered to be the most dangerous pests of pepper because of their biology and biotic potential (Ben Halima Kamel 1991; Blackman and Eastop 2000. There are several ways of controlling these pests with chemical control being the most widely used. This method has more disadvantages than benefits (Gibson et al. 1982. The use of natural enemies to control aphids is an effective way of improving the yield and quality of protected crops. There are many studies on the following naturally occurring enemies of A. gossypii: Aphidius matricariae Haliday, Lysiphlebus fabarum Marshall, Aphidoletes aphidimyza (Rondani, Episyrphus balteatus (De Geer (Ben Halima Kamel and Ben Hamouda 1998 and Lysiphlebus testaceipes (Cresson (Ben Halima Kamel, unpublished data, 1999. It is now important to evaluate the effectiveness of L. testaceipes as a biocontrol agent of A. gossypii. This parasitoďd was introduced into the Mediterranean area (Carver and Franzmann 2001 and is thought to be an important parasite of A. gossypii (Lopes et al. 2007. The aim of this mainly laboratory study was to determine the factors affecting the establishment and success of a biological control agent, in particular the number of L. testaceďpes relative to the initial density of A. gossypii, needed to control the aphid. In addition, the effect of the L. testaceďpes on structure of A. gossypii populations was evaluated. Furthermore, the effectiveness of L. testaceipes in controlling A. gossypii infesting a protected crop of pepper plants and the subsequent effect on the growth of the pepper plants was also evaluated.

  3. Endophytic Bacillus subtilis Strain E1R-J Is a Promising Biocontrol Agent for Wheat Powdery Mildew

    Science.gov (United States)

    Gong, Yufei; Huo, Yunxia; Han, Qingmei; Kang, Zhensheng; Huang, Lili

    2015-01-01

    In this study, the biocontrol efficacies of 14 endophytic bacterial strains were tested against Blumeria graminis f. sp. tritici (Bgt) in pot experiments under greenhouse conditions. Bacillus subtilis strain E1R-j significantly reduced disease index and exhibited the best control (90.97%). When different formulations of E1R-j were sprayed 24 h before Bgt inoculation, fermentation liquid without bacterial cell and crude protein suspension displayed the similar effects; and they reduced disease index more than bacterial cell suspension (109 cfu mL−1) and fermentation liquid without protein. The control effects were not significantly different between 1011 and 109 cfu mL−1 of bacterial cell suspension but were higher than 107 cfu mL−1. Further observations showed that conidial germination and appressorial formation of Bgt were retarded by spraying E1R-j 24 h before Bgt inoculation. Compared with the water check, conidial germination and appressorial formation were decreased by 43.3% and 42.7%, respectively. In the treatment with E1R-j, the number of houstoria significantly reduced and the speed of mycelial extension was slowed down in the wheat leaves. Scanning electron microscopy observation revealed that E1R-j significantly suppressed the conidial germination and caused rupture and deformation of germ tubes. On the surface of wheat leaves, mycelia and conidiophores became shrinking. PMID:25759819

  4. Endophytic Bacillus subtilis Strain E1R-J Is a Promising Biocontrol Agent for Wheat Powdery Mildew

    Directory of Open Access Journals (Sweden)

    Xiaoning Gao

    2015-01-01

    Full Text Available In this study, the biocontrol efficacies of 14 endophytic bacterial strains were tested against Blumeria graminis f. sp. tritici (Bgt in pot experiments under greenhouse conditions. Bacillus subtilis strain E1R-j significantly reduced disease index and exhibited the best control (90.97%. When different formulations of E1R-j were sprayed 24 h before Bgt inoculation, fermentation liquid without bacterial cell and crude protein suspension displayed the similar effects; and they reduced disease index more than bacterial cell suspension (109 cfu mL−1 and fermentation liquid without protein. The control effects were not significantly different between 1011 and 109 cfu mL−1 of bacterial cell suspension but were higher than 107 cfu mL−1. Further observations showed that conidial germination and appressorial formation of Bgt were retarded by spraying E1R-j 24 h before Bgt inoculation. Compared with the water check, conidial germination and appressorial formation were decreased by 43.3% and 42.7%, respectively. In the treatment with E1R-j, the number of houstoria significantly reduced and the speed of mycelial extension was slowed down in the wheat leaves. Scanning electron microscopy observation revealed that E1R-j significantly suppressed the conidial germination and caused rupture and deformation of germ tubes. On the surface of wheat leaves, mycelia and conidiophores became shrinking.

  5. The fungal biocontrol agent Coniothyrium minitans: production by solid-state fermentation, application and marketing

    NARCIS (Netherlands)

    Vrije, de T.; Antoine, N.; Buitelaar, R.M.; Oostra, J.; Rinzema, A.; Weber, F.J.

    2001-01-01

    Biological control agents (BCAs) are potential alternatives for the chemical fungicides presently used in agriculture to fight plant diseases. Coniothyrium minitans is an example of a promising fungal BCA. It is a naturally occurring parasite of the fungus Sclerotinia sclerotiorum, a wide-spread

  6. The Potential of Bdellovibrio For the Biocontrol of the Infectious Agent Vibrio cholerae

    Directory of Open Access Journals (Sweden)

    Natalia Olsson Markelova

    2015-12-01

    Full Text Available Members of the genus Bdellovibrio are small and highly motile Gram-negative predators of other Gram-negative bacteria. Bdellovibrio enters the prey cell, transforming it into a structure that is referred to as a bdelloplast. It then grows and divides inside the bdelloplast, ending in lysis and the release of the Bdellovibrio progeny. Because of this capability, Bdellovibrio is a potential antibacterial agent. In this article, we report the results of studies on the interactions of Bdellovibrio with actively growing and viable but nonculturable (VBNC Vibrio cholerae. A significant observation was that Bdellovibrio attacked both VBNC and actively growing V. cholerae. These results indicate that Bdellovibrio, a “living antibiotic,” has potential as an antibacterial agent in environmental and public health bioprotection.

  7. Identifying, Developing and Releasing Insect Biocontrol Agents for the Management of Phragmites australis

    Science.gov (United States)

    2013-07-01

    Intro) x x x x x x x Phragmites australis americanus x x x x Plantago major x Potentilla fructicosa x Potentilla palustris...five major objectives:  Objective 1: Identify potential agents for more in-depth study  Objective 2: Develop testing procedures and conditions...to first instars of either moth species. While this requirement is a great help in rendering the vast majority of test plant species unacceptable to

  8. Studies of plant colonisation by closely related Bacillus amyloliquefaciens biocontrol agents using strain specific quantitative PCR assays.

    Science.gov (United States)

    Johansson, Anna H; Bejai, Sarosh; Niazi, Adnan; Manzoor, Shahid; Bongcam-Rudloff, Erik; Meijer, Johan

    2014-12-01

    Certain strains of Bacillus amyloliquefaciens can colonize plants and improve growth and stress management. In order to study these effects, bacterial growth dynamics on plants and in the rhizosphere are of interest calling for specific analytical tools. For that purpose, quantitative real-time PCR (qPCR) assays were developed in order to differentiate among three closely related B. amyloliquefaciens subsp. plantarum strains (UCMB5033, UCMB5036, UCMB5113) and to determine their levels with high accuracy. Oligonucleotide primers were designed for strain unique gene sequences and used for SYBR green based qPCR analysis. Standard curves covered a wide linear range (10(6)) of DNA amounts with the lowest detection level at 50 fg. Post-reaction melting curve analysis showed only a single product. Accurate threshold cycles were obtained, even in the presence of high excess of related Bacillus strains and total bacterial DNA from soil. Analysis of Bacillus colonisation after seed treatment of two oilseed rape cultivars (Oase and Ritz) grown on agar support showed a time dependent effect but that the bacteria mostly were found on root tissues and little on green tissues. The colonisation on plants grown in soil varied among the Bacillus strains where Oase seemed to house more bacteria than Ritz. Applied as a mixture, all three Bacillus strains co-existed on the roots of plants grown in soil. The qPCR assay in combination with other techniques will be a powerful tool to study plant interactions of these B. amyloliquefaciens biocontrol agents to further understand the requirements for successful interactions and improvement of plant properties.

  9. Streptomyces globosus UAE1, a Potential Effective Biocontrol Agent for Black Scorch Disease in Date Palm Plantations

    Directory of Open Access Journals (Sweden)

    Esam E. Saeed

    2017-07-01

    Full Text Available Many fungal diseases affect date palm causing considerable losses in date production worldwide. We found that the fungicide Cidely® Top inhibited the mycelial growth of the soil-borne pathogenic fungus Thielaviopsis punctulata, the causal agent of black scorch disease of date palm, both in vitro and in vivo. Because the use of biocontrol agents (BCAs can minimize the impact of pathogen control on economic and environmental concerns related to chemical control, we aimed at testing local actinomycete strains isolated from the rhizosphere soil of healthy date palm cultivated in the United Arab Emirates (UAE against T. punctulata. The selected isolate can thus be used as a potential agent for integrated disease management programs. In general, the BCA showed antagonism in vitro and in greenhouse experiments against this pathogen. The most promising actinomycete isolate screened showed the highest efficacy against the black scorch disease when applied before or at the same time of inoculation with T. punctulata, compared with BCA or fungicide application after inoculation. The nucleotide sequence and phylogenetic analyses using the 16S ribosomal RNA gene with other Streptomyces spp. in addition to morphological and cultural characteristics revealed that the isolated UAE strain belongs to Streptomyces globosus UAE1. The antagonistic activity of S. globosus against T. punctulata, was associated with the production by this strain of diffusible antifungal metabolites i.e., metabolites that can inhibit mycelial growth of the pathogen. This was evident in the responses of the vegetative growth of pure cultures of the pathogen when exposed to the culture filtrates of the BCA. Altogether, the pathogenicity tests, disease severity indices and mode of action tests confirmed that the BCA was not only capable of suppressing black scorch disease symptoms, but also could prevent the spread of the pathogen, as a potential practical method to improve disease

  10. Isolation of Ralstonia solanacearum-infecting bacteriophages from tomato fields in Chiang Mai, Thailand, and their experimental use as biocontrol agents.

    Science.gov (United States)

    Bhunchoth, A; Phironrit, N; Leksomboon, C; Chatchawankanphanich, O; Kotera, S; Narulita, E; Kawasaki, T; Fujie, M; Yamada, T

    2015-04-01

    To isolate and characterize novel bacteriophages infecting the phytopathogen, Ralstonia solanacearum, and to evaluate them as resources with potential uses in the biocontrol of bacterial wilt. Fourteen phages infecting R. solanacearum were isolated from soil samples collected in Chiang Mai, Thailand. The phages showed different host ranges when tested against 59 R. solanacearum strains isolated from Thailand and Japan. These phages were characterized as nine podoviruses and five myoviruses based on their morphology. Podovirus J2 in combination with another podovirus (φRSB2) lysed host cells very efficiently in contaminated soil. J2 treatment prevented wilting of tomato plants infected with a highly virulent R. solanacearum strain. Treatment with J2 effectively reduced the amount of the bacterial wilt pathogen in contaminated soil and prevented bacterial wilt of tomato in pot experiments. Myovirus J6 possessed jumbo phage features, giving a unique opportunity to study its utilization as a biocontrol agent. As exemplified by J2, the phages isolated in this study represent valuable resources with potential uses in biocontrol of bacterial wilt. A rare jumbo phage J6 served as a valuable subject to understand and utilize this new group of phages. © 2015 The Society for Applied Microbiology.

  11. Biocontrol agents of Botrytis cinerea tested in climate chambers by making artificial infection on tomato leafs.

    Science.gov (United States)

    Gielen, S; Aerts, R; Seels, B

    2004-01-01

    To reduce the use of chemical agents, that are causing damage to the environment, in the fight against Botrytis cinerea, different BCA's were tested for their possibility to control Botrytis cinerea in a biological way. In order to investigate the effectiveness of the different micro organisms and Elot-Vis, experiments were carried out in climate chambers with 5 weeks old tomato plants. Leafs on the plant were inoculated with drops of a suspension that contained spores of Botrytis cinerea. The possible antagonists that were tested in these experiments were Trichoderma harzianum (Trichodex), T. asperellum (Biofungus), T. hamatum (T382), Bacillus subtilis (Serenade and Phytovit) and Pseudomonas aeruginosa (7NSK2 and KMPCH). For all these different micro organisms the direct and the indirect influence on Botrytis cinerea was investigated. In tests where the direct influence of the antagonists was examined, the spores of the moulds or the bacteria were suspended together with spores of Botrytis cinerea and subsequently drops of this suspension were pippeted on the leafs. After a while by ideal circumstances for Botrytis cinerea the infections on the inoculated leafs were counted. For the indirect influence of the antagonists, also leafs of 5 weeks old tomato plants were inoculated with a suspension of Botrytis cinerea spores. The roots of the tomato plants that were used for testing the indirect influence were treated during there growth with a suspension of the antagonist to see if induced systemic resistance pathway (ISR) was activated. For testing the effectiveness of Elot-Vis, tomato plants were sprayed a few times with a solution of this product during their growth. Results of the climate chamber test of the plants that were treated with Elot-Vis, showed a reduction of Botrytis cinerea infections on the inoculated leafs. Biological control agents seem to be not always very effective against Botrytis cinerea. The biological control agents that are containing micro

  12. Combined effects of biocontrol agents and soil amendments on soil microbial populations, plant growth and incidence of charcoal rot of cowpea and wilt of cumin

    Directory of Open Access Journals (Sweden)

    Vijeta SINGH

    2012-09-01

    Full Text Available Field experiments were conducted for 2 years to determine the effectiveness of combined use of two biocontrol agents, Bacillus firmus and Aspergillus versicolor for control of Macrophomina phaseolina induced charcoal rot of cowpea and Fusarium oxysporum f. sp. cumini induced wilt of cumin. The lowest level of plant mortality (3‒4% due to charcoal rot of cowpea was recorded when bacterium coated seeds were sown in radish compost amended soil compared to the non-amended soil (13.8‒20.5%, but this was not significantly better than some other treatments. Cowpea roots from B. firmus coated seeds had better nodulation than any of the individual A. versicolor treatments. Although B. firmus coated seeds + A. versicolor + farmyard manure resulted in maximum nodulation this was not significantly different to B. firmus seed coating. Root colonization by the combined biocontrol agent treatments was better than the individual biocontrol agent treatments. Combining A. versicolor with farmyard manure supported the maximum populations of total fungi and actinomycetes. In both winter seasons, the lowest incidence of wilt (1.0‒5.2% on cumin was recorded when A. versicolor was amended with neem compost compared to the non-amended soil (5.7‒10.5%. Maximum colonization of A. versicolor on roots was observed in B. firmus + A. versicolor + farmyard manure amended plots. During both years, the treatment combination of A. versicolor in neem compost amended plots resulted in maximum populations of fungi, bacteria and A. versicolor in the soil, which was greater than in the non-amended soil. Significant increases in disease control were not recorded after single or repeated delivery of A. versicolor. These results suggest that combining B. firmus as seed coatings with A. versicolor as soil applications gives improved control of M. phaseolina and Fusarium induced diseases on legume and seed spice crops in arid soils.

  13. Entomopathogenic marine actinomycetes as potential and low-cost biocontrol agents against bloodsucking arthropods.

    Science.gov (United States)

    Loganathan, Karthik; Kumar, Gaurav; Kirthi, Arivarasan Vishnu; Rao, Kokati Venkata Bhaskara; Rahuman, Abdul Abdul

    2013-11-01

    A novel approach to control strategies for integrated blood-feeding parasite management is in high demand, including the use of biological control agents. The present study aims to determine the efficacy of optimized crude extract of actinomycetes strain LK1 as biological control agent against the fourth-instar larvae of Anopheles stephensi and Culex tritaeniorhynchus (Diptera: Culicidae) and adults of Haemaphysalis bispinosa, Rhipicephalus (Boophilus) microplus (Acari: Ixodidae), and Hippobosca maculata (Diptera: Hippoboscidae). Antiparasitic activity was optimized using the Plackett-Burman method, and the design was developed using the software Design-Expert version 8.0.7.1. The production of the optimized crude actinomycetes LK1 strain extract was performed using response surface methodology to optimize the process parameters of protease inhibitor activity of marine actinobacteria for the independent variables like pH, temperature, glucose, casein, and NaCl at two levels (-1 and +1). The potential actinomycetes strain was identified as Saccharomonas spp., and the metamodeling surface simulation procedure was followed. It was studied using a computer-generated experimental design, automatic control of simulation experiments, and sequential optimization of the metamodels fitted to a simulation response surface function. The central composite design (CCD) used for the analysis of treatment showed that a second-order polynomial regression model was in good agreement with the experimental results at R (2) = 0.9829 (p < 0.05). The optimized values of the variables for antioxidant production were pH 6.00, glucose 1.3%, casein 0.09%, temperature 31.23 °C, and NaCl 0.10%. The LK1 strain-optimized crude extract was purified using reversed-phase high-pressure liquid chromatography, and the isolated protease inhibitor showed antiparasitic activity. The antiparasitic activity of optimized crude extract of LK1 was tested against larvae of A. stephensi (LC₅₀ = 31.82 ppm

  14. Occupational exposure to microorganisms used as biocontrol agents in plant production.

    Science.gov (United States)

    Madsen, Anne Mette

    2011-01-01

    Exposure to bioaerosols containing fungi and bacteria may cause various deleterious respiratory health effects. Fungi and bacteria are commercially produced and applied to the environment as microbiological pest control agents (MPCAs). Attention has been drawn towards the exposure and health risks due to the use of commercially important MPCAs. As part of a risk evaluation this paper intends to review whether the exposure to MPCAs (Beauveria bassiana, Verticillium lecanii, Trichoderma harzianum, T. viride, T. polysporum, Paecilomyces fumosoroseus, P. lilacinus, Streptomyces griseoviridis, Bacillus subtilis and Ba. thuringiensis) exceeds background exposure levels. The paper is further aimed to focus on the aerosolization of MPCAs in relation to exposure and human inhalation. From the few studies about exposures it is concluded that both people handling MPCAs in occupational settings and residents of an area where MPCAs have been applied may be exposed to MPCAs. The highest exposures to MPCAs are found for people applying MPCAs. In 2 of 12 environments exposure to applied MPCAs were higher than exposure to the total number of bacteria or fungi.

  15. Use of biocontrol agents and botanicals in integrated management of Botrytis cinerea in table grape vineyards.

    Science.gov (United States)

    Rotolo, Caterina; De Miccolis Angelini, Rita M; Dongiovanni, Crescenza; Pollastro, Stefania; Fumarola, Giulio; Di Carolo, Michele; Perrelli, Donato; Natale, Patrizia; Faretra, Francesco

    2018-03-01

    There is increasing interest in the use of biological control agents (BCAs) and botanicals (BOTs) due to increasing awareness of the environmental and human health risks associated with synthetic plant protection products. The BCAs Bacillus subtilis strain QST713, Bacillus amyloliquefaciens strain D747 and Aureobasidium pullulans strains DSM14940 and DSM14941, and the BOTs Melaleuca alternifolia and terpenic extracts are proposed for the control of grey mould in vineyards. This study was aimed at evaluating their effectiveness in integrated crop management strategies and their outcomes in terms of the management of fungicide resistance and residues. In field trials carried out on table grapes in southern Italy, use of BCAs or BOTs alternately or mixtures of BCAs or BOTs with the succinate dehydrogenase inhibitor fungicide fluopyram showed efficacy of up to 96% against grey mould on bunches, comparable with the chemical reference strategy (up to 87%). By contrast, use of BCAs or BOTs (up to 11 sprays) alone was not effective (integrated use of BCAs or BOTs reduced the spread of succinate dehydrogenase inhibitor-resistant conidia, as well as fungicide residues in grapes. Spray schedules based on integration of BCAs or BOTs with fungicides are effective against grey mould and reduce the risk of fungicide resistance in B. cinerea and fungicide residues in grapes. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  16. Molecular Identification Of Trichoderma Strains Collected To Develop Plant Growth-Promoting And Biocontrol Agents

    Directory of Open Access Journals (Sweden)

    Oskiera Michał

    2015-06-01

    Full Text Available Trichoderma strains that are beneficial to both the growth and health of plants can be used as plant growth-promoting fungi (PGPF or biological control agents (BCA in agricultural and horticultural practices. In order to select PGPF or BCA strains, their biological properties and taxonomy must be carefully studied. In this study, 104 strains of Trichoderma collected at geographically different locations in Poland for selection as PGPF or BCA were identified by DNA barcoding, based on the sequences of internal transcribed spacers 1 and 2 (ITS1 and 2 of the ribosomal RNA gene cluster and on the sequences of translation elongation factor 1 alpha (tef1, chitinase 18-5 (chi18-5, and RNA polymerase II subunit (rpb2 gene fragments. Most of the strains were classified as: T. atroviride (38%, T. harzianum (21%, T. lentiforme (9%, T. virens (9%, and T. simmonsii (6%. Single strains belonging to T. atrobrunneum, T. citrinoviride, T. crassum, T. gamsii, T. hamatum, T. spirale, T. tomentosum, and T. viridescens were identified. Three strains that are potentially pathogenic to cultivated mushrooms belonging to T. pleuroticola and T. aggressivum f. europaeum were also identified. Four strains: TRS4, TRS29, TRS33, and TRS73 were classified to Trichoderma spp. and molecular identification was inconclusive at the species level. Phylogeny analysis showed that three of these strains TRS4, TRS29, and TRS33 belong to Trichoderma species that is not yet taxonomically established and strain TRS73 belongs to the T. harzianum complex, however, the species could not be identified with certainty.

  17. Potential Alternatives to Classical Biocontrol: Using Native Agents in Invaded Habitats and Genetically Engineered Sterile Cultivars for Invasive Plant Management

    Science.gov (United States)

    ShiLi Miao; Yi Li; Qinfeng Guo; Hua Yu; JiangQing Ding; et al.

    2012-01-01

    The development of an effective approach to control and eradication of invasive species has become a major challenge to scientists, managers, and society. Biocontrol has been widely utilized to control exotic plants in the past few decades with some degree of sucess. However, there have been an increasing number of controversies pertaining to this approach, largely...

  18. Potential of osmoadaptation for improving Pantoea agglomerans E325 as biocontrol agent for fire blight of apple and pear

    Science.gov (United States)

    Pantoea agglomerans biocontrol strain E325 is the active ingredient in a commercial product for fire blight, a destructive disease of apple and pear initiated by Erwinia amylovora in flowers. Osmoadaptation, involving the combination of saline osmotic stress and osmolyte amendment to growth media, w...

  19. Study on Interactions between the Major Apple Valsa Canker Pathogen Valsa mali and Its Biocontrol Agent Saccharothrix yanglingensis Hhs.015 Using RT-qPCR.

    Directory of Open Access Journals (Sweden)

    Dongying Fan

    Full Text Available The mechanism of biocontrol agent Saccharothrix yanglingensis Hhs.015 action against Valsa mali, a major apple Valsa canker pathogen, was examined using a novel, sensitive (minimum detection limit 100 pg/μL and reliably RT-qPCR technique. Prior to lesion formation, total concentration of V. mali in the bark showed a significant decrease (p<0.05 after 24 h of Hhs.015 treatment. This was more pronounced at 48 and 96 h post treatment. After lesion formation, levels of V. mali remained constant at the boundary between infected and uninfected bark tissues, although the relative expansion rate of the lesion was significantly reduced (p<0.05. Gene expression levels of endo-polygalacturonase, a marker for fungal pathogenicity, were sharply reduced while host induced resistance callose synthase levels increased significantly (p<0.05 at the boundary bark at 9 d after Hhs.015 treatment. The results showed that biocontrol agent Hhs.015 prevented infection of V. mali by inhibiting pathogen growth, down-regulating pathogenicity factor expression and inducing a high level of host resistance.

  20. Acid tolerance response induced in the biocontrol agent Pantoea agglomerans CPA-2 and effect on its survival ability in acidic environments.

    Science.gov (United States)

    Cañamás, T P; Viñas, I; Abadias, M; Usall, J; Torres, R; Teixidó, N

    2009-01-01

    The aim of this work was to optimize acid stress conditions for induction of acid tolerance response (ATR) in the biocontrol agent Pantoea agglomerans and study the effect of ATR induced on the ability to survive under acidic conditions. Initially, Pantoea agglomerans was grown in mild acidic conditions (pH 6.0, 5.5, 5.0 and 4.0) in order to induce ATR. The highest ATR was induced at initial pH of 5 using malic or citric acid. A first in vitro experiment was carried out. Thus, basal liquid medium at different pHs (3.0, 3.5, 4.0 and non-acidified) were then inoculated with acid-adapted and non-adapted inocula of P. agglomerans and survivals were examined during incubation at 25 or 4 degrees C. It was found that acid adaptation enhanced the survivals of Pantoea agglomerans CPA-2 cells at pH levels at which the cells were unable to grow (Pantoea agglomerans to mild acidic conditions could induce acid resistance in this biocontrol agent.

  1. Biocontrol Agents Increase the Specific Rate of Patulin Production by Penicillium expansum but Decrease the Disease and Total Patulin Contamination of Apples

    Science.gov (United States)

    Zheng, Xiangfeng; Yang, Qiya; Zhang, Xiaoyun; Apaliya, Maurice T.; Ianiri, Giuseppe; Zhang, Hongyin; Castoria, Raffaello

    2017-01-01

    Synthetic fungicides are commonly employed for the control of postharvest diseases of fruits. However, due to health concerns about the use of these chemicals, alternative control methods including biocontrol based on antagonistic yeasts are gaining in popularity. In this study, we investigated the effects of two biocontrol yeasts, Rhodotorula mucilaginosa strain 3617 and Rhodotorula kratochvilovae strain LS11, on blue mold and patulin (PAT) contamination caused by Penicillium expansum strains PY and FS7 in artificially inoculated Fuji apples stored at 20°C for 9 days. To correlate the development of the P. expansum strains in yeast-treated and untreated apples with PAT production, we quantified their biomass in the infected fruits using a recently published quantitative real-time polymerase chain reaction method based on specific primers for patF, a gene from P. expansum that is involved in PAT biosynthesis. Both yeasts significantly reduced the disease incidence caused by the two strains of P. expansum up to 5–7 days of incubation, and lowered their biomass and the progression of symptoms up to 9 days. Interestingly, both yeasts strains increased the rate of PAT production (expressed as ng patulin/μg fungal DNA) by the two pathogenic strains. Nevertheless, both biocontrol agents reduced the total PAT contamination, especially in the case of P. expansum strain FS7, the higher PAT producer of the two tested P. expansum strains. Comparing between the yeast strains, R. kratochvilovae LS11 was more effective than R. mucilaginosa 3617 for the control of P. expansum. PMID:28713362

  2. Dry formulations of the biocontrol agent Candida sake CPA-1 using fluidised bed drying to control the main postharvest diseases on fruits.

    Science.gov (United States)

    Carbó, Anna; Torres, Rosario; Usall, Josep; Fons, Estanislau; Teixidó, Neus

    2017-08-01

    The biocontrol agent Candida sake CPA-1 is effective against several diseases. Consequently, the optimisation of a dry formulation of C. sake to improve its shelf life and manipulability is essential for increasing its potential with respect to future commercial applications. The present study aimed to optimise the conditions for making a dry formulation of C. sake using a fluidised bed drying system and then to determine the shelf life of the optimised formulation and its efficacy against Penicillium expansum on apples. The optimal conditions for the drying process were found to be 40 °C for 45 min and the use of potato starch as the carrier significantly enhanced the viability. However, none of the protective compounds tested increased the viability of the dried cells. A temperature of 25 °C for 10 min in phosphate buffer was considered as the optimum condition to recover the dried formulations. The dried formulations should be stored at 4 °C and air-packaged; moreover, shelf life assays indicated good results after 12 months of storage. The formulated products maintained their biocontrol efficacy. A fluidised bed drying system is a suitable process for dehydrating C. sake cells; moreover, the C. sake formulation is easy to pack, store and transport, and is a cost-effective process. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  3. Efficacy of Bacillus amyloliquefaciens as biocontrol agent to fight fungal diseases of maize under tropical climates: from lab to field assays in south Kivu.

    Science.gov (United States)

    Kulimushi, Parent Zihalirwa; Basime, Géant Chuma; Nachigera, Gustave Mushagalusa; Thonart, Philippe; Ongena, Marc

    2017-06-09

    In the province of South Kivu (Democratic Republic of Congo), warm and humid climatic conditions favor the development and spreading of phytopathogens. The resulting diseases cause important losses in production both in crop and after harvest. In this study, we wanted to evaluate the potential of Bacillus amyloliquefaciens as biocontrol agent to fight some newly isolated endemic fungal pathogens infesting maize. The strain S499 has been selected based on its high in vitro antagonistic activity correlating with a huge potential to secrete fungitoxic lipopeptides upon feeding on maize root exudates. Biocontrol activity of S499 was further tested on infected plantlets in growth chamber and on plants grown under field conditions over an entire cropping period. We observed a strong protective effect of this strain evaluated at two different locations with specific agro-ecological conditions. Interestingly, disease protection was associated with higher yields and our data strongly suggest that, in addition to directly inhibit pathogens, the strain may also act as biofertilizer through the solubilization of phosphorus and/or by producing plant growth hormones in the rhizosphere. This work supports the hope of exploiting such technologically advantageous bacilli for the sake of sustainable local production of this important crop in central Africa.

  4. Trusted intermediating agents in electronic trade networks

    NARCIS (Netherlands)

    T.B. Klos (Tomas); F. Alkemade (Floortje)

    2005-01-01

    htmlabstract Electronic commerce and trading of information goods significantly impact the role of intermediaries: consumers can bypass intermediating agents by forming direct links to producers. One reason that traditional intermediaries can still make a profit, is that they have more knowledge of

  5. Cow dung extract: a medium for the growth of pseudomonads enhancing their efficiency as biofertilizer and biocontrol agent in rice.

    Science.gov (United States)

    Srivastava, Rashmi; Aragno, Michel; Sharma, A K

    2010-09-01

    Some pseudomands are being utilized as biofertilizers and biopesticides because of their role in plant growth promotion and plant protection against root parasites, respectively. Two strains of Pseudomonas, P. jessenii LHRE62 and P. synxantha HHRE81, recovered from wheat rhizosphere, have shown their potential in field bioinoculation tests under rice-wheat and pulse-wheat rotation systems. Normally, pseudomonads are cultivated on synthetic media-like King's B and used for inoculation on seeds/soil drench with talcum or charcoal as carrier material. Cow dung is being used for different purposes from the ancient time and has a significant role in crop growth because of the content in humic compounds and fertilizing bioelements available in it. Here, cow dung extract was tested as a growth medium for strains LHRE62 and HHRE81, in comparison with growth in King's B medium. The log phase was delayed by 2 h as compared to growth in King's B medium. The bacterial growth yield, lower in plain cow dung extract as compared to King's B medium, was improved upon addition of different carbon substrates. Growth of rice var. Pant Dhan 4 in pot cultures was increased using liquid formulation of cow dung extract and bacteria as foliar spray, compared to their respective controls. Biocontrol efficacy of the bioagents was assessed by challenging rice crop with Rhizoctonia solani, a sheath blight pathogen. The growth promotion and biocontrol efficiencies were more pronounced in the case of mixed inocula of strains LHRE62 and HHRE81.

  6. Wheat seeds harbour bacterial endophytes with potential as plant growth promoters and biocontrol agents of Fusarium graminearum.

    Science.gov (United States)

    Díaz Herrera, Silvana; Grossi, Cecilia; Zawoznik, Myriam; Groppa, María Daniela

    2016-01-01

    The role of endophytic communities of seeds is still poorly characterised. The purpose of this work was to survey the presence of bacterial endophytes in the seeds of a commercial wheat cultivar widely sown in Argentina and to look for plant growth promotion features and biocontrol abilities against Fusarium graminearum among them. Six isolates were obtained from wheat seeds following a culture-dependent protocol. Four isolates were assignated to Paenibacillus genus according to their 16S rRNA sequencing. The only gammaproteobacteria isolated, presumably an Enterobactereaceae of Pantoea genus, was particularly active as IAA and siderophore producer, and also solubilised phosphate and was the only one that grew on N-free medium. Several of these isolates demonstrated ability to restrain F. graminearum growth on dual culture and in a bioassay using barley and wheat kernels. An outstanding ability to form biofilm on an inert surface was corroborated for those Paenibacillus which displayed greater biocontrol of F. graminearum, and the inoculation with one of these isolates in combination with the Pantoea isolate resulted in greater chlorophyll content in barley seedlings. Our results show a significant ecological potential of some components of the wheat seed endophytic community. Copyright © 2016 Elsevier GmbH. All rights reserved.

  7. Isolation of a potential biocontrol agent Paenibacillus polymyxa NSY50 from vinegar waste compost and its induction of host defense responses against Fusarium wilt of cucumber.

    Science.gov (United States)

    Du, Nanshan; Shi, Lu; Yuan, Yinghui; Sun, Jin; Shu, Sheng; Guo, Shirong

    2017-09-01

    Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum (FOC) is one of the major destructive soil-borne diseases infecting cucumber. In this study, we screened 60 target strains isolated from vinegar waste compost, from which 10 antagonistic strains were identified to have the disease suppression capacity of bio-control agents. The 16S rDNA gene demonstrated that the biocontrol agents were Paenibacillus polymyxa (P. polymyxa), Bacillus amyloliquefaciens (B. amyloliquefaciens) and Bacillus licheniformis (B. licheniformis). Based on the results of antagonistic activity experiments and pot experiment, an interesting strain of P. polymyxa (named NSY50) was selected for further research. Morphological, physiological and biochemical characteristics indicated that this strain was positive for protease and cellulase and produced indole acetic acid (22.21±1.27μg mL -1 ) and 1-aminocyclopropane-1-carboxylate deaminase (ACCD). NSY50 can significantly up-regulate the expression level of defense related genes PR1 and PR5 in cucumber roots at the early stages upon challenge with FOC. However, the gene expression levels of a set of defense-related genes, such as the plant nucleotide-binding site (NBS)-leucine-rich repeat (LRR) gene family (e.g., Csa001236, Csa09775, Csa018159), 26kDa phloem protein (Csa001568, Csa003306), glutathione-S-transferase (Csa017734) and phenylalanine ammonia-lyase (Csa002864) were suppressed by pretreatment with NSY50 compared with the single challenge with FOC after nine days of inoculation. Of particular interest was the reduced expression of these genes at disease progression stages, which may be required for F. oxysporum dependent necrotrophic disease development. Copyright © 2017 Elsevier GmbH. All rights reserved.

  8. Potential of Epicoccum purpurascens Strain 5615 AUMC as a Biocontrol Agent of Pythium irregulare Root Rot in Three Leguminous Plants.

    Science.gov (United States)

    Koutb, Mostafa; Ali, Esam H

    2010-12-01

    Epicoccum purpurascens stain 5615 AUMC was investigated for its biocontrol activity against root rot disease caused by Pythium irregulare. E. purpurascens greenhouse pathogenicity tests using three leguminous plants indicated that the fungus was nonpathogenic under the test conditions. The germination rate of the three species of legume seeds treated with a E. purpurascens homogenate increased significantly compared with the seeds infested with P. irregulare. No root rot symptoms were observed on seeds treated with E. purpurascens, and seedlings appeared more vigorous when compared with the non-treated control. A significant increase in seedling growth parameters (seedling length and fresh and dry weights) was observed in seedlings treated with E. purpurascens compared to pathogen-treated seedlings. Pre-treating the seeds with the bioagent fungus was more efficient for protecting seeds against the root rot disease caused by P. irregulare than waiting for disease dispersal before intervention. To determine whether E. purpurascens produced known anti-fungal compounds, an acetone extract of the fungus was analyzed by gas chromatography mass spectrometry. The extract revealed a high percentage of the cinnamic acid derivative (trimethylsiloxy) cinnamic acid methyl ester. The E. purpurascens isolate grew more rapidly than the P. irregulare pathogen in a dual culture on potato dextrose agar nutrient medium, although the two fungi grew similarly when cultured separately. This result may indicate antagonism via antibiosis or competition.

  9. Lipopeptides, a novel protein, and volatile compounds contribute to the antifungal activity of the biocontrol agent Bacillus atrophaeus CAB-1.

    Science.gov (United States)

    Zhang, Xiaoyun; Li, Baoqing; Wang, Ye; Guo, Qinggang; Lu, Xiuyun; Li, Shezeng; Ma, Ping

    2013-11-01

    Bacillus atrophaeus CAB-1 displays a high inhibitory activity against various fungal pathogens and suppresses cucumber powdery mildew and tomato gray mold. We extracted and identified lipopeptides and secreted proteins and volatile compounds produced by strain CAB-1 to investigate the mechanisms involved in its biocontrol performance. In vitro assays indicated all three types of products contributed to the antagonistic activity against the fungal pathogen Botrytis cinerea. Each of these components also effectively prevented the occurrence of the cucumber powdery mildew caused by Sphaerotheca fuliginea under greenhouse conditions. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry revealed that the major bioactive lipopeptide was fengycin A (C15-C17). We isolated the crude-secreted proteins of CAB-1 and purified a fraction with antifungal activity. This protein sequence shared a high identity with a putative phage-related pre-neck appendage protein, which has not been reported as an antifungal factor. The volatile compounds produced by CAB-1 were complex, including a range of alcohols, phenols, amines, and alkane amides. O-anisaldehyde represented one of the most abundant volatiles with the highest inhibition on the mycelial growth of B. cinerea. To our knowledge, this is the first report on profiling three types of antifungal substances in Bacilli and demonstrating their contributions to plant disease control.

  10. Biocontrol ability and action mechanismof Starmerella bacillaris (synonym Candida zemplinina) isolated from wine musts against grey mold disease agent Botrytis cinerea on grape and their effects on alcoholic fermentation

    OpenAIRE

    Wilson Josè Fernandes Lemos; Barbara Bovo; Chiara Nadai; Giulia Crosato; Milena Carlot; Francesco Favaron; Alessio Giacomini; Viviana Corich

    2016-01-01

    Gray mold is one of the most important diseases of grapevine in temperate climates. This plant pathogen affects plant growth and reduces wine quality. The use of yeasts as biocontrol agents to apply in the vineyard have been investigated in recent years as an alternative to agrochemicals. In this work, fermenting musts obtained from overripe grape berries, therefore more susceptible to infection by fungal pathogens such as Botrytis cinerea, were considered for the selection of yeasts carrying...

  11. Influence of container design on predation rate of potential biocontrol agent, Toxorhynchites splendens (Diptera: Culicidae) against dengue vector.

    Science.gov (United States)

    Mohamad, N; Zuharah, W F

    2014-03-01

    Toxorhynchites splendens larvae are a natural predator of dengue vector mosquito larvae, Aedes albopictus. This study was carried out to evaluate the predation rate of Tx. splendens third instar larvae on Ae. albopictus larvae in 24 h. Each predator was offered prey at a density between 10 to 50 individuals. Predation rate of Tx. splendens were also tested with two manipulated factors; various types of container and different water volumes. The experiment was evaluated in man-made containers (tin cans, plastic drinking glasses and rubber tires) and natural container (bamboo stumps) which were filled with different water volumes (full, half full, 1/4 full, and 1/8 full). The prey density and the characteristics of the container were found as significant factors which influence the predation rate of Tx. splendens. The predator consumed significantly more prey at higher prey densities (40 and 50 preys) compared to the lowest density (10 preys) (F=3.935, df=4, p=0.008). The results showed significantly higher consumption in horizontal shaped container of rubber tire than in vertical shape of bamboo stumps (F=3.100, df=3, p=0.029). However, the water volume had no significant effect on predation rate of Tx. splendens (F=1.736, df=3, p=0.162). We generally suggest that Tx. splendens is best to be released in discarded tires or any other containers with horizontal shape design with wide opening since Tx. splendens can become more effective in searching prey in this type of container design. This predator is also a suitable biocontrol candidates to be introduced either in wet and dry seasons in Malaysia.

  12. Streptomyces rochei ACTA1551, an indigenous Greek isolate studied as a potential biocontrol agent against Fusarium oxysporum f.sp. lycopersici.

    Science.gov (United States)

    Kanini, Grammatiki S; Katsifas, Efstathios A; Savvides, Alexandros L; Karagouni, Amalia D

    2013-01-01

    Many studies have shown that several Greek ecosystems inhabit very interesting bacteria with biotechnological properties. Therefore Streptomyces isolates from diverse Greek habitats were selected for their antifungal activity against the common phytopathogenic fungus Fusarium oxysporum. The isolate encoded ACTA1551, member of Streptomyces genus, could strongly suppress the fungal growth when examined in antagonistic bioassays in vitro. The isolate was found phylogenetically relative to Streptomyces rochei after analyzing its 16S rDNA sequence. The influence of different environmental conditions, such as medium composition, temperature, and pH on the expression of the antifungal activity was thoroughly examined. Streptomyces rochei ACTA1551 was able to protect tomato seeds from F. oxysporum infection in vivo while it was shown to promote the growth of tomato plants when the pathogen was absent. In an initial effort towards the elucidation of the biochemical and physiological nature of ACTA1551 antifungal activity, extracts from solid streptomycete cultures under antagonistic or/and not antagonistic conditions were concentrated and fractionated. The metabolites involved in the antagonistic action of the isolate showed to be more than one and produced independently of the presence of the pathogen. The above observations could support the application of Streptomyces rochei ACTA1551 as biocontrol agent against F. oxysporum.

  13. Streptomyces rochei ACTA1551, an Indigenous Greek Isolate Studied as a Potential Biocontrol Agent against Fusarium oxysporum f.sp. lycopersici

    Directory of Open Access Journals (Sweden)

    Grammatiki S. Kanini

    2013-01-01

    Full Text Available Many studies have shown that several Greek ecosystems inhabit very interesting bacteria with biotechnological properties. Therefore Streptomyces isolates from diverse Greek habitats were selected for their antifungal activity against the common phytopathogenic fungus Fusarium oxysporum. The isolate encoded ACTA1551, member of Streptomyces genus, could strongly suppress the fungal growth when examined in antagonistic bioassays in vitro. The isolate was found phylogenetically relative to Streptomyces rochei after analyzing its 16S rDNA sequence. The influence of different environmental conditions, such as medium composition, temperature, and pH on the expression of the antifungal activity was thoroughly examined. Streptomyces rochei ACTA1551 was able to protect tomato seeds from F. oxysporum infection in vivo while it was shown to promote the growth of tomato plants when the pathogen was absent. In an initial effort towards the elucidation of the biochemical and physiological nature of ACTA1551 antifungal activity, extracts from solid streptomycete cultures under antagonistic or/and not antagonistic conditions were concentrated and fractionated. The metabolites involved in the antagonistic action of the isolate showed to be more than one and produced independently of the presence of the pathogen. The above observations could support the application of Streptomyces rochei ACTA1551 as biocontrol agent against F. oxysporum.

  14. Field observation on the efficacy of Toxorhynchites splendens (Wiedemann) as a biocontrol agent against Aedes albopictus (Skuse) larvae in a cemetery.

    Science.gov (United States)

    Nyamah, M A; Sulaiman, S; Omar, B

    2011-08-01

    This study explored the efficacy of Toxorhynchites splendens, predator of Aedes albopictus as a biocontrol agent. There was a negative correlation between Ae. albopictus larval population and Tx. splendens larval population in ovitraps (r=-0.287, R²=0.0821). The correlation is higher between the mean number of Ae. albopictus larvae per ovitrap and the number of Tx. splendens larvae in an ovitrap (r=-0.987, R²=0.9737). Larvae of Tx. splendens were observed to co-exist with larvae of Ae. albopictus and Culex fuscocephala in the ovitraps placed in the study area. The existence of Tx. splendens larvae in the study area coincides with their habit, preferring to breed in bamboo stumps. A total of 480 ovitraps were inspected for 30-week study period and 281 ovitraps were positive with Ae. albopictus larvae respectively. There was a significant difference between numbers of ovitrap positive for Ae. albopictus larvae with number of Tx. splendens larvae in the ovitraps (ANOVA, F((4,475)) 2.655, p<0.05). Of 281 ovitraps positive with Ae. albopictus larvae, 255 ovitraps contained only one Tx. splendens larva each. Only one ovitrap contained four, the most number of Tx. splendens larvae (p< 0.05). Thus, Tx. splendens could be utilised as an alternative for dengue vector control programme.

  15. Beneficial effects of bio-controlling agent Bacillus cereus IB311 on the agricultural crop production and its biomass optimization through response surface methodology

    Directory of Open Access Journals (Sweden)

    GOUTAM BANERJEE

    2017-10-01

    Full Text Available ABSTRACT Disease in agricultural field is a big problem that causes a massive loss in production. In this present investigation, we have reported a soil-borne bacterium Bacillus cereus IB311 which is antagonistic to plant pathogens (Pseudomonas syringae and Agrobacterium tumefaciens, and could make a substantial contribution to the prevention of plant diseases. To prove the practical application, the strain was directly applied in agricultural field. The results demonstrated that B. cereus IB311 has increased the production (20% and 26% in term of average pod number per plant, average seed number per pod, and seed yield per experimental plot in ground nut (Arachis hypogaea var. Koushal, G201 and sesame (Sesamum indicum var. Kanak, respectively. To reduce the production cost, the biomass production was optimized through response surface methodology (RSM. Interactions of three variables (glucose, beef extract and inoculum were studied using Central Composite Design. According to our analysis, optimum production of Bacillus cereus IB311 (5.383 µg/ mL may be obtained at glucose 1.985%, beef extract 1.615% and inoculums size 0.757%. Therefore, we strongly believe that the application of this strain in agricultural field as bio-controlling agent will definitely enhance the production yield and will reduce the disease risk.

  16. Identification and characterization of a new Bacillus atrophaeus strain B5 as biocontrol agent of postharvest anthracnose disease in soursop (Annona muricata) and avocado (Persea americana).

    Science.gov (United States)

    Guardado-Valdivia, Lizeth; Tovar-Pérez, Erik; Chacón-López, Alejandra; López-García, Ulises; Gutiérrez-Martínez, Porfirio; Stoll, Alexandra; Aguilera, Selene

    2018-05-01

    Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous fruit, including soursop and avocado. The use of fungicides to maintain the high quality of fruit creates a potential health risk. One alternative to this problem is the biological control, which has been applied successfully during postharvest. The Bacillus species are one of the most studied biological agents against postharvest pathogens because accomplish their biocontrol performance by producing a variety of metabolites. In this study, we evaluated the activity of metabolites contained in the cell free supernatant, obtained from Bacillus strain B5 culture, against micelial growth and spore germination of two virulent strains of C. gloeosporioides isolated from soursop and avocado. On the basis of 16S rDNA gene sequence analysis, this strain was identified as Bacillus atrophaeus. A preventive treatment using cell free supernatant, reduced severity and incidence of anthracnose disease on harvested soursop and avocado fruit. B. atrophaeus strain B5 harbors genes involved in the production of antibiotics such as surfactin, bacillomycin and iturin, which could be contributing to the efficiency of the preventive treatment during postharvest. The antagonistic role of metabolites contained in the cell free supernatant against anthracnose disease, provide a new approach by which to attack this problem and can help reduce the use of chemical pesticides, environmental pollution, leading to the safer fruit preservation. Copyright © 2018 Elsevier GmbH. All rights reserved.

  17. The development of genetic and molecular markers to register and commercialize Penicillium rubens (formerly Penicillium oxalicum) strain 212 as a biocontrol agent.

    Science.gov (United States)

    Villarino, Maria; De Cal, Antonieta; Melgarejo, Paloma; Larena, Inmaculada; Espeso, Eduardo A

    2016-01-01

    Penicillium oxalicum strain 212 (PO212) is an effective biocontrol agent (BCA) against a large number of economically important fungal plant pathogens. For successful registration as a BCA in Europe, PO212 must be accurately identified. In this report, we describe the use of classical genetic and molecular markers to characterize and identify PO212 in order to understand its ecological role in the environment or host. We successfully generated pyrimidine (pyr-) auxotrophic mutants. In addition we also designed specific oligonucleotides for the pyrF gene at their untranslated regions for rapid and reliable identification and classification of strains of P. oxalicum and P. rubens, formerly P. chrysogenum. Using these DNA-based technologies, we found that PO212 is a strain of P. rubens, and is not a strain of P. oxalicum. This work presents PO212 as the unique P. rubens strain to be described as a BCA and the information contained here serves for its registration and commercialization in Europe. © 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  18. Production and characterization of rhamnolipids produced by Serratia rubidaea SNAU02 under solid-state fermentation and its application as biocontrol agent.

    Science.gov (United States)

    Nalini, S; Parthasarathi, R

    2014-12-01

    The present study aimed at exploring mahua (Madhuca indica) oil cake as a novel substrate for the production of biosurfactant by Serratia rubidaea SNAU02 under solid-state fermentation (SSF). Response surface methodology showed followings as the optimal conditions for the production of biosurfactant: mahua oil cake 7.48 g, 2.5 ml inoculum size (1×10(8) cells/ml), and pH 7.22 and 31 °C temperature. The characterization of the biosurfactant by TLC, FT-IR and GC-MS revealed the presence of rhamnolipid. The presence of rhamnosyl transferase gene responsible for biosynthesis of rhamnolipid was identified. The strain SNAU02 exhibited antifungal activity and demonstrated no toxicity against the seeds of Brassica oleracea and Artemia salina employed as a bio-indicator. The present findings indicated the potential of mahua oil cake as suitable substrate for the production of rhamnolipids in SSF by S. rubidaea SNAU02 and application potential of the biosurfactant produced as biocontrol agent against plant pathogens. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Study on optimum growth condition and designing formulation for increasing shelf life of Streptomyces rimosus strain C-2012 as biocontrol agent

    Directory of Open Access Journals (Sweden)

    Ebrahim Karimi

    2015-12-01

    Full Text Available Introduction: An important issue in microbial biotechnology is linkage between screened beneficial strains in laboratory and industry. Therefore, to develop beneficial microbial biocontrol agents; optimization of nutritional and physiological condition for high level production and selection of carrier for final formulation are necessary. In this research we tried to find the best growth condition and suitable formulation for biocontrol Streptomyces rimosus strain C-2012. Materials and methods: For optimization of growth condition of strain C-2012, utilization of carbon sources, growth in different media, effect of temperature, pH and NaCl were investigated. Then the effect of different carriers and additives in final formulation and shelf life of microbial community were studied. Results: Study on utilization of carbon sources showed that glucose, fructose and mannitole were suitable carbon sources for growth and the best initial pH and temperature were 7 and 28°C, respectively. Results showed that the culture medium containing glucose, yeast extract and malt extract was the best medium. Investigation on NaCl effect showed that from 0 up to 300 mM sodium chloride could increase microbial community and salinity more than this range decreased microbial community. Based on the results we found that sand is suitable as microbial carrier comparing hydrogel polymers. Viability test during 36 months showed that formulation with NaCl content could keep 200 times (8*106 cfu/g more than samples without salinity at last month. Discussion and conclusion: Using suitable carbon sources such as glucose at 28 °C and pH at 7 are important items in optimum growth and preparing final formulation with good level of microbial community. Capability in secondary volatile and liquid metabolites production and fungal pathogen control by Streptomyces rimosus in the presence of NaCl showed that this strain has high potentiality to apply in both normal and saline area

  20. Genomic and metabolic traits endow Bacillus velezensis CC09 with a potential biocontrol agent in control of wheat powdery mildew disease.

    Science.gov (United States)

    Cai, Xun-Chao; Liu, Chang-Hong; Wang, Bao-Tong; Xue, Ya-Rong

    2017-03-01

    Bacillus velezensis CC09, which was isolated from healthy leaves of Cinnamomum camphora and previously identified as Bacillus amyloliquefaciens CC09, shows great potential as a new biocontrol agent, in control of many phytopathogenic diseases. To extend our understanding of the potential antifungal capacities, we did a whole genome analysis of strain CC09. Result shows that strain CC09 has a relatively large genome size (4.17Mb) with an average GC content of 46.1%, and 4021 predicted genes. Thirteen secondary metabolites encoding clusters have been identified within the genome of B. velezensis CC09 using genome mining technique. Data of comparative genomic analysis indicated that 3 of the clusters are conserved by all strains of B. velezensis, B. amyloliquefaciens and B. subtilis 168, 9 by B. velezensis and B. amyloliquefaciens, and 2 by all strains of B. velezensis. Another 2 clusters encoding NRPS (Non-Ribosomal Peptide Synthetases) and NRPS-TransATPKS (NRPS and trans-Acyl Transferase Polyketide Synthetases) respectively are observed only in 15 B. velezensis strains, which might lead to the synthesis of novel bioactive compounds and could be explored as antimicrobial agents in the future. These clusters endow B. velezensis CC09 with strong and broad antimicrobial activities, for example, in control of wheat powdery mildew disease. Moreover, our data further confirmed the taxonomy of strain CC09 is a member of B. velezensis rather than a strain of B. amyloliquefaciens based on core genome sequence analysis using phylogenomic approach. Copyright © 2016 Elsevier GmbH. All rights reserved.

  1. Whole genome sequencing of the Braconid parasitoid wasp Fopius arisanus, an important biocontrol agent of pest Tepritid fruit flies

    Science.gov (United States)

    The braconid wasp Fopius arisanus (Sonan) is an important biological control agent of tropical and subtropical pest fruit flies including two important global pests, the Mediterranean fruit fly (Ceratitis capitata), and the oriental fruit fly (Bactrocera dorsalis}). The goal of this study was to dev...

  2. The Potential Application and Risks Associated With the Use of Predatory Bacteria as a Biocontrol Agent Against Wound Infections

    Science.gov (United States)

    2014-09-01

    temperature of 39oC. Aim II. Determining the effect of predatory bacteria on eukaryotic cells . Although the effect of predation on prokaryotic Gram...negative cells is documented, limited data is available regarding predation on eukaryotic cells . As the goal of our research is to utilize predatory...bio-control agent. The goal of this aim is to determine if predatory bacteria have an adverse affect on eukaryotic cells . The aim is divided into

  3. Mejora de la eficacia de Penicillium oxalicum como agente de biocontrol en enfermedades de plantas hortícolas

    OpenAIRE

    Vázquez García, Gema

    2014-01-01

    Actualmente, la reducción de materias activas (UE) y la implantación de la nueva Directiva comunitaria 2009/128/ que establece el marco de actuación para conseguir un uso sostenible de los plaguicidas químicos y la preferencia de uso de métodos biológicos, físicos y otros no químicos, obliga a buscar métodos de control menos perjudiciales para el medio ambiente. El control biológico (CB) de enfermedades vegetales empleando agentes de control biológico (ACB) se percibe como una alternativa más...

  4. Assessment of the potential of competitor snails and African catfish (Clarias gariepinus) as biocontrol agents against snail hosts transmitting schistosomiasis.

    Science.gov (United States)

    Gashaw, Fikru; Erko, Berhanu; Teklehaymanot, Tilahun; Habtesellasie, Redeat

    2008-08-01

    The objective of this study was to assess the potential of the snails Physa acuta and Melanoides tuberculata and the African catfish Clarias gariepinus as biological control agents against the Schistosoma mansoni intermediate host Biomphalaria pfeifferi under laboratory conditions. Groups of five target and five competitor snails were raised together in experimental aquaria and same number in separate aquaria as controls. Shell size, number of eggs and mortality rate were recorded for twelve consecutive weeks. The stocking density for C. gariepinus was one fish per aquarium. Fish were provided with adequate or inadequate supplementary food and fifteen B. pfeifferi were added to each aquarium. The snails and their eggs were counted daily. Significant differences in shell growth and fecundity were noted between B. pfeifferi and M. tuberculata. Physa acuta was noted to be voracious in food consumption. Snail consumption was faster by fish provided with inadequate supplementary food. Based on the present findings, it is suggested that the two competitor snails and African catfish could be used as biological control agents against B. pfeifferi. Nevertheless, the susceptibility of the competitor snails to other trematodes in Ethiopia must first be ruled out before introducing these snails into new habitats. Follow-up field observation and rigorous laboratory studies remain areas for further research.

  5. Methods for the Evaluation of the Bioactivity and Biocontrol Potential of Species of Trichoderma.

    Science.gov (United States)

    Steyaert, Johanna; Hicks, Emily; Kandula, Janaki; Kandula, Diwakar; Alizadeh, Hossein; Braithwaite, Mark; Yardley, Jessica; Mendoza-Mendoza, Artemio

    2016-01-01

    Members of the genus Trichoderma comprise the majority of commercial fungal biocontrol agents of plant diseases. As such, there is a wealth of information available on the analysis of their biocontrol potential and the mechanisms behind their superior abilities. This chapter aims to summarize the most common methods utilized within a Trichoderma biocontrol program for assessing the biological properties of individual strains.

  6. Tailoring biocontrol to maximize top-down effects: on the importance of underlying site fertility.

    Science.gov (United States)

    Hovick, Stephen M; Carson, Walter P

    2015-01-01

    The degree to which biocontrol agents impact invasive plants varies widely across landscapes, often for unknown reasons. Understanding this variability can help optimize invasive species management while also informing our understanding of trophic linkages. To address these issues, we tested three hypotheses with contrasting predictions regarding the likelihood of biocontrol success. (1) The biocontrol effort hypothesis: invasive populations are regulated primarily by top-down effects, predicting that increased biocontrol efforts alone (e.g., more individuals of a given biocontrol agent or more time since agent release) will enhance biocontrol success. (2) The relative fertility hypothesis: invasive populations are regulated primarily by bottom-up effects, predicting that nutrient enrichment will increase dominance by invasives and thus reduce biocontrol success, regardless of biocontrol efforts. (3) The fertility-dependent biocontrol effort hypothesis: top-down effects will only regulate invasive populations if bottom-up effects are weak. It predicts that greater biocontrol efforts will increase biocontrol success, but only in low-nutrient sites. To test these hypotheses, we surveyed 46 sites across three states with prior releases of Galerucella beetles, the most common biocontrol agents used against invasive purple loosestrife (Lythrum salicaria). We found strong support for the fertility-dependent biocontrol effort hypothesis, as biocontrol success occurred most often with greater biocontrol efforts, but only in low-fertility sites. This result held for early stage metrics of biocontrol success (higher Galerucella abundance) and ultimate biocontrol outcomes (decreased loosestrife plant size and abundance). Presence of the invasive grass Phalaris arundinacea was also inversely related to loosestrife abundance, suggesting that biocontrol-based reductions in loosestrife made secondary invasion by P. arundinacea more likely. Our data suggest that low-nutrient sites

  7. Whole Genome Sequencing of the Braconid Parasitoid Wasp Fopius arisanus, an Important Biocontrol Agent of Pest Tepritid Fruit Flies

    Directory of Open Access Journals (Sweden)

    Scott M. Geib

    2017-08-01

    Full Text Available The braconid wasp Fopius arisanus (Sonan is an important biological control agent of tropical and subtropical pest fruit flies, including two important global pests, the Mediterranean fruit fly (Ceratitis capitata, and the oriental fruit fly (Bactrocera dorsalis. The goal of this study was to develop foundational genomic resources for this species to provide tools that can be used to answer questions exploring the multitrophic interactions between the host and parasitoid in this important research system. Here, we present a whole genome assembly of F. arisanus, derived from a pool of haploid offspring from a single unmated female. The genome is ∼154 Mb in size, with a N50 contig and scaffold size of 51,867 bp and 0.98 Mb, respectively. Utilizing existing RNA-Seq data for this species, as well as publicly available peptide sequences from related Hymenoptera, a high quality gene annotation set, which includes 10,991 protein coding genes, was generated. Prior to this assembly submission, no RefSeq proteins were present for this species. Parasitic wasps play an important role in a diverse ecosystem as well as a role in biological control of agricultural pests. This whole genome assembly and annotation data represents the first genome-scale assembly for this species or any closely related Opiine, and are publicly available in the National Center for Biotechnology Information Genome and RefSeq databases, providing a much needed genomic resource for this hymenopteran group.

  8. Genome Sequence, Assembly and Characterization of Two Metschnikowia fructicola Strains Used as Biocontrol Agents of Postharvest Diseases

    Directory of Open Access Journals (Sweden)

    Edoardo Piombo

    2018-04-01

    Full Text Available The yeast Metschnikowia fructicola was reported as an efficient biological control agent of postharvest diseases of fruits and vegetables, and it is the bases of the commercial formulated product “Shemer.” Several mechanisms of action by which M. fructicola inhibits postharvest pathogens were suggested including iron-binding compounds, induction of defense signaling genes, production of fungal cell wall degrading enzymes and relatively high amounts of superoxide anions. We assembled the whole genome sequence of two strains of M. fructicola using PacBio and Illumina shotgun sequencing technologies. Using the PacBio, a high-quality draft genome consisting of 93 contigs, with an estimated genome size of approximately 26 Mb, was obtained. Comparative analysis of M. fructicola proteins with the other three available closely related genomes revealed a shared core of homologous proteins coded by 5,776 genes. Comparing the genomes of the two M. fructicola strains using a SNP calling approach resulted in the identification of 564,302 homologous SNPs with 2,004 predicted high impact mutations. The size of the genome is exceptionally high when compared with those of available closely related organisms, and the high rate of homology among M. fructicola genes points toward a recent whole-genome duplication event as the cause of this large genome. Based on the assembled genome, sequences were annotated with a gene description and gene ontology (GO term and clustered in functional groups. Analysis of CAZymes family genes revealed 1,145 putative genes, and transcriptomic analysis of CAZyme expression levels in M. fructicola during its interaction with either grapefruit peel tissue or Penicillium digitatum revealed a high level of CAZyme gene expression when the yeast was placed in wounded fruit tissue.

  9. Chitinolytic activity of endophytic Streptomyces and potential for biocontrol.

    Science.gov (United States)

    Quecine, M C; Araujo, W L; Marcon, J; Gai, C S; Azevedo, J L; Pizzirani-Kleiner, A A

    2008-12-01

    Biological sources for the control of plant pathogenic fungi remain an important objective for sustainable agricultural practices. Actinomycetes are used extensively in the pharmaceutical industry and agriculture owing to their great diversity in enzyme production. In the present study, therefore, we evaluated chitinase production by endophytic actinomycetes and the potential of this for control of phytopathogenic fungi. Endophytic Streptomyces were grown on minimum medium supplemented with chitin, and chitinase production was quantified. The strains were screened for any activity towards phytopathogenic fungi and oomycetes by a dual-culture in vitro assay. The correlation between chitinase production and pathogen inhibition was calculated and further confirmed on Colletotrichum sublineolum cell walls by scanning electron microscopy. This paper reports a genetic correlation between chitinase production and the biocontrol potential of endophytic actinomycetes in an antagonistic interaction with different phytopathogens, suggesting that this control could occur inside the host plant. A genetic correlation between chitinase production and pathogen inhibition was demonstrated. Our results provide an enhanced understanding of endophytic Streptomyces and its potential as a biocontrol agent. The implications and applications of these data for biocontrol are discussed.

  10. Characterization and Genomic Study of the Novel Bacteriophage HY01 Infecting Both Escherichia coli O157:H7 and Shigella flexneri: Potential as a Biocontrol Agent in Food.

    Directory of Open Access Journals (Sweden)

    Heyn Lee

    Full Text Available Escherichia coli O157:H7 and Shigella flexneri are well-known food-borne pathogens causing severe food poisoning at low infectious doses. Bacteriophages have been approved for food applications by the US Food and Drug Administration (FDA and have been suggested as natural food preservatives to control specific food-borne pathogens. To develop a novel natural food preservative against E. coli O157:H7 and S. flexneri, a new bacteriophage needs to be isolated and characterized.Bacteriophage HY01 infecting both E. coli O157:H7 and S. flexneri was isolated from a swine fecal sample. HY01 belongs to the family Myoviridae and is stable under various temperature and pH conditions. One-step growth curve analysis showed relatively short eclipse and latent periods as well as large burst size. The 167-kb genome sequence of HY01 was sequenced, and a comparative genome analysis with T4 for non-O157:H7 E. coli suggests that the receptor recognition protein of HY01 plays an important role in determination of host recognition and specificity. In addition, food applications using edible cabbage were conducted with two E. coli O157:H7 strains (ATCC 43890 and ATCC 43895, showing that treatment with HY01 inhibits these clinical and food isolates with >2 log reductions in bacterial load during the first 2 h of incubation.HY01 can inhibit both E. coli O157:H7 and S. flexneri with large burst size and stability under stress conditions. The ability of HY01 to infect both E. coli O157:H7 and S. flexneri may be derived from the presence of two different host specificity-associated tail genes in the genome. Food applications revealed the specific ability of HY01 to inhibit both pathogens in food, suggesting its potential as a novel biocontrol agent or novel natural food preservative against E. coli O157:H7 and potentially S. flexneri.

  11. The roles of inoculants' carbon source use in the biocontrol of potato scab disease.

    Science.gov (United States)

    Sun, Pingping; Zhao, Xinbei; Shangguan, Nini; Chang, Dongwei; Ma, Qing

    2015-04-01

    Despite the application of multiple strains in the biocontrol of plant diseases, multistrain inoculation is still constrained by its inconsistency in the field. Nutrients, especially carbons, play an important role in the biocontrol processes. However, little work has been done on the systematic estimation of inoculants' carbon source use on biocontrol efficacies in vivo. In the present study, 7 nonpathogenic Streptomyces strains alone and in different combinations were inoculated as biocontrol agents against the potato scab disease, under field conditions and greenhouse treatments. The influence of the inoculants' carbon source use properties on biocontrol efficacies was investigated. The results showed that increasing the number of inoculated strains did not necessarily result in greater biocontrol efficacy in vivo. However, single strains with higher growth rates or multiple strains with less carbon source competition had positive effects on the biocontrol efficacies. These findings may shed light on optimizing the consistent biocontrol of plant disease with the consideration of inoculants' carbon source use properties.

  12. Construction of new GFP-tagged fusants for Trichoderma harzianum with enhanced biocontrol activity

    Directory of Open Access Journals (Sweden)

    Kowsari Mojegan

    2014-07-01

    Full Text Available Trichoderma is one of the most exploited biocontrol agents for the management of plant diseases. In biocontrol ecology, the critical factors are detection, and the monitoring and recovery of specific biocontrol agents either naturally present or deliberately released into the environment. Protoplast fusion is an appropriate tool for the improvement of biocontrol Trichoderma strains. Protoplast isolation from Trichoderma harzianum was achieved using 24 h culture age, 6.6 mg/ml Novazym L 1412 at 30°C which resulted the maximum protoplast yield of 5 × 108/ml. The self-fused protoplasts were regenerated and 12 fusants were selected based on their growth rate on 2% colloidal chitin medium. Next, a comparison was done for chitinase and antagonistic activity. Transcriptomic analysis based on quantitative real-time RT-PCR, demonstrated that T8-05 fusant expressed 1.5 fold of chit42 transcript as compared with the parental line. This fusant with 7.02±0.15U chitinase activity showed a higher growth inhibition rate (100% than the parent strain, against Rhizoctonia solani. To obtain a genetically marked fusant that can be used as a biomonitor, the fusant was cotransformed with the gfp and amdS genes. The morphology and viability of selected cotransformant (FT8-7MK-05-2 was similar to the parent. Green fluorescing conidia were observed within the first 2 days of incubation in the soil, and this was followed by the formation of chlamydopores after 60 days. The colonisation of the gfp-tagged fusant was also monitored visually on R. solani sclerotia by scanning electron microscopy. Production of gfp-tagged fusant of Trichoderma spp. provides a potentially useful tool for monitoring hyphal growth patterns and the population of biocontrol agent isolates introduced into environmental systems.

  13. Short communication. A review on the efficacy tests and risk analyses conducted on Chondrostereum purpureum, a potential biocontrol agent, in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Hantula, J.; Hamberg, L.; Vartiamaki, H.; Korhonen, K.; Uotila, A.

    2012-11-01

    Hardwood sprouting is a problem in forest regeneration areas, under electric lines, on roadsides and railways. In Finland, isolates of Chondrostereum purpureum were screened by field experiments for their efficiency to control sprouting. The proportion of dead stumps with the best isolates exceeded 80% on birch (Betula pendula and B. pubescens), and C. purpureum was also found to affect the sprouting of aspen (Populus tremula) and rowan (Sorbus aucuparia). The risks of C. purpureum based biocontrol were evaluated by population genetic analysis. It showed that C. purpureum is a geographically undifferentiated species that does not reproduce clonally. The risk of infection of non-target trees was found to be highest in early spring. These findings suggest that the risks of using C. purpureum in biocontrol are small. (Author) 36 refs.

  14. METAL CHELATING AGENTS IV: ELECTRON IONIZATION AND ...

    African Journals Online (AJOL)

    The electron ionization (EI) and ammonia chemical ionization [CI (NH3)] mass spectral studies on 2-phenyl acetophenone semicarbazone are reported. The El spectrum shows a clearly identifiable molecular ion peak of weak intensity at m/z 253 and the base peak is observed at m/z 77. The CI (NH3) spectrum is ...

  15. Beyond electronic disintermediation through multi-agent systems

    OpenAIRE

    Nissen, Mark E.

    2001-01-01

    Supply chain management represents a critical competency in today's global business environment and has been the focus of considerable, but mixed, information systems research. The research described in this paper builds on work in multi-agent systems to argue that intelligent agents offer excellent potential and capability for supply chain management, and contributes to discussion and theory pertaining to electronic markets and supply chain disintermediation. Argues t...

  16. Dynamic electronic institutions in agent oriented cloud robotic systems.

    Science.gov (United States)

    Nagrath, Vineet; Morel, Olivier; Malik, Aamir; Saad, Naufal; Meriaudeau, Fabrice

    2015-01-01

    The dot-com bubble bursted in the year 2000 followed by a swift movement towards resource virtualization and cloud computing business model. Cloud computing emerged not as new form of computing or network technology but a mere remoulding of existing technologies to suit a new business model. Cloud robotics is understood as adaptation of cloud computing ideas for robotic applications. Current efforts in cloud robotics stress upon developing robots that utilize computing and service infrastructure of the cloud, without debating on the underlying business model. HTM5 is an OMG's MDA based Meta-model for agent oriented development of cloud robotic systems. The trade-view of HTM5 promotes peer-to-peer trade amongst software agents. HTM5 agents represent various cloud entities and implement their business logic on cloud interactions. Trade in a peer-to-peer cloud robotic system is based on relationships and contracts amongst several agent subsets. Electronic Institutions are associations of heterogeneous intelligent agents which interact with each other following predefined norms. In Dynamic Electronic Institutions, the process of formation, reformation and dissolution of institutions is automated leading to run time adaptations in groups of agents. DEIs in agent oriented cloud robotic ecosystems bring order and group intellect. This article presents DEI implementations through HTM5 methodology.

  17. Agent-based services for B2B electronic commerce

    Science.gov (United States)

    Fong, Elizabeth; Ivezic, Nenad; Rhodes, Tom; Peng, Yun

    2000-12-01

    The potential of agent-based systems has not been realized yet, in part, because of the lack of understanding of how the agent technology supports industrial needs and emerging standards. The area of business-to-business electronic commerce (b2b e-commerce) is one of the most rapidly developing sectors of industry with huge impact on manufacturing practices. In this paper, we investigate the current state of agent technology and the feasibility of applying agent-based computing to b2b e-commerce in the circuit board manufacturing sector. We identify critical tasks and opportunities in the b2b e-commerce area where agent-based services can best be deployed. We describe an implemented agent-based prototype system to facilitate the bidding process for printed circuit board manufacturing and assembly. These activities are taking place within the Internet Commerce for Manufacturing (ICM) project, the NIST- sponsored project working with industry to create an environment where small manufacturers of mechanical and electronic components may participate competitively in virtual enterprises that manufacture printed circuit assemblies.

  18. Influence of Environmental Parameters on Trichoderma Strains with Biocontrol Potential

    Directory of Open Access Journals (Sweden)

    Zsuzsanna Antal

    2003-01-01

    Full Text Available Several mycoparasitic strains belonging to the filamentous fungal genus Trichoderma are promising candidates for the biological control of plant pathogenic fungi. When planning the application of antagonistic Trichoderma strains for the purposes of biological control, it is very important to consider the environmental parameters affecting the biocontrol agents in the soil. A series of abiotic and biotic environmental parameters has an influence on the biocontrol efficacy of Trichoderma. Some important parameters to be considered are the effects of temperature, water potential and pH, and the presence of pesticides, metal ions and antagonistic bacteria in the soil. Most of the Trichoderma strains are mesophilic. Low temperatures in winter may cause a problem during biological control by influencing the activity of the biocontrol agents. Another problem emerging during the application of Trichoderma strains as biocontrol agents is that they cannot tolerate dry conditions, however, we may need biocontrol agents against plant pathogenic fungi which are able to grow and cause disease even in dry soils. The pH characteristics of the soil also belong to the most important environmental parameters affecting the activities of mycoparasitic Trichoderma strains. Within the frames of a complex integrated plant protection strategy, we may have to combine Trichoderma strains with chemical pesticides or metal compounds, therefore it is important to collect information about the effects of pesticides and metal ions on the biocontrol strains. Antagonistic soil bacteria may also have negative effects on the biocontrol abilities of Trichoderma strains, therefore it may be advantageous if a biocontrol strain possesses bacterium- degrading abilities as well. This review will discuss the literature about the influence of temperature, water potential, pH, pesticides, metal ions and antagonistic bacteria on mycoparasitic Trichoderma strains including the results of our

  19. Agent Technologies in the Electronic Classroom: Some Pedagogical Issues.

    Science.gov (United States)

    Dowling, Carolyn

    The use of intelligent software agents within computer mediated learning environments has become an important focus of research and development in both AI and educational contexts. Some of the roles envisaged and implemented for these electronic entities involve direct interactions with students, participating in the "social" dimension of the…

  20. Wheat bran soil inoculant of sumateran nematode-trapping fungi as biocontrol agents of the root-knot nematode meloidogyne incognita on deli tobacco (nicotiana tabaccum l) cv. deli 4

    Science.gov (United States)

    Dwi Sri Hastuti, Liana; Faull, Jane

    2018-03-01

    A pot experiment was carried out to test the effectiveness of nematode-trapping fungi (NTF) isolated from Sumatera for controlling infection by the root-knot nematode (RKN) on Deli tobacco plant. Wheat bran soil containing 109 conidia of Arthrobotrys. oligospora, Candellabrella musiformis and Dactylella eudermata was added to the soil as a dry inoculum. Carbofuran was also applied as chemical agent and comparison treatment. Seedling tobacco (Nicotiana tabacum L.) cv. Deli 4 was inoculated with root knot (Meloidogyne incognita Chitwood.) seven days after the plant were transplanted to the pots. A. oligospora, C. musiformis and D. eudermata were found to be reliable as biocontrol agents, reducing the number of vermiform nematodes, swollen root, sausage shaped and galls in tobacco plant after 7, 15 and 30 days of infection with M. incognita. Treatment with NTF produced results that were comparable with Carbofuran® as a control agent in the reduction of the number of infections in tobacco plant caused by M. incognita in Nicotiana tabacum var. Deli 4. They also optimize the growth of the tobacco plants especially up to 15 days after infection.

  1. Biocontrol ability and action mechanismof Starmerella bacillaris (synonym Candida zemplinina isolated from wine musts against grey mold disease agent Botrytis cinerea on grape and their effects on alcoholic fermentation

    Directory of Open Access Journals (Sweden)

    Wilson Josè Fernandes Lemos

    2016-08-01

    Full Text Available Gray mold is one of the most important diseases of grapevine in temperate climates. This plant pathogen affects plant growth and reduces wine quality. The use of yeasts as biocontrol agents to apply in the vineyard have been investigated in recent years as an alternative to agrochemicals. In this work, fermenting musts obtained from overripe grape berries, therefore more susceptible to infection by fungal pathogens such as Botrytis cinerea, were considered for the selection of yeasts carrying antifungal activity. Thirty-six isolates were identified as Starmerella bacillaris, a species recently proven to be of enological interest. Among them 14 different strains were studied and antifungal activity against B. cinerea was demonstrated, for the first time, to be present in S. bacillaris species. The production of volatile organic compounds (VOCs, tested in vitro, was found to be the main responsible of S. bacillaris antifungal effects. All the strains were able to reduce B. cinerea decay on wounded grape berries artificially inoculated with gray mold. The colonization level of wound was very high reaching, after five days, a concentration of 106 cells per ml of grape juice obtained after berry crushing. At this cell concentration S. bacillaris strains were used to ferment synthetic and natural musts. The sequential yeast inoculation, performed by adding S. cerevisiae 48 h after S. bacillaris, was needed to complete sugar consumption and determined a significant increase in glycerol content and a reduction of ethanol and acetic acid concentrations.The high wound colonization ability, found in this work, together with the propensity to colonize grape berry and the interesting enological traits possessed by the selected S. bacillaris strains allow the use of this yeast as biocontrol agent on vine and grape berries with possible positive effects on must fermentation, although the presence of S. cerevisiae is needed to complete the fermentation process

  2. Potential of Burkholderia seminalis TC3.4.2R3 as Biocontrol Agent Against Fusarium oxysporum Evaluated by Mass Spectrometry Imaging

    Science.gov (United States)

    Araújo, Francisca Diana da Silva; Araújo, Welington Luiz; Eberlin, Marcos Nogueira

    2017-05-01

    Species of genus Burkholderia display different interaction profiles in the environment, causing either several diseases in plants and animals or being beneficial to some plants, promoting their growth, and suppressing phytopathogens. Burkholderia spp. also produce many types of biomolecules with antimicrobial activity, which may be commercially used to protect crops of economic interest, mainly against fungal diseases. Herein we have applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate secondary metabolites produced by B. seminalis TC3.4.2R3 in monoculture and coculture with plant pathogen Fusarium oxysporum. The siderophore pyochelin and the rhamnolipid Rha-Rha-C15-C14 were detected in wild-type B. seminalis strain, and their productions were found to vary in mutant strains carrying disruptions in gene clusters associated with antimicrobial compounds. Two mycotoxins were detected in F. oxysporum. During coculture with B. seminalis, metabolites probably related to defense mechanisms of these microorganisms were observed in the interspecies interaction zone. Our findings demonstrate the effective application of MALDI-MSI in the detection of bioactive molecules involved in the defense mechanism of B. seminalis, and these findings suggest the potential use of this bacterium in the biocontrol of plant diseases caused by F. oxysporum.

  3. Genome analysis reveals insights of the endophytic Bacillus toyonensis BAC3151 as a potentially novel agent for biocontrol of plant pathogens.

    Science.gov (United States)

    Lopes, Ralf; Cerdeira, Louise; Tavares, Grace S; Ruiz, Jeronimo C; Blom, Jochen; Horácio, Elvira C A; Mantovani, Hilário C; Queiroz, Marisa Vieira de

    2017-09-25

    Diseases caused by phytopathogenic microorganisms account for enormous losses for agribusiness. Although Bacillus species are recognized as being antimicrobial producers and some may provide benefits to plants, the association between Bacillus toyonensis and plants has not been studied. In this study, the whole-genome sequenced endophytic B. toyonensis BAC3151, which has demonstrated antimicrobial activity and quorum sensing inhibition of phytopathogenic bacteria, was investigated for its potential for the production of compounds for biocontrol of plant pathogens. Four whole-genome sequenced B. toyonensis strains shared 3811 protein-coding DNA sequences (CDSs), while strain-specific CDSs, such as biosynthetic gene clusters of antimicrobials, were associated with specific chromosomal regions and mobile genetic elements of the strains. B. toyonensis strains had a higher frequency of putative bacteriocins gene clusters than that of Bacillus species traditionally used for the production of antimicrobials. In addition, gene clusters potentially involved in the production of novel bacteriocins were found in BAC3151, as well as biosynthetic genes of several other compounds, including non-ribosomal peptides, N-acyl homoserine lactonase and chitinases, revealing a genetic repertoire for antimicrobial synthesis greater than that of other Bacillus strains that have demonstrated effective activity against phytopathogens. This study showed for the first time that B. toyonensis has potential to produce various antimicrobials, and the analyses performed indicated that the endophytic strain BAC3151 can be useful for the development of new strategies to control microbial diseases in plants that are responsible for large damages in agricultural crops.

  4. Can Plant Microbiome Studies Lead to Effective Biocontrol of Plant Diseases?

    Science.gov (United States)

    Ellis, Jeffrey G

    2017-03-01

    In this review, the wisdom and efficacy of studies seeking disease attenuating microbes and microbiomes only in healthy plant communities is questioned and an alternative view is posited, namely that success in biocontrol of crop diseases may also come from studies of microbiota, or at least individual species isolates, associated with diseased plants. In support of this view, I summarize the current extensive knowledge of the biology behind what is probably the most successful biocontrol of a plant disease, namely the biocontrol of crown gall of stone fruit using non-pathogenic Rhizobium rhizogenes K84, in which the biocontrol agent itself came from a diseased plant.

  5. In Vitro Assay of Paecilomyces lilacinus Biocontrol Effects on Fasciola hepatica Eggs Illustrated in Scanning Electron Micrographs

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    Faezeh NAJAFI

    2017-02-01

    Full Text Available Background: Fascioliasis is a zoonotic disease caused by the liver fluke Fasciola hepatica. Drug resistance, high costs of treatment and economic losses in meat production have emerged the need of alternative control measures into consideration. The aim of this study was to evaluate the in vitro ovicidal activity of Paecilomyces lilacinus fungus on F. hepatica eggs. Methods: P. lilacinus isolated from the soil of natural environment was challenged on F. hepatica eggs to observe the bio control effect of nematophagous fungi on trematode helminth eggs. The study was conducted in Tehran University of Medical Sciences, in 2015. Within 21 d of experiment, destructive effects exhibited on the eggshells were investigated using optical and Scanning Electron Microscopy. Results: The effective role of P. lilacinus on damaging the eggs of F. hepatica was noticed. Conclusion: This finding is promising for advantageous use of nematophagus fungi as a natural constituent in hyper endemic areas for certain helminthic infections like fascioliasis with diverse kinds of herbivores as egg passer hosts.

  6. Anti-phytopathogen potential of endophytic actinobacteria isolated from tomato plants (Lycopersicon esculentum) in southern Brazil, and characterization of Streptomyces sp. R18(6), a potential biocontrol agent.

    Science.gov (United States)

    de Oliveira, Margaroni Fialho; da Silva, Mariana Germano; Van Der Sand, Sueli T

    2010-09-01

    Tomato plants (Lycopersicon esculentum) are highly susceptible to phytopathogen attack. The resulting intensive application of pesticides on tomato crops can affect the environment and health of humans and animals. The objective of this study was to select potential biocontrol agents among actinobacteria from tomato plants, in a search for alternative phytopathogen control. We evaluated 70 endophytic actinobacteria isolated from tomato plants in southern Brazil, testing their antimicrobial activity, siderophore production, indoleacetic acid production, and phosphate solubility. The actinomycete isolate with the highest antimicrobial potential was selected using the agar-well diffusion method, in order to optimize conditions for the production of compounds with antimicrobial activity. For this study, six growth media (starch casein-SC, ISP2, Bennett's, Sahin, Czapek-Dox, and TSB), three temperatures (25 degrees C, 30 degrees C, and 35 degrees C) and different pH were tested. Of the actinobacteria tested, 88.6% showed antimicrobial activity against at least one phytopathogen, 72.1% showed a positive reaction for indoleacetic acid production, 86.8% produced siderophores and 16.2% showed a positive reaction for phosphate solubility. Isolate R18(6) was selected due to its antagonistic activity against all phytopathogenic microorganisms tested in this study. The best conditions for production were observed in the SC medium, at 30 degrees C and pH 7.0. The isolate R18(6) showed close biochemical and genetic similarity to Streptomyces pluricolorescens. Copyright 2010 Elsevier Masson SAS. All rights reserved.

  7. Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent

    Directory of Open Access Journals (Sweden)

    Petti Carloalberto

    2012-11-01

    Full Text Available Abstract Background Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA and abscisic acid (ABA, are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens –mediated control of Fusarium head blight (FHB disease of barley and to determine if biocontrol-associated hormones directly affect disease development. Results A previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth. Conclusions Both IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced

  8. Electron beam radiation of resin luting agents - a cytotoxic evaluation

    International Nuclear Information System (INIS)

    Shabin, S.

    2013-01-01

    The aim of this study was to evaluate and compare the cytotoxicity of three resin luting agents rely x luting cement, rely x luting 2 cement, and clearfil SA luting agent on human dental pulp cells before and after electron beam irradiation. Growth and maintenance of cell cultures of human pulp cells was done in Dulbecco's modified Eagle's Medium (DMEM). The test samples were divided into two categories based on radiation exposure, irradiated category and non-radiated category. Samples in Irradiated category were exposed to electron beam radiation after dose standardisation (Microtron, Electron Beam Accelerator, Microtron Centre, Mangalore University). The dose of radiation used was 200 Gy. Two subgroups of radiated category were made. In 1st sub-group (containing 18 samples), all the 3 luting cements will be placed in sterile packets and irradiated without mixing the two components. In 2nd sub-group (containing 18 samples), all the 3 luting cements will be mixed separately, placed in sterile packets and exposed to electron-beam radiations. Samples in non radiated category were also made 2 groups. In 1st sub-group (containing 18 samples), all the 3 luting cements will be placed in sterile teflon moulds and kept in a humid chamber at 37℃ without mixing the two components. In 2nd sub-group (containing 18 samples), all the 3 the luting cements will be mixed separately, placed in sterile teflon moulds and kept in a humid chamber at 37℃. All the samples were subjected to MTT assay and spectrophotometric analysis and their cytotoxicity was assessed. (author)

  9. Effects of two different soil amendments on the biocontrol efficacy of ...

    African Journals Online (AJOL)

    Effects of two different soil amendments on the biocontrol efficacy of biological control agents (BCA) against Ralstonia wilt on ginger. Wei Yang, Hongxia Liu, Yunpeng Wang, Yuming Luo, Hetong Yang, Jianhua Guo ...

  10. Weed biocontrol in the EU: from serendipity to strategy

    Science.gov (United States)

    Biological control of weeds is a globally-recognized approach to the management of the worst invasive plants in the world. Unfortunately, accidental introduction of agents account for most weed biocontrol in the EU, but do include a number of current or emerging successes. From the redistribution of...

  11. Biocontrol genes from Trichoderma species: A review | Sharma ...

    African Journals Online (AJOL)

    In the world, the traditional agricultural practices are getting affected by various problems such as disease, pest, drought, decreased soil fertility due to use of hazardous chemical pesticides, pollution and global warming. As a result, there is a need for some eco-friendly biocontrol agents that help in resolving the previous ...

  12. Induced systemic resistance and symbiotic performance of peanut plants challenged with fungal pathogens and co-inoculated with the biocontrol agent Bacillus sp. CHEP5 and Bradyrhizobium sp. SEMIA6144.

    Science.gov (United States)

    Figueredo, María Soledad; Tonelli, María Laura; Ibáñez, Fernando; Morla, Federico; Cerioni, Guillermo; Del Carmen Tordable, María; Fabra, Adriana

    2017-04-01

    Synergism between beneficial rhizobacteria and fungal pathogens is poorly understood. Therefore, evaluation of co-inoculation of bacteria that promote plant growth by different mechanisms in pathogen challenged plants would contribute to increase the knowledge about how plants manage interactions with different microorganisms. The goals of this work were a) to elucidate, in greenhouse experiments, the effect of co-inoculation of peanut with Bradyrhizobium sp. SEMIA6144 and the biocontrol agent Bacillus sp. CHEP5 on growth and symbiotic performance of Sclerotium rolfsii challenged plants, and b) to evaluate field performance of these bacteria in co-inoculated peanut plants. The capacity of Bacillus sp. CHEP5 to induce systemic resistance against S. rolfsii was not affected by the inoculation of Bradyrhizobium sp. SEMIA6144. This microsymbiont, protected peanut plants from the S. rolfsii detrimental effect, reducing the stem wilt incidence. However, disease incidence in plants inoculated with the isogenic mutant Bradyrhizobium sp. SEMIA6144 V2 (unable to produce Nod factors) was as high as in pathogen challenged plants. Therefore, Bradyrhizobium sp. SEMIA6144 Nod factors play a role in the systemic resistance against S. rolfsii. Bacillus sp. CHEP5 enhanced Bradyrhizobium sp. SEMIA6144 root surface colonization and improved its symbiotic behavior, even in S. rolfsii challenged plants. Results of field trials confirmed the Bacillus sp. CHEP5 ability to protect against fungal pathogens and to improve the yield of extra-large peanut seeds from 2.15% (in Río Cuarto) to 16.69% (in Las Vertientes), indicating that co-inoculation of beneficial rhizobacteria could be a useful strategy for the peanut production under sustainable agriculture system. Copyright © 2017 Elsevier GmbH. All rights reserved.

  13. Biological Characterization of the Biocontrol Agent Bacillus amyloliquefaciens CPA-8: The Effect of Temperature, pH and Water Activity on Growth, Susceptibility to Antibiotics and Detection of Enterotoxic Genes.

    Science.gov (United States)

    Gotor-Vila, Amparo; Teixidó, Neus; Sisquella, María; Torres, Rosario; Usall, Josep

    2017-09-01

    This work focuses on the biological understanding of the biocontrol agent Bacillus amyloliquefaciens CPA-8 in order to accomplish the characterization required in the registration process for the development of a microorganism-based product. The tolerance of CPA-8 to grow under different pH-temperature and water activity (a w )-temperature conditions was widely demonstrated. Regarding the pH results, optimum growth at the evaluated conditions was observed at 37 °C and pH between 7 and 5. On the contrary, the slowest growth was recorded at 20 °C and pH 4.5. Moreover, the type of solute used to reduce a w had a great influence on the minimum a w at which the bacterium was able to grow. The lowest a w values for CPA-8 growth in media modified with glycerol and glucose were 0.950 and 0.960, respectively. Besides, the lowest a w for CPA-8 growth increased when the temperature decreased to 20 °C, at which CPA-8 was not able to grow at less than 0.990 a w , regardless of the type of solute. Antibiotic susceptibility tests were carried out to determine which antibiotic could affect the behavior of the bacteria and revealed that CPA-8 was clearly resistant to hygromycin. Finally, a PCR amplification assay to detect the presence of enterotoxic genes from Bacillus cereus in CPA-8 was also performed. CPA-8 gave negative results for all the genes tested except for nheA gene, which is not enough for the toxicity expression, suggesting that fruit treated with this antagonist will not be a potential vehicle for foodborne illnesses.

  14. Draft Genome Sequence of a Chitinase-producing Biocontrol Bacterium Serratia sp. C-1

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    Seur Kee Park

    2015-09-01

    Full Text Available The chitinase-producing bacterial strain C-1 is one of the key chitinase-producing biocontrol agents used for effective bioformulations for biological control. These bioformulations are mixed cultures of various chitinolytic bacteria. However, the precise identification, biocontrol activity, and the underlying mechanisms of the strain C-1 have not been investigated so far. Therefore, we evaluated in planta biocontrol efficacies of C-1 and determined the draft genome sequence of the strain in this study. The bacterial C-1 strain was identified as a novel Serratia sp. by a phylogenic analysis of its 16S rRNA sequence. The Serratia sp. C-1 bacterial cultures showed strong in planta biocontrol efficacies against some major phytopathogenic fungal diseases. The draft genome sequence of Serratia sp. C-1 indicated that the C-1 strain is a novel strain harboring a subset of genes that may be involved in its biocontrol activities.

  15. Toxicity and sublethal effects of six insecticides to last instar larvae and adults of the biocontrol agents Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) and Adalia bipunctata (L.) (Coleoptera: Coccinellidae).

    Science.gov (United States)

    Garzón, A; Medina, P; Amor, F; Viñuela, E; Budia, F

    2015-08-01

    To further develop Integrated Pest Management (IPM) strategies against crop pests, it is important to evaluate the effects of insecticides on biological control agents. Therefore, we tested the toxicity and sublethal effects (fecundity and fertility) of flonicamid, flubendiamide, metaflumizone, spirotetramat, sulfoxaflor and deltamethrin on the natural enemies Chrysoperla carnea and Adalia bipunctata. The side effects of the active ingredients of the insecticides were evaluated with residual contact tests for the larvae and adults of these predators in the laboratory. Flonicamid, flubendiamide, metaflumizone and spirotetramat were innocuous to last instar larvae and adults of C. carnea and A. bipunctata. Sulfoxaflor was slightly toxic to adults of C. carnea and was highly toxic to the L4 larvae of A. bipunctata. For A. bipunctata, sulfoxaflor and deltamethrin were the most damaging compounds with a cumulative larval mortality of 100%. Deltamethrin was also the most toxic compound to larvae and adults of C. carnea. In accordance with the results obtained, the compounds flonicamid, flubendiamide, metaflumizone and spirotetramat might be incorporated into IPM programs in combination with these natural enemies for the control of particular greenhouse pests. Nevertheless, the use of sulfoxaflor and deltamethrin in IPM strategies should be taken into consideration when releasing either of these biological control agents, due to the toxic behavior observed under laboratory conditions. The need for developing sustainable approaches to combine the use of these insecticides and natural enemies within an IPM framework is discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Bioprospecting endophytic bacteria for biological control of coffee leaf rust Bioprospecção de bactérias endofíticas como agentes de biocontrole da ferrugem do cafeeiro

    Directory of Open Access Journals (Sweden)

    Humberto Franco Shiomi

    2006-02-01

    Full Text Available Suppression of plant diseases due to the action of endophytic microorganisms has been demonstrated in several pathosystems. Experiments under controlled conditions involving endophytic bacteria isolated from leaves and branches of Coffea arabica L and Coffea robusta L were conducted with the objective of evaluating the inhibition of germination of Hemileia vastatrix Berk. & Br., race II, urediniospores and the control of coffee leaf rust development in tests with leaf discs, detached leaves, and on potted seedling of cv. Mundo Novo. The endophytic bacterial isolates tested proved to be effective in inhibiting urediniospore germination and/or rust development, with values above 50%, although the results obtained in urediniospore germination tests were inferior to the treatment with fungicide propiconazole. Endophytic isolates TG4-Ia, TF2-IIc, TF9-Ia, TG11-IIa, and TF7-IIa, demonstrated better coffee leaf rust control in leaf discs, detached leaves, and coffee plant tests. The endophytic isolates TG4-Ia and TF9-Ia were identified as Bacillus lentimorbus Dutky and Bacillus cereus Frank. & Frank., respectively. Some endophytic bacterial isolates were effective in controlling the coffee leaf rust, although some increased the severity of the disease. Even though a relatively small number of endophytic bacteria were tested, promising results were obtained regarding the efficiency of coffee leaf rust biocontrol. These selected agents appears to be an alternative for future replacement of chemical fungicide.Supressão de doenças de plantas por microrganismos endofíticos tem sido demonstrada em diversos patossistemas. Neste trabalho foram selecionados isolados de bactérias endofíticas de folhas e ramos de cafeeiro com potencial para o controle biológico da ferrugem do cafeeiro, pois é conhecido que esses microrganismos podem possuir essa característica. Bactérias endofíticas isoladas previamente de folhas e ramos de Coffea arabica L e Coffea

  17. Estudo do potencial do pacu (Piaractus mesopotamicus como agente de controle biológico de Egeria densa, E. najas e Ceratophyllum demersum Evaluation of the biocontrol potential of pacu (Piaractus mesopotamicus for Egeria densa, E. najas and Ceratophyllum demersum

    Directory of Open Access Journals (Sweden)

    D.M.Y. Miyazaki

    2003-01-01

    Full Text Available Visando fornecer subsídios para elaboração de sistema de manejo integrado das grandes massas de plantas daninhas aquáticas submersas em lagos e represas, o presente trabalho teve como objetivo verificar a eficiência do pacu (Piaractus mesopotamicus como agente de controle biológico de Egeria densa, E. najas e Ceratophyllum demersum. As espécies de plantas daninhas foram oferecidas individualmente, duas a duas e as três espécies juntas. Verificou-se que este peixe tem uma eficiência média de controle dessas plantas daninhas variando entre 28 e 100%, podendo eliminar uma massa verde dessas plantas, com a mesma quantidade de seu peso, em sete dias. A eficiência de controle diária aumentou com o tempo de predação. O pacu é mais seletivo para E. densa ou E. najas quando na presença de C. demersum. Não ocorreu alteração na eficiência de controle do pacu sobre E. densa ou E. najas em todos os tratamentos e nos três períodos estudados (três, cinco e sete dias.In order to provide basic information for the establishment of integrated management systems for submersed aquatic weeds in lakes and reservoirs, this research evaluated the efficiency of pacu (Piaractus mesopotamicus as a biocontrol agent of Egeria densa, E. najas and Ceratophyllum demersum. One, two and the three plant species together were offered to the fish. The average efficacy of this fish to control these plants ranged between 28 and 100%. The fish could eliminate a fresh mass of these plants, equivalent to its body weight, in seven days of predation period. Control efficiency increased with increasing duration of the trials. Pacu is more selective in controlling E. densa or E. najas when in the presence of C. demersum. No decreased efficacy was observed in the control of E. densa or E. najas in any of the treatments nor in any of three time periods studied (3, 5, and 7 days.

  18. Draft Genome Sequence of a Biocontrol Rhizobacterium, Chryseobacterium kwangjuense Strain KJ1R5, Isolated from Pepper (Capsicum annuum)

    Science.gov (United States)

    Jeong, Jin-Ju; Park, Hongjae; Park, Byeong Hyeok; Mannaa, Mohamed; Sang, Mee Kyung

    2016-01-01

    Strain KJ1R5 of the rhizobacterium Chryseobacterium kwangjuense is an effective biocontrol agent against Phytophthora blight of pepper caused by a destructive soilborne oomycete, Phytophthora capsici. Here, we present the draft genome sequence of strain KJ1R5, which contains genes related to biocontrol, plant growth promotion, and environmental stress adaptation. PMID:27103726

  19. An Electronic Market Space Architecture Based On Intelligent Agents And Data Mining Technologies

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available This paper presents an overview of current trends in electronic Business (E-Business, and discusses how an enterprise can use the Electronic Market space based on intelligent agents and data mining techniques to its strategic advantage. We define an agency as a multi-agent system created by integrating agents, selected from a library of reusable agents that have formed a federation. A federation of agents comprises of a set of registered agents, witch are themselves complete knowledge-based system [1].

  20. Identification and Characterisation of New Microbial Antagonists for Biocontrol of Monilinia laxa, the Causal Agent of Brown Rot on Stone Fruit

    Directory of Open Access Journals (Sweden)

    Peter Jeffries

    2013-10-01

    Full Text Available Monilinia laxa is the causal agent of brown rot disease on stone fruits, and also causes blossom wilt and twig canker. The common practice used to manage this disease is through fungicide treatments. However the demand to reduce fungicide inputs has been increasing and there is a growing number of reports of M. laxa strains that are resistant to fungicides. There is an urgent need to search for an alternative strategy to control the disease. This study focused on the isolation and characterisation of biological control agents (BCAs using indigenous isolates isolated from cherries and plums collected within the UK. A total of 192 isolates were screened against two strains of M. laxa in a series of in vitro dual culture tests. From this in vitro screen, 12 isolates were selected for a subsequent in vivo screen on detached fruits, which then narrowed these isolates down to two potential BCAs. These two strains were identified as Bacillus amyloliquefaciens/subtilis (isolate B91 and Aureobasidium pullulans (isolate Y126. The capability of these two potential BCAs to grow and survive at a range of temperatures likely to be experienced under field and storage conditions was studied in order to gain knowledge for product formulation and field application. Bacillus sp. B91 was shown to be a mesophilic bacterium that could grow at 10–25 °C but suffered significant mortality at 0 and 5 °C, while A. pullulans Y126 was both mesophilic and psychrotolerant as it grew between 0–25 °C with the optimum at 20 °C. When all nutrients were removed, Y126 was able to survive for several weeks in all test temperatures (0–25 °C but showed significant mortality at 25 °C. The capability of B91 to survive at 20 and 25 °C was higher than at low temperatures (0–15 °C. In addition, the modes of action of the potential BCAs were studied. B91 was shown to produce soluble and volatile organic compounds that inhibited M. laxa, while A. pullulans Y126 did not

  1. Bacillus velezensis RC 218 as a biocontrol agent to reduce Fusarium head blight and deoxynivalenol accumulation: Genome sequencing and secondary metabolite cluster profiles.

    Science.gov (United States)

    Palazzini, Juan M; Dunlap, Christopher A; Bowman, Michael J; Chulze, Sofía N

    2016-11-01

    Bacillus subtilis RC 218 was originally isolated from wheat anthers as a potential antagonist of Fusarium graminearum, the causal agent of Fusarium head blight (FHB). It was demonstrated to have antagonist activity against the plant pathogen under in vitro and greenhouse assays. The current study extends characterizing B. subtilis RC 218 with a field study and genome sequencing. The field study demonstrated that B. subtilis RC 218 could reduce disease severity and the associated mycotoxin (deoxynivalenol) accumulation, under field conditions. The genome sequencing allowed us to accurately determine the taxonomy of the strain using a phylogenomic approach, which places it in the Bacillus velezensis clade. In addition, the draft genome allowed us to use bioinformatics to mine the genome for potential metabolites. The genome mining allowed us to identify 9 active secondary metabolites conserved by all B. velezensis strains and one additional secondary metabolite, the lantibiotic ericin, which is unique to this strain. This study represents the first confirmed production of ericin by a B. velezensis strain. The genome also allowed us to do a comparative genomics with its closest relatives and compare the secondary metabolite production of the publically available B. velezensis genomes. The results showed that the diversity in secondary metabolites of strains in the B. velezensis clade is driven by strains making different antibacterials. Copyright © 2016 Elsevier GmbH. All rights reserved.

  2. Complete genome sequence of Bacillus velezensis QST713: a biocontrol agent that protects Agaricus bisporus crops against the green mould disease.

    Science.gov (United States)

    Pandin, Caroline; Le Coq, Dominique; Deschamps, Julien; Védie, Régis; Rousseau, Thierry; Aymerich, Stéphane; Briandet, Romain

    2018-04-24

    Bacillus subtilis QST713 is extensively used as a biological control agent in agricultural fields including in the button mushroom culture, Agaricus bisporus. This last use exploits its inhibitory activity against microbial pathogens such as Trichoderma aggressivum f. europaeum, the main button mushroom green mould competitor. Here, we report the complete genome sequence of this bacterium with a genome size of 4 233 757 bp, 4263 predicted genes and an average GC content of 45.9%. Based on phylogenomic analyses, strain QST713 is finally designated as Bacillus velezensis. Genomic analyses revealed two clusters encoding potential new antimicrobials with NRPS and TransATPKS synthetase. B. velezensis QST713 genome also harbours several genes previously described as being involved in surface colonization and biofilm formation. This strain shows a strong ability to form in vitro spatially organized biofilm and to antagonize T. aggressivum. The availability of this genome sequence could bring new elements to understand the interactions with micro or/and macroorganisms in crops. Copyright © 2018. Published by Elsevier B.V.

  3. Stimulative effect of the fungal biocontrol agent Fusarium oxysporum f.sp. Striga on abundance of nitrifying prokaryotes in a maize rhizosphere

    Science.gov (United States)

    Musyoki, Mary; Enowashu, Esther; Zimmermann, Judith; Muema, Esther; Wainright, Henry; Vanlauwe, Bernard; Cadisch, Georg; Rasche, Frank

    2014-05-01

    The integration of resistant crop varieties and Fusarium oxysporum f.sp. strigae (Foxy-2) strains as biological control agent (BCA) has shown to be an effective control of the weed Striga hermonthica which is parasitic to several cereals (e.g., maize) cultivated in Sub-Saharan Africa. Most studies have examined the efficacy of the BCA and its interactions with host crops, while overlooking the interplay among key microorganisms in the soil nitrogen (N) cycle. Hence, we postulated that both Foxy-2 and Striga pose threats to the indigenous plant root-associated microbial communities involved in N cycling through direct or indirect competition for nutrients and that the application of high quality organic residues would compensate these effects. The primary objective of this study was thus to assess the potential impact of Foxy-2 on indigenous nitrifying prokaryotes in maize rhizosphere cultivated on two distinct soils (sandy Ferric Alisol versus clayey Humic Nitisol) obtained from Machanga and Embu, respectively, in central Kenya. These soils were treated with or without Foxy-2 and Striga; and in combination with high quality (i.e. CN ratio; 13, lignins, 8.9 % and polyphenols, 1.7 %) organic residues (i.e., Tithonia diversifolia) as N source. Using quantitative polymerase chain reaction (qPCR), we followed at three pre-defined sampling dates (14, 28 and 42 days after planting) the responses of ammonia-oxidizing archaea (AOA) and bacteria (AOB), total bacteria and archaea in four treatments of a rhizobox experiment: (i) Foxy-2 plus Striga (F+S), (ii) Striga only (C+S), (iii) Foxy-2 plus Striga plus Tithonia diversifolia residues (F+S+T), and (iv) a non-treated control (C). Overall, the treatment effects on soil microbial populations were, in comparison to the clayey Embu soil, more pronounced in the sandy Machanga soil. Contrary to our expectations, we observed a distinct stimulative, but no resource competition effect of Foxy-2 on the abundance of AOA, as well as

  4. A modularized electronic payment system for agent-based e-commerce

    OpenAIRE

    Guan, SU; Tan, SL; Hua, F

    2004-01-01

    With the explosive growth of the Internet, electronic-commerce (e-commerce) is an increasingly important segment of commercial activities on the web. The Secure Agent Fabrication, Evolution & Roaming (SAFER) architecture was proposed to further facilitate e-commerce using agent technology. In this paper, the electronic payment aspect of SAFER will be explored. The Secure Electronic Transaction (SET) protocol and E-Cash were selected as the bases for the electronic payment system implementatio...

  5. EVALUACIÓN DE MICROORGANISMOS AISLADOS DE GALLINAZA POR SU POTENCIAL PARA EL BIOCONTROL DE FUSARIUM (F. OXYSPORUM EN PLÁNTULAS DE UCHUVA (PHYSALIS PERUVIANA EVALUATION OF MICROORGANISMS INSOLATED FROM HEN MANURE FOR THEIR POTENCIAL AS BIOCONTROL AGENTS OF FUSARIUM (F. OXYSPORUM IN GOOSEBERRY (PHYSALIS PERUVIANA SEEDLINGS

    Directory of Open Access Journals (Sweden)

    Jorge Enrique Rodríguez Amézquita

    2010-12-01

    Full Text Available En Colombia, las pérdidas económicas ocasionadas por Fusarium oxysporum en el cultivo de uchuva son considerables. Se evaluaron hongos y bacterias aislados de 2 fuentes de gallinaza, su potencial como agentes de biocontrol de este patógeno. La evaluación se realizó en cajas de Petri con PDA para lo cual se colocó en el centro de las mismas, un disco de 5 mm de diámetro colonizado por el patógeno y a 3 cm del centro, sobre los ejes horizontal y vertical, cada uno de los aislamientos de la gallinaza. Los aislamientos que mostraron antagonismo fueron posteriormente evaluados in vitro por su capacidad de restringir el crecimiento y esporulación de F. oxysporum. Cada uno de los aislamientos que mostró el mayor potencial antagónico fue inoculado simultáneamente con el patógeno en plántulas de uchuva y evaluado por sus efectos en contra de la incidencia de la enfermedad y la muerte de las plántulas. Los resultados indicaron que de los 39 microorganismos aislados de la gallinaza pura, 6 mostraron antagonismo contra F. oxysporum y entre ellos los más efectivos para restringir in vitro su crecimiento y esporulación fueron los hongos H2 y H6 y las bacterias B17 y B19. Las bacterias B17 y B19 resultaron ser las más efectivas en reducir no sólo la incidencia sino también la muerte de plántulas ocasionada por el patógeno. Según los resultados de la identificación, los hongos H2 y H6 pertenecen a los géneros Geotrichum sp. y Trichoderma sp, respectivamente y las bacterias B17 y B19 al género Bacillus.In Colombia, economic losses due to attack of Fusarium oxysporum in the gooseberry plantation are considerable. Fungi and bacteria isolated from 2 hen manure sources were evaluated for their potential as biological control agents of this pathogen. The evaluation was conducted in Petri dishes containing PDA by placing a 5 mm diameter disk, colonized by this pathogen, in the center of the plates and at 3 cm from the center, over the

  6. Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes.

    Science.gov (United States)

    Solans, Mariana; Scervino, Jose Martin; Messuti, María Inés; Vobis, Gernot; Wall, Luis Gabriel

    2016-11-01

    Control of fungal plant diseases by using naturally occurring non-pathogenic microorganisms represents a promising approach to biocontrol agents. This study reports the isolation, characterization, and fungal antagonistic activity of actinobacteria from forage soils in the Flooding Pampa, Argentina. A total of 32 saprophytic strains of actinobacteria were obtained by different isolation methods from rhizospheric soil of Lotus tenuis growing in the Salado River Basin. Based on physiological traits, eight isolates were selected for their biocontrol-related activities such as production of lytic extracellular enzymes, siderophores, hydrogen cyanide (HCN), and antagonistic activity against Cercospora sojina, Macrophomia phaseolina, Phomopsis sp., Fusarium oxysporum, and Fusarium verticilloides. These actinobacteria strains were characterized morphologically, physiologically, and identified by using molecular techniques. The characterization of biocontrol-related activities in vitro showed positive results for exoprotease, phospholipase, fungal growth inhibition, and siderophore production. However, none of the strains was positive for the production of hydrogen cyanide (HCN). Streptomyces sp. MM140 presented the highest index for biocontrol, and appear to be promising pathogenic fungi biocontrol agents. These results show the potential capacity of actinobacteria isolated from forage soils in the Argentine Pampas lowlands as promising biocontrol agents, and their future agronomic applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Antibiotic production by bacterial biocontrol agents

    NARCIS (Netherlands)

    Raaijmakers, J.M.; Vlami, M.; Souza, de J.T.

    2002-01-01

    Interest in biological control of plant pathogens has been stimulated in recent years by trends in agriculture towards greater sustainability and public concern about the use of hazardous pesticides. There is now unequivocal evidence that antibiotics play a key role in the suppression of various

  8. Production Methods for Microbial Biocontrol Agents

    Science.gov (United States)

    A critical constraint to the commercial use of microbial biopesticides is the development of an economic production process. The production process must be cost-effective and yield a microbial propagule that is stable and efficacious under field conditions. Currently, the commercial production of ...

  9. Animated Pedagogical Agents: A Review of Agent Technology Software in Electronic Learning Environments

    Science.gov (United States)

    Govindasamy, Malliga K.

    2014-01-01

    Agent technology has become one of the dynamic and most interesting areas of computer science in recent years. The dynamism of this technology has resulted in computer generated characters, known as pedagogical agent, entering the digital learning environments in increasing numbers. Commonly deployed in implementing tutoring strategies, these…

  10. EPR and DNP Properties of Certain Novel Single Electron Contrast Agents Intended for Oximetric Imaging

    DEFF Research Database (Denmark)

    Ardenkjær-Larsen, J. H.; Laursen, I; Leunbach, I.

    1998-01-01

    Parameters of relevance to oximetry with Overhauser magnetic resonance imaging (OMRI) have been measured for three single electron contrast agents of the triphenylmethyl type. The single electron contrast agents are stable and water soluble. Magnetic resonance properties of the agents have been...... examined with electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and dynamic nuclear polarization (DNP) at 9.5 mT in water, isotonic saline, plasma, and blood at 23 and 37°C. The relaxivities of the agents are about 0.2–0.4 mM−1s−1and the DNP enhancements extrapolate close...... than 1 μT in water at room temperature. The longitudinal electron spin relaxation rate is calculated from the DNP enhancement curves. The oxygen broadening in water is about 50 μT/mM O2at 37°C. These agents have good properties for oximetry with OMRI....

  11. Endophytic Bacteria from Pinus taeda L. as Biocontrol Agents of Fusarium circinatum Nirenberg & O'Donnell Bacterias Endófitas de Pinus taeda L. como Agentes de control Biológico de Fusarium circinatum Nirenberg & O'Donnell

    Directory of Open Access Journals (Sweden)

    Silvina Soria

    2012-06-01

    Full Text Available Fusarium circinatum Nirenberg & O'Donnell, the pitch canker fungus, has been recently reported in Uruguay affecting Pinus taeda L. seedlings. The spread of this pathogen to plantations constitute a risk to forestry production. The aim of this work was to evaluate the inhibitory effect of live bacteria and their thermostable metabolites on F. circinatum growth in vitro. Four Bacillus subtilis strains and one of Burkholderia sp. isolated as P. taeda endophytes were evaluated as biological control agents of F. circinatum. Dual cultures between live bacteria and pathogen were performed. Furthermore, bacteria metabolites obtained from liquid cultures were sterilized and added to the culture media where fungus was grown. In this study all bacteria showed an antagonist effect on the pathogen growth arresting the mycelia at one cm of the edge of the bacteria colony. Bacteria thermostable metabolites reduced over 50% fungal growth. These results demonstrates that endophytic bacteria, well adapted to live in host tissues, constitute a good alternative to control F. circinatum affecting Pinus seedlings.La presencia de Fusarium circinatum Niremberg & O'Donnell, agente causal del cancro resinoso en pino, ha sido detectada recientemente en plántulas de Pinus taeda L. en Uruguay. La propagación de este patógeno en las plantaciones constituye un riesgo para la producción forestal. El objetivo de este trabajo fue determinar la capacidad inhibitoria de bacterias vivas y de sus metabolitos termoestables sobre el crecimiento de F. circinatum in vitro. Cuatro cepas de Bacillus subtilis y una de Burkholderia sp. aisladas como endófitas de P. taeda, fueron evaluadas como potenciales agentes de control biológico sobre F. circinatum. Para ello, se realizaron enfrentamientos directos entre las bacterias vivas y el micelio del patógeno. Por otra parte, los metabolitos bacterianos obtenidos de cultivos líquidos fueron esterilizados en autoclave y se incorporaron al

  12. Miconia biocontrol: Where are we going and when will we get there?

    Science.gov (United States)

    M.T. Johnson

    2010-01-01

    We have made much progress in evaluating potential agents for biocontrol of miconia, and several appear likely to be suitable for future introduction to Hawaiÿi. Unfortunately, none of them is an obvious silver bullet. We face the challenge of prioritizing the existing candidates and inventing the combination of agents that will achieve our goals. Now is an opportune...

  13. Buying Time: Preliminary Assessment of Biocontrol in the Recovery of Native Forest Vegetation in the Aftermath of the Invasive Emerald Ash Borer

    Science.gov (United States)

    Elan Margulies; Leah Bauer; Inés Ibáñez

    2017-01-01

    Introduced forest pests have become one of the major threats to forests, and biological control is one of the few environmentally acceptable management practices. Assessing the impacts of a biocontrol program includes evaluating the establishment of biocontrol agents, the control of target pest, the impact on the affected organism, and the indirect impacts that the...

  14. Seasonal variation in the biocontrol efficiency of bacterial wilt is driven by temperature-mediated changes in bacterial competitive interactions.

    Science.gov (United States)

    Wei, Zhong; Huang, Jianfeng; Yang, Tianjie; Jousset, Alexandre; Xu, Yangchun; Shen, Qirong; Friman, Ville-Petri

    2017-10-01

    Microbe-based biocontrol applications hold the potential to become an efficient way to control plant pathogen disease outbreaks in the future. However, their efficiency is still very variable, which could be due to their sensitivity to the abiotic environmental conditions.Here, we assessed how environmental temperature variation correlates with ability of Ralstonia pickettii , an endophytic bacterial biocontrol agent, to suppress the Ralstonia solanacearum pathogen during different tomato crop seasons in China.We found that suppression of the pathogen was highest when the seasonal mean temperatures were around 20 °C and rapidly decreased with increasing mean crop season temperatures. Interestingly, low levels of disease incidence did not correlate with low pathogen or high biocontrol agent absolute densities. Instead, the biocontrol to pathogen density ratio was a more important predictor of disease incidence levels between different crop seasons. To understand this mechanistically, we measured the growth and strength of competition between the biocontrol agent and the pathogen over a naturally occurring temperature gradient in vitro . We found that the biocontrol strain grew relatively faster at low temperature ranges, and the pathogen at high temperature ranges, and that similar to field experiments, pathogen suppression peaked at 20 °C.Together, our results suggest that temperature-mediated changes in the strength of bacterial competition could potentially explain the variable R. solanacearum biocontrol outcomes between different crop seasons in China. Synthesis and applications . Our results suggest that abiotic environmental conditions, such as temperature, can affect the efficacy of biocontrol applications. Thus, in order to develop more consistent biocontrol applications in the future, we might need to find and isolate bacterial strains that can retain their functionality regardless of the changing environmental conditions.

  15. Novel routes for improving biocontrol activity of Bacillus based bioinoculants

    Directory of Open Access Journals (Sweden)

    Liming eWu

    2015-12-01

    Full Text Available Biocontrol formulations prepared from plant-growth-promoting bacteria are increasingly applied in sustainable agriculture. Especially inoculants prepared from endospore-forming Bacillus strains have been proven as efficient and environmental-friendly alternative to chemical pesticides due to their long shelf life, which is comparable with that of agrochemicals. However, these formulations of the first generation are sometimes hampered in their action and do not fulfill in each case the expectations of the appliers. In this review we use the well-known plant-associated Bacillus amyloliquefaciens type strain FZB42 as example for the successful application of different techniques offered today by comparative, evolutionary and functional genomics, site-directed mutagenesis and strain construction including marker removal, for paving the way for preparing a novel generation of biocontrol agents.

  16. Phages of Listeria offer novel tools for diagnostics and biocontrol

    Directory of Open Access Journals (Sweden)

    Martin J Loessner

    2014-04-01

    Full Text Available Historically, bacteriophages infecting their hosts have perhaps been best known and even notorious for being a nuisance in dairy-fermentation processes. However, with the rapid progress in molecular microbiology and microbial ecology, a new dawn has risen for phages. This review will provide an overview on possible uses and applications of Listeria phages, including phage-typing, reporter phage for bacterial diagnostics, and use of phage as biocontrol agents for food safety. The use of phage-encoded enzymes such as endolysins for the detection and as antimicrobial will also be addressed. Desirable properties of candidate phages for biocontrol will be discussed. While emphasizing the enormous future potential for applications, we will also consider some of the intrinsic limitations dictated by both phage and bacterial ecology.

  17. Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola.

    Science.gov (United States)

    Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie; Hélias, Valérie; Faure, Denis

    2015-10-23

    Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. Biocontrol Activity of the Local Strain of Metschnikowia pulcherrima on Different Postharvest Pathogens.

    Science.gov (United States)

    Türkel, Sezai; Korukluoğlu, Mihriban; Yavuz, Mümine

    2014-01-01

    The strains of the yeast Metschnikowia pulcherrima have strong biocontrol activity against various microorganisms. Biocontrol activity of M. pulcherrima largely depends on its iron immobilizing pigment pulcherrimin. Biocontrol activity of pulcherrimin producing strain, M. pulcherrima UMY15, isolated from local vineyards, was tested on different molds that cause food spoilage. M. pulcherrima UMY15 was a very effective biocontrol agent against Penicillium roqueforti, P. italicum, P. expansum, and Aspergillus oryzae in in-vitro plate tests. However, the inhibitory activity of M. pulcherrima UMY15 was less effective on Fusarium sp. and A. niger species in biocontrol assays. In addition, M. pulcherrima UMY15 strain completely inhibited the germination and mycelia growth of A. oryzae, A. parasiticus, and Fusarium sp. spores on artificial wounds of apples when they coinoculated with M. pulcherrima UMY15. Moreover, when coinoculated, M. pulcherrima UMY15 strain also inhibited the growth of P. roqueforti, P. italicum, P. expansum, A. oryzae, Fusarium sp., and Rhizopus sp. in grape juice, indicating that M. pulcherrima UMY15 can be used as a very effective biocontrol yeast against various species of postharvest pathogens, including Penicillium, Aspergillus, Fusarium, and Rhizopus.

  19. Molecular evolution and phylogenetic analysis of biocontrol genes acquired from SCoT polymorphism of mycoparasitic Trichoderma koningii inhibiting phytopathogen Rhizoctonia solani Kuhn.

    Science.gov (United States)

    Gajera, H P; Hirpara, Darshna G; Katakpara, Zinkal A; Patel, S V; Golakiya, B A

    2016-11-01

    The biocontrol agent Trichoderma (T. harzianum, T. viride, T. virens, T. hamantum, T. koningii, T. pseudokoningii and Trichoderma species) inhibited variably (15.32 - 88.12%) the in vitro growth of Rhizoctonia solani causing root rot in cotton. The T. koningii MTCC 796 evidenced highest (88.12%) growth inhibition of test pathogen followed by T. viride NBAII Tv23 (85.34%). Scanning electron microscopic study confirmed mycoparasitism for MTCC 796 and Tv23 which were capable of completely overgrowing on R. solani by degrading mycelia, coiling around the hyphae with hook-like structures. The antagonists T. harzianum NBAII Th1 and, T. virens NBAII Tvs12 exhibited strong antibiosis and formed 2-4 mm zone of inhibition for 70.28% and 46.62%, respectively growth inhibition of test pathogen. Mycoparasitism is a strong mode of action for biocontrol activity compared with antibiosis. The antagonists Trichoderma strains were performed for start codon targeted (SCoT) polymorphism to acquire biocontrol genes from potent antagonist. The six unique SCoT fragments amplified by genomic DNA of best mycoparasitic antagonist MTCC 796 strain are subjected to DNA sequencing resulted to confirm two functional sequences for activity related to biocontrol genes. The phylogenetic and molecular evolution of functional 824 bp of SCoT-3 (920) and 776 bp of SCoT-6 (806) fragments signify sequence homology with biocontrol genes endochitinase (partial cds of 203 amino acids) and novel hmgR genes (partial cds of 239 amino acids), respectively and the same were annotated and deposited in NCBI GenBank database. The hmgR gene is liable to be express hmg - CoA reductase which is a key enzyme for regulation of terpene biosynthesis and mycoparasitic strains produced triterpenes during antagonism to inhibit growth of fungal pathogen as evidenced with GC-MS profile. The biocontrol genes are found in best antagonist T. koningii MTCC 796 for mycoparasitic activity to restrain the growth of test pathogen R

  20. Pseudomonas fluorescens F113 Mutant with Enhanced Competitive Colonization Ability and Improved Biocontrol Activity against Fungal Root Pathogens ▿

    Science.gov (United States)

    Barahona, Emma; Navazo, Ana; Martínez-Granero, Francisco; Zea-Bonilla, Teresa; Pérez-Jiménez, Rosa María; Martín, Marta; Rivilla, Rafael

    2011-01-01

    Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible. PMID:21685161

  1. Pseudomonas fluorescens F113 mutant with enhanced competitive colonization ability and improved biocontrol activity against fungal root pathogens.

    Science.gov (United States)

    Barahona, Emma; Navazo, Ana; Martínez-Granero, Francisco; Zea-Bonilla, Teresa; Pérez-Jiménez, Rosa María; Martín, Marta; Rivilla, Rafael

    2011-08-01

    Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible.

  2. Surfactin triggers biofilm formation of Bacillus subtilis in melon phylloplane and contributes to the biocontrol activity.

    Science.gov (United States)

    Zeriouh, Houda; de Vicente, Antonio; Pérez-García, Alejandro; Romero, Diego

    2014-07-01

    The biocontrol activity of many Bacillus species has been traditionally related to the direct antagonism of pathogens. In previous works, we reported that B. subtilis strain UMAF6614 was an efficient biocontrol agent that produced bacillomycin, fengycin and surfactin lipopeptides. Bacillomycins and fengycins were shown to have antagonistic activity towards fungal and bacterial pathogens of cucurbits; however, the functionality of surfactin remained unclear. In this study, the role of surfactin in the biocontrol activity of this strain was investigated. We observed that a deficiency in surfactin production led to a partial reduction of disease suppression by this biocontrol agent, which coincided with a defect in biofilm formation and the colonization of the melon phylloplane. These effects were due to a dramatic reduction in the production of exopolysaccharide and the TasA protein, which are the two major components of the extracellular matrix. We propose that the biocontrol activity of this strain is the result of the coordinated action of the three families of lipopeptides. B. subtilis UMAF6614 produces surfactin to trigger biofilm formation on melon phylloplane, which ensures the long-term persistence and the adequate secretion of suppressive lipopeptides, bacillomycins and fengycins, which efficiently target pathogens. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Biocontrol attack exacerbates pollen-limitation in the invasive plant Centaurea solstitialis

    Science.gov (United States)

    Pollen-limited seed set is rarely studied in invasive plants despite the fact that >50% of the most problematic invaders in North America are pollinator-dependent. Further, pollinators are rarely considered in the use biocontrol agents to manage invaders. The ecological literature shows that herbivo...

  4. Selection of phosphorus solubilizing bacteria with biocontrol potential for growth in phosphorus rich animal bone charcoal

    NARCIS (Netherlands)

    Postma, J.; Nijhuis, E.H.; Sommeus, E.

    2010-01-01

    Bacteria with the ability to solubilize phosphorus (P) and to improve plant health were selected and tested for growth and survival in P-rich animal bone charcoal (ABC). ABC is suggested to be suitable as a carrier for biocontrol agents, offering them a protected niche as well as delivering

  5. Antagonistic activity of Bacillus subtilis SB1 and its biocontrol effect on tomato bacterial wilt

    Science.gov (United States)

    A potential biocontrol agent of bacterial wilt, Bacillus subtilis SB1, isolated from tomato roots, showed a broad-spectrum of antimicrobial activity in in vitro experiments. It inhibited the growth of many plant pathogens, including Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Fusarium ox...

  6. Indirect effects of biocontrol of an invasive riparian plant (Tamarix) alters habitat and reduces herpetofauna abundance

    Science.gov (United States)

    Bateman, H.L.; Merritt, D.M.; Glenn, E.P.; Nagler, P.L.

    2014-01-01

    The biological control agent (tamarisk leaf beetle, Diorhabda spp.) is actively being used to defoliate exotic saltcedar or tamarisk (Tamarix spp.) in riparian ecosystems in western USA. The Virgin River in Arizona and Nevada is a system where tamarisk leaf beetle populations are spreading. Saltcedar biocontrol, like other control methods, has the potential to affect non-target species. Because amphibians and reptiles respond to vegetation changes in habitat and forage in areas where beetles are active, herpetofauna are model taxa to investigate potential impacts of biocontrol defoliation. Our objectives related herpetofauna abundance to vegetation cover and indices (normalized difference vegetation index, NDVI; enhanced vegetation index, EVI) and timing of biocontrol defoliation. We captured herpetofauna and ground-dwelling arthropods in trap arrays and measured vegetation using remotely sensed images and on-the-ground measurements at 16–21 sites 2 years before (2009–2010) and 2 years following (2011–2012) biocontrol defoliation. Following defoliation, riparian stands (including stands mixed with native and exotic trees and stands of monotypic exotic saltcedar) had significantly lower NDVI and EVI values and fewer captures of marked lizards. Total captures of herpetofauna (toads, lizards, and snakes) were related to higher vegetation cover and sites with a lower proportion of saltcedar. Our results suggest that effects of biocontrol defoliation are likely to be site-specific and depend upon the proportion of native riparian trees established prior to biocontrol introduction and defoliation. The mechanisms by which habitat structure, microclimate, and ultimately vertebrate species are affected by exotic plant biocontrol riparian areas should be a focus of natural-resource managers.

  7. Whole genome shotgun sequence of Bacillus amyloliquefaciens TF28, a biocontrol entophytic bacterium.

    Science.gov (United States)

    Zhang, Shumei; Jiang, Wei; Li, Jing; Meng, Liqiang; Cao, Xu; Hu, Jihua; Liu, Yushuai; Chen, Jingyu; Sha, Changqing

    2016-01-01

    Bacillus amyloliquefaciens TF28 is a biocontrol endophytic bacterium that is capable of inhibition of a broad range of plant pathogenic fungi. The strain has the potential to be developed into a biocontrol agent for use in agriculture. Here we report the whole-genome shotgun sequence of the strain. The genome size of B. amyloliquefaciens TF28 is 3,987,635 bp which consists of 3754 protein-coding genes, 65 tandem repeat sequences, 47 minisatellite DNA, 2 microsatellite DNA, 63 tRNA, 7rRNA, 6 sRNA, 3 prophage and CRISPR domains.

  8. Differential Selection by Nematodes on an Introduced Biocontrol Fungus vs. Indigenous Fungi in Nonsterile Soil.

    Science.gov (United States)

    Kim, Tae Gwan; Knudsen, Guy R

    2018-03-15

    Trophic interactions of introduced biocontrol fungi with soil animals can bea key determinant in the fungal proliferation and activity.This study investigated trophic interaction of an introduced biocontrol fungus with soil nematodes. The biocontrol fungus Trichoderma harzianum ThzID1-M3 and the fungivorous nematode Aphelenchoides sp. (10 per gram of soil) were added to nonsterile soil, and microbial populations were monitored for 40 days. Similar results were obtained when the experiment was duplicated. ThzID1-M3 stimulated the population growth of indigenous nematodes ( p fungus when densely localized did.The results suggest that soil fungivorous nematodes are an important constraint onhyphal proliferation of fungal agents introduced into natural soils.

  9. Impact of a Recombinant Biocontrol Bacterium, Pseudomonas fluorescens pc78, on Microbial Community in Tomato Rhizosphere

    Directory of Open Access Journals (Sweden)

    Hyun Gi Kong

    2016-04-01

    Full Text Available Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer.

  10. Impact of a Recombinant Biocontrol Bacterium, Pseudomonas fluorescens pc78, on Microbial Community in Tomato Rhizosphere.

    Science.gov (United States)

    Kong, Hyun Gi; Kim, Nam Hee; Lee, Seung Yeup; Lee, Seon-Woo

    2016-04-01

    Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer.

  11. Potential Pseudomonas Isolated from Soybean Rhizosphere as Biocontrol against Soilborne Phytopathogenic Fungi

    Directory of Open Access Journals (Sweden)

    ARI SUSILOWATI

    2011-06-01

    Full Text Available Plants are liable to be attacked by soilborne fungal pathogens which are responsible to reduce plant growth and losses in yield. In Indonesia, indigenous soybeans’ rhizobacteria such as antifungal producing Pseudomonas sp. have not many been reported yet. Therefore, the potential of the Pseudomonas sp. as biocontrol agent should be deeply explored. The aim of this study was to screen the indigenous soybeans’ rhizobacteria Pseudomonas sp. that possessing biocontrol characters against soilborne mainly i.e. Sclerotium rolfsii, Fusarium oxysporum, and Rhizoctonia solani, in vitro and in planta. Eleven isolates identified Pseudomonas sp. CRB numbered by CRB-3, CRB-16, CRB-17, CRB-31, CRB-44, CRB-75, CRB-80, CRB-86, CRB-102, CRB-109, and CRB-112 were affirmed to be candidates of biocontrol agents toward the soilborne fungal pathogens. Pseudomonas sp. CRB inhibited growth of the pathogenic fungi approximately 11.1-60.0% in vitro. Among of them, 7 isolates were also produced siderophore, 2 isolates produced chitinase, and 4 isolates produced hydrogen cyanide. Seed coating with the Pseudomonas sp. CRB accomplished disease suppression in planta about 14.3-100% in sterile soil condition and 5.2-52.6% in non sterile soil condition. Consistency in high performance more than 30% of disease suppression in non sterile soil condition suggested that 5 isolates i.e. CRB-16, CRB-44, CRB-86, CRB-102, and CRB-109 isolates have great promising to be developed as biocontrol agents of soilborne pathogenic fungi.

  12. Indigenous bacteria may interfere with the biocontrol of plant diseases

    Science.gov (United States)

    Someya, Nobutaka; Akutsu, Katsumi

    2009-06-01

    Prodigiosin is a reddish antibiotic pigment that plays an important role in the biocontrol of plant diseases by the bacterium Serratia marcescens. However, its activity is unstable under agricultural conditions; further, it can be degraded by various environmental factors. To examine the effect of epiphytic microbes on the stability of prodigiosin used for biological control processes, we collected a total of 1,280 bacterial isolates from the phylloplane of cyclamen and tomato plants. Approximately 72% of the bacterial strains isolated from the cyclamen plants and 66% of those isolated from the tomato plants grew on minimal agar medium containing 100 μg ml-1 prodigiosin. Certain isolates obtained from both plant species exhibited prodigiosin-degrading activity. We compared the 16S rRNA gene sequences derived from the isolates with sequences in a database. The comparison revealed that the sequences determined for the prodigiosin-degrading isolates were homologous to those of the genera Pseudomonas, Caulobacter, Rhizobium, Sphingomonas, Janthinobacterium, Novosphingobium, and Rathayibacter. These results indicate that indigenous epiphytic microorganisms may interfere with the interaction between plant pathogens and biocontrol agents by degrading the antibiotics produced by the agents.

  13. Life history and biocontrol potential of the first female-producing parthenogenetic species of Diglyphus (Hymenoptera: Eulophidae) against agromyzid leafminers.

    Science.gov (United States)

    Ye, Fu-Yu; Zhu, Chao-Dong; Yefremova, Zoya; Liu, Wan-Xue; Guo, Jian-Yang; Wan, Fang-Hao

    2018-02-19

    Diglyphus species are dominant biocontrol agents for suppressing outbreaks of agromyzid leafminers in fields. In July 2015, we collected a new thelytokous species of Diglyphus in Qinghai, China. The wasp is here named as D. wani Liu, Zhu & Yefremova sp. nov., based on morphological and molecular analyses. The life history and biocontrol potential of the wasp were studied in the laboratory and by providing Liriomyza sativae larvae. The intrinsic rate of increase, finite rate of increase, and mean generation time were 0.2373 d -1 , 1.2678 d -1 , and 15.9 d, respectively. The wasps showed three types of host-killing behaviour, namely parasitism, host feeding and host stinging, resulting in 47.6, 94.4 and 3.4 host larvae killed per wasp over a lifetime, respectively. The finite total host-killing rate was 1.0071 and the wasp showed strong synovigeny. The wasp may be a crucial biocontrol agent against agromyzid leafminers.

  14. Whole-genome sequence of Pseudomonas fluorescens EK007-RG4, a promising biocontrol agent against a broad range of bacteria, including the fire blight bacterium Erwinia amylovora

    DEFF Research Database (Denmark)

    Habibi, Roghayeh; Tarighi, Saeed; Behravan, Javad

    2017-01-01

    Here, we report the first draft whole-genome sequence of Pseudomonas fluorescens strain EK007-RG4, which was isolated from the phylloplane of a pear tree. P. fluorescens EK007-RG4 displays strong antagonism against Erwinia amylovora, the causal agent for fire blight disease, in addition to several...

  15. Endophytic Trichoderma gamsii YIM PH30019: a promising biocontrol agent with hyperosmolar, mycoparasitism, and antagonistic activities of induced volatile organic compounds on root-rot pathogenic fungi of Panax notoginseng

    Directory of Open Access Journals (Sweden)

    Jin-Lian Chen

    2016-10-01

    Conclusion: The results suggest that the endophytic fungus T. gamsii YIM PH30019 may have a good potential as a biological control agent against notoginseng phytodiseases and can provide a clue to further illuminate the interactions between Trichoderma and phytopathogens.

  16. Key-Insulated Undetachable Digital Signature Scheme and Solution for Secure Mobile Agents in Electronic Commerce

    Directory of Open Access Journals (Sweden)

    Yang Shi

    2016-01-01

    Full Text Available Considering the security of both the customers’ hosts and the eShops’ servers, we introduce the idea of a key-insulated undetachable digital signature, enabling mobile agents to generate undetachable digital signatures on remote hosts with the key-insulated property of the original signer’s signing key. From the theoretical perspective, we provide the formal definition and security notion of a key-insulated undetachable digital signature. From the practical perspective, we propose a concrete scheme to secure mobile agents in electronic commerce. The scheme is mainly focused on protecting the signing key from leakage and preventing the misuse of the signature algorithm on malicious servers. Agents do not carry the signing key when they generate digital signatures on behalf of the original signer, so the key is protected on remote servers. Furthermore, if a hacker gains the signing key of the original signer, the hacker is still unable to forge a signature for any time period other than the key being accessed. In addition, the encrypted function is combined with the original signer’s requirement to prevent the misuse of signing algorithm. The scheme is constructed on gap Diffie–Hellman groups with provable security, and the performance testing indicates that the scheme is efficient.

  17. Involvement of phenazines and biosurfactants in biocontrol of Pythium myriotylum root rot on cocoyam by Pseudomonas sp. CMR12A

    Science.gov (United States)

    Pseudomonas sp. CMR12a was isolated from the rhizosphere of the tropical tuber crop cocoyam and produces both phenazines and cyclic lipopeptide (CLP) biosurfactants. CMR12a was shown to be an efficient biocontrol agent of P. myriotylum on cocoyam. To assess the importance of phenazine and biosurfact...

  18. Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa

    Directory of Open Access Journals (Sweden)

    Jia Liu

    2017-10-01

    Full Text Available Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc on biomass production and viability of the antagonistic yeast, Candida diversa. Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg2+, Fe2+, and Zn2+ concentrations were adjusted in a minimal mineral (MM medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy.

  19. Novel Routes for Improving Biocontrol Activity of Bacillus Based Bioinoculants

    Science.gov (United States)

    Wu, Liming; Wu, Hui-Jun; Qiao, Junqing; Gao, Xuewen; Borriss, Rainer

    2015-01-01

    Biocontrol (BC) formulations prepared from plant-growth-promoting bacteria are increasingly applied in sustainable agriculture. Especially inoculants prepared from endospore-forming Bacillus strains have been proven as efficient and environmental-friendly alternative to chemical pesticides due to their long shelf life, which is comparable with that of agrochemicals. However, these formulations of the first generation are sometimes hampered in their action and do not fulfill in each case the expectations of the appliers. In this review we use the well-known plant-associated Bacillus amyloliquefaciens type strain FZB42 as example for the successful application of different techniques offered today by comparative, evolutionary and functional genomics, site-directed mutagenesis and strain construction including marker removal, for paving the way for preparing a novel generation of BC agents. PMID:26696998

  20. Biocontrol of Bacterial Fruit Blotch byBacillus subtilis9407 via Surfactin-Mediated Antibacterial Activity and Colonization.

    Science.gov (United States)

    Fan, Haiyan; Zhang, Zhanwei; Li, Yan; Zhang, Xun; Duan, Yongming; Wang, Qi

    2017-01-01

    In this study, Bacillus subtilis 9407 showed a strong antibacterial activity against Acidovorax citrulli in vitro and 61.7% biocontrol efficacy on melon seedlings 4 days post inoculation under greenhouse conditions. To understand the biocontrol mechanism of B. subtilis 9407, identify the primary antibacterial compound and determine its role in controlling bacterial fruit blotch (BFB), a srfAB deletion mutant (Δ srfAB ) was constructed. The Δ srfAB which was deficient in production of surfactin, not only showed almost no ability to inhibit growth of A. citrulli but also decreased biofilm formation and reduced swarming motility. Colonization assay demonstrated that B. subtilis 9407 could conlonize on melon roots and leaves in a large population, while Δ srfAB showed a four- to ten-fold reduction in colonization of melon roots and leaves. Furthermore, a biocontrol assay showed that Δ srfAB lost the biocontrol efficacy. In summary, our results indicated that surfactin, which consists of C13- to C16-surfactin A was the primary antibacterial compound of B. subtilis 9407, and it played a major role in biofilm formation, swarming motility, colonization and suppressing BFB. We propose that the biocontrol activity of B. subtilis 9407 is the results of the coordinated action of surfactin-mediated antibacterial activity and colonization. This study reveals for the first time that the use of a B. subtilis strain as a potential biological control agent could efficiently control BFB by producing surfactin.

  1. Trichoderma Biocontrol: Signal Transduction Pathways Involved in Host Sensing and Mycoparasitism

    Directory of Open Access Journals (Sweden)

    Susanne Zeilinger

    2007-01-01

    Full Text Available Fungi of the genus Trichoderma are used as biocontrol agents against several plant pathogenic fungi like Rhizoctonia spp., Pythium spp., Botrytis cinerea and Fusarium spp. which cause both soil-borne and leaf- or flower-borne diseases of agricultural plants. Plant disease control by Trichoderma is based on complex interactions between Trichoderma, the plant pathogen and the plant. Until now, two main components of biocontrol have been identified: direct activity of Trichoderma against the plant pathogen by mycoparasitism and induced systemic resistance in plants. As the mycoparasitic interaction is host-specific and not merely a contact response, it is likely that signals from the host fungus are recognised by Trichoderma and provoke transcription of mycoparasitism-related genes.In the last few years examination of signalling pathways underlying Trichoderma biocontrol started and it was shown that heterotrimeric G-proteins and mitogen-activated protein (MAP kinases affected biocontrol-relevant processes such as the production of hydrolytic enzymes and antifungal metabolites and the formation of infection structures. MAPK signalling was also found to be involved in induction of plant systemic resistance in Trichoderma virens and in the hyperosmotic stress response in Trichoderma harzianum. Analyses of the function of components of the cAMP pathway during Trichoderma biocontrol revealed that mycoparasitism-associated coiling and chitinase production as well as secondary metabolism are affected by the internal cAMP level; in addition, a cross talk between regulation of light responses and the cAMP signalling pathway was found in Trichoderma atroviride.

  2. Biocontrol potential of Trichoderma harzianum isolate T-aloe against Sclerotinia sclerotiorum in soybean.

    Science.gov (United States)

    Zhang, Fuli; Ge, Honglian; Zhang, Fan; Guo, Ning; Wang, Yucheng; Chen, Long; Ji, Xiue; Li, Chengwei

    2016-03-01

    Sclerotinia stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary is a major disease of soybean (Glycine max (L.) Merr.). At present, we revealed the three-way interaction between Trichoderma harzianum T-aloe, pathogen S. sclerotiorum and soybean plants in order to demonstrate biocontrol mechanism and evaluate biocontrol potential of T-aloe against S. sclerotiorum in soybean. In our experiments, T-aloe inhibited the growth of S. sclerotiorum with an efficiency of 56.3% in dual culture tests. T-aloe hyphae grew in parallel or intertwined with S. sclerotiorum hyphae and produced hooked contact branches, indicating mycoparasitism. Plate tests showed that T-aloe culture filtrate inhibited S. sclerotiorum growth with an inhibition efficiency of 51.2% and sclerotia production. T-aloe pretreatment showed growth-promoting effect on soybean plants. The activities of peroxidase, superoxide dismutase, and catalase increased, and the hydrogen peroxide (H2O2) as well as the superoxide radical (O2(-)) content in soybean leaves decreased after T-aloe pretreatment in response to S. sclerotiorum pathogen challenge. T-aloe treatment diminished damage caused by pathogen stress on soybean leaf cell membrane, and increased chlorophyll as well as total phenol contents. The defense-related genes PR1, PR2, and PR3 were expressed in the leaves of T-aloe-treated plants. In summary, T-aloe displayed biocontrol potential against S. sclerotiorum. This is the first report of unraveling biocontrol potential of Trichoderma Spp. to soybean sclerotinia stem rot from the three-way interaction between the biocontrol agent, pathogen S. sclerotiorum and soybean plants. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  3. One-electron reduction of 2- and 6-methyl-1,4-naphthoquinone bioreductive alkylating agents

    International Nuclear Information System (INIS)

    Wilson, I.; Wardman, P.; Lin, T.S.; Sartorelli, A.C.

    1986-01-01

    The semiquinones, Q.-, of derivatives of 2- and 6-methyl-1,4-naphthoquinones, some incorporating leaving groups with substituents such as CH 2 Br or CH 2 OCONHCH 3 , have been produced by radiolytic reduction of Q by (CH 3 )2COH radicals. The absorption spectra and decay kinetics of Q.- were all closely similar to that produced from 2-methyl-1,4-naphthoquinone, with no evidence for unimolecular elimination of a leaving group in the semiquinone form, but immediate loss of leaving group upon two-electron reduction of Q to the hydroquinone. The redox equilibria between Q/Q.- and O2/O2.- were characterized, and reduction potentials of the couples Q/Q.- in water at pH 7.6 were calculated. The implications of these observations for the use of these compounds as bioreductive alkylating agents or as radiosensitizers with potential selective activity toward hypoxic cells are discussed

  4. Scanning electron microscopic and X-ray micro analysis on tooth enamel exposed to alkaline agents.

    Science.gov (United States)

    Taubee, Fabian; Steiniger, Frank; Nietzsche, Sandor; Norén, Jörgen G

    2010-01-01

    The background of this study comprises two clinical cases, where patients exposed to aerosols of an alkaline and surface active cleaning agent developed loss of enamel substance on their teeth, further resulting in loss of teeth and partially destroyed soft tissues. The alkaline cleaning agent consisted of potassium hydroxide and various surfactants. The purpose of this study was to investigate possible changes in morphology and composition in human teeth enamel exposed to alkaline solutions, by means of X-ray micro analysis (XRMA), FTIR-spectroscopic analyses and scanning electron microscopy (SEM). Extracted premolars, exposed to potassium hydroxide solutions and alkaline cleaning solution,were analyzed by means of XRMA and SEM. Enamel powder, exposed to cleaning solution, was analyzed by means of FTIR. The SEM analysis revealed an increased porosity of the enamel surface and partially loss of enamel substance after exposure to alkaline solutions. The XRMA analyses revealed a decrease in carbon concentration while phosphorous and calcium showed no marked changes. The FTIR analyses showed no significant changes in peak heights or peak positions for phosphate, carbonate or hydroxide. It was concluded that human teeth enamel exposed to alkaline solutions showed loss of organic substance, marked pores in enamel surface and loss of substance in the enamel surface.

  5. Isolation of Dickeya dadantii strains from potato disease and biocontrol by their bacteriophages.

    Science.gov (United States)

    Soleimani-Delfan, Abbas; Etemadifar, Zahra; Emtiazi, Giti; Bouzari, Majid

    2015-01-01

    One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains.

  6. Biological Control of Aflatoxin Contamination in U.S. Crops and the Use of Bioplastic Formulations of Aspergillus flavus Biocontrol Strains To Optimize Application Strategies.

    Science.gov (United States)

    Abbas, Hamed K; Accinelli, Cesare; Shier, W Thomas

    2017-08-23

    Aflatoxin contamination has a major economic impact on crop production in the southern United States. Reduction of aflatoxin contamination in harvested crops has been achieved by applying nonaflatoxigenic biocontrol Aspergillus flavus strains that can out-compete wild aflatoxigenic A. flavus, reducing their numbers at the site of application. Currently, the standard method for applying biocontrol A. flavus strains to soil is using a nutrient-supplying carrier (e.g., pearled barley for Afla-Guard). Granules of Bioplastic (partially acetylated corn starch) have been investigated as an alternative nutritive carrier for biocontrol agents. Bioplastic granules have also been used to prepare a sprayable biocontrol formulation that gives effective reduction of aflatoxin contamination in harvested corn kernels with application of much smaller amounts to leaves later in the growing season. The ultimate goal of biocontrol research is to produce biocontrol systems that can be applied to crops only when long-range weather forecasting indicates they will be needed.

  7. Identification and Characterization of Novel Biocontrol Bacterial

    Directory of Open Access Journals (Sweden)

    Young Cheol Kim

    2014-09-01

    Full Text Available Because bacterial isolates from only a few genera have been developed commercially as biopesticides, discovery and characterization of novel bacterial strains will be a key to market expansion. Our previous screen using plant bioassays identified 24 novel biocontrol isolates representing 12 different genera. In this study, we characterized the 3 isolates showing the best biocontrol activities. The isolates were Pantoea dispersa WCU35, Proteus myxofaciens WCU244, and Exiguobacterium acetylicum WCU292 based on 16S rRNA sequence analysis. The isolates showed differential production of extracellular enzymes, antimicrobial activity against various fungal or bacterial plant pathogens, and induced systemic resistance activity against tomato gray mold disease caused by Botrytis cinerea. E. acetylicum WCU292 lacked strong in vitro antimicrobial activity against plant pathogens, but induced systemic resistance against tomato gray mold disease. These results confirm that the trait of biological control is found in a wide variety of bacterial genera

  8. Biocontrol of larval mosquitoes by Acilius sulcatus (Coleoptera: Dytiscidae

    Directory of Open Access Journals (Sweden)

    Banerjee Siddhartha S

    2008-10-01

    Full Text Available Abstract Background Problems associated with resistant mosquitoes and the effects on non-target species by chemicals, evoke a reason to find alternative methods to control mosquitoes, like the use of natural predators. In this regard, aquatic coleopterans have been explored less compared to other insect predators. In the present study, an evaluation of the role of the larvae of Acilius sulcatus Linnaeus 1758 (Coleoptera: Dytiscidae as predator of mosquito immatures was made in the laboratory. Its efficacy under field condition was also determined to emphasize its potential as bio-control agent of mosquitoes. Methods In the laboratory, the predation potential of the larvae of A. sulcatus was assessed using the larvae of Culex quinquefasciatus Say 1823 (Diptera: Culicidae as prey at varying predator and prey densities and available space. Under field conditions, the effectiveness of the larvae of A. sulcatus was evaluated through augmentative release in ten cemented tanks hosting immatures of different mosquito species at varying density. The dip density changes in the mosquito immatures were used as indicator for the effectiveness of A. sulcatus larvae. Results A single larva of A. sulcatus consumed on an average 34 IV instar larvae of Cx. quinquefasciatus in a 24 h period. It was observed that feeding rate of A. sulcatus did not differ between the light-on (6 a.m. – 6 p.m., and dark (6 p.m. – 6 a.m. phases, but decreased with the volume of water i.e., space availability. The prey consumption of the larvae of A. sulcatus differed significantly (P A. sulcatus larvae, while with the withdrawal, a significant increase (p A. sulcatus in regulating mosquito immatures. In the control tanks, mean larval density did not differ (p > 0.05 throughout the study period. Conclusion the larvae of the dytiscid beetle A. sulcatus proved to be an efficient predator of mosquito immatures and may be useful in biocontrol of medically important mosquitoes.

  9. Biocontrol of larval mosquitoes by Acilius sulcatus (Coleoptera: Dytiscidae).

    Science.gov (United States)

    Chandra, Goutam; Mandal, Samir K; Ghosh, Arup K; Das, Dipanwita; Banerjee, Siddhartha S; Chakraborty, Sumanta

    2008-10-15

    Problems associated with resistant mosquitoes and the effects on non-target species by chemicals, evoke a reason to find alternative methods to control mosquitoes, like the use of natural predators. In this regard, aquatic coleopterans have been explored less compared to other insect predators. In the present study, an evaluation of the role of the larvae of Acilius sulcatus Linnaeus 1758 (Coleoptera: Dytiscidae) as predator of mosquito immatures was made in the laboratory. Its efficacy under field condition was also determined to emphasize its potential as bio-control agent of mosquitoes. In the laboratory, the predation potential of the larvae of A. sulcatus was assessed using the larvae of Culex quinquefasciatus Say 1823 (Diptera: Culicidae) as prey at varying predator and prey densities and available space. Under field conditions, the effectiveness of the larvae of A. sulcatus was evaluated through augmentative release in ten cemented tanks hosting immatures of different mosquito species at varying density. The dip density changes in the mosquito immatures were used as indicator for the effectiveness of A. sulcatus larvae. A single larva of A. sulcatus consumed on an average 34 IV instar larvae of Cx. quinquefasciatus in a 24 h period. It was observed that feeding rate of A. sulcatus did not differ between the light-on (6 a.m. - 6 p.m.), and dark (6 p.m. - 6 a.m.) phases, but decreased with the volume of water i.e., space availability. The prey consumption of the larvae of A. sulcatus differed significantly (P sulcatus larvae, while with the withdrawal, a significant increase (p sulcatus in regulating mosquito immatures. In the control tanks, mean larval density did not differ (p > 0.05) throughout the study period. the larvae of the dytiscid beetle A. sulcatus proved to be an efficient predator of mosquito immatures and may be useful in biocontrol of medically important mosquitoes.

  10. Transcriptome analysis of Brassica juncea var. tumida Tsen responses to Plasmodiophora brassicae primed by the biocontrol strain Zhihengliuella aestuarii.

    Science.gov (United States)

    Luo, Yuanli; Dong, Daiwen; Su, Yu; Wang, Xuyi; Peng, Yumei; Peng, Jiang; Zhou, Changyong

    2018-05-01

    Mustard clubroot, caused by Plasmodiophora brassicae, is a serious disease that affects Brassica juncea var. tumida Tsen, a mustard plant that is the raw material for a traditional fermented food manufactured in Chongqing, China. In our laboratory, we screened the antagonistic bacteria Zhihengliuella aestuarii against P. brassicae. To better understand the biocontrol mechanism, three transcriptome analyses of B. juncea var. tumida Tsen were conducted using Illumina HiSeq 4000, one from B. juncea only inoculated with P. brassicae (P), one inoculated with P. brassica and the biocontrol agent Z. aestuarii at the same time (P + B), and the other was the control (H), in which P. brassicae was replaced by sterile water. A total of 19.94 Gb was generated by Illumina HiSeq sequencing. The sequence data were de novo assembled, and 107,617 unigenes were obtained. In total, 5629 differentially expressed genes between biocontrol-treated (P + B) and infected (P) samples were assigned to 126 KEGG pathways. Using multiple testing corrections, 20 pathways were significantly enriched with Qvalue ≤ 0.05. The resistance-related genes, involved in the production of pathogenesis-related proteins, pathogen-associated molecular pattern-triggered immunity, and effector-triggered immunity signaling pathways, calcium influx, salicylic acid pathway, reactive oxygen intermediates, and mitogen-activated protein kinase cascades, and cell wall modification, were obtained. The various defense responses induced by the biocontrol strain combatted the P. brassicae infection. The genes and pathways involved in plant resistance were induced by a biocontrol strain. The transcriptome data explained the molecular mechanism of the potential biocontrol strain against P. brassicae. The data will also serve as an important public information platform to study B. juncea var. tumida Tsen and will be useful for breeding mustard plants resistant to P. brassicae.

  11. Emerging microbial biocontrol strategies for plant pathogens.

    Science.gov (United States)

    Syed Ab Rahman, Sharifah Farhana; Singh, Eugenie; Pieterse, Corné M J; Schenk, Peer M

    2018-02-01

    To address food security, agricultural yields must increase to match the growing human population in the near future. There is now a strong push to develop low-input and more sustainable agricultural practices that include alternatives to chemicals for controlling pests and diseases, a major factor of heavy losses in agricultural production. Based on the adverse effects of some chemicals on human health, the environment and living organisms, researchers are focusing on potential biological control microbes as viable alternatives for the management of pests and plant pathogens. There is a growing body of evidence that demonstrates the potential of leaf and root-associated microbiomes to increase plant efficiency and yield in cropping systems. It is important to understand the role of these microbes in promoting growth and controlling diseases, and their application as biofertilizers and biopesticides whose success in the field is still inconsistent. This review focusses on how biocontrol microbes modulate plant defense mechanisms, deploy biocontrol actions in plants and offer new strategies to control plant pathogens. Apart from simply applying individual biocontrol microbes, there are now efforts to improve, facilitate and maintain long-term plant colonization. In particular, great hopes are associated with the new approaches of using "plant-optimized microbiomes" (microbiome engineering) and establishing the genetic basis of beneficial plant-microbe interactions to enable breeding of "microbe-optimized crops". Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Pseudomonads and symbiotic micro-organisms as biocontrol agents ...

    African Journals Online (AJOL)

    KEN

    2007-02-05

    Feb 5, 2007 ... Key words: antagonism, beneficial micro-organisms, biological control, Glomus deserticola, Pseudomonas spp.,. Pythium aphanidermaturm. ... The importance of this plant is related to its leaves and seeds which are ..... fluorescens F113: P. ultimum represses the expression of genes in. P. fluorescens F133 ...

  13. RHIZOBACTERIA AS BIOCONTROL AGENTS OF ROOT ROT DISEASE ON SHALLOT

    Directory of Open Access Journals (Sweden)

    Nunik Iriyanti Ramadhan

    2015-01-01

    Full Text Available Shallot is a high-economic value commodity, but so far the supply is still lower than the demand. One of the production problem is “moler” disease of shallot (MDS caused by Fusarium oxysporum f.sp. cepae (FOCe. The aim of this research was to study the potentiality of shallot rhizobacteria (SRB from various soil ordo to inhibit (MDS. This research was held in the Laboratory of Biology and Soil Health and Greenhouse at UNS. This research was carried out by exploring rhizobacteria of shallot planted on Entisols, Andisols, and Vertisols. Rhizobacteria exploration results were tested for their ability to control Fusarium oxysporum f.sp.cepae (FOCe. Inhibitory ability test of SRB to FOCe was carried out in vitro and on shallot in the greenhouse. The green house research used a Completely Randomized Design (CDR with two factors. The first factor was rhizobacteria combination and the second factor was various soil ordo (Andisols, Entisols, and Vertisols. Each treatment was replicated three times. It was obtained three rhizobacteria isolates from Vertisols (B15: 70%, Andisols (B12:45,55%, and Entisols (B10:46,67% being the highest inhibition results to FOCe. The combination of rhizobacteria B12 and B10 provided the lowest intensity.

  14. Allelopathic potential of some biocontrol agents for the control of ...

    African Journals Online (AJOL)

    user

    2015-02-11

    Feb 11, 2015 ... dispensed into separate 9-cm Petri dishes. PDA and nutrient agar maintained at 45°C were poured over the suspension for fungal and bacterial antagonists, respectively. However, P. fluorescens was cultured on Kings B medium which is selective and encourages the production of fluorescent pigments.

  15. Pseudomonads and symbiotic micro-organisms as biocontrol agents ...

    African Journals Online (AJOL)

    Evaluation was made using selected strains of pseudomonad (Pseudomonas fluorescens, P. putida and Pseudomonas sp.) isolated from V. unguiculata and Solanum tuberosum rhizospheric soils collected in three agroecological zones of Cameroon. Cultures were conducted on agar plates and in liquid media to evaluate ...

  16. Eliciting maize defense pathways aboveground attracts belowground biocontrol agents

    Science.gov (United States)

    Filgueiras, Camila Cramer; Willett, Denis S.; Pereira, Ramom Vasconcelos; Moino Junior, Alcides; Pareja, Martin; Duncan, Larry W.

    2016-01-01

    Plant defense pathways mediate multitrophic interactions above and belowground. Understanding the effects of these pathways on pests and natural enemies above and belowground holds great potential for designing effective control strategies. Here we investigate the effects of aboveground stimulation of plant defense pathways on the interactions between corn, the aboveground herbivore adult Diabrotica speciosa, the belowground herbivore larval D. speciosa, and the subterranean ento-mopathogenic nematode natural enemy Heterorhabditis amazonensis. We show that adult D. speciosa recruit to aboveground herbivory and methyl salicylate treatment, that larval D. speciosa are relatively indiscriminate, and that H. amazonensis en-tomopathogenic nematodes recruit to corn fed upon by adult D. speciosa. These results suggest that entomopathogenicnematodes belowground can be highly attuned to changes in the aboveground parts of plants and that biological control can be enhanced with induced plant defense in this and similar systems. PMID:27811992

  17. Comparison among four commonly used demineralizing agents for root conditioning: a scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Nathalia Godoy do Amaral

    2011-10-01

    Full Text Available Dental roots that have been exposed to the oral cavity and periodontal pocket environment present superficial changes, which can prevent connective tissue reattachment. Demineralizing agents have been used as an adjunct to the periodontal treatment aiming at restoring the biocompatibility of roots. OBJECTIVE: This study compared four commonly used demineralizing agents for their capacity of removing smear layer and opening dentin tubules. METHODS: Fifty fragments of human dental roots previously exposed to periodontal disease were scaled and randomly divided into the following groups of treatment: 1 CA: demineralization with citric acid for 3 min; 2 TC-HCl: demineralization with tetracycline-HCl for 3 min; 3 EDTA: demineralization with EDTA for 3 min; 4 PA: demineralization with 37% phosphoric acid for 3 min; 5 Control: rubbing of saline solution for 3 min. Scanning electron microscopy was used to check for the presence of residual smear layer and for measuring the number and area of exposed dentin tubules. RESULTS: Smear layer was present in 100% of the specimens from the groups PA and control; in 80% from EDTA group; in 33.3% from TC-HCl group and 0% from CA group. The mean numbers of exposed dentin tubules in a standardized area were: TC-HCl=43.8±25.2; CA=39.3±37; PA=12.1±16.3; EDTA=4.4±7.5 and Control=2.3±5.7. The comparison showed significant differences between the following pairs of groups: TC-HCl and Control; TC-HCl and EDTA; CA and Control; and CA and EDTA. The mean percentages of area occupied by exposed dentin tubules were: CA=0.12±0.17%; TC-HCl=0.08±0.06%; PA=0.03±0.05%; EDTA=0.01±0.01% and Control=0±0%. The CA group differed significantly from the others except for the TC-HCl group. CONCLUSION: There was a decreasing ability for smear layer removal and dentin tubule widening as follows: AC>TC-HCl>PA>EDTA. This information can be of value as an extra parameter for choosing one of them for root conditioning.

  18. Biocontrol evaluation of wheat take-all disease by Trichoderma ...

    African Journals Online (AJOL)

    Wheat take-all disease, caused by Gaeumannomyces graminis var tritici (Ggt), has been observed in different areas of Iran in recent years. Current biocontrol studies have confirmed the effectiveness of the. Trichoderma species against many fungal phytopathogens. In this study, biocontrol effects of Trichoderma isolates ...

  19. Biocontrol ability and putative mode of action of yeasts against Geotrichum citri-aurantii in citrus fruit.

    Science.gov (United States)

    Ferraz, Luriany Pompeo; Cunha, Tatiane da; da Silva, Aline Caroline; Kupper, Katia Cristina

    2016-01-01

    Sour rot is a major postharvest disease of citrus fruit and is caused by the fungal pathogen Geotrichum citri-aurantii. A lack of chemicals certified for the control of this disease has led to the consideration of alternative methods and strategies, such as the use of yeasts as biocontrol agents. The purpose of the present study was to test the ability of yeasts isolated from leaves, flowers, fruit, and soil, and six Saccharomyces cerevisiae isolates to control citrus sour rot, to assess the mechanisms of action of the yeast isolates that were demonstrated to be effective for biocontrol, and to identify the most effective yeast isolates for the biocontrol of G. citri-aurantii. In in vivo assays, three yeast isolates (ACBL-23, ACBL-44, and ACBL-77) showed a potential for controlling sour rot in citrus fruits, both preventatively and curatively. Most of the eight yeast isolates that were assessed for a mechanism of action did not produce antifungal compounds in an amount sufficient to inhibit the growth of the pathogen. Additionally, nutrient competition among the yeast strains was not found to be a biocontrol strategy. Instead, killer activity and hydrolytic enzyme production were identified as the major mechanisms involved in the biocontrol activity of the yeasts. Isolates ACBL-23, ACBL-44, and ACBL-77, which controlled sour rot most effectively, were identified as Rhodotorula minuta, Candida azyma, and Aureobasidium pullulans, respectively. To our knowledge, this is the first report of the potential of C. azyma as a biological control agent against a postharvest pathogen and its ability to produce a killer toxin. Copyright © 2016 Elsevier GmbH. All rights reserved.

  20. Prevalence of type III secretion system in effective biocontrol pseudomonads.

    Science.gov (United States)

    Almario, Juliana; Gobbin, Davide; Défago, Geneviève; Moënne-Loccoz, Yvan; Rezzonico, Fabio

    2014-05-01

    Functional type III secretion system (T3SS) genes are needed for effective biocontrol of Pythium damping-off of cucumber by Pseudomonas fluorescens KD, but whether biocontrol Pseudomonas strains with T3SS genes display overall a higher plant-protecting activity is unknown. The assessment of 198 biocontrol fluorescent pseudomonads originating from 60 soils worldwide indicated that 32% harbour the ATPase-encoding T3SS gene hrcN, which was most often found in tomato isolates. The hrcN(+) biocontrol strains (and especially those also producing 2,4-diacetylphloroglucinol and displaying 1-aminocyclopropane-1-carboxylate deaminase activity) displayed higher plant-protecting ability in comparison with hrcN(-) biocontrol strains, both in the Pythium/cucumber and Fusarium/cucumber pathosystems. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  1. Endophytic fungi associated with Monarda citriodora, an aromatic and medicinal plant and their biocontrol potential.

    Science.gov (United States)

    Katoch, Meenu; Pull, Shipra

    2017-12-01

    The Food and Agriculture Organization has estimated that every year considerable losses of the food crops occur due to plant diseases. Although fungicides are extensively used for management of plant diseases, they are expensive and hazardous to the environment and human health. Alternatively, biological control is the safe way to overcome the effects of plant diseases and to sustain agriculture. Since Monarda citriodora Cerv. ex Lag. (Lamiaceae/Labiatae) is known for its antifungal properties, it was chosen for the study. The isolation of endophytic fungi from M. citriodora and assessing their biocontrol potential. The isolated endophytes were characterized using ITS-5.8 S rDNA sequencing. Their biocontrol potential was assessed using different antagonistic assays against major plant pathogens. Twenty-eight endophytes representing 11 genera were isolated, of which, around 82% endophytes showed biocontrol potential against plant pathogens. MC-2 L (Fusarium oxysporum), MC-14 F (F. oxysporum), MC-22 F (F. oxysporum) and MC-25 F (F. redolens) displayed significant antagonistic activity against all the tested pathogens. Interestingly, MC-10 L (Muscodor yucatanensis) completely inhibited the growth of Sclerotinia sp., Colletotrichum capsici, Aspergillus flavus and A. fumigatus in dual culture assay, whereas MC-8 L (A. oryzae) and MC-9 L (Penicillium commune) completely inhibited the growth of the Sclerotinia sp. in fumigation assay. Endophytes MC-2 L, MC-14 F, MC-22 F and MC-25 F could effectively be used to control broad range of phytopathogens, while MC-10 L, MC-8 L and MC-9 L could be used to control specific pathogens. Secondly, endophytes showing varying degrees of antagonism in different assays represented the chemo-diversity not only as promising biocontrol agents but also as a resource of defensive and bioactive metabolites.

  2. Potential role of exoglucanase genes (WaEXG1 and WaEXG2) in the biocontrol activity of Wickerhamomyces anomalous

    Science.gov (United States)

    The use of yeasts, including Wickerhamomyces anomalus, as biocontrol agents against fungi responsible for postharvest diseases of fruits and vegetables has been investigated for the past two decades. Among a variety of killer mechanisms, the production of glucanases coded by the genes WaEXG1 and Wa...

  3. DNA barcodes, expanded distribution, and redescription of Apanteles hemara Nixon, 1965 (Hymenoptera, Braconidae, Microgastrinae), a potential biocontrol species against amaranth leaf-webbers in Africa

    NARCIS (Netherlands)

    Fernandez-Triana, J.; Beaudin, M.; Achterberg, van K.; Agbodzavu, M.K.; Othim, S.T.O.; Nyamu, F.W.; Fiaboe, K.K.M.

    2017-01-01

    The microgastrine parasitoid wasp Apanteles hemara Nixon, 1965, is currently being considered as a potential biocontrol agent of amaranth leaf-webber pests in Africa. To facilitate future research and identification of the species, we characterize it from an integrative taxonomy perspective by

  4. An Agent-Based Model of Message Propagation in the Facebook Electronic Social Network

    OpenAIRE

    Nasrinpour, Hamid Reza; Friesen, Marcia R.; D., Robert; McLeod

    2016-01-01

    A large scale agent-based model of common Facebook users was designed to develop an understanding of the underlying mechanism of information diffusion within online social networks at a micro-level analysis. The agent-based model network structure is based on a sample from Facebook. Using an erased configuration model and the idea of common neighbours, a new correction procedure was investigated to overcome the problem of missing graph edges to construct a representative sample of the Faceboo...

  5. Recent Trends in Salmonella Outbreaks and Emerging Technology for Biocontrol of Salmonella Using Phages in Foods: A Review.

    Science.gov (United States)

    Oh, Jun-Hyun; Park, Mi-Kyung

    2017-12-28

    Salmonella is one of the principal causes of foodborne outbreaks. As traditional control methods have shown less efficacy against emerging Salmonella serotypes or antimicrobialresistant Salmonella , new approaches have been attempted. The use of lytic phages for the biocontrol of Salmonella in the food industry has become an attractive method owing to the many advantages offered by the use of phages as biocontrol agents. Phages are natural alternatives to traditional antimicrobial agents; they have proven effective in the control of bacterial pathogens in the food industry, which has led to the development of different phage products. The treatment with specific phages in the food industry can prevent the decay of products and the spread of bacterial diseases, and ultimately promotes safe environments for animal and plant food production, processing, and handling. After an extensive investigation of the current literature, this review focuses predominantly on the efficacy of phages for the successful control of Salmonella spp. in foods. This review also addresses the current knowledge on the pathogenic characteristics of Salmonella , the prevalence of emerging Salmonella outbreaks, the isolation and characterization of Salmonella -specific phages, the effectiveness of Salmonella -specific phages as biocontrol agents, and the prospective use of Salmonella -specific phages in the food industry.

  6. The Pochonia chlamydosporia serine protease gene vcp1 is subject to regulation by carbon, nitrogen and pH: implications for nematode biocontrol.

    Directory of Open Access Journals (Sweden)

    Elaine Ward

    Full Text Available The alkaline serine protease VCP1 of the fungus Pochonia chlamydosporia belongs to a family of subtilisin-like enzymes that are involved in infection of nematode and insect hosts. It is involved early in the infection process, removing the outer proteinaceous vitelline membrane of nematode eggs. Little is known about the regulation of this gene, even though an understanding of how nutrients and other factors affect its expression is critical for ensuring its efficacy as a biocontrol agent. This paper provides new information on the regulation of vcp1 expression. Sequence analysis of the upstream regulatory region of this gene in 30 isolates revealed that it was highly conserved and contained sequence motifs characteristic of genes that are subject to carbon, nitrogen and pH-regulation. Expression studies, monitoring enzyme activity and mRNA, confirmed that these factors affect VCP1 production. As expected, glucose reduced VCP1 expression and for a few hours so did ammonium chloride. Surprisingly, however, by 24 h VCP1 levels were increased in the presence of ammonium chloride for most isolates. Ambient pH also regulated VCP1 expression, with most isolates producing more VCP1 under alkaline conditions. There were some differences in the response of one isolate with a distinctive upstream sequence including a variant regulatory-motif profile. Cryo-scanning electron microscopy studies indicated that the presence of nematode eggs stimulates VCP1 production by P. chlamydosporia, but only where the two are in close contact. Overall, the results indicate that readily-metabolisable carbon sources and unfavourable pH in the rhizosphere/egg-mass environment may compromise nematode parasitism by P. chlamydosporia. However, contrary to previous indications using other nematophagous and entomopathogenic fungi, ammonium nitrate (e.g. from fertilizers may enhance biocontrol potential in some circumstances.

  7. Bacteriophage cocktail for biocontrol of Salmonella in dried pet food.

    Science.gov (United States)

    Heyse, Serena; Hanna, Leigh Farris; Woolston, Joelle; Sulakvelidze, Alexander; Charbonneau, Duane

    2015-01-01

    Human salmonellosis has been associated with contaminated pet foods and treats. Therefore, there is interest in identifying novel approaches for reducing the risk of Salmonella contamination within pet food manufacturing environments. The use of lytic bacteriophages shows promise as a safe and effective way to mitigate Salmonella contamination in various food products. Bacteriophages are safe, natural, highly targeted antibacterial agents that specifically kill bacteria and can be targeted to kill food pathogens without affecting other microbiota. In this study, we show that a cocktail containing six bacteriophages had a broadspectrum activity in vitro against a library of 930 Salmonella enterica strains representing 44 known serovars. The cocktail was effective against 95% of the strains in this tested library. In liquid culture dose-ranging experiments, bacteriophage cocktail concentrations of ≥10(8) PFU/ml inactivated more than 90% of the Salmonella population (10(1) to 10(3) CFU/ml). Dried pet food inoculated with a mixture containing equal proportions of Salmonella serovars Enteritidis (ATCC 4931), Montevideo (ATCC 8387), Senftenberg (ATCC 8400), and Typhimurium (ATCC 13311) and then surface treated with the six-bacteriophage cocktail (≥2.5 ± 1.5 × 10(6) PFU/g) achieved a greater than 1-log (P food that tested positive for Salmonella. Our results indicate that bacteriophage biocontrol of S. enterica in dried pet food is technically feasible.

  8. Involvement of the Transcriptional Coactivator ThMBF1 in the Biocontrol Activity of Trichoderma harzianum

    Directory of Open Access Journals (Sweden)

    M. Belén Rubio

    2017-11-01

    Full Text Available Trichoderma harzianum is a filamentous fungus well adapted to different ecological niches. Owing to its ability to antagonize a wide range of plant pathogens, it is used as a biological control agent in agriculture. Selected strains of T. harzianum are also able to increase the tolerance of plants to biotic and abiotic stresses. However, little is known about the regulatory elements of the T. harzianum transcriptional machinery and their role in the biocontrol by this species. We had previously reported the involvement of the transcription factor THCTF1 in the T. harzianum production of the secondary metabolite 6-pentyl-pyrone, an important volatile compound related to interspecies cross-talk. Here, we performed a subtractive hybridization to explore the genes regulated by THCTF1, allowing us to identify a multiprotein bridging factor 1 (mbf1 homolog. The gene from T. harzianum T34 was isolated and characterized, and the generated Thmbf1 overexpressing transformants were used to investigate the role of this gene in the biocontrol abilities of the fungus against two plant pathogens. The transformants showed a reduced antifungal activity against Fusarium oxysporum f. sp. lycopersici race 2 (FO and Botrytis cinerea (BC in confrontation assays on discontinuous medium, indicating that the Thmbf1 gene could affect T. harzianum production of volatile organic compounds (VOC with antifungal activity. Moreover, cellophane and dialysis membrane assays indicated that Thmbf1 overexpression affected the production of low molecular weight secreted compounds with antifungal activity against FO. Intriguingly, no correlation in the expression profiles, either in rich or minimal medium, was observed between Thmbf1 and the master regulator gene cross-pathway control (cpc1. Greenhouse assays allowed us to evaluate the biocontrol potential of T. harzianum strains against BC and FO on susceptible tomato plants. The wild type strain T34 significantly reduced the

  9. Striga Biocontrol on a Toothpick: A Readily Deployable and Inexpensive Method for Smallholder Farmers.

    Science.gov (United States)

    Nzioki, Henry S; Oyosi, Florence; Morris, Cindy E; Kaya, Eylul; Pilgeram, Alice L; Baker, Claire S; Sands, David C

    2016-01-01

    Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: (1) Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; (2) Training of smallholder farmers (85% women), to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; (3) Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but innocuous to maize

  10. Striga Biocontrol on a Toothpick: A Readily Deployable and Inexpensive Method for Smallholder Farmers

    Directory of Open Access Journals (Sweden)

    David Chandler Sands

    2016-08-01

    Full Text Available Striga hermonthica (witchweed is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: 1. Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; 2. Training of smallholder farmers (85% women, to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; 3. Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but

  11. Improvement of a dry formulation of Pseudomonas fluorescens EPS62e for fire blight disease biocontrol by combination of culture osmoadaptation with a freeze-drying lyoprotectant.

    Science.gov (United States)

    Cabrefiga, J; Francés, J; Montesinos, E; Bonaterra, A

    2014-10-01

    To study the effect of lyoprotectants and osmoadaptation on viability of Pseudomonas fluorescens EPS62e during freeze-drying and storage and to evaluate the formulation in terms of efficacy in biocontrol and fitness on pear flowers. A wettable powder formulation of a biocontrol agent of fire blight was optimized by means of lyoprotectants and culture osmoadaptation. Freeze-drying was used to obtain dehydrated cells, and the best viability (70% of survival) was obtained using lactose as lyoprotectant. Survival during lyophilization was additionally improved using physiological adaptation of cells during cultivation under salt-amended medium (osmoadaptation). The procedure increased the survival of cells after freeze-drying attaining viability values close to a 100% in the lactose-formulated product (3 × 10(11) CFU g(-1) ), and through the storage period of 1 year at 4°C. The dry formulation showed also an improved biocontrol efficacy and survival of EPS62e on pear flowers under low relative humidity conditions. Cell viability after freeze-drying was improved using lactose as lyoprotectant combined with a procedure of osmoadaptation during cultivation. The powder-formulated product remained active for 12 months and retained biocontrol levels similar to that of fresh cells. The formulation showed an improved survival of EPS62e on flowers and an increase of the efficacy of biocontrol of fire blight at low relative humidity. The results have a potential value for commercial application in biocontrol agents not only of fire blight but also of other plant diseases. © 2014 The Society for Applied Microbiology.

  12. Intelligent Agents: Software Servants for an Electronic Information World (And More!).

    Science.gov (United States)

    Roesler, Marina; Hawkins, Donald T.

    1994-01-01

    Discusses the concept and characteristics of artificial intelligence software for information retrieval, news filtering, clerical support, personal shopping, and investment counseling. Research projects on artificial intelligence at six academic institutions and examples of nine retrieval agent software packages are highlighted. Sidebars discuss…

  13. Biocontrol interventions for inactivation of foodborne pathogens on produce

    Science.gov (United States)

    Post-harvest interventions for control of foodborne pathogens on minimally processed foods are crucial for food safety. Biocontrol interventions have the primary objective of developing novel antagonists in combinations with physical and chemical interventions to inactivate pathogenic microbes. Ther...

  14. Tick control: trapping, biocontrol, host management and other alternative strategies

    Science.gov (United States)

    Ginsberg, Howard S.; Edited by Sonenshine, Daniel E.; Roe, R. Michael

    2014-01-01

    Biology of Ticks is the most comprehensive work on tick biology and tick-borne diseases. This second edition is a multi-authored work, featuring the research and analyses of renowned experts across the globe. Spanning two volumes, the book examines the systematics, biology, structure, ecological adaptations, evolution, genomics and the molecular processes that underpin the growth, development and survival of these important disease-transmitting parasites. Also discussed is the remarkable array of diseases transmitted (or caused) by ticks, as well as modern methods for their control. This book should serve as a modern reference for students, scientists, physicians, veterinarians and other specialists. Volume I covers the biology of the tick and features chapters on tick systematics, tick life cycles, external and internal anatomy, and others dedicated to specific organ systems, specifically, the tick integument, mouthparts and digestive system, salivary glands, waste removal, salivary glands, respiratory system, circulatory system and hemolymph, fat body, the nervous and sensory systems and reproductive systems. Volume II includes chapters on the ecology of non-nidicolous and nidicolous ticks, genetics and genomics (including the genome of the Lyme disease vector Ixodes scapularis) and immunity, including host immune responses to tick feeding and tick-host interactions, as well as the tick's innate immune system that prevents and/or controls microbial infections. Six chapters cover in depth the many diseases caused by the major tick-borne pathogens, including tick-borne protozoa, viruses, rickettsiae of all types, other types of bacteria (e.g., the Lyme disease agent) and diseases related to tick paralytic agents and toxins. The remaining chapters are devoted to tick control using vaccines, acaricides, repellents, biocontrol, and, finally, techniques for breeding ticks in order to develop tick colonies for scientific study.

  15. Protozoa Drive the Dynamics of Culturable Biocontrol Bacterial Communities.

    Science.gov (United States)

    Müller, Maren Stella; Scheu, Stefan; Jousset, Alexandre

    2013-01-01

    Some soil bacteria protect plants against soil-borne diseases by producing toxic secondary metabolites. Such beneficial biocontrol bacteria can be used in agricultural systems as alternative to agrochemicals. The broad spectrum toxins responsible for plant protection also inhibit predation by protozoa and nematodes, the main consumers of bacteria in soil. Therefore, predation pressure may favour biocontrol bacteria and contribute to plant health. We analyzed the effect of Acanthamoeba castellanii on semi-natural soil bacterial communities in a microcosm experiment. We determined the frequency of culturable bacteria carrying genes responsible for the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG), pyrrolnitrin (PRN) and hydrogen cyanide (HCN) in presence and absence of A. castellanii. We then measured if amoebae affected soil suppressiveness in a bioassay with sugar beet seedlings confronted to the fungal pathogen Rhizoctonia solani. Amoebae increased the frequency of both DAPG and HCN positive bacteria in later plant growth phases (2 and 3 weeks), as well as the average number of biocontrol genes per bacterium. The abundance of DAPG positive bacteria correlated with disease suppression, suggesting that their promotion by amoebae may enhance soil health. However, the net effect of amoebae on soil suppressiveness was neutral to slightly negative, possibly because amoebae slow down the establishment of biocontrol bacteria on the recently emerged seedlings used in the assay. The results indicate that microfaunal predators foster biocontrol bacterial communities. Understanding interactions between biocontrol bacteria and their predators may thus help developing environmentally friendly management practices of agricultural systems.

  16. Protozoa Drive the Dynamics of Culturable Biocontrol Bacterial Communities.

    Directory of Open Access Journals (Sweden)

    Maren Stella Müller

    Full Text Available Some soil bacteria protect plants against soil-borne diseases by producing toxic secondary metabolites. Such beneficial biocontrol bacteria can be used in agricultural systems as alternative to agrochemicals. The broad spectrum toxins responsible for plant protection also inhibit predation by protozoa and nematodes, the main consumers of bacteria in soil. Therefore, predation pressure may favour biocontrol bacteria and contribute to plant health. We analyzed the effect of Acanthamoeba castellanii on semi-natural soil bacterial communities in a microcosm experiment. We determined the frequency of culturable bacteria carrying genes responsible for the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG, pyrrolnitrin (PRN and hydrogen cyanide (HCN in presence and absence of A. castellanii. We then measured if amoebae affected soil suppressiveness in a bioassay with sugar beet seedlings confronted to the fungal pathogen Rhizoctonia solani. Amoebae increased the frequency of both DAPG and HCN positive bacteria in later plant growth phases (2 and 3 weeks, as well as the average number of biocontrol genes per bacterium. The abundance of DAPG positive bacteria correlated with disease suppression, suggesting that their promotion by amoebae may enhance soil health. However, the net effect of amoebae on soil suppressiveness was neutral to slightly negative, possibly because amoebae slow down the establishment of biocontrol bacteria on the recently emerged seedlings used in the assay. The results indicate that microfaunal predators foster biocontrol bacterial communities. Understanding interactions between biocontrol bacteria and their predators may thus help developing environmentally friendly management practices of agricultural systems.

  17. Antimicrobial Activity of Bacillus sp. Natural Isolates and Their Potential Use in the Biocontrol of Phytopathogenic Bacteria

    Directory of Open Access Journals (Sweden)

    Tanja Berić

    2012-01-01

    Full Text Available Screening of 203 Bacillus sp. natural isolates for antimicrobial activity against phytopathogenic bacteria showed that 127 tested strains inhibit at least one sensitive strain, which illustrates their potential use as biocontrol agents. Among them, 104 isolates showed significant antagonism against Xanthomonas oryzae pv. oryzae, and only one of these (VPS50.2 synthesizes bacteriocin. An additional screening tested whether 51 isolates contained genes involved in the biosynthesis of lipopeptides of the iturin and surfactin classes. Results show that 33 isolates harbour the operon for iturin biosynthesis, and six of them carry the sfp gene, responsible for the biosynthesis of surfactin. Lipopeptide purification from the supernatant of isolate SS12.9 (identified as B. subtilis or B. amyloliquefaciens was performed using ethyl acetate extraction, ultrafiltration and reversed phase HPLC. Mass spectrometry analysis confirmed that isolate SS12.9 produces a substance of the iturin class with potential for biocontrol of X. oryzae pv. oryzae.

  18. BIOCONTROL FOR RHIZOCTONIA STEM ROT DISEASE BY USING COMBINATION OF SPECIFIC ENDOPHYTE IN PADDY TIDAL SWAMP

    Directory of Open Access Journals (Sweden)

    Ismed Setya Budi

    2013-10-01

    Full Text Available The use of combination of specific endophytic in tidal swamps to control stem root disease as biological control agents has not been done. It is expected that this combination is able to continuously protect plants from pathogen interference. The research was carried out in type C tidal swamp in Banjar regency of South Kalimantan, from March to November 2011, temperature 29-32oC, and pH 4.0-5.5. The method used was Split Plot design. Biocontrol preparation for both types of endophytic was applied in seeds in 7 days after planting (DAP. Observation on high intensity and plant diseases of planting stage on tidal swamps (taradak, ampak and lacak was conducted. The results showed that there was a reduction of disease ranging from 58.70 to 87.29%. The application of combination of two biocontrol agents (T. viride PS-2.1 + P. fluorescent PS-4.8, (Fusarium non-pathogenic PS-1.5 + P. fluorescent PS-4.8 and (T. viride PS-2.1+ FNP PS-1.5 isolate gave the best inhibition result, reduced disease intensity, and increased plant height. The result of soil analysis before and after application of endophytic showed that there was an increase in soil fertility with the element addition of N, P, K and pH.

  19. Fungal endophytes of wild and hybrid Vitis leaves and their potential for vineyard biocontrol.

    Science.gov (United States)

    Kernaghan, Gavin; Mayerhofer, Michael; Griffin, Amanda

    2017-07-01

    Plants are colonized by diverse assemblages of fungal endophytes that have potential as biocontrol agents for a variety of crops, including grapevine. Although the diversity of symbionts can be very high in wild plants, the fungal endophytes of wild Vitis plants have not yet been investigated. We surveyed the fungal endophytes of 6 wild populations of Vitis riparia, as well as a cold-tolerant, hybrid grapevine in 5 vineyards (1 certified organic), using 454 pyrosequencing. We detected between 43 and 235 operational taxonomic units per sample, with the highest richness and diversity in the wild, the lowest in conventional vineyards, and intermediate levels in the organic vineyard. Wild plants supported a range of taxa not seen in the conventional vineyards, and vineyards were dominated by relatively few taxa. We also isolated fungi from the wild plants and tested them for their ability to inhibit pathogens of grapevine. Several wild isolates (e.g., Ramularia spp.) were strongly inhibitory to grapevine pathogens. We show that wild Vitis supports a distinct and highly diverse community of fungal endophytes and may represent a rich repository of potential vineyard biocontrol agents.

  20. Mining the Volatilomes of Plant-Associated Microbiota for New Biocontrol Solutions.

    Science.gov (United States)

    Bailly, Aurélien; Weisskopf, Laure

    2017-01-01

    Microbial lifeforms associated with land plants represent a rich source for crop growth- and health-promoting microorganisms and biocontrol agents. Volatile organic compounds (VOCs) produced by the plant microbiota have been demonstrated to elicit plant defenses and inhibit the growth and development of numerous plant pathogens. Therefore, these molecules are prospective alternatives to synthetic pesticides and the determination of their bioactivities against plant threats could contribute to the development of control strategies for sustainable agriculture. In our previous study we investigated the inhibitory impact of volatiles emitted by Pseudomonas species isolated from a potato field against the late blight-causing agent Phytophthora infestans . Besides the well-documented emission of hydrogen cyanide, other Pseudomonas VOCs impeded P. infestans mycelial growth and sporangia germination. Current advances in the field support the emerging concept that the microbial volatilome contains unexploited, eco-friendly chemical resources that could help select for efficient biocontrol strategies and lead to a greener chemical disease management in the field.

  1. Controlled release of Pantoea agglomerans E325 for biocontrol of fire blight disease of apple.

    Science.gov (United States)

    Kim, In-Yong; Pusey, Paul Lawrence; Zhao, Youfu; Korban, Schuyler S; Choi, Hyungsoo; Kim, Kyekyoon Kevin

    2012-07-10

    Microencapsulation and controlled release of the biocontrol agent Pantoea agglomerans strain E325 (E325), an antagonist to the bacterial plant pathogen Erwinia amylovora that causes fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 μm in diameter, were fabricated to encapsulate E325 within the core, along with nutrients, to preserve viability and promote proliferation. Controlled release of E325 was achieved by separately adjusting alginate concentrations in the shell and core solutions, and by modifying the AMC size. Viability of E325 was monitored via fluorescent staining, revealing either lack of or minimal stress during or after encapsulation. Proliferation of E325 within AMCs, followed by their subsequent release, and colonization activities within confines of apple flowers were studied under different encapsulation conditions using rfp-labeled E325 to obtain highly promising results. This study provided a 'proof of concept' of the successful use of a microencapsulated biocontrol agent, E325, against E. amylovora, and could serve as a model for further studies on the development of effective plant disease management strategies. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Action of the antitumor and antispermatogenic agent lonidamine on electron transport in Ehrlich ascites tumor mitochondria.

    Science.gov (United States)

    Floridi, A; Lehninger, A L

    1983-10-01

    The effect of lonidamine, an antispermatogenic and antitumor drug, on the oxygen consumption, ATPase activity, and redox state of the electron carriers of Ehrlich ascites tumor mitochondria has been studied. Lonidamine inhibits ADP- and uncoupler-stimulated respiration on various NAD- and FAD-linked substrates, but does not affect state 4 respiration. Experiments to determine its site of action showed that lonidamine does not significantly inhibit electron flow through cytochrome oxidase. Electron flow through site 2, the ubiquinone-cytochrome b-cytochrome c1 complex, also was unaffected by lonidamine, which failed to inhibit the oxidation of duroquinol. Moreover, inhibition of electron flow through site 2 was also excluded because of the inability of the N,N,N',N'-tetramethyl-p-phenylenediamine bypass to relieve the lonidamine inhibition of the oxidation of pyruvate + malate. The F0F1ATPase activity and vectorial H+ ejection are also unaffected by lonidamine. The inhibition of succinate oxidation by lonidamine was found to take place at a point between succinate and iron-sulfur center S3. Spectroscopic experiments demonstrated that lonidamine inhibits the reduction of mitochondrial NAD+ by pyruvate + malate and other NAD-linked substrates in the transition from state 1 to state 4. However, lonidamine does not inhibit reduction of added NAD+ by submitochondrial vesicles or by soluble purified NAD-linked dehydrogenases. These observations, together with other evidence, suggest that electron transport in tumor mitochondria is inhibited by lonidamine at the dehydrogenase-coenzyme level, particularly when the electron carriers are in a relatively oxidized state and/or when the inner membrane-matrix compartment is in the condensed state. The action of lonidamine in several respects resembles the selective inhibition of electron transport in tumor cells produced by cytotoxic macrophages (D. L. Granger and A. L. Lehninger (1982) J. Cell Biol. 95, 527).

  3. Cross Talk between 2,4-Diacetylphloroglucinol-Producing Biocontrol Pseudomonads on Wheat Roots

    Science.gov (United States)

    Maurhofer, Monika; Baehler, Eric; Notz, Regina; Martinez, Vicente; Keel, Christoph

    2004-01-01

    The performance of Pseudomonas biocontrol agents may be improved by applying mixtures of strains which are complementary in their capacity to suppress plant diseases. Here, we have chosen the combination of Pseudomonas fluorescens CHA0 with another well-characterized biocontrol agent, P. fluorescens Q2-87, as a model to study how these strains affect each other's expression of a biocontrol trait. In both strains, production of the antimicrobial compound 2,4-diacetylphloroglucinol (DAPG) is a crucial factor contributing to the suppression of root diseases. DAPG acts as a signaling compound inducing the expression of its own biosynthetic genes. Experimental setups were developed to investigate whether, when combining strains CHA0 and Q2-87, DAPG excreted by one strain may influence expression of DAPG-biosynthetic genes in the other strain in vitro and on the roots of wheat. DAPG production was monitored by observing the expression of lacZ fused to the biosynthetic gene phlA of the respective strain. Dual-culture assays in which the two strains were grown in liquid medium physically separated by a membrane revealed that Q2-87 but not its DAPG-negative mutant Q2-87::Tn5-1 strongly induced phlA expression in a ΔphlA mutant of strain CHA0. In the same way, phlA expression in a Q2-87 background was induced by DAPG produced by CHA0. When coinoculated onto the roots of wheat seedlings grown under gnotobiotic conditions, strains Q2-87 and CHA0, but not their respective DAPG-negative mutants, were able to enhance phlA expression in each other. In summary, we have established that two nonrelated pseudomonads may stimulate each other in the expression of an antimicrobial compound important for biocontrol. This interpopulation communication occurs in the rhizosphere, i.e., at the site of pathogen inhibition, and is mediated by the antimicrobial compound itself acting as a signal exchanged between the two pseudomonads. PMID:15066789

  4. Polysiloxane-based lacquer binding agent suited for electron radiation hardening

    International Nuclear Information System (INIS)

    Johnson, O.B.; Nordstrom, J.D.

    1976-01-01

    The binding agent has a high degree of weather resistance and is suitable for use in varnishes and paints applied to wood, metals and plastics. It consists of 20-90% by weight of an alkene-unsaturated reaction product of a polysiloxane and 10-80% by weight of another alkene-unsaturated compound. The reaction product of polysiloxane is produced by etherisation of the polysiloxane with a hydroxyester of an α,β-alkene-unsaturated carboxylic acid and the other component may be an unsaturated epoxy resin, an unsaturated diurethane, or an unsaturated copolymer of vinyl monomers, preferably together with one or more vinyl monomers. (JIW)

  5. Effect of various chemical agents used in gingival retraction systems on smear layer: Scanning electron microscope study

    Directory of Open Access Journals (Sweden)

    Krishna Shivraj Lahoti

    2016-01-01

    Full Text Available Background: Chemical agents used for gingival retraction affects the smear layer. Aim: To determine the effect of three different chemical agents used for gingival retraction systems on smear layer. Materials and Methods: Four human premolars were prepared using air-rotor with air-water spray to receive full crown restoration. Three of them were treated with 21.3% aluminum chloride for 10 min, 0.05% oxymetazoline hydrochloride for 10 min, and expasyl for 2 min, respectively. One sample was left untreated. Then, the tooth specimens were rinsed with tap water to remove any residue of test materials. All the samples (treated and untreated were processed by scanning electron microscope (SEM. Processed samples were examined under SEM at ×2400 to evaluate the effect of chemical agents on smear layer. Results: SEM examination revealed that 0.05% oxymetazoline hydrochloride for 10 min produced no alteration to smear layer followed by minimum alteration by expasyl for 2 min and complete removal of smear layer with etching of dentin with 21.3% aluminum chloride for 10 min. Conclusion: 0.05% oxymetazoline hydrochloride and expasyl are kind to smear layer.

  6. Electronic support tools for identification and management of rice weeds in Africa for better-informed agricultural change agents

    Directory of Open Access Journals (Sweden)

    Rodenburg Jonne

    2016-01-01

    Full Text Available We developed an interactive electronic weed identification tool, AFROweeds, and an online network, Weedsbook, for agricultural change agents to aid communication and offer assistance to rice farmers with specific weed problems. We collected quantitative and qualitative data to assess effectiveness and usefulness of these products with potential users. With the online version of AFROweeds, used on an electronic tablet, average weed identification time in the field was 7 min 6 s with 44% successful identifications. Poor mobile network coverage and slow internet were the main reasons for the relative long identification time and low success rate. A second trial was done with the offline version, pre-installed on a tablet. The average identification time was 6 min 34 s, with a success rate of 75%. The online network Weedsbook, established alongside AFROweeds, was assessed by the test users as a useful additional aid, enabling agricultural change agents and agronomists to exchange information or request assistance on all aspects of weeds and weed management. The potential improvements of both products are discussed.

  7. Biocontrol potential of Trichoderma harzianum in controlling wilt disease of pistachio caused by Verticillium dahliae

    Directory of Open Access Journals (Sweden)

    Fotoohiyan Zeinab

    2017-06-01

    Full Text Available Verticillium wilt caused by Verticillium dahliae, is one of the most devastating diseases in pistachio orchards in the world including Iran. In search for an effective non-chemical strategy for the management of this disease, we evaluated the biocontrol potential of Trichoderma harzianum isolates obtained from the rhizosphere of healthy pistachio trees in different locations of the Kerman province of Iran against V. dahliae under laboratory and greenhouse conditions. Dual culture tests in the laboratory were conducted in a completely randomized design using 72 T. harzianum isolates. Twenty isolates showed the highest in vitro antagonistic activity. The results indicated that all 20 isolates were capable of inhibiting the mycelial growth of V. dahliae significantly. Among them, isolates Tr8 and Tr19 were the most effective by 88.89% and 85.12% inhibition, respectively. Extracted cell free metabolites of all effective isolates also inhibited the growth of V. dahliae in the culture medium significantly. According to the results, isolates Tr4 and Tr6 inhibited fungal pathogen growth by 94.94% and 88.15% respectively, through production of non-volatile metabolites. In the evaluation of volatile metabolites, isolates Tr5 and Tr4 were the most effective by 26.27% and 24.49% growth inhibition, respectively. Based on the results of the in vitro experiments, the five most effective isolates were selected for evaluation under greenhouse conditions for their biocontrol potential in controlling Verticillium wilt of pistachio. Results of the greenhouse, (in vivo experiments were positive and indicated that the occurrence of wilt disease in plants treated with the antagonists alone or in combination with pathogenic fungus was lower than in plants inoculated with pathogen alone. The overall results of this study suggest that Trichoderma fungal antagonist may be an effective biocontrol agent for the control of Verticillium wilt of pistachio.

  8. Remote sensing bio-control damage on aquatic invasive alien plant ...

    African Journals Online (AJOL)

    Popular machine learning algorithms that offer operational potential to classify bio-control damage are proposed. This paper concludes with the challenges of remote sensing bio-control damage as well as proposes recommendations to guide future research to successfully detect and map bio-control damage on AIAP ...

  9. Biocontrol potential of Halotolerant bacterial chitinase from high yielding novel Bacillus Pumilus MCB-7 autochthonous to mangrove ecosystem.

    Science.gov (United States)

    Rishad, K S; Rebello, Sharrel; Shabanamol, P S; Jisha, M S

    2017-04-01

    The multifaceted role of chitinase in medicine, agriculture, environmental remediation and various other industries greatly demands the isolation of high yielding chitinase producing microorganisms with improved properties. The current study aimed to investigate the isolation, characterization and biocontrol prospective of chitinase producing bacterial strains autochthonous to the extreme conditions of mangrove ecosystems. Among the 51 bacterial isolates screened, Bacillus pumilus MCB-7 with highest chitinase production potential was identified and confirmed by 16S rDNA typing. Chitinase enzyme of MCB-7 was purified; the chitin degradation was evaluated by SEM and LC-MS. Unlike previously reported B.pumilus isolates, MCB-7 exhibited highest chitinase activity of 3.36U/mL, active even at high salt concentrations and temperature up to 60°C. The crude as well as purified enzyme showed significant antimycotic activity against agricultural pathogens such as Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, Ceratorhiza hydrophila and Fusarium oxysporum. The enzyme also exhibited biopesticidal role against larvae of Scirpophaga incertulas (Walker). [Lep.: Pyralidae], a serious agricultural pest of rice. The high chitinolytic and antimycotic potential of MCB-7 increases the prospects of the isolate as an excellent biocontrol agent. To the best of our knowledge, this is the first report of high chitinase yielding Bacillus pumilus strain from mangrove ecosystem with a biocontrol role against phytopathogenic fungi and insect larval pests. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Rhodococcus erythropolis and Its γ-Lactone Catabolic Pathway: An Unusual Biocontrol System That Disrupts Pathogen Quorum Sensing Communication

    Directory of Open Access Journals (Sweden)

    Xavier Latour

    2013-12-01

    Full Text Available Rhodococcus erythropolis is an environmental Gram-positive Actinobacterium with a versatile metabolism involved in various bioconversions and degradations. Rhodococci are best known for their great potential in numerous decontamination and industrial processes. However, they can also prevent plant disease by disrupting quorum sensing-based communication of Gram-negative soft-rot bacteria, by degrading N-acyl-homoserine lactone signaling molecules. Such biocontrol activity results partly from the action of the γ-lactone catabolic pathway. This pathway is responsible for cleaving the lactone bond of a wide range of compounds comprising a γ-butyrolactone ring coupled to an alkyl or acyl chain. The aliphatic products of this hydrolysis are then activated and enter fatty acid metabolism. This short pathway is controlled by the presence of the γ-lactone, presumably sensed by a TetR-like transcriptional regulator, rather than the presence of the pathogen or the plant-host in the environment of the Rhodococci. Both the density and biocontrol activity of R. erythropolis may be boosted in crop systems. Treatment with a cheap γ-lactone stimulator, for example, the food flavoring γ-caprolactone, induces the activity in the biocontrol agent, R. erythropolis, of the pathway degrading signaling molecules; such treatments thus promote plant protection.

  11. Biocontrol of Alternaria alternata on cherry tomato fruit by use of marine yeast Rhodosporidium paludigenum Fell & Tallman.

    Science.gov (United States)

    Wang, Yifei; Bao, Yihong; Shen, Danhong; Feng, Wu; Yu, Ting; Zhang, Jia; Zheng, Xiao Dong

    2008-04-30

    The basidiomycetous yeast Rhodosporidium paludigenum Fell & Tallman isolated from the south of East China Sea was evaluated for its activity in reducing postharvest decay of cherry tomatoes caused by Alternaria alternata in vitro and in vivo tests. The results showed that washed cell suspension of R. paludigenum provided better control of A. alternata than any other treatment, while the autoclaved cell culture failed to provide protection against the pathogen. The concentration of antagonist had significant effect on biocontrol effectiveness in vivo: when the concentration of the washed yeast cell suspension was used at 1 x 10(9)cells/ml, the percentage rate of black rot of cherry tomato fruit was only 37%, which was remarkably lower than that treated with water (the control) after 5days of incubation at 25 degrees C. Furthermore, a great biocontrol efficacy of R. paludigenum was observed when it was applied prior to inoculation with A. alternata: the longer the incubation time of R. paludigenum, the lower disease incidence would be. However, there was little efficacy when R. paludigenum was applied after A. alternata inoculation. In addition, on the wounds of cherry tomato, it was observed that R. paludigenum grew rapidly increasing 50-fold during the first 12h at 25 degrees C. To the best of our knowledge, this is a first report concerning that the marine yeast R. paludigenum could be used as a biocontrol agent of postharvest fungal disease.

  12. Augmentative biocontrol in natural marine habitats: persistence, spread and non-target effects of the sea urchin Evechinus chloroticus.

    Directory of Open Access Journals (Sweden)

    Javier Atalah

    Full Text Available Augmentative biocontrol aims to control established pest populations through enhancement of their indigenous enemies. To our knowledge, this approach has not been applied at an operational scale in natural marine habitats, in part because of the perceived risk of adverse non-target effects on native ecosystems. In this paper, we focus on the persistence, spread and non-target effects of the sea urchin Evechinus chloroticus when used as biocontrol agent to eradicate an invasive kelp from Fiordland, New Zealand. Rocky reef macrobenthic assemblages were monitored over 17 months in areas where the indigenous algal canopy was either removed or left intact prior to the translocation of a large number of urchins (>50 ind.·m(-2. Urchin densities in treated areas significantly declined ∼9 months after transplant, and began spreading to adjacent sites. At the end of the 17-month study, densities had declined to ∼5 ind.·m(-2. Compared to controls, treatment sites showed persistent shifts from kelp forest to urchin barrens, which were accompanied by significant reductions in taxa richness. Although these non-target effects were pronounced, they were considered to be localised and reversible, and arguably outweigh the irreversible and more profound ecological impacts associated with the establishment of an invasive species in a region of high conservation value. Augmentative biocontrol, used in conjunction with traditional control methods, represents a promising tool for the integrated management of marine pests.

  13. Relationship between mycoparasites lifestyles and biocontrol behaviors against Fusarium spp. and mycotoxins production.

    Science.gov (United States)

    Kim, Seon Hwa; Vujanovic, Vladimir

    2016-06-01

    Global food security research is seeking eco-friendly solutions to control mycotoxins in grain infected by fungi (molds). In particular, mycotoxigenic Fusarium spp. outbreak is a chronic threat for cereal grain production, human, and animal health. In this review paper, we discuss up-to-date biological control strategies in applying mycoparasites as biological control agents (BCA) to prevent plant diseases in crops and mycotoxins in grain, food, and feed. The aim is to increase food safety and to minimize economic losses due to the reduced grain yield and quality. However, recent papers indicate that the study of the BCA specialists with biotrophic lifestyle lags behind our understanding of the BCA generalists with necrotrophic lifestyle. We examine critical behavioral traits of the two BCA groups of mycoparasites. The goal is to highlight their major characteristics in the context of future research towards an efficient biocontrol strategy against mycotoxin-producing Fusarium species. The emphasis is put on biocontrol of Fusarium graminearum, F. avenaceum, and F. culmorum causing Fusarium head blight (FHB) in cereals and their mycotoxins.

  14. Tamarisk biocontrol using tamarisk beetles: Potential consequences for riparian birds in the southwestern United States

    Science.gov (United States)

    Paxton, Eben H.; Theimer, Tad C.; Sogge, Mark K.

    2011-01-01

    The tamarisk beetle (Diorhabda spp.), a non-native biocontrol agent, has been introduced to eradicate tamarisk (Tamarix spp.), a genus of non-native tree that has become a dominant component of riparian woodlands in the southwestern United States. Tamarisk beetles have the potential to spread widely and defoliate large expanses of tamarisk habitat, but the effects of such a widespread loss of riparian vegetation on birds remains unknown. We reviewed literature on the effects of other defoliating insects on birds to investigate the potential for tamarisk beetles to affect birds positively or negatively by changing food abundance and vegetation structure. We then combined data on the temporal patterns of tamarisk defoliation by beetles with nest productivity of a well-studied riparian obligate, the Southwestern Willow Flycatcher (Empidonax traillii extimus), to simulate the potential demographic consequences of beetle defoliation on breeding riparian birds in both the short and long term. Our results highlight that the effects of tamarisk biocontrol on birds will likely vary by species and population, depending upon its sensitivity to seasonal defoliation by beetles and net loss of riparian habitat due to tamarisk mortality. Species with restricted distributions that include areas dominated by tamarisk may be negatively affected both in the short and long term. The rate of regeneration and/or restoration of native cottonwoods (Populus spp.) and willows (Salix spp.) relative to the rate of tamarisk loss will be critical in determining the long-term effect of this large-scale ecological experiment.

  15. Biocontrol of Burkholderia cepacia complex bacteria and bacterial phytopathogens by Bdellovibrio bacteriovorus.

    Science.gov (United States)

    McNeely, Damian; Chanyi, Ryan M; Dooley, James S; Moore, John E; Koval, Susan F

    2017-04-01

    Bdellovibrio and like organisms are predatory bacteria that have the unusual property of using the cytoplasmic constituents of other Gram-negative bacteria as nutrients. These predators may thus provide an alternative approach to the biocontrol of human and plant pathogens. Predators were isolated on Burkholderia cenocepacia K56-2 and J2315 as prey cells, in enrichment cultures with soil and sewage. Three isolates (DM7C, DM8A, and DM11A) were identified as Bdellovibrio bacteriovorus on the basis of morphology, a periplasmic life cycle, and 16S rRNA gene sequencing. The prey range of these isolates was tested on Burkholderia cepacia complex bacteria and several phytopathogenic bacteria of agricultural importance. Of 31 strains of the Burkholderia cepacia complex tested, only 4 were resistant to predation by strain DM7C. A subset of 9 of the prey tested were also susceptible to strains DM8A and DM11A. Of 12 phytopathogens tested, 4 were resistant to strains DM7C and DM8A, and only 2 were resistant to strain DM11A. Thus, Bdellovibrio bacteriovorus strains retrieved from environmental samples on 2 Burkholderia cenocepacia isolates from cystic fibrosis patients did not distinguish in their prey range between other isolates of that pathogen or phytopathogens. Such strains hold promise as potential wide-spectrum biocontrol agents.

  16. Biofertilization and Biocontrol in the fight against soilborne fungal root pathogens in Australian soils

    Science.gov (United States)

    Cooper, Sarah; Agnew, Linda; Pereg, Lily

    2015-04-01

    Control of soilborne fungal root pathogens that severely compromise cotton production and other crops worldwide has historically been through the use of synthetic fungicides and fertilizers, these often have hazardous implications for environmental and soil health. The search for sustainable alternatives has lead to heightened interest in biocontrol, using soil microorganisms that suppress the growth of phytopathogens directly and biofertilization, the use of microorganisms to increasing the nutrient availability in soils, increasing seedling vigour. Soil properties and consequently soil microbial properties are strongly impacted by agricultural practices, therefore we are isolating indigenous microorganisms from soils collected from ten different geographical locations within the Australian cotton-growing region. These differ vastly in soil type and management practices. Soils are being analysed to compare the abundance of phosphate solubilising, auxin producing and nitrogen cycling bacteria. Rhizospheric bacteria capable of plant growth promoting through a multiple actions are being isolated. In addition, a method for isolating soilborne fungal suppressive microbes directly from soil samples has been designed and is currently being used. Comparisons between agricultural practices and the plant growth promoting microbial component of soil microbiome will be reported on. We will discuss the microbial isolates identified, their modes of action and their potential use as biocontrol agents and/or biofertilizers in Australian cotton growing soils.

  17. Correlation between Biosurfactants and Antifungal Activity of a Biocontrol Bacterium, Bacillus amyloliquefaciens LM11

    Directory of Open Access Journals (Sweden)

    Beom Ryong Kang

    2017-06-01

    Full Text Available Bacillus amyloliquefaciens LM11 was isolated from the feces of larvae of the rhino beetle and showed strong antifungal activities against various phytopathogenic fungi by producing biosurfactants. In this study, our overall goal was to determine relationship between biosurfactants produced from the LM11 strain and its role in growth inhibition of phytopathogenic fungi. Production and expression levels of B. amyloliquefaciens LM11 biosurfactants were significantly differed depending on growth phases. Transcriptional and biochemical analysis indicated that the biosurfactants of the LM11 strain were greatly enhanced in late log-phase to stationary phase. Inhibitions of phytopathogenic mycelial growth and spore germination were directly correlated (P<0.001, R=0.761 with concentrations of the LM11 cell-free culture filtrates. The minimum inhibitory surface tension of the culture filtrate of the B. amyloliquefaciens LM11 grown in stationary phase to inhibit mycelial growth of the phytopathogenic fungi was 38.5 mN/m (P<0.001, R=0.951–0.977. Our results indicated that the biosurfactants of B. amyloliquefaciens LM11 act as key antifungal metabolites in biocontrol of plant diseases, and measuring surface tension of the cell-free culture fluids can be used as an easy indicator for optimal usage of the biocontrol agents.

  18. Screening of novel microorganisms for biosurfactant and biocontrol activity against Phytophthora infestans.

    Science.gov (United States)

    Tomar, Sonica; Singh, B P; Lal, Mehi; Ma, Khan; Hussain, Touseef; Sharma, Sanjeev; Kaushik, S K; Kumar, Satish

    2014-09-01

    In the present study, 95 isolates of bacteria were tested for their biosurfactant as well as biocontrol activity against Phytophthora infestans. The results revealed that only 15.8% isolates showed biosurfactant activity. The emulsification index ranged from 0-68% and 24.2% isolates showed positive reaction for biosurfactant properties. In emulsification assay and oil spreading test, 18.95% and 5.26% isolates, respectively scored positive for biosurfactant production. Among all, only five isolates were found effective against P. infestans, for biocontrol properties. Pseudomonas aeruginosa-1 showed 62.22% inhibition zone after 72 hrs while P. aeruginosa-3 showed 46.42%. Forty-eight hrs old culture supernatants were highly effective in food-poisoning test, tuber slice test and detached leaf method against P. infestans. In whole potato plant test, bacterial cell based formulation, culture supernatant and bacterial cell suspension of P. aeruginosa-1 showed 10.42%, 9.94% and 17.96% diseases severity respectively, as against 53.96% in control. This isolate holds promise as biological control agent against P. infestans in field.

  19. Screening for Pseudomonas and Bacillus antagonistic rhizobacteria strains for the biocontrol of Fusarium wilt of chickpea

    Directory of Open Access Journals (Sweden)

    Hannane Abed

    2016-07-01

    Full Text Available The aim of this work is to study the ability of several isolates belonging to Rhizobacteria (Pseudomonas and Bacillus collected from several chickpea growing areas in Algeria, to control the mycelium growth of Fusarium oxysporum f. sp. ciceris. Interesting isolates were characterized for their morphological characteristics, physiological and biochemical activities as potential bio-control agent. Fungal inhibition tests were performed using plate assay and each isolate were tested for the production of protease, cyanide hydrogen, indole acetic acid, antifungal volatile and extracellular compound. According to API 50 CH, we are able to identify six Bacillus species (B. subtilis, B. circulans, B. lentus, B. aneurinilyticus, B. firmus, B. licheniformis; and with API 20NE test we have identified three Pseudomonas species (P. aeruginosa, P. luteola, P. fluorescens. The ability of bacterial isolates was varied in production of Protease, Gelatinase, Amylase, Cellulase, Acid Indole acetic, Lipase, Catalase and Cyanid Hydrogen. This is traduced in different rate of inhibition growth due to various extracellular compounds, where B61 (Bacillus aneurinilyticus and P39 (Pseudomonas luteola and P70 (Pseudomonas fluorescens were the most efficient with 77 and 55.5% respectively, while B39 (Bacillus firmus and P41 (Pseudomonas luteola were the most efficient by volatile compounds with 70.5 and 77.5% respectively. Our results indicate that these bacteria isolates can be used in the biocontrol of Fusarium oxysporum f. sp. ciceris.

  20. Biocontrol mechanism by root-associated Bacillus amyloliquefaciens FZB42 - a review

    Directory of Open Access Journals (Sweden)

    Soumitra ePaul Chowdhury

    2015-07-01

    Full Text Available Bacillus amyloliquefaciens subsp. plantarum FZB42 is a gram-positive model bacterium for unraveling plant-microbe interactions in Bacilli. In addition, FZB42 is used commercially as biofertilizer and biocontrol agent in agriculture. Genome analysis of FZB42 revealed that nearly 10% of the FZB42 genome is devoted to synthesizing antimicrobial metabolites and their corresponding immunity genes. However, recent investigations in planta demonstrated that - except surfactin - the amount of such compounds found in vicinity of plant roots is relatively low, making doubtful a direct function in suppressing competing microflora including plant pathogens. These metabolites have been also suspected to induce changes within the rhizosphere microbial community, which might affect environment and plant health. However, sequence analysis of rhizosphere samples revealed only marginal changes in the root microbiome, suggesting that secondary metabolites are not the key factor in protecting plants from pathogenic microorganisms. On the other hand, adding FZB42 to plants compensate, at least in part, changes in the community structure caused by the pathogen, indicating an interesting mechanism of plant protection by beneficial Bacilli.Sub-lethal concentrations of cyclic lipopeptides and volatiles produced by plant-associated Bacilli trigger pathways of induced systemic resistance (ISR, which protect plants against attacks of pathogenic microbes, viruses and nematodes. Stimulation of ISR by bacterial metabolites is likely the main mechanism responsible for biocontrol action of FZB42.

  1. Biocontrol mechanism by root-associated Bacillus amyloliquefaciens FZB42 – a review

    Science.gov (United States)

    Chowdhury, Soumitra Paul; Hartmann, Anton; Gao, XueWen; Borriss, Rainer

    2015-01-01

    Bacillus amyloliquefaciens subsp. plantarum FZB42 is a Gram-positive model bacterium for unraveling plant–microbe interactions in Bacilli. In addition, FZB42 is used commercially as biofertilizer and biocontrol agent in agriculture. Genome analysis of FZB42 revealed that nearly 10% of the FZB42 genome is devoted to synthesizing antimicrobial metabolites and their corresponding immunity genes. However, recent investigations in planta demonstrated that – except surfactin – the amount of such compounds found in vicinity of plant roots is relatively low, making doubtful a direct function in suppressing competing microflora including plant pathogens. These metabolites have been also suspected to induce changes within the rhizosphere microbial community, which might affect environment and plant health. However, sequence analysis of rhizosphere samples revealed only marginal changes in the root microbiome, suggesting that secondary metabolites are not the key factor in protecting plants from pathogenic microorganisms. On the other hand, adding FZB42 to plants compensate, at least in part, changes in the community structure caused by the pathogen, indicating an interesting mechanism of plant protection by beneficial Bacilli. Sub-lethal concentrations of cyclic lipopeptides and volatiles produced by plant-associated Bacilli trigger pathways of induced systemic resistance (ISR), which protect plants against attacks of pathogenic microbes, viruses, and nematodes. Stimulation of ISR by bacterial metabolites is likely the main mechanism responsible for biocontrol action of FZB42. PMID:26284057

  2. Protonated ions as systemic trapping agents for noble gases: From electronic structure to radiative association

    Science.gov (United States)

    Ozgurel, O.; Pauzat, F.; Pilmé, J.; Ellinger, Y.; Bacchus-Montabonel, M.-C.; Mousis, O.

    2017-10-01

    The deficiencies of argon, krypton, and xenon observed in the atmosphere of Titan as well as anticipated in some comets might be related to a scenario of sequestration by H3+ in the gas phase at the early evolution of the solar nebula. The chemical process implied is a radiative association, evaluated as rather efficient in the case of H3+, especially for krypton and xenon. This mechanism of chemical trapping might not be limited to H3+ only, considering that the protonated ions produced in the destruction of H3+ by its main competitors present in the primitive nebula, i.e., H2O, CO, and N2, might also give stable complexes with the noble gases. However the effective efficiency of such processes is still to be proven. Here, the reactivity of the noble gases Ar, Kr, and Xe, with all protonated ions issued from H2O, CO, and N2, expected to be present in the nebula with reasonably high abundances, has been studied with quantum simulation method dynamics included. All of them give stable complexes and the rate coefficients of their radiative associations range from 10-16 to 10-19 cm3 s-1, which is reasonable for such reactions and has to be compared to the rates of 10-16 to 10-18 cm3 s-1, obtained with H3+. We can consider this process as universal for all protonated ions which, if present in the primitive nebula as astrophysical models predict, should act as sequestration agents for all three noble gases with increasing efficiency from Ar to Xe.

  3. Electrochemical Sensing of Neurotoxic Agents Based on Their Electron Transfer Promotion Effect on an Au Electrode.

    Science.gov (United States)

    Shimada, Hiroshi; Noguchi, Shiori; Yamamoto, Masahiro; Nishiyama, Katsuhiko; Kitamura, Yusuke; Ihara, Toshihiro

    2017-06-06

    An electrochemical molecular sensor based on a new principle is reported. Nereistoxin (NRT, 4-N,N-dimethylamino-1,2-dithiolane), a naturally occurring neurotoxin (nicotinic acetylcholine receptor agonist), was adsorbed on an Au electrode via Au-S covalent bonding and accelerated the electron transfer between the electrode and the marker, ferricyanide anion. The contrast between the electrochemical responses obtained with the bare and NRT-modified Au electrodes was more pronounced at a low ionic strength of the supporting electrolyte, KCl. In the presence of 1 mM KCl, almost a 0/1 contrast between the signals was obtained through electrostatic interaction between the protonated tertiary amino group of NRT and the anionic ferricyanide ion. No current was observed with an electrode modified with mercaptopropionic acid. An unusually low ionic strength thickened the electric double layer to the degree where current was not observed with the bare electrode. The effect of the electrostatic concentration of the marker ion becomes obvious under such conditions. Commercially available NRT-related pesticides such as Cartap and Bensultap were also detected using the same format after pretreatments by hydrolysis/reduction. The present sensing method was successfully applied to human serum with satisfactory sensitivity.

  4. The phosphotransferase system gene ptsI in the endophytic bacterium Bacillus cereus is required for biofilm formation, colonization, and biocontrol against wheat sharp eyespot.

    Science.gov (United States)

    Xu, Yu-Bin; Chen, Mai; Zhang, Ying; Wang, Miao; Wang, Ying; Huang, Qiu-bin; Wang, Xue; Wang, Gang

    2014-05-01

    Natural resistance of wheat plants to wheat sharp eyespot is inadequate, and new strategies for controlling the disease are required. Biological control is an alternative and attractive way of reducing the use of chemicals in agriculture. In this study, we investigated the biocontrol properties of endophytic bacterium Bacillus cereus strain 0-9, which was isolated from the root systems of healthy wheat varieties. The phosphotransferase system is a major regulator of carbohydrate metabolism in bacteria. Enzyme I is one of the protein components of this system. Specific disruption and complementation of the enzyme I-coding gene ptsI from B. cereus was achieved through homologous recombination. Disruption of ptsI in B. cereus caused a 70% reduction in biofilm formation, a 30.4% decrease in biocontrol efficacy, and a 1000-fold reduction in colonization. The growth of ΔptsI mutant strain on G-tris synthetic medium containing glucose as the exclusive carbon source was also reduced. Wild-type properties could be restored to the ΔptsI mutant strain by ptsI complementation. These results suggested that ptsI may be one of the key genes involved in biofilm formation, colonization, and biocontrol of B. cereus and that B. cereus wild-type strain 0-9 may be an ideal biocontrol agent for controlling wheat sharp eyespot. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  5. Construction of a Streptomyces lydicus A01 transformant with a chit42 gene from Trichoderma harzianum P1 and evaluation of its biocontrol activity against Botrytis cinerea.

    Science.gov (United States)

    Wu, Qiong; Bai, Linquan; Liu, Weicheng; Li, Yingying; Lu, Caige; Li, Yaqian; Fu, Kehe; Yu, Chuanjin; Chen, Jie

    2013-04-01

    Streptomyces lydicus A01 and Trichoderma harzianum P1 are potential biocontrol agents of fungal diseases in plants. S. lydicus A01 produces natamycin to bind the ergosterol of the fungal cell membrane and inhibits the growth of Botrytis cinerea. T. harzianum P1, on the other hand, features high chitinase activity and decomposes the chitin in the cell wall of B. cinerea. To obtain the synergistic biocontrol effects of chitinase and natamycin on Botrytis cinerea, this study transformed the chit42 gene from T. harzianum P1 to S. lydicus A01. The conjugal transformant (CT) of S. lydicus A01 with the chit42 gene was detected using polymerase chain reaction (PCR). Associated chitinase activity and natamycin production were examined using the 3, 5-dinitrosalicylic acid (DNS) method and ultraviolet spectrophotometry, respectively. The S. lydicus A01-chit42 CT showed substantially higher chitinase activity and natamycin production than its wild type strain (WT). Consequently, the biocontrol effects of S. lydicus A01-chit42 CT on B. cinerea, including inhibition to spore germination and mycelial growth, were highly improved compared with those of the WT. Our research indicates that the biocontrol effect of Streptomyces can be highly improved by transforming the exogenous resistance gene, i.e. chit42 from Trichoderma, which not only enhances the production of antibiotics, but also provides a supplementary function by degrading the cell walls of the pathogens.

  6. Microbial inoculants for the biocontrol of Fusarium spp. in durum wheat.

    Science.gov (United States)

    Baffoni, Loredana; Gaggia, Francesca; Dalanaj, Nereida; Prodi, Antonio; Nipoti, Paola; Pisi, Annamaria; Biavati, Bruno; Di Gioia, Diana

    2015-10-30

    Fusarium head blight (FHB) is a severe disease caused by different Fusarium species, which affects a wide range of cereal crops, including wheat. It determines from 10 to 30% of yield loss in Europe. Chemical fungicides are mainly used to reduce the incidence of FHB, but low environmental impact solutions are looked forward. Applications of soil/rhizobacteria as biocontrol agents against FHB in wheat are described in literature, whereas the potential use of lactobacilli in agriculture has scarcely been explored. The aim of this work was to study the inhibitory effect of two bacterial strains, Lactobacillus plantarum SLG17 and Bacillus amyloliquefaciens FLN13, against Fusarium spp. in vitro and to assess their efficacy in field, coupled to the study of the microbial community profile of wheat seeds. Antimicrobial assays were performed on agar plates and showed that the two antagonistic strains possessed antimicrobial activity against Fusarium spp. In the field study, a mixture of the two strains was applied to durum wheat i) weekly from heading until anthesis and ii) at flowering, compared to untreated and fungicide treated plots. The FHB index, combining both disease incidence and disease severity, was used to evaluate the extent of the disease on wheat. A mixture of the two microorganisms, when applied in field from heading until anthesis, was capable of reducing the FHB index. Microbial community profile of seeds was studied via PCR-DGGE, showing the presence of L. plantarum SLG17 in wheat seeds and thus underlining an endophytic behavior of the strain. L. plantarum SLG17 and B. amyloliquefaciens FLN13, applied as biocontrol agents starting from the heading period until anthesis of wheat plants, are promising agents for the reduction of FHB index.

  7. Evaluation of the Effects of Fluoride Prophylactic Agents on Mechanical Properties of Nickel Titanium Wires using Scanning Electron Microscope.

    Science.gov (United States)

    Gupta, Ajay K; Shukla, Gita; Sharma, Poonam; Gupta, Amit K; Kumar, Amit; Gupta, Deepika

    2018-03-01

    Orthodontic treatment these days is increasing in demand, and therefore, it is relatively imperative for the orthodontist to prescribe the use of fluoride-containing products, such as mouthwashes and gels, to help prevent dental caries and maintain healthy oral health. The aim of the study was to assess and evaluate the effects of fluoride prophylactic agents on mechanical properties of nickel titanium (NiTi) wires during orthodontic treatment using scanning electron microscope (SEM). We used the commercially available round preformed NiTi orthodontic archwire (3M company) and three different mouthwash solutions, i.e., Phos-Flur gel (1.1% sodium acidulated phosphate fluoride, APF, 0.5% w/v fluoride, pH = 5.1; Colgate Oral Pharmaceuticals) and Prevident 5000 (1.1% sodium fluoride neutral agent, 0.5% w/v fluoride, pH = 7; Colgate Oral Pharmaceuticals). All the specimens were subjected to a three-point bending test on a universal testing machine. To observe the surface morphological changes, one wire from each group was randomly selected and observed under a SEM. It was observed that there was not much difference in the values of both modulus of elasticity and yield strength obtained after loading of stress on the wires in all the three experimental conditions. A significant difference in both modulus of elasticity and yield strength was observed during unloading of stress. Further, when the surface characteristics were observed for all the specimens using SEM images, it was observed that NiTi wires treated with Phos-Flur showed large surface defects which appeared as round, pitted areas depicting corrosion, numerous white inclusions, and overall damaged surface structure of the wire as compared with the control. Thus, fluoridated mouthwashes are essential to maintain good oral hygiene and decrease instance of caries in patients undergoing orthodontic treatment. The prophylactic usage of topical fluoride agents on NiTi wire seems to diminish the mechanical properties

  8. The effect of different chemical agents on human enamel: an atomic force and scanning electron microscopy study

    Science.gov (United States)

    Rominu, Roxana O.; Rominu, Mihai; Negrutiu, Meda Lavinia; Sinescu, Cosmin; Pop, Daniela; Petrescu, Emanuela

    2010-12-01

    PURPOSE: The goal of our study was to investigate the changes in enamel surface roughess induced by the application of different chemical substances by atomic force microscopy and scanning electron microscopy. METHOD: Five sound human first upper premolar teeth were chosen for the study. The buccal surface of each tooth was treated with a different chemical agent as follows: Sample 1 - 38% phosphoric acid etching (30s) , sample 2 - no surface treatment (control sample), 3 - bleaching with 37.5 % hydrogen peroxide (according to the manufacturer's instructions), 4 - conditioning with a self-etching primer (15 s), 5 - 9.6 % hydrofluoric acid etching (30s). All samples were investigated by atomic force microscopy in a non-contact mode and by scanning electron microscopy. Several images were obtained for each sample, showing evident differences regarding enamel surface morphology. The mean surface roughness and the mean square roughness were calculated and compared. RESULTS: All chemical substances led to an increased surface roughness. Phosphoric acid led to the highest roughness while the control sample showed the lowest. Hydrofluoric acid also led to an increase in surface roughness but its effects have yet to be investigated due to its potential toxicity. CONCLUSIONS: By treating the human enamel with the above mentioned chemical compounds a negative microretentive surface is obtained, with a morphology depending on the applied substance.

  9. From biocontrol to cancer, probiotics and beyond.

    Science.gov (United States)

    Dunne, Colum

    2013-01-01

    This invited commentary covers the period 1997-2012 and has seen changes in terminology that progressed from "basic" and "applied" to "translational" research. In the context of Bioengineered, these changes map readily onto the processes of identifying microbial characteristics appropriate for specific applications, isolation of suitable cultures, strain or genome manipulation and exploitation of these or their metabolomes across a range of settings.   To a great degree, this commentary and my career reflect an engagement with molecular microbiology and the trialling of bacteria and derived constructs in applications ranging from intensive-scale crop protection to amelioration of gastrointestinal disease. This engagement began with laboratory and field evaluations of biocontrol, specifically use of pseudomonads effective against nematode and fungal plant pathogens, characterization of mechanisms mediating beneficial effects of probiotic lactobacilli and bifidobacteria and assessment of functional foods in multinational clinical trials relating to inflammatory bowel disease. Subsequent work focused on (1) intellectual property (IP)-based medical devices for localized delivery of systemically toxic and gene cancer therapies; (2) growth of the science base supporting expansion of a multinational business including company acquisitions; (3) complementing existing inter-institutional research capabilities through development of a national industry-led collaboration; and, most recently, (4) strategic research programs at Ireland's newest medical school. My activities as outlined above parallel two distinct aspects of translational research: (1) involvement in knowledge-driven (commercial and research) organizations that brought together necessary resources and infrastructure and (2) availability of scale research funding from European Framework and Irish national programs.

  10. Topographic assessment of human enamel surface treated with different topical sodium fluoride agents: Scanning electron microscope consideration

    Directory of Open Access Journals (Sweden)

    Gurlal Singh Brar

    2017-01-01

    Full Text Available Introduction: Continuous balanced demineralization and remineralization are natural dynamic processes in enamel. If the balance is interrupted and demineralization process dominates, it may eventually lead to the development of carious lesions in enamel and dentine. Fluoride helps control decay by enhancing remineralization and altering the structure of the tooth, making the surface less soluble. Methodology: One hundred and twenty sound human permanent incisors randomly and equally distributed into six groups as follows: Group I - Control, II - Sodium fluoride solution, III - Sodium fluoride gel, IV - Sodium fluoride varnish, V - Clinpro Tooth Crème (3M ESPE, and VI-GC Tooth Mousse Plus or MI Paste Plus. The samples were kept in artificial saliva for 12 months, and the topical fluoride agents were applied to the respective sample groups as per the manufacturer instructions. Scanning electron microscope (SEM evaluation of all the samples after 6 and 12 months was made. Results: Morphological changes on the enamel surface after application of fluoride in SEM revealed the presence of globular precipitate in all treated samples. Amorphous, globular, and crystalline structures were seen on the enamel surface of the treated samples. Clear differences were observed between the treated and untreated samples. Conclusion: Globular structures consisting of amorphous CaF2precipitates, which acted as a fluoride reservoir, were observed on the enamel surface after action of different sodium fluoride agents. CPP-ACPF (Tooth Mousse and Tricalcium phosphate with fluoride (Clinpro tooth crème are excellent delivery vehicles available in a slow release amorphous form to localize fluoride at the tooth surface.

  11. Three-way interactions between Fusarium species, their plant hosts and biocontrol organisms

    DEFF Research Database (Denmark)

    Kosawang, Chatchai

    Deoxynivalenol (DON) and Zearalenone (ZEA) are among the most predominant mycotoxins produced by Fusarium head blight pathogens. DON is a potent protein inhibitor while ZEA is a potent estrogenic metabolite. The toxins are known to inhibit growth and development of fungi with the exception...... of the mycoparasitic fungus Clonostachys rosea IK726, which is effective in controlling mycotoxin-producing Fusarium species. This thesis reports on aspects regarding (I) detoxification of ZEA in connection to biocontrol activities of the IK726, (II) mechanisms conferring resistance to DON and ZEA and (III) evolution...... of ABC transporters in mycoparasitic fungi focused on C. rosea and Trichoderma spp. We showed that expression of zhd101 depended on concentrations of ZEA and that the gene was not induced by other agents, suggesting specificity of the enzyme towards ZEA and its derivates. To investigate effects of ZEA...

  12. Effeciency of fungal and bacterial biocontrol organisms for the ...

    African Journals Online (AJOL)

    Fungal and bacterial biocontrol organisms with known activity against soil borne fungal pathogens were tested for their efficacy in controlling Fusarium wilt of tomato in the screen house. The trial tested five organisms (Trichoderma virile, Trichoderma harzianum, Penicillium oxalicum, Bacilius subtilis and Pseudomonas ...

  13. Grouper as a Natural Biocontrol of Invasive Lionfish

    Science.gov (United States)

    Mumby, Peter J.; Harborne, Alastair R.; Brumbaugh, Daniel R.

    2011-01-01

    Lionfish (Pterois volitans/miles) have invaded the majority of the Caribbean region within five years. As voracious predators of native fishes with a broad habitat distribution, lionfish are poised to cause an unprecedented disruption to coral reef diversity and function. Controls of lionfish densities within its native range are poorly understood, but they have been recorded in the stomachs of large-bodied Caribbean groupers. Whether grouper predation of lionfish is sufficient to act as a biocontrol of the invasive species is unknown, but pest biocontrol by predatory fishes has been reported in other ecosystems. Groupers were surveyed along a chain of Bahamian reefs, including one of the region's most successful marine reserves which supports the top one percentile of Caribbean grouper biomass. Lionfish biomass exhibited a 7-fold and non-linear reduction in relation to the biomass of grouper. While Caribbean grouper appear to be a biocontrol of invasive lionfish, the overexploitation of their populations by fishers, means that their median biomass on Caribbean reefs is an order of magnitude less than in our study. Thus, chronic overfishing will probably prevent natural biocontrol of lionfishes in the Caribbean. PMID:21731769

  14. Screening mycotoxins for quorum inhibition in a biocontrol bacterial endophyte

    Science.gov (United States)

    Bacterial endophytes are used as biocontrol organisms for plant pathogens such as the maize endophyte Fusarium verticillioides and its production of fumonisin mycotoxins. However, such applications are not always predictable and efficient. Bacteria communicate via cell-dependent signals, which are r...

  15. Biocontrol properties of indigenous Trichoderma isolates from North ...

    African Journals Online (AJOL)

    Trichoderma is one of the best known and well described biocontrol fungi for its lytic activity and antagonistic properties against phytopathogens. In the present study, a total of 114 isolates of Trichoderma were isolated from the soil collected from diverse climatic conditions of Manipur on selective medium. Out of the total ...

  16. Biocontrol of bacterial spot diseases of muskmelon using ...

    African Journals Online (AJOL)

    The biocontrol activity of PpG14 was examined by pot and field tests. Results show that the strain significantly reduced the development and suppressed the incidence of bacterial spot diseases. Moreover, the prevention treatment was better than the therapy treatment when using this strain. Based on its main bacteriological ...

  17. Pathology smorgasboard: Biocontrol, pathogen movement, and recent fumigation results

    Science.gov (United States)

    Research on soilborne pathogens, disease control, and new forest diseases of interest were presented at the Western Forest and Conservation Nursery Association meeting in 2016. Research topics included reduced-rate soil fumigation, Pythium diversity and biocontrol, pathogen movement among nurseries,...

  18. The effectivity of Tilletiopsis albescens in biocontrol of powdery mildew

    DEFF Research Database (Denmark)

    Knudsen, I.M.B.; Skou, J.P.

    1993-01-01

    Tilletiopsis albescens grows well on powdery mildew fungi inoculated on barley or cucumber leaves and causes collapse of the colonies. Application of ballistospores or cut mycelium was equally effective for biocontrol, and the effectiveness tended to increase exponentially with the concentration...

  19. Grouper as a natural biocontrol of invasive lionfish.

    Directory of Open Access Journals (Sweden)

    Peter J Mumby

    Full Text Available Lionfish (Pterois volitans/miles have invaded the majority of the Caribbean region within five years. As voracious predators of native fishes with a broad habitat distribution, lionfish are poised to cause an unprecedented disruption to coral reef diversity and function. Controls of lionfish densities within its native range are poorly understood, but they have been recorded in the stomachs of large-bodied Caribbean groupers. Whether grouper predation of lionfish is sufficient to act as a biocontrol of the invasive species is unknown, but pest biocontrol by predatory fishes has been reported in other ecosystems. Groupers were surveyed along a chain of Bahamian reefs, including one of the region's most successful marine reserves which supports the top one percentile of Caribbean grouper biomass. Lionfish biomass exhibited a 7-fold and non-linear reduction in relation to the biomass of grouper. While Caribbean grouper appear to be a biocontrol of invasive lionfish, the overexploitation of their populations by fishers, means that their median biomass on Caribbean reefs is an order of magnitude less than in our study. Thus, chronic overfishing will probably prevent natural biocontrol of lionfishes in the Caribbean.

  20. Influence of Commercial Antibiotics on Biocontrol of Soft Rot and Plant Growth Promotion in Chinese Cabbages by Bacillus vallismortis EXTN-1 and BS07M

    Directory of Open Access Journals (Sweden)

    Mee Kyung Sang

    2015-12-01

    Full Text Available We investigated influence of three commercial antibiotics viz., oxolinic acid, streptomycin, and validamycin A, on biocontrol and plant growth promoting activities of Bacillus vallismortis EXTN-1 and BS07M in Chinese cabbage. Plants were pre-drenched with these strains followed by antibiotics application at recommended and ten-fold diluted concentration to test the effect on biocontrol ability against soft rot caused by Pectobacterium carotovorum SCC1. The viability of the two biocontrol strains and bacterial pathogen SCC1 was significantly reduced by oxolinic acid and streptomycin in vitro assay, but not by validamycin A. In plant trials, strains EXTN- 1 and BS07M controlled soft rot in Chinese cabbage, and there was a significant difference in disease severity when the antibiotics were applied to the plants drenched with the two biocontrol agents. Additional foliar applications of oxolinic acid and streptomycin reduced the disease irrespective of pre-drench treatment of the PGPRs. However, when the plants were pre-drenched with EXTN-1 followed by spray of validamycin A at recommended concentration, soft rot significantly reduced compared to untreated control. Similarly, strains EXTN-1 and BS07M significantly enhanced plant growth, but it did not show synergistic effect with additional spray of antibiotics. Populations of the EXTN-1 or BS07M in the rhizosphere of plants sprayed with antibiotics were significantly affected as compared to control. Taken together, our results suggest that the three antibiotics used for soft rot control in Chinese cabbage could affect bacterial mediated biocontrol and plant growth promoting activities. Therefore, combined treatment of the PGPRs and the commercial antibiotics should be carefully applied to sustain environmental friendly disease management.

  1. Biocontrol of Gray Mold Decay in Pear by Bacillus amyloliquefaciens Strain BA3

    Science.gov (United States)

    Qu, Hui; Zhao, Longyu; Zhao, Fengchun; Liu, Yufang; Yang, Zhengyou

    2016-01-01

    The economic losses caused by postharvest fruits diseases have attracted global attention. Traditional chemical fungicide could not meet the need of humans. In recent years, microbial agent which has begun to take the place of chemical fungicide comes into people’s vision. The aim of this paper was to investigate the potential of Bacillus amyloliquefaciens strain BA3 for its biocontrol capability on gray mold decay of pears and its effect on postharvest quality of pears. Compared with other treatments, the inhibition effect on gray mold of washed cell suspension of B. amyloliquefaciens was the best. Consequently it was utilized in subsequent experiments. Spore germination and germ tube length of Botrytis cinerea was 18.72% and 12.85 μm treated with BA3, while the control group was 62.88% and 30.44 μm. We confirmed that increase of the concentration of B. amyloliquefaciens, improved the efficacy of BA3 in controlling gray mold decay of pears. Colonization variation of BA3 in wounds of pears was recorded. To begin with, the populations of B. amyloliquefaciens increased rapidly and remained stable. On the fourth day, there was a declining trend , after that the population increased to 4 × 10(5) CFU/wound and remained stable. BA3 had no significant effect on mass loss, titratable acidity, firmness and total soluble solids of pears that were stored at 25°C for 7 days comparing with control group. However, the effect of B. amyloliquefaciens on ascorbic acid was significantly higher than that of the control group. Our study indicates that B. amyloliquefaciens has a potential as postharvest biocontrol agent on pears.

  2. Variabilidade genética na região its do rDNA de isolados de trichoderma spp. (Biocontrolador e Fusarium oxysporum f. sp. Chrysanthemi Genetic variability in rDNA ITS region of Trichoderma spp. (biocontrole agent and Fusarium oxysporum f. sp. chrysanthemi isolates

    Directory of Open Access Journals (Sweden)

    Josiane Pacheco Menezes

    2010-02-01

    Full Text Available A análise de características morfológicas e culturais podem não ser suficientes para uma caracterização precisa das espécies de Trichoderma e Fusarium. Objetivou-se, neste trabalho, caracterizar a região do Espaço Interno Transcrito (ITS do rDNA dos isolados UFSMT15.1, UFSMT16 e UFSMT17 de Trichoderma spp. utilizados no biocontrole de Fusarium oxysporum f. sp. chrysanthemi (isolado UFSMF6. A extração de DNA de cada isolado foi realizada a partir de micélio produzido em meio líquido Batata-Dextrose. As amostras de DNA genômico foram submetidas à Reação em Cadeia da Polimerase (PCR com os oligonucleotídeos iniciadores universais ITS1 e ITS4 e o produto gerado foi sequenciado. Os fragmentos gerados pela amplificação da PCR foram tratados com as enzimas de restrição HaeIII, HinfI e MboI. As regiões ITS1, ITS2 e 5.8S do rDNA desses isolados fúngicos foram amplificadas com sucesso. A região ITS dos isolados UFSMT15.1, UFSMT16 e UFSMT17 de Trichoderma e o isolado UFSMF6 de Fusarium apresentaram uma banda simples com um fragmento de aproximadamente 600 pares de base (pb. As enzimas de restrição HaeIII, HinfI e MboI geraram polimorfismo de bandas entre os isolados. Com base nas análises da sequência de DNA, os isolados UFSMT15.1, UFSMT16, UFSMT17 e UFSMF6 apresentaram maior similaridade com as espécies Trichoderma koningiopsis, Hypocrea virens, Hypocrea lixii e Fusarium oxysporum, respectivamente.The analysis of morphological and cultural characteristics may not enough for the characterization of the species of Trichoderma and Fusarium. The aim of this work was to characterize the Internal Transcribed Spacer (ITS region of the rDNA of UFSMT15.1, UFSMT16 and UFSMT17 isolates of Trichoderma spp. used in the biocontrol of Fusarium oxysporum f. sp. chrysanthemi UFSMF6. DNA extraction of each isolate was accomplished starting from hyphae produced in liquid medium Potato-Dextrose-Agar. The samples of genomic DNA were submitted to

  3. Four-trophic level food webs reveal the cascading impacts of an invasive plant targeted for biocontrol.

    Science.gov (United States)

    López-Núñez, Francisco A; Heleno, Ruben H; Ribeiro, Sérgio; Marchante, Hélia; Marchante, Elizabete

    2017-03-01

    Biological invasions are a major threat to biodiversity and as such understanding their impacts is a research priority. Ecological networks provide a valuable tool to explore such impacts at the community level, and can be particularly insightful for planning and monitoring biocontrol programmes, including the potential for their seldom evaluated indirect non-target effects. Acacia longifolia is among the worst invasive species in Portugal, and has been recently targeted for biocontrol by a highly specific gall-wasp. Here we use an ambitious replicated network approach to: (1) identify the mechanisms by which direct and indirect impacts of A. longifolia can cascade from plants to higher trophic levels, including gallers, their parasitoids and inquilines; (2) reveal the structure of the interaction networks between plants, gallers, parasitoids and inquilines before the biocontrol; and (3) explore the potential for indirect interactions among gallers, including those established with the biocontrol agent, via apparent competition. Over a 15-month period, we collected 31,737 galls from native plants and identified all emerging insects, quantifying the interactions between 219 plant-, 49 galler-, 65 parasitoid- and 87 inquiline-species-one of the largest ecological networks to date. No galls were found on any of the 16 alien plant species. Invasion by A. longifolia caused an alarming simplification of plant communities, with cascading effects to higher trophic levels, namely: a decline of overall gall biomass, and on the richness, abundance and biomass of galler insects, their parasitoids, and inquilines. Correspondingly, we detected a significant decline in the richness of interactions between plants and galls. The invasion tended to increase overall interaction evenness by promoting the local extinction of the native plants that sustained more gall species. However, highly idiosyncratic responses hindered the detection of further consistent changes in network

  4. Nontarget herbivory by a weed biocontrol insect is limited to spillover, reducing the chance of population-level impacts.

    Science.gov (United States)

    Catton, Haley A; Lalonde, Robert G; De Clerck-Floate, Rosemarie A

    2015-03-01

    recommendations for monitoring and management of biocontrol systems with similar attributes, such as removing target plants around nontarget populations of interest. Because M. crucifer is among the least host-specific of the modern weed biocontrol agents, and H. micrantha is likely one of its most highly preferred nontargets, these conclusions are, arguably, generally applicable to other nontarget plants and biocontrol systems.

  5. Comparative transcriptome analysis of the biocontrol strain Bacillus amyloliquefaciens FZB42 as response to biofilm formation analyzed by RNA sequencing.

    Science.gov (United States)

    Kröber, Magdalena; Verwaaijen, Bart; Wibberg, Daniel; Winkler, Anika; Pühler, Alfred; Schlüter, Andreas

    2016-08-10

    The strain Bacillus amyloliquefaciens FZB42 is a plant growth promoting rhizobacterium (PGPR) and biocontrol agent known to keep infections of lettuce (Lactuca sativa) by the phytopathogen Rhizoctonia solani down. Several mechanisms, including the production of secondary metabolites possessing antimicrobial properties and induction of the host plant's systemic resistance (ISR), were proposed to explain the biocontrol effect of the strain. B. amyloliquefaciens FZB42 is able to form plaques (biofilm-like structures) on plant roots and this feature was discussed to be associated with its biocontrol properties. For this reason, formation of B. amyloliquefaciens biofilms was studied at the transcriptional level using high-throughput sequencing of whole transcriptome cDNA libraries from cells grown under biofilm-forming conditions vs. planktonic growth. Comparison of the transcriptional profiles of B. amyloliquefaciens FZB42 under these growth conditions revealed a common set of highly transcribed genes mostly associated with basic cellular functions. The lci gene, encoding an antimicrobial peptide (AMP), was among the most highly transcribed genes of cells under both growth conditions suggesting that AMP production may contribute to biocontrol. In contrast, gene clusters coding for synthesis of secondary metabolites with antimicrobial properties were only moderately transcribed and not induced in biofilm-forming cells. Differential gene expression revealed that 331 genes were significantly up-regulated and 230 genes were down-regulated in the transcriptome of B. amyloliquefaciens FZB42 under biofilm-forming conditions in comparison to planktonic cells. Among the most highly up-regulated genes, the yvqHI operon, coding for products involved in nisin (class I bacteriocin) resistance, was identified. In addition, an operon whose products play a role in fructosamine metabolism was enhanced in its transcription. Moreover, genes involved in the production of the extracellular

  6. The effect of reducing agents on the electronic, magnetic and electrocatalytic properties of thiol-capped Pt/Co and Pt/Ni nanoparticles

    CSIR Research Space (South Africa)

    Mathe, NR

    2015-05-01

    Full Text Available The electronic, magnetic and electrocatalytic properties of bimetallic thiol-capped Pt/Co and Pt/Ni nanoparticles were synthesised using two reducing agents, NaBH(sub4) and N(sub2)H(sub4). X-ray diffraction analysis of the nanoparticles showed Pt...

  7. SEVERAL PESTA TABLET TRIALS WITH Aspergillus alliaceus Thom & Church FOR EFFECTIVE UNDERGROUND AND ABOVEGROUND Orobanche L. BIOCONTROL

    Directory of Open Access Journals (Sweden)

    Mehmet AYBEKE

    2016-06-01

    Full Text Available The present study was performed in order to determine the efficiency of the fungi Aspergillus alliaceus in fighting broomrape by the pesta-tablet trials under below- and above-ground conditions and to determine the appropriate tablet formulations for both conditions. For this purpose, different tablets were used in different experimental steps and their efficiencies were evaluated. The results showed that the tablets T-1, T-2, T-3, T-5, T-12 and T-13 greatly reduced the amount of broomrape in below-ground conditions, particularly with previous and high amount or crushed-tablet applications before crop-sowing. In above-ground conditions, any tablet formulation or directly sclerotial contacting were very effective in broomrape control and it was determined that close presence to or direct contact with broomrape is essential for successful biocontrol. In conclusion, considering the durability of the fungal agent against harsh environmental conditions and its sclerotial structure, it was deduced that if the fungi could be implemented in a stand-alone or especially integrated with each other, it will provide long-term, high-level broomrape biocontrol, indicating the advantages of A. alliaceus against other alternative fungal agents.

  8. Antifungal Activity of Isolated Bacillus amyloliquefaciens SYBC H47 for the Biocontrol of Peach Gummosis.

    Science.gov (United States)

    Li, Xunhang; Zhang, Yanzhou; Wei, Zhiwen; Guan, Zhengbing; Cai, Yujie; Liao, Xiangru

    2016-01-01

    and the growth of mycelia from B. dothidea; therefore, this strain behaves as a potential biocontrol agent against the gummosis disease.

  9. Trichoderma virens as a biocontrol of Toxocara canis: In vivo evaluation.

    Science.gov (United States)

    de Souza Maia Filho, Fernando; da Silva Fonseca, Anelise Oliveira; Persici, Beatriz Maroneze; de Souza Silveira, Julia; Braga, Caroline Quintana; Pötter, Luciana; de Avila Botton, Sônia; Brayer Pereira, Daniela Isabel

    Microorganisms have been widely studied as biological control agents of parasites of medical and veterinary importance. Coprophagous arthropods, bacteria and fungi are among the different organisms evaluated as potential biological control agents. Nematophagous fungi capture and digest the free forms of nematodes in the soil. Due to its zoonotic potential, Toxocara canis have been brought to the attention of researchers. The aim of the present study was to determine whether the administration of embryonated T. canis eggs exposed to the nematophagous fungus Trichoderma virens reduces parasite infection in experimental animals. Embryonated T. canis eggs were exposed to T. virens mycelium for 15 days at 25°C. Subsequently, 100 fungus-exposed eggs were orally administered to 20 Swiss mice. As a positive control, another 20 mice received 100 embryonated eggs that were not exposed to the fungus. After 48h, the animals were killed, and heart, lungs and liver were harvested for the recovery of larvae. The organs of the animals that received embryonated T. canis eggs exposed to the fungus showed a lower mean larval recovery when compared with the animals that received embryonated eggs without fungus exposure (p<0.05). The exposure of T. canis eggs to T. virens reduces the experimental infection, demonstrating the potential of this nematophagous fungus as a biocontrol agent. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  10. Biocontrol strategies for Mediterranean-style fermented sausages.

    Science.gov (United States)

    Oliveira, Márcia; Ferreira, Vânia; Magalhães, Rui; Teixeira, Paula

    2018-01-01

    Naturally fermented meat sausages have a long tradition in Mediterranean countries and are one of the most important groups of traditional foods consumed throughout Europe. Despite all the advances in food science and technology and increased regulatory requirements and concerns for safety and quality during the last decades, the challenge to control important foodborne pathogens in this type of meat products still persists. Simultaneously, growing consumer interest in safe, high quality and minimal processed products, with less additives/preservatives have driven the food industry and scientists in a crusade for innovative technologies to maintain the safety of these products by natural means. Biological control (biocontrol) fits well within this tendency. This review summarizes the latest achievements on biocontrol strategies applied to Mediterranean-style fermented sausages, namely: (i) bioprotective cultures; (ii) bacteriocins; and, (iii) essential oils (EOs). Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Selection for biocontrol bacteria antagonistic toward Rosellinia necatrix by enrichment of competitive avocado root tip colonizers.

    Science.gov (United States)

    Pliego, Clara; Cazorla, Francisco Manuel; González-Sánchez, María Angeles; Pérez-Jiménez, Rosa María; de Vicente, Antonio; Ramos, Cayo

    2007-06-01

    Biological control of soil-borne pathogens is frequently based on the application of antagonistic microorganisms selected solely for their ability to produce in vitro antifungal factors. The aim of this work was to select bacteria that efficiently colonize the roots of avocado plants and display antagonism towards Rosellinia necatrix, the causal agent of avocado white root rot. A high frequency of antagonistic strains (ten isolates, 24.4%) was obtained using a novel procedure based on the selection of competitive avocado root tip colonizers. Amplification and sequencing of the 16S rRNA gene, in combination with biochemical characterization, showed that eight and two of the selected isolates belonged to the genera Pseudomonas and Stenotrophomonas, respectively. Characterization of antifungal compounds produced by the antagonistic strains showed variable production of exoenzymes and HCN. Only one of these strains, Pseudomonas sp. AVO94, produced a compound that could be related to antifungal antibiotics. All of the ten selected strains showed twitching motility, a cell movement involved in competitive colonization of root tips. Production of N-acyl-homoserine lactones and indole-3-acetic acid was also reported for some of these isolates. Resistance to several bacterial antibiotics was tested, and three strains showing resistance to only one of them were selected for biocontrol assays. The three selected strains persisted in the rhizosphere of avocado plants at levels considered crucial for efficient biocontrol, 10(5)-10(6) colony forming units/g of root; two of them, Pseudomonas putida AVO102 and Pseudomonas pseudoalcaligenes AVO110, demonstrated significant protection of avocado plants against white root rot.

  12. Characteristics of the biocontrol rhizobacterium Pseudomonas chlororaphis PCL1606

    OpenAIRE

    Tienda, Sandra; de Vicente, Antonio; Cazorla, Francisco M.

    2017-01-01

    The major disease affecting avocado crops in the Mediterranean area is Rosellinia necatrix, causing the avocado white root rot. The biocontrol rhizobacterium Pseudomonas chlororaphis PCL1606 has been isolated from rhizosphere of healthy avocado trees, growing in an area affected by white root rot. As a main characteristic, PCL1606 showed a strong in vitro antagonism against R. necatrix and other important soil borne pathogens, mainly due to the production of the antimicrobial compound 2- hexy...

  13. Genome Sequence of the Biocontrol Strain Pseudomonas fluorescens F113

    Science.gov (United States)

    Redondo-Nieto, Miguel; Barret, Matthieu; Morrisey, John P.; Germaine, Kieran; Martínez-Granero, Francisco; Barahona, Emma; Navazo, Ana; Sánchez-Contreras, María; Moynihan, Jennifer A.; Giddens, Stephen R.; Coppoolse, Eric R.; Muriel, Candela; Stiekema, Willem J.; Rainey, Paul B.; Dowling, David; O'Gara, Fergal; Martín, Marta

    2012-01-01

    Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) that has biocontrol activity against fungal plant pathogens and is a model for rhizosphere colonization. Here, we present its complete genome sequence, which shows that besides a core genome very similar to those of other strains sequenced within this species, F113 possesses a wide array of genes encoding specialized functions for thriving in the rhizosphere and interacting with eukaryotic organisms. PMID:22328765

  14. Assessinent of streptomycesgriseo viridis (mycostop as a biocontrol agent for fusarium oxysporum f. sp. dianthiin two cultivars of standard carnation under commercial conditions Evaluación de Streptomyces griseoviridis (MYCOSTOP en el control de Fusarium oxysporum f.sp. dianthi, en dos variedades de clavel estándar bajo condiciones comerciales

    Directory of Open Access Journals (Sweden)

    Ortega Luis Miguel

    1994-06-01

    Full Text Available The research was carried out in a commercial farm, located in Madrid, Cundinamarca. The purpose of the study was to established the rate and irequency of application of Streptomyces griseoviridis (Mycostop in the control of vascular wilt of carnation caused by Fusarium oxysporum f.sp. dianthi. Two experiments were conducted to compare three rates of application (0,025;0,05 and 0,01 g/m2 and
    three intervals of application (1,2 and 4 weeks of
    Mycostop, in two standard carnation varieties. Disease
    progress data were analized by comparing their godness of fit to Gompertz and Monomolecular epidemiological models. By using the simpler linear regression model, the rate of inlection (k and the coefficient of determination (Al were calculated.
    Inlection rates were subjected to analysis of variance.
    The results showed no satislactory control of the disease. Rates and frecuencies of applícation of Streptomyces griseoviridis (Mycostop did not show appreciable differences. Epidemiologically, "k" values were highly homogeneous among the different Mycostop treatments. Streptomyces
    griseoviridisis highly dependent upon culture media
    pH, and it grows only at a pH 016,4 or higher, with an optimal growth at a pH 7,0. No relation was detected between growth of the biocontrol organism and levels of electrical conductivity.La investigación se realizó en un cultivo comercial de clavel localizado en el municipio de Madrid (Cundinamarca, con el objetivo de determinar la dosis y la frecuencia de aplicación de Streptomyces griseoviridis (Mycostop en el control del
    marchitamiento vascular ocasionado por Fusarium oxysporom lsp. dianthi. En el campo, se realizaron dos experimentos simultáneos, para probar diferentes dosis (0,025; 0,05 y 0,1 g/m2 y frecuencias (1, 2 y 4 semanas de aplicación de
    Streptomyces griseoviridis Mycostop en dos variedades de clavel estándar. El análisis estadístico consistió en utilizar algunos

  15. Effect of bleaching agents having a neutral pH on the surface of mineral trioxide aggregate using electron microscopy and energy dispersive X-ray microanalysis

    Science.gov (United States)

    Kazia, Nooh; Suvarna, Nithin; Shetty, Harish Kumar; Kumar, Pradeep

    2016-01-01

    Aim: To investigate the effect of bleaching agents having a neutral pH on the surface of mineral trioxide aggregate (MTA) used as a coronal seal material for nonvital bleaching, beneath the bleaching agent, with the help of energy dispersive X-ray microanalysis and scanning electron microscopy (SEM). Materials and Methods: Six samples of plastic tubes filled with white MTA (Angelus white) were kept in 100% humidity for 21 days. Each sample was divided into 2 and made into 12 samples. These were then divided into three groups. Group A was exposed to Opalescence Boost 40% hydrogen peroxide (HP) (Ultradent). Group B to Opalescence 10% carbamide peroxide (Ultradent) and Group C (control group) not exposed to any bleaching agent. After recommended period of exposure to bleaching agents according to manufacturers’ instructions, the samples were observed under SEM with an energy dispersive X-ray microanalysis system (JSM-6380 LA). Results: There were no relevant changes in color and no statistically significant surface structure changes of the MTA in both the experimental groups. Conclusion: The present findings suggest that even high concentration HP containing bleaching agents with neutral pH can be used on the surface of MTA without causing structural changes. The superior sealing ability of MTA and the high alkalinity would prevent cervical resorption postbleaching. PMID:27656061

  16. Combinative effects of a bacterial type-III effector and a biocontrol ...

    Indian Academy of Sciences (India)

    Madhu

    Expression of HpaGXoo, a bacterial type-III effector, in transgenic plants induces disease resistance. Resistance also can be elicited by biocontrol bacteria. In both cases, plant growth is often promoted. Here we address whether biocontrol bacteria and HpaGXoo can act together to provide better results in crop improvement ...

  17. Characterization of the Biosynthetic Operon for the Antibacterial Peptide Herbicolin in Pantoea vagans Biocontrol Strain C9-1 and Incidence in Pantoea Species

    Science.gov (United States)

    Kamber, Tim; Lansdell, Theresa A.; Stockwell, Virginia O.; Ishimaru, Carol A.; Smits, Theo H. M.

    2012-01-01

    Pantoea vagans C9-1 is a biocontrol strain that produces at least two antibiotics inhibiting the growth of Erwinia amylovora, the causal agent of fire blight disease of pear and apple. One antibiotic, herbicolin I, was purified from culture filtrates of P. vagans C9-1 and determined to be 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine, also known as Nß-epoxysuccinamoyl-DAP-valine. A plasposon library was screened for mutants that had lost the ability to produce herbicolin I. It was shown that mutants had reduced biocontrol efficacy in immature pear assays. The biosynthetic gene cluster in P. vagans C9-1 was identified by sequencing the flanking regions of the plasposon insertion sites. The herbicolin I biosynthetic gene cluster consists of 10 coding sequences (CDS) and is located on the 166-kb plasmid pPag2. Sequence comparisons identified orthologous gene clusters in Pantoea agglomerans CU0119 and Serratia proteamaculans 568. A low incidence of detection of the biosynthetic cluster in a collection of 45 Pantoea spp. from biocontrol, environmental, and clinical origins showed that this is a rare trait among the tested strains. PMID:22504810

  18. Biocontrol of Sugarcane Smut Disease by Interference of Fungal Sexual Mating and Hyphal Growth Using a Bacterial Isolate.

    Science.gov (United States)

    Liu, Shiyin; Lin, Nuoqiao; Chen, Yumei; Liang, Zhibin; Liao, Lisheng; Lv, Mingfa; Chen, Yufan; Tang, Yingxin; He, Fei; Chen, Shaohua; Zhou, Jianuan; Zhang, Lianhui

    2017-01-01

    Sugarcane smut is a fungal disease caused by Sporisorium scitamineum , which can cause severe economic losses in sugarcane industry. The infection depends on the mating of bipolar sporida to form a dikaryon and develops into hyphae to penetrate the meristematic tissue of sugarcane. In this study, we set to isolate bacterial strains capable of blocking the fungal mating and evaluate their potential in control of sugarcane smut disease. A bacterial isolate ST4 from rhizosphere displayed potent inhibitory activity against the mating of S. scitamineum bipolar sporida and was selected for further study. Phylogenetic analyses and biochemical characterization showed that the isolate was most similar to Pseudomonas guariconensis . Methanol extracts from minimum and potato dextrose agar (PDA) agar medium, on which strain ST4 has grown, showed strong inhibitory activity on the sexual mating of S. scitamineum sporida, without killing the haploid cells MAT-1 or MAT-2. Further analysis showed that only glucose, but not sucrose, maltose, and fructose, could support strain ST4 to produce antagonistic chemicals. Consistent with the above findings, greenhouse trials showed that addition of 2% glucose to the bacterial inoculum significantly increased the strain ST4 biocontrol efficiency against sugarcane smut disease by 77% than the inoculum without glucose. The results from this study depict a new strategy to screen for biocontrol agents for control and prevention of the sugarcane smut disease.

  19. Biocontrol of tomato wilt disease by Bacillus subtilis isolates from natural environments depends on conserved genes mediating biofilm formation

    Science.gov (United States)

    Liu, Hongxia; Kolter, Roberto; Losick, Richard; Guo, Jian-hua

    2014-01-01

    Summary Bacillus subtilis and other Bacilli have long been used as biological control agents against plant bacterial diseases but the mechanisms by which the bacteria confer protection are not well understood. Our goal in this study was to isolate strains of B. subtilis that exhibit high levels of biocontrol efficacy from natural environments and to investigate the mechanisms by which these strains confer plant protection. We screened a total of sixty isolates collected from various locations across China and obtained six strains that exhibited above 50% biocontrol efficacy on tomato plants against the plant pathogen Ralstonia solanacearum under greenhouse conditions. These wild strains were able to form robust biofilms both in defined medium and on tomato plant roots and exhibited strong antagonistic activities against various plant pathogens in plate assays. We show that plant protection by those strains depended on widely conserved genes required for biofilm formation, including regulatory genes and genes for matrix production. We provide evidence suggesting that matrix production is critical for bacterial colonization on plant root surfaces. Finally, we have established a model system for studies of B. subtilis-tomato plant interactions in protection against a plant pathogen. PMID:22934631

  20. Genetic responses induced in olive roots upon colonization by the biocontrol endophytic bacterium Pseudomonas fluorescens PICF7.

    Directory of Open Access Journals (Sweden)

    Elisabetta Schilirò

    Full Text Available Knowledge on the genetic basis underlying interactions between beneficial bacteria and woody plants is still very limited, and totally absent in the case of olive. We aimed to elucidate genetic responses taking place during the colonization of olive roots by the native endophyte Pseudomonas fluorescens PICF7, an effective biocontrol agent against Verticillium wilt of olive. Roots of olive plants grown under non-gnotobiotic conditions were collected at different time points after PICF7 inoculation. A Suppression Subtractive Hybridization cDNA library enriched in induced genes was generated. Quantitative real time PCR (qRT-PCR analysis validated the induction of selected olive genes. Computational analysis of 445 olive ESTs showed that plant defence and response to different stresses represented nearly 45% of genes induced in PICF7-colonized olive roots. Moreover, quantitative real-time PCR (qRT-PCR analysis confirmed induction of lipoxygenase, phenylpropanoid, terpenoids and plant hormones biosynthesis transcripts. Different classes of transcription factors (i.e., bHLH, WRKYs, GRAS1 were also induced. This work highlights for the first time the ability of an endophytic Pseudomonas spp. strain to mount a wide array of defence responses in an economically-relevant woody crop such as olive, helping to explain its biocontrol activity.

  1. The impact of changing antiseptic skin preparation agent used for cardiac implantable electronic device (CIED) procedures on the risk of infection.

    Science.gov (United States)

    Qintar, Mohammed; Zardkoohi, Omeed; Hammadah, Muhammad; Hsu, Amy; Wazni, Oussama; Wilkoff, Bruce L; Tarakji, Khaldoun G

    2015-02-01

    Cardiac implantable electronic device (CIED) infection is a major complication that is associated with increased morbidity and mortality. Recent data suggested a relationship between the antiseptic agent used for skin preparation at time of CIED procedure and risk for infection. On April 30, 2011, we changed the antiseptic agent used for skin preparation at our tertiary care facility from chlorhexidine-alcohol to povidone-iodine for all CIED procedures. We retrospectively reviewed records of all patients who underwent CIED procedure 1 year before and after the change. CIED infection was defined as pocket or endovascular systemic infection that required removal within 1 year of the index procedure. We examined if the change affected the risk of CIED infection. A total of 2,792 patients underwent 2,840 CIED procedures; 1,748 (61.5%) had implantable cardioverter defibrillator procedures and 1,092 (38.4%) had permanent pacemaker procedures. Chlorhexidine-alcohol agent was used in 1,450 (51.1%) procedures, and povidone-iodine agent was used in 1,390 (48.9%). After 1 year of follow-up, 31 patients (1.09%) developed CIED infection that required system removal. The 1-year infection rate was 1.1% among both antiseptic agent groups and there were no significant differences in the infection presentations among both groups (P = 0.950). Multivariate Cox proportional hazards regression model showed that risk factors for infection within 1 year included age, diabetes, and African American race. In one large cohort of patients undergoing CIED procedures, the antiseptic agent used for skin preparation (chlorhexidine-alcohol vs povidone-iodine) was not associated with increased risk of developing CIED infection. ©2014 Wiley Periodicals, Inc.

  2. Mapping the Flowering of an Invasive Plant Using Unmanned Aerial Vehicles: Is There Potential for Biocontrol Monitoring?

    Directory of Open Access Journals (Sweden)

    Nuno C. de Sá

    2018-03-01

    Full Text Available Invasion by alien species is a worldwide phenomenon with negative consequences at both natural and production areas. Acacia longifolia is an invasive shrub/small tree well known for its negative ecological impacts in several places around the world. The recent introduction of a biocontrol agent (Trichilogaster acaciaelongifoliae, an Australian bud-galling wasp which decreases flowering of A. longifolia, in Portugal, demands the development of a cost-efficient method to monitor its establishment. We tested how unmanned aerial vehicles (UAV can be used to map A. longifolia flowering. Our core assumption is as the population of the biocontrol agent increases, its impacts on the reduction of A. longifolia flowering will be increasingly visible. Additionally, we tested if there is a simple linear correlation between the number of flowers of A. longifolia counted in field and the area covered by flowers in the UAV imagery. UAV imagery was acquired over seven coastal areas including frontal dunes, interior sand dunes and pine forests considering two phenological stages: peak and off-peak flowering season. The number of flowers of A. longifolia was counted, in a minimum of 60 1 m2 quadrats per study area. For each study area, flower presence/absence maps were obtained using supervised Random Forest. The correlation between the number of flowers and the area covered by flowering plants could then be tested. The flowering of A. longifolia was mapped using UAV mounted with RGB and CIR Cannon IXUS/ELPH cameras (Overall Accuracy > 0.96; Cohen’s Kappa > 0.85 varying according to habitat type and flowering season. The correlation between the number of flowers counted and the area covered by flowering was weak (r2 between 0.0134 and 0.156. This is probably explained, at least partially, by the high variability of A. longifolia in what regards flowering morphology and distribution. The very high accuracy of our approach to map A. longifolia flowering proved to

  3. Real-time RT-PCR expression analysis of chitinase and endoglucanase genes in the three-way interaction between the biocontrol strain Clonostachys rosea IK726, Botrytis cinera and strawberry

    DEFF Research Database (Denmark)

    Mamarabadi, Mojtaba; Jensen, Birgit; Jensen, Søren Dan Funck

    2008-01-01

    Clonostachys rosea is a well-known biocontrol agent against Botrytis cinerea, the causal agent of gray mold in strawberry. The activity of cell wall-degrading enzymes might play a significant role for successful biocontrol by C. rosea. The expression pattern of four chitinases, and two...... endoglucanase genes from C. rosea strain IK726 was analyzed using real-time RT-PCR in vitro and in strawberry leaves during interaction with B. cinerea. Specific primers were designed for ß-tubulin genes from C. rosea and B. cinerea, respectively, and a gene encoding a DNA-binding protein (DBP) from strawberry......, allowing in situ activity assessment of each fungus in vitro and during their interaction on strawberry leaves. Growth of B. cinerea was inhibited in all pathogen-antagonist interactions while the activity of IK726 was slightly increased. In all in vitro interactions, four of the six genes were upregulated...

  4. Electron beam induced water-soluble silk fibroin nanoparticles as a natural antioxidant and reducing agent for a green synthesis of gold nanocolloid

    Science.gov (United States)

    Wongkrongsak, Soraya; Tangthong, Theeranan; Pasanphan, Wanvimol

    2016-01-01

    The research proposes a novel water-soluble silk fibroin nanoparticles (WSSF-NPs) created by electron beam irradiation. In this report, we demonstrate the effects of electron beam irradiation doses ranging from 1 to 30 kGy on the molecular weight (MW), nanostructure formation, antioxidant activity and reducing power of the WSSF-NPs. Electron beam-induced degradation of SF causing MW reduction from 250 to 37 kDa. Chemical characteristic functions of SF still remained after exposing to electron beam. The WSSF-NPs with the MW of 37 kDa exhibited spherical morphology with a nanoscaled size of 40 nm. Antioxidant activities and reducing powers were investigated using 2,2-diphenyl-1-picrylhryl free radical (DPPH•) scavenging activity and ferric reducing antioxidant power (FRAP) assays, respectively. The WSSF-NPs showed greater antioxidant activity and reducing power than non-irradiated SF. By increasing their antioxidant and reducing power efficiencies, WSSF-NPs potentially created gold nanocolloid. WSSF-NPs produced by electron beam irradiation would be a great merit for the uses as a natural antioxidant additive and a green reducing agent in biomedical, cosmetic and food applications.

  5. Biocontrol of Fusarium circinatum Infection of Young Pinus radiata Trees

    Directory of Open Access Journals (Sweden)

    Eugenia Iturritxa

    2017-01-01

    Full Text Available Pitch canker, caused by the fungus Fusarium circinatum, is a major disease of Pinus radiata currently controlled to some extent in nurseries by good hygiene and application of synthetic fungicides. The aim of this study was to evaluate alternative strategies to control fungal infections in nurseries and young pine plantations. The antagonistic effects of biocontrol bacteria and essential oils against F. circinatum in vitro and in young P. radiata trees were assessed. Pseudomonas fluorescens, Erwinia billingiae, and Bacillus simplex reduced the growth of the fungus in vitro by 17%–29%, and decreased the density of the mycelial mat. In young P. radiata trees, the length of F. circinatum lesions was reduced by 22%–25% by the same bacterial strains. Direct application of cinnamon and/or clove essential oils to wounds in stems of two-year-old P. radiata trees also limited the damage caused by F. circinatum. Lesion length was reduced by 51% following treatment with cinnamon oil (10% v/v, and by 45% following treatment with clove oil (15% v/v or a combination of both oils. However, the oils were toxic to younger trees. The biocontrol bacteria and essential oils show promise as prophylactic treatments to reduce the devastating effects of F. circinatum on P. radiata.

  6. Biocontrol of postharvest Rhizopus decay of peaches with Pichia caribbica.

    Science.gov (United States)

    Xu, Baitian; Zhang, Hongyin; Chen, Keping; Xu, Qin; Yao, Yao; Gao, Hui

    2013-08-01

    A new yeast antagonist, Pichia caribbica, isolated in our laboratory from the soil collected from unsprayed orchards, was evaluated for its biocontrol capability against Rhizopus stolonifer on peaches and the possible mechanisms involved. The decay incidence and lesion diameter of Rhizopus decay of peaches treated by P. caribbica were significantly reduced compared with the control fruits, and the higher the concentration of P. caribbica, the better the efficacy of the biocontrol. Rapid colonization of the yeast in peach wounds stored at 25 °C was observed. In peaches, the activities of peroxidase (POD), catalase (CAT), and phenylalanine ammonia-lyase (PAL) were significantly induced by P. caribbica treatment compared to those of the control fruits. All these results indicated that P. caribbica has a great potential for the development of commercial formulations to control postharvest Rhizopus decay of peaches. Its modes of action were based on competition for space and nutrients with pathogens, inducement of activities of defense-related enzymes such as POD, CAT, and PAL of peaches.

  7. Introducing the term 'Biocontrol Plants' for integrated pest management

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    Pia Parolin

    2014-02-01

    Full Text Available Studies of interactions between crops, additional plants, pests and beneficial organisms already exist as well as studies of natural enemy preference, dispersal, and abundance. However, these studies focus on tri-trophic interactions from an "arthropod" point of view. We think that in order to optimize crop protection methods we need to understand the effects that plant structures have on the various arthropods and on subsequent tri-trophic interactions. Although studies and reviews describing the role of secondary plants in Integrated Pest Management (IPM exist, to date a general term which encompasses all plants added to a cropping system with the aim of enhancing IPM strategies has yet to be formulated. Therefore, we suggest a new term, "biocontrol plants", which we define as plants that are intentionally added to a crop system with the aim of enhancing crop productivity through pest attraction and/or pest regulation; a term that will promote the use of biocontrol services, and can ultimately lead to an increase in the sustainability of cropping systems.

  8. Effects of biological control agents and exotic plant invasion on deer mouse populations

    Science.gov (United States)

    Yvette K. Ortega; Dean E. Pearson; Kevin S. McKelvey

    2004-01-01

    Exotic insects are commonly introduced as biological control agents to reduce densities of invasive exotic plants. Although current biocontrol programs for weeds take precautions to minimize ecological risks, little attention is paid to the potential nontarget effects of introduced food subsidies on native consumers. Previous research demonstrated that two gall flies (...

  9. Bacillus amyloliquefaciens GA1 as a source of potent antibiotics and other secondary metabolites for biocontrol of plant pathogens

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    Brans Alain

    2009-11-01

    Full Text Available Abstract Background Phytopathogenic fungi affecting crop and post-harvested vegetables are a major threat to food production and food storage. To face these drawbacks, producers have become increasingly dependent on agrochemicals. However, intensive use of these compounds has led to the emergence of pathogen resistance and severe negative environmental impacts. There are also a number of plant diseases for which chemical solutions are ineffective or non-existent as well as an increasing demand by consumers for pesticide-free food. Thus, biological control through the use of natural antagonistic microorganisms has emerged as a promising alternative to chemical pesticides for more rational and safe crop management. Results The genome of the plant-associated B. amyloliquefaciens GA1 was sample sequenced. Several gene clusters involved in the synthesis of biocontrol agents were detected. Four gene clusters were shown to direct the synthesis of the cyclic lipopeptides surfactin, iturin A and fengycin as well as the iron-siderophore bacillibactin. Beside these non-ribosomaly synthetised peptides, three additional gene clusters directing the synthesis of the antibacterial polyketides macrolactin, bacillaene and difficidin were identified. Mass spectrometry analysis of culture supernatants led to the identification of these secondary metabolites, hence demonstrating that the corresponding biosynthetic gene clusters are functional in strain GA1. In addition, genes encoding enzymes involved in synthesis and export of the dipeptide antibiotic bacilysin were highlighted. However, only its chlorinated derivative, chlorotetaine, could be detected in culture supernatants. On the contrary, genes involved in ribosome-dependent synthesis of bacteriocin and other antibiotic peptides were not detected as compared to the reference strain B. amyloliquefaciens FZB42. Conclusion The production of all of these antibiotic compounds highlights B. amyloliquefaciens GA1 as

  10. Morphological and chemical changes in dentin after using endodontic agents: Fourier transform Raman spectroscopy, energy-dispersive x-ray fluorescence spectrometry, and scanning electron microscopy study

    Science.gov (United States)

    Pascon, Fernanda Miori; Kantovitz, Kamila Rosamilia; Soares, Luís Eduardo Silva; Santo, Ana Maria do Espírito; Martin, Airton Abraha~o.; Puppin-Rontani, Regina Maria

    2012-07-01

    We examine the morphological and chemical changes in the pulp chamber dentin after using endodontic agents by scanning electron microscopy (SEM), Fourier transform Raman spectroscopy (FT-Raman), and micro energy-dispersive x-ray fluorescence spectrometry (μEDXRF). Thirty teeth were sectioned exposing the pulp chamber and divided by six groups (n=5): NT-no treatment; CHX-2% chlorhexidine; CHXE-2% chlorhexidine+17% EDTA E-17% EDTA; SH5-5.25% NaOCl; SH5E-5.25% NaOCl+17% EDTA. The inorganic and organic content was analyzed by FT-Raman. μEDXRF examined calcium (Ca) and phosphorus (P) content as well as Ca/P ratio. Impressions of specimens were evaluated by SEM. Data were submitted to Kruskal-Wallis and Dunn tests (pNT=SH5E>CHX>E>CHXE). CHXE and E presented the highest Ca/P ratio values compared to the other groups (p<0.05). The SEM images in the EDTA-treated groups had the highest number of open tubules. Erosion in the tubules was observed in CHX and SH5E groups. Endodontic agents change the inorganic and organic content of pulp chamber dentin. NaOCl used alone, or in association with EDTA, was the most effective agent considering chemical and morphological approaches.

  11. Endophytic fungi harbored in the root of Sophora tonkinensis Gapnep: Diversity and biocontrol potential against phytopathogens.

    Science.gov (United States)

    Yao, Yu Qun; Lan, Fang; Qiao, Yun Ming; Wei, Ji Guang; Huang, Rong Shao; Li, Liang Bo

    2017-06-01

    This work, for the first time, investigated the diversity of endophytic fungi harbored in the xylem and phloem of the root of Sophora tonkinensis Gapnep from three geographic localities with emphasis on the influence of the tissue type and geographic locality on endophytic fungal communities and their potential as biocontrol agents against phytopathogens of Panax notoginseng. A total of 655 fungal strains representing 47 taxa were isolated. Forty-two taxa (89.4%) were identified but not five taxa (10.6%) according to morphology and molecular phylogenetics. Out of identifiable taxa, the majority of endophyte taxa were Ascomycota (76.6%), followed by Basidiomycota (8.5%) and Zygomycota (4.3%). The alpha-diversity indices indicated that the species diversity of endophytic fungal community harbored in the root of S. tonkinensis was very high. The colonization and species diversity of endophytic fungal communities were significantly influenced by the geographic locality but not tissue type. The geographic locality and tissue type had great effects on the species composition of endophytic fungal communities. Forty-seven respective strains were challenged by three fungal phytopathogens of P. notoginseng and six strains exhibited significant inhibitory activity. It was noteworthy that endophytic Rhexocercosporidium sp. and F. solani strongly inhibited pathogenic F. solani and other fungal phytopathogens of P. notoginseng. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  12. Identifying relevant hyperspectral bands using Boruta: a temporal analysis of water hyacinth biocontrol

    Science.gov (United States)

    Agjee, Na'eem Hoosen; Ismail, Riyad; Mutanga, Onisimo

    2016-10-01

    Water hyacinth plants (Eichhornia crassipes) are threatening freshwater ecosystems throughout Africa. The Neochetina spp. weevils are seen as an effective solution that can combat the proliferation of the invasive alien plant. We aimed to determine if multitemporal hyperspectral data could be utilized to detect the efficacy of the biocontrol agent. The random forest (RF) algorithm was used to classify variable infestation levels for 6 weeks using: (1) all the hyperspectral bands, (2) bands selected by the recursive feature elimination (RFE) algorithm, and (3) bands selected by the Boruta algorithm. Results showed that the RF model using all the bands successfully produced low-classification errors (12.50% to 32.29%) for all 6 weeks. However, the RF model using Boruta selected bands produced lower classification errors (8.33% to 15.62%) than the RF model using all the bands or bands selected by the RFE algorithm (11.25% to 21.25%) for all 6 weeks, highlighting the utility of Boruta as an all relevant band selection algorithm. All relevant bands selected by Boruta included: 352, 754, 770, 771, 775, 781, 782, 783, 786, and 789 nm. It was concluded that RF coupled with Boruta band-selection algorithm can be utilized to undertake multitemporal monitoring of variable infestation levels on water hyacinth plants.

  13. Rhizosphere Bacteria for Biocontrol of Bacterial Blight and Growth Promotion of Rice

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    Palaniyandi VELUSAMY

    2013-09-01

    Full Text Available Several bacterial strains were isolated from different rhizospheres. Among these, strain PDY7 exhibited strong antibacterial activity against the rice bacterial blight (BB pathogen Xanthomonas oryzae pv. oryzae (Xoo by the laboratory dual plate assays. The antibacterial property of the strain PDY7 was further investigated for the production of 2,4-diacetylphloroglucinol (DAPG, which amplified a characteristic of 629-bp DNA fragment by PCR-based screening method using phlD primers. The application of phlD positive strains was carefully evaluated for disease control and growth promotion of rice plants under field conditions. The selected strain PDY7 suppressed the rice BB by 58.83% and 51.88% under glass house and field conditions, respectively. In addition, the strain PDY7 showed significant two-fold increase in root length (18.08 cm, shoot length (29.81 cm, and grain yield (96.07 g. Strain PDY7 promoted the growth of rice plants by production of indole-3-acetic acid (IAA, which was determined by high performance liquid chromatography (HPLC analysis. Our findings suggest that PDY7 belongs to the P. fluorescens group and can serve as potential biocontrol of BB as well as biofertilizer agent for growth promotion of rice.

  14. What Magnitude Are Observed Non-Target Impacts from Weed Biocontrol?

    Science.gov (United States)

    Suckling, David Maxwell; Sforza, René François Henri

    2014-01-01

    A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a risk management framework for ecological impacts of invasive species (minimal, minor, moderate, major, massive). The vast majority of agents introduced for classical biological control of weeds (>99% of 512 agents released) have had no known significant adverse effects on non-target plants thus far; major effects suppressing non-target plant populations could be expected to be detectable. Most direct non-target impacts on plants (91.6%) were categorized as minimal or minor in magnitude with no known adverse long-term impact on non-target plant populations, but a few cacti and thistles are affected at moderate (n = 3), major (n = 7) to massive (n = 1) scale. The largest direct impacts are from two agents (Cactoblastis cactorum on native cacti and Rhinocyllus conicus on native thistles), but these introductions would not be permitted today as more balanced attitudes exist to plant biodiversity, driven by both society and the scientific community. Our analysis shows (as far as is known), weed biological control agents have a biosafety track record of >99% of cases avoiding significant non-target impacts on plant populations. Some impacts could have been overlooked, but this seems unlikely to change the basic distribution of very limited adverse effects. Fewer non-target impacts can be expected in future because of improved science and incorporation of wider values. Failure to use biological control represents a significant opportunity cost from the certainty of ongoing adverse impacts from invasive weeds. It is recommended that a simple five-step scale be used to better communicate the risk of consequences from both action (classical biological control) and no

  15. Biocontrol of the toxigenic plant pathogen Fusarium culmorum by soil fauna in an agroecosystem.

    Science.gov (United States)

    Meyer-Wolfarth, Friederike; Schrader, Stefan; Oldenburg, Elisabeth; Weinert, Joachim; Brunotte, Joachim

    2017-08-01

    L. terrestris revealed a considerable potential as an effective biocontrol agent contributing to a sustainable control of a Fusarium plant pathogen in wheat straw, thus reducing the infection risk for specific plant diseases in arable fields.

  16. Endophytic fungal diversity in Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) trees and their potential for growth promotion and biocontrol of black-pod disease.

    Science.gov (United States)

    Hanada, Rogério Eiji; Pomella, Alan William V; Costa, Heron Salazar; Bezerra, José Luiz; Loguercio, Leandro L; Pereira, José O

    2010-01-01

    The endophytic niches of plants are a rich source of microbes that can directly and indirectly promote plant protection, growth and development. The diversity of culturable endophytic fungi from stems and branches of Theobroma cacao (cacao) and Theobroma grandiflorum (cupuaçu) trees growing in the Amazon region of Brazil was assessed. The collection of fungal endophytic isolates obtained was applied in field experiments to evaluate their potential as biocontrol agents against Phytophthora palmivora, the causal agent of the black-pod rot disease of cacao, one of the most important pathogens in cocoa-producing regions worldwide. The isolated endophytic fungi from 60 traditional, farmer-planted, healthy cacao and 10 cupuaçu plants were cultured in PDA under conditions inducing sporulation. Isolates were classified based upon the morphological characteristics of their cultures and reproductive structures. Spore suspensions from a total of 103 isolates that could be classified at least up to genus level were tested against P. palmivora in pods attached to cacao trees in the field. Results indicated that ∼70% of isolates showed biocontrol effects to a certain extent, suggesting that culturable endophytic fungal biodiversity in this system is of a mostly mutualistic type of interaction with the host. Eight isolates from genera Trichoderma (reference isolate), Pestalotiopsis, Curvularia, Tolypocladium and Fusarium showed the highest level of activity against the pathogen, and were further characterized. All demonstrated their endophytic nature by colonizing axenic cacao plantlets, and confirmed their biocontrol activity on attached pods trials by showing significant decrease in disease severity in relation to the positive control. None, however, showed detectable growth-promotion effects. Aspects related to endophytic biodiversity and host-pathogen-endophyte interactions in the environment of this study were discussed on the context of developing sustainable strategies

  17. New series of aromatic/ five-membered heteroaromatic butanesulfonyl hydrazones as potent biological agents: Synthesis, physicochemical and electronic properties

    Science.gov (United States)

    Hamurcu, Fatma; Mamaş, Serhat; Ozdemir, Ummuhan Ozmen; Gündüzalp, Ayla Balaban; Senturk, Ozan Sanlı

    2016-08-01

    The aromatic/five-membered heteroaromatic butanesulfonylhydrazone derivatives; 5-bromosalicylaldehydebutanesulfonylhydrazone(1), 2-hydroxy-1-naphthaldehydebutane sulfonylhydrazone(2), indole-3-carboxaldehydebutanesulfonylhydrazone (3), 2-acetylfuran- carboxyaldehydebutanesulfonylhydrazone(4), 2-acetylthiophenecarboxyaldehydebutane- sulfonylhydrazone(5) and 2-acetyl-5-chlorothiophenecarboxyaldehydebutanesulfonyl hydrazone (6) were synthesized by the reaction of butane sulfonic acid hydrazide with aldehydes/ketones and characterized by using elemental analysis, 1H NMR, 13C NMR and FT-IR technique. Their geometric parameters and electronic properties consist of global reactivity descriptors were also determined by theoretical methods. The electrochemical behavior of the butanesulfonylhydrazones were investigated by using cyclic voltammetry (CV), controlled potential electrolysis and chronoamperometry (CA) techniques. The number of electrons transferred (n), diffusion coefficient (D) and standard heterogeneous rate constants (ks) were determined by electrochemical methods.

  18. Risk assessment: progress of quarantine biocontrol research on Chinese Tallow, Melaleuca, and Downy Rose Myrtle

    Science.gov (United States)

    Risk assessments of two biocontrol candidates for Chinese tallow, Triadica sebifera (Euphoriales: Euphorbiaceae), and one for Melaleuca, Melaleuca quinquenervia (Myrtales: Myrtaceae), were conducted during 2009 and continuing into 2010 by USDA scientists located at the Florida Department of Agricul...

  19. Characterization of streptomycetes with potential to promote plant growth and biocontrol Caracterização de estreptomicetos com potencial para promoção de crescimento de plantas e biocontrole

    Directory of Open Access Journals (Sweden)

    Carla da Silva Sousa

    2008-02-01

    Full Text Available Studies with streptomycetes in biocontrol programs and plant growth promotion are presented as technological alternatives for environmental sustainable production. This work has the objective of characterizing six isolates of streptomycetes aiming the production of extracellular enzymes, indole acetic acid, capacity for phosphate solubilization, root colonization and growth under different pH and salinity levels. For detection of enzyme activity the isolates were grown in culture media with the enzyme substrates as sole carbon source. The root colonization assay was performed on tomato seedlings grown on 0.6% water-agar medium. Growth under different pH and salinity levels was evaluated in AGS medium with 1%, 1.5%, 2%, 2.5%, and 3% NaCl, and pH levels adjusted to 5.0, 5.5, 6.0, 6.5, and 7.0. All isolates produced the enzymes amylase, catalase, and lipase, as well as indole acetic acid. With one exception (AC-92, all isolates presented cellulolytic and chitinolytic activity, and only AC-26 did not show xylanolytic activity. The isolates AC-147, AC-95, and AC-29 were the highest producers of siderophores. The isolates AC-26 and AC-29 did not show capacity for phosphate solubilization. All isolates colonized tomato roots in vitro, and AC-92 grew under all pH and salinity levels tested. The streptomycetes tested were considered as potential biocontrol and plant growth promotion agents.Estudos com estreptomicetos em programas de biocontrole e promoção de crescimento de plantas são alternativas tecnológicas de produção sustentáveis ao ambiente. O presente trabalho teve como objetivo caracterizar seis isolados de estreptomicetos quanto à produção de enzimas extracelulares, ácido indolacético e sideróforos, capacidade de solubilização de fosfatos, colonização radicular e de crescimento em diferentes níveis de pH e salinidade. Para detectar a produção das enzimas extracelulares, os isolados foram cultivados em meio de cultura contendo

  20. Multifunctional exopolysaccharides from Pseudomonas aeruginosa PF23 involved in plant growth stimulation, biocontrol and stress amelioration in sunflower under saline conditions.

    Science.gov (United States)

    Tewari, Sakshi; Arora, Naveen Kumar

    2014-10-01

    Isolate PF23 selected from among 110 fluorescent pseudomonads, identified as Pseudomonas aeruginosa, displayed salinity tolerance and exopolysaccharides (EPS) production up to 2,000 mM NaCl concentration. EPS-defective mutant PF23(EPS-) of the isolate showed 86 % reduction in EPS production in comparison with wild strain. Defect in EPS production brought loss in salt tolerance capability. Purified EPS obtained from PF23 displayed multiple roles. At low concentration EPS functioned as biocontrol agent, at high concentration EPS behaved as osmoprotective or stress ameliorating metabolite and when introduced in saline soil, served as a plant growth promotor along with seed biopriming agent. Both in planta and in vivo studies were performed taking sunflower as a test crop and it was observed that PF23 showed plant growth promotion and significant biocontrol potential against dreadful phytopathogen Macrophomina phaseolina (under saline conditions). The mutant PF23(EPS-) was ineffective under saline conditions both in growth enhancement as well as in disease suppression. The study reports a potent strain, Pseudomonas aeruginosa PF23, capable of enhancing production of sunflower crop in semiarid regions and minimizing the incidence of charcoal rot disease in sunflower.

  1. Evaluation of biocontrol potential of epiphytic fluorescent pseudomonas as associated with healthy fruits and vegetables against root rot and root knot pathogens of mungbean

    International Nuclear Information System (INIS)

    Habiba, A.; Noreen, R.; Ali, S. A.; Sultana, V.; Ara, J.

    2016-01-01

    Endophytic and rhizospheric fluorescent Pseudomonas have widely been used as biological control agents against soilborne plant pathogens. In this study, fifteen epiphytic fluorescent Pseudomonas isolated from the surfaces of citrus (grapefruit, orange and lemon) melon and tomato fruits were characterized for their in vitro activity against root rotting fungi viz., Macrophomina phaseolina, Fusarium solani, F. oxysporum and Rhizoctonia solani and nematicidal activity against the second stage juveniles of Meloidogyne javanica. Out of fifteen Pseudomonas isolates HAB-16, HAB-1 and HAB-25 inhibited the growth of all the test fungi and showed maximum nematicidal activity against second stage juvenile of M. javanica. Based on their effective in vitro activity nine epiphytic fluorescent Pseudomonas were evaluated for their growth promoting ability and biocontrol activity in screen house on mungbean. Pseudomonas isolates (HAB-13, HAB-2, HAB-4, HAB-1, HAB-14, HAB-9, HAB-7 and HAB-25) used as soil drench greatly reduced the root rot-root knot infection and thereby enhanced plant growth, root nodulation and yield in mungbean. Besides, rhizospheric and endophytic, epiphytic fluorescent Pseudomonas associated with healthy fruits may be used as biocontrol agent against root rotting fungi, besides, using for the mangemnet of postharvest diseases. (author)

  2. Efficacy of Eucalyptus cinerea as a Source of Bioactive Compounds for Curative Biocontrol of Crown Gall Caused by Agrobacterium tumefaciens Strain B6.

    Science.gov (United States)

    Kahla, Yosra; Zouari-Bouassida, Karama; Rezgui, Fatma; Trigui, Mohamed; Tounsi, Slim

    2017-01-01

    This research investigated the Eucalyptus cinerea leaves efficiency in the Agrobacterium tumefaciens biocontrol, the causative agent of crown gall. GC-MS analysis of the essential oil (EO) showed that the main components were 1,8-cineole (61%) and camphene (15.13%). Thanks to its polyphenols, flavonoids, quinones, terpenoids, alkaloids, and tannins richness, the EtOAc-F exhibited the most potent antibacterial activity in vitro. Indeed, compared to the other fractions, it has the lowest MIC and MBC values of 0.312 mg/mL and 2.5 mg/mL, respectively. The GC-MS analysis of EtOAc-F confirmed its richness in antibacterial compounds including gallic acid (7.18%), shikimic acid (5.07%), and catechin (3.12%). The time-kill curve assay of EtOAc-F (2.5 mg/mL) showed a potent bactericidal effect after 20 min of direct contact with A. tumefaciens . In planta experiments, gall weights were significantly reduced when EtOAc-F was applied at 0.625 and 2.5 mg/wounds. Besides, the disease reduction rates in gall weight were 95% and 97.5%, respectively. Interestingly, no phytotoxic effect was observed since tomato seeds germinated in the presence of the different concentrations of EtOAc-F. These results suggest that EtOAc-F has a good potential to be a curative biocontrol agent for crown gall disease.

  3. Biocontrole de Listeria monocytogenes por Pediococcus acidilactici em couve minimamente processada Biocontrol of Listeria monocytogenes by Pediococcus acidilactici in fresh-cut kale

    Directory of Open Access Journals (Sweden)

    Wanessa Altimiras Costa

    2009-12-01

    Full Text Available Este estudo avaliou um sistema de biocontrole para inibição de Listeria monocytogenes em couve minimamente processada, objetivando sua segurança durante estocagem sob refrigeração e em condições de abuso de temperatura. O potencial inibitório de bactérias láticas tolerantes ao sal e psicrotróficas contaminantes naturais da couve e Lactobacillus plantarum, Lactobacillus delbrueckii ATCC 9649 e Lactobacillus casei CCT 1465 foram avaliadas contra L. monocytogenes. O isolado de couve identificado como P. acidilactici CCA3 inibiu L. monocytogenes a 10 e 15 °C em ágar MRS e foi selecionado como possível agente de biocontrole. O número de L. monocytogenes na couve minimamente processada aumentou 3,7 e 4,7 ciclos logarítmicos a 5 e 10 °C, respectivamente, após 20 dias de armazenamento e 4,6 ciclos logarítmicos após oito dias a 15 °C. Entretanto, quando 10(8 UFC.g-1 de P. acidilactici CCA3 foram inoculados no produto processado, o crescimento de L. monocytogenes reduziu 2,3 ciclos logarítmicos sob temperatura abusiva de 15 °C. A acidez titulável e as características sensoriais da couve não foram alteradas pela presença de CCA3 ao longo do período de vida útil. Estes resultados sugerem o potencial de aplicação dos bioconservantes na couve minimamente processada, que necessitam estar associados à refrigeração e sanitização para garantir segurança.This study evaluated a biological control system for the inhibition of Listeria monocytogenes in minimally processed kale focusing on its freshness under refrigeration and extreme temperatures. The inhibitory potential of salt and cold tolerant lactic bacteria from natural microflora of kale, Lactobacillus delbrueckii ATCC 9649, Lactobacillus plantarum, and Lactobacillus casei CCT 1465 strains were evaluated against L. monocytogenes. Pediococcus acidilactici CCA3 isolated from kale exhibited a large inhibition zone of L. monocytogenes at 10 and 15 °C in MRS agar and was

  4. Trading Agents

    CERN Document Server

    Wellman, Michael

    2011-01-01

    Automated trading in electronic markets is one of the most common and consequential applications of autonomous software agents. Design of effective trading strategies requires thorough understanding of how market mechanisms operate, and appreciation of strategic issues that commonly manifest in trading scenarios. Drawing on research in auction theory and artificial intelligence, this book presents core principles of strategic reasoning that apply to market situations. The author illustrates trading strategy choices through examples of concrete market environments, such as eBay, as well as abst

  5. The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots

    Directory of Open Access Journals (Sweden)

    Carmen eGómez-Lama Cabanás

    2014-09-01

    Full Text Available Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets, many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR experiments aiming to: (i validate the induction of these genes, and (ii shed light on their expression pattern along time (from 1 to 15 days. Induction of olive genes potentially coding for lypoxigenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e. jerf, bHLH, WRKYs, as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mount a wide array of systemic defense responses in distant tissues (stems, leaves. This sheds light on how olive plants respond to the ‘non-hostile’ colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7.

  6. The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots.

    Science.gov (United States)

    Gómez-Lama Cabanás, Carmen; Schilirò, Elisabetta; Valverde-Corredor, Antonio; Mercado-Blanco, Jesús

    2014-01-01

    Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA) against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH) cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets), many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR) experiments aiming to: (1) validate the induction of these genes, and (2) shed light on their expression pattern along time (from 1 to 15 days). Induction of olive genes potentially coding for lipoxygenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase, and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e., JERF, bHLH, WRKY), as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mounts a wide array of systemic defense responses in distant tissues (stems, leaves). This sheds light on how olive plants respond to the "non-hostile" colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7.

  7. Biocontrol of verticillium wilt and colonization of cotton plants by an endophytic bacterial isolate.

    Science.gov (United States)

    Li, C-H; Shi, L; Han, Q; Hu, H-L; Zhao, M-W; Tang, C-M; Li, S-P

    2012-09-01

    To explore biocontrol potential of 39 DAEB isolates (doubly antagonistic towards both Verticillium dahliae Kleb and Fusarium oxysporum) against verticillium wilt of cotton and to elucidate colonization and category characteristics of an endophytic bacterium with significant biocontrol activity. Thirty-nine antagonistic endophytic bacteria strains were tested for their ability to control verticillium wilt in cotton plants caused by a defoliating pathotype of V. dahliae 107 in cotton under controlled conditions. The biocontrol trial revealed that an endophytic bacterium, designated HA02, showed a significant biocontrol activity to V. dahliae 107. After cotton seedlings were inoculated with a gfp gene-tagged HA02 (HA02-gfp), HA02-gfp populations were higher in the root than in the stem; in addition, the HA02-gfp was distributed in the maturation zone of cotton root. Furthermore, HA02-gfp also colonized seedlings of maize, rape and soybean after the bacteria inoculation. Phylogenetic trees based on 16S rDNA sequences combined with morphological, physiological and identification showed that the bacterium belongs to the Enterobacter genus. Our results showed that only 1 of 39 DAEB isolates demonstrated more efficient biocontrol potential towards V. dahliae 107 in greenhouse and field trials. HA02-gfp mainly colonized cotton in roots. In addition, we quantitatively observed HA02 colonization in other hosts. HA02 belongs to the Enterobacter genus. This is the first study on biocontrol to defoliating pathotype of V. dahliae Kleb by endophytic bacteria. The HA02 showed effective biocontrol to V. dahliae 107 in greenhouse and field trials. Furthermore, we assessed the quantitative and qualitative colonization of HA02 in cotton seedlings. Our study provides basic information to further explore managing strategies to control this critical disease. © 2012 The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

  8. An alpha-glucosidase inhibitor from an endophytic Cladosporium sp. with potential as a biocontrol agent.

    Science.gov (United States)

    Singh, Bahaderjeet; Kaur, Tamanreet; Kaur, Sanehdeep; Manhas, Rajesh K; Kaur, Amarjeet

    2015-02-01

    This study highlights the importance of alpha-glucosidase inhibitors as mechanisms for endophyte-mediated resistance to insect pests. One of the major benefits which endophytes confer on plants is providing resistance against insect pests. This built-in defense mechanism of the plant can be used for exploring ecofriendly strategies for pest control. In the present study, 34 endophytic fungi were isolated from Tinospora cordifolia and screened for their ability to produce alpha-glucosidase inhibitors. Maximum inhibitory activity was observed in an isolate from T. cordifolia (TN-9S), identified to be Cladosporium sp. The inhibitor was purified using chromatographic techniques. The insecticidal activity of the purified inhibitor was evaluated against Spodoptera litura. The inhibitor induced a significant mortality in the larvae of S. litura and adversely affected its survival and development. It also inhibited the activity of α-glycosidases in vivo in the gut of the larvae. The purified inhibitor was determined to be a phenolic compound with amine groups, demonstrating a noncompetitive type of inhibition in vitro. The production of the inhibitor was optimized. Response surface methodology (RSM) analysis revealed a significant interaction between dextrose and malt extract, with first-order effect of pH.

  9. Wild Grape-Associated Yeasts as Promising Biocontrol Agents against Vitis vinifera Fungal Pathogens

    Directory of Open Access Journals (Sweden)

    Gustavo Cordero-Bueso

    2017-11-01

    Full Text Available The increasing level of hazardous residues in the environment and food chains has led the European Union to restrict the use of chemical fungicides. Thus, exploiting new natural antagonistic microorganisms against fungal diseases could serve the agricultural production to reduce pre- and post-harvest losses, to boost safer practices for workers and to protect the consumers' health. The main aim of this work was to evaluate the antagonistic potential of epiphytic yeasts against Botrytis cinerea, Aspergillus carbonarius, and Penicillium expansum pathogen species. In particular, yeast isolation was carried out from grape berries of Vitis vinifera ssp sylvestris populations, of the Eurasian area, and V. vinifera ssp vinifera cultivars from three different farming systems (organic, biodynamic, and conventional. Strains able to inhibit or slow the growth of pathogens were selected by in vitro and in vivo experiments. The most effective antagonist yeast strains were subsequently assayed for their capability to colonize the grape berries. Finally, possible modes of action, such as nutrients and space competition, iron depletion, cell wall degrading enzymes, diffusible and volatile antimicrobial compounds, and biofilm formation, were investigated as well. Two hundred and thirty-one yeast strains belonging to 26 different species were isolated; 20 of them, ascribed to eight species, showed antagonistic action against all molds. Yeasts isolated from V. vinifera ssp sylvestris were more effective (up to 50% against B. cinerea rather than those isolated from V. vinifera ssp vinifera. Six strains, all isolated from wild vines, belonging to four species (Meyerozyma guilliermondii, Hanseniaspora uvarum, Hanseniaspora clermontiae, and Pichia kluyveri revealed one or more phenotypical characteristics associated to the analyzed modes of antagonistic action.

  10. Tracking the movement and colonization of biocontrol agent Bacillus subtilis using radiolabelling and tracer techniques

    International Nuclear Information System (INIS)

    Kavitha, P.G.; Jonathan, E.I.; Nakkeeran, S.

    2017-01-01

    Bacillus subtilis, an endophytic bacteria that lives inside the plant system is viewed as a potential source of novel genes with antimicrobial activity. B. subtilis strain Bs5 isolated from noni was found to be antagonistic to root knot nematode, Meloidogyne incognitainvitro. The endophytic nature of the bacteria was ascertained by labeling the bacteria with radioactive 32 P and introduced in to the plant system. Autoradiograph of young noni seedlings was developed 28 days after exposure period in the X-ray film. The work was carried out in the Radioisotope Laboratory, Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore. Autoradiography indicated a difference in intensity of darkening of photographic emulsion. A closer scrutiny of the autoradiograph showed intensity of the film darkening to be accentuated in the top leaves. It revealed that the radio labelled bacteria effectively translocated from root to shoot and colonized the stem, mid ribs and actively growing regions. From the study it becomes evident that the radio labelling and tracer analysis is an effective tool for tracking the movement and colonization of endophytic bacteria which are potential candidates for combating plant pathogens including plant parasitic nematodes. (author)

  11. Identification, Development, and Release of Insect Biocontrol Agents for the Management of Phragmites australis

    Science.gov (United States)

    2014-07-01

    control of P. australis in North America. Bird predation, parasitism , and mortality due to unknown causes were the main mortality factors of noctuid...through bird predation, with additional losses due to attack by a tachinid fly and a pupal parasitoid. Future investigations will assess the danger...an important migratory habitat for many birds , the same habitats are nearly devoid of specialized bird species in North America, particularly of

  12. Two Entomophagous Isolated From Sumatera Utara; Potential as Biocontrol Agent Againts Nematode

    OpenAIRE

    Hastuti, Liana Dwi Sri; Nicklin, Jane; Siregar, Ameilia Zuliyanti

    2016-01-01

    Two species of nematophagous fungi has been isolated from Sumatera Utara soil, with an aim of harnessing their potential in the biological control of plant parasitic nematodes or animal parasitic nematodes in Indonesia, especially in Sumatera Utara. Soil samples were collected from tobacco plantations, vegetable fields and ornamental plantings in the Berastagi area, and also from livestock in local farms and a dairy farm in Berastagi Area, Karo Regency. Soil also collected from un-cultivated ...

  13. Genetic Control of Plant Root Colonization by the Biocontrol agent, Pseudomonas fluorescens

    Energy Technology Data Exchange (ETDEWEB)

    Cole, Benjamin J.; Fletcher, Meghan; Waters, Jordan; Wetmore, Kelly; Blow, Matthew J.; Deutschbauer, Adam M.; Dangl, Jeffry L.; Visel, Axel

    2015-03-19

    Plant growth promoting rhizobacteria (PGPR) are a critical component of plant root ecosystems. PGPR promote plant growth by solubilizing inaccessible minerals, suppressing pathogenic microorganisms in the soil, and directly stimulating growth through hormone synthesis. Pseudomonas fluorescens is a well-established PGPR isolated from wheat roots that can also colonize the root system of the model plant, Arabidopsis thaliana. We have created barcoded transposon insertion mutant libraries suitable for genome-wide transposon-mediated mutagenesis followed by sequencing (TnSeq). These libraries consist of over 105 independent insertions, collectively providing loss-of-function mutants for nearly all genes in the P.fluorescens genome. Each insertion mutant can be unambiguously identified by a randomized 20 nucleotide sequence (barcode) engineered into the transposon sequence. We used these libraries in a gnotobiotic assay to examine the colonization ability of P.fluorescens on A.thaliana roots. Taking advantage of the ability to distinguish individual colonization events using barcode sequences, we assessed the timing and microbial concentration dependence of colonization of the rhizoplane niche. These data provide direct insight into the dynamics of plant root colonization in an in vivo system and define baseline parameters for the systematic identification of the bacterial genes and molecular pathways using TnSeq assays. Having determined parameters that facilitate potential colonization of roots by thousands of independent insertion mutants in a single assay, we are currently establishing a genome-wide functional map of genes required for root colonization in P.fluorescens. Importantly, the approach developed and optimized here for P.fluorescens>A.thaliana colonization will be applicable to a wide range of plant-microbe interactions, including biofuel feedstock plants and microbes known or hypothesized to impact on biofuel-relevant traits including biomass productivity and pathogen resistance.

  14. Proteomic analysis of the metabolic adaptation of the biocontrol agent Pseudozyma flocculosa leading to glycolipid production

    Directory of Open Access Journals (Sweden)

    Bélanger Richard R

    2010-02-01

    Full Text Available Abstract The yeast-like epiphytic fungus Pseudozyma flocculosa is known to antagonize powdery mildew fungi through proliferation on colonies presumably preceded by the release of an antifungal glycolipid (flocculosin. In culture conditions, P. flocculosa can be induced to produce or not flocculosin through manipulation of the culture medium nutrients. In order to characterize and understand the metabolic changes in P. flocculosa linked to glycolipid production, we conducted a 2-DE proteomic analysis and compared the proteomic profile of P. flocculosa growing under conditions favoring the development of the fungus (control or conducive to flocculosin synthesis (stress. A large number of protein spots (771 were detected in protein extracts of the control treatment compared to only 435 matched protein spots in extracts of the stress cultures, which clearly suggests an important metabolic reorganization in slow-growing cells producing flocculosin. From the latter treatment, we were able to identify 21 protein spots that were either specific to the treatment or up-regulated significantly (2-fold increase. All of them were identified based on similarity between predicted ORF of the newly sequenced genome of P. flocculosa with Ustilago maydis' available annotated sequences. These proteins were associated with the carbon and fatty acid metabolism, and also with the filamentous change of the fungus leading to flocculosin production. This first look into the proteome of P. flocculosa suggests that flocculosin synthesis is elicited in response to specific stress or limiting conditions.

  15. Evaluation of potential bio-control agents on root-knot nematode ...

    African Journals Online (AJOL)

    Indigenous strains of Trichoderma viride (ITCC No. 6889), Pseudomonas fluorescens (ITCC No. B0034) and Purpureocillium lilacinum (ITCC No.6887) were isolated from undisturbed forest eco-system of Southern India. These three bio-mediators were evaluated for their antagonism towards root knot nematode, ...

  16. Essential oils from Algerian species of Mentha as new bio-control agents against phytopathogen strains.

    Science.gov (United States)

    Benomari, Fatima Zahra; Andreu, Vanessa; Kotarba, Jules; Dib, Mohammed El Amine; Bertrand, Cédric; Muselli, Alain; Costa, Jean; Djabou, Nassim

    2017-09-02

    Chemical composition and antifungal activity of essential oils of Algerian Mentha species were studied. Chemical compositions of different Mentha species oils (Mentha rotundifolia, M. spicata, M. pulegium, and M. piperita) were investigated by capillary GC and GC/MS, and their antifungal activities were evaluated by means of paper disc diffusion method and minimum inhibitory concentration (MIC) assays. In total, 98 components from all Mentha species were identified. All oils were rich in monoterpene-oxygenated components. In addition, we reported fumigant antifungal activity of Algerian Mentha essential oils against four fungi: Botrytis cinerea, Penicillium expansum, Monilinia laxa, and M. fructigena. All oils demonstrated very good inhibition especially against B. cinerea, M. laxa, and M. fructigena. Both Monilinia fungi were extremely sensitive to all Algerian Mentha oils, which suggests that Mentha essential oils have the potential to be used as bio-pesticides to protect fruit trees, such as apple and pear trees, and provides an alternative to chemical pesticides.

  17. Brazilian peppertree seed-borne pathogen Neofusicoccum batangarum a potential biocontrol agent

    Science.gov (United States)

    The invasive exotic Brazilian peppertree, Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae) has become a serious threat to the delicate ecosystem of Everglades National Park. More than 4,000 acres land in the Hole-in-the-Donut (HID) area within the Park has been infested with Brazilian pep...

  18. Use of the Endophytic Fungus Daldinia cf. concentrica and Its Volatiles as Bio-Control Agents.

    Directory of Open Access Journals (Sweden)

    Orna Liarzi

    Full Text Available Endophytic fungi are organisms that spend most of their life cycle within plant tissues without causing any visible damage to the host plant. Many endophytes were found to secrete specialized metabolites and/or emit volatile organic compounds (VOCs, which may be biologically active and assist fungal survival inside the plant as well as benefit their hosts. We report on the isolation and characterization of a VOCs-emitting endophytic fungus, isolated from an olive tree (Olea europaea L. growing in Israel; the isolate was identified as Daldinia cf. concentrica. We found that the emitted VOCs were active against various fungi from diverse phyla. Results from postharvest experiments demonstrated that D. cf. concentrica prevented development of molds on organic dried fruits, and eliminated Aspergillus niger infection in peanuts. Gas chromatography-mass spectrometry analysis of the volatiles led to identification of 27 VOCs. On the basis of these VOCs we prepared two mixtures that displayed a broad spectrum of antifungal activity. In postharvest experiments these mixtures prevented development of molds on wheat grains, and fully eliminated A. niger infection in peanuts. In light of these findings, we suggest use of D. cf. concentrica and/or its volatiles as an alternative approach to controlling phytopathogenic fungi in the food industry and in agriculture.

  19. Yeasts isolated from figs (Ficus carica L.) as biocontrol agents of postharvest fruit diseases.

    Science.gov (United States)

    Ruiz-Moyano, S; Martín, A; Villalobos, M C; Calle, A; Serradilla, M J; Córdoba, M G; Hernández, A

    2016-08-01

    Fresh fruit is highly perishable during postharvest life, mainly due to fungal growth. Thus, fungal control is an important goal for the fruit industry. In this work, a selection of antagonistic yeasts isolated from fig and breba crops were screened in vitro. The isolated yeasts were challenged with three moulds isolated from decayed figs and breba crops, identified as Penicillium expansum M639 and Cladosporium cladosporioides M310 and M624, and pathogenic moulds Botrytis cinerea CECT20518 and Monilia laxa CA1 from culture collections. Two yeast isolates, Hanseniaspora opuntiae L479 and Metschnikowia pulcherrima L672, were selected for their ability to inhibit the growth of aforementioned moulds. These yeasts reduced the radial growth of moulds on PDA by between 45.23% and 66.09%. Antagonistic activity was associated with the interaction of live yeast cells with moulds. M. pulcherrima L672 apparently parasitised C. cladosporioides isolates. In addition, challenges were assayed using wounded apples and nectarines, with significant reductions in percent infection and lesion size for all moulds tested. To our knowledge, this is the first report identifying H. opuntiae as an antagonist against different pathogenic moulds. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Wild Grape-Associated Yeasts as Promising Biocontrol Agents against Vitis vinifera Fungal Pathogens

    OpenAIRE

    Cordero-Bueso, Gustavo; Mangieri, Nicola; Maghradze, David; Foschino, Roberto; Valdetara, Federica; Cantoral, Jesús M.; Vigentini, Ileana

    2017-01-01

    The increasing level of hazardous residues in the environment and food chains has led the European Union to restrict the use of chemical fungicides. Thus, exploiting new natural antagonistic microorganisms against fungal diseases could serve the agricultural production to reduce pre- and post-harvest losses, to boost safer practices for workers and to protect the consumers' health. The main aim of this work was to evaluate the antagonistic potential of epiphytic yeasts against Botrytis cinere...

  1. Greenhouse evaluation of rhizobia as biocontrol agent of root-infecting fungi in okra

    Directory of Open Access Journals (Sweden)

    I. A. Siddiqui

    2013-12-01

    Full Text Available Nine rhizobial strains isolated from the root nodules of Cicer arietinum, Vigna radiata, V. mungo, Samania saman, Sesbania sesban, Leucinia sp., Prosopis cineraria and Medicago sativa were used to study their effects on root-infecting fungi viz., Macrophomina phaseolina, Fusarium solani and Rhizoctonia solani. In dual culture plate assay, strains of Bradyrhizobium sp., and R. meliloti were found to inhibit radial growth of M. phaseolina, F. solani and R. solani producing zones of inhibition. Bradyrhizobium sp., and R. meliloti either used as seed dressing or as soil drench significantly suppressed root-rot infection caused by M. phaseolina, F. solani and R. solani in okra, a non-1eguminous crop under greenhouse conditions. Biomass of plants was also higher in the presence of rhizobia.

  2. Potential of endophytic fungi as biocontrol agents of Duponchelia fovealis (Zeller (Lepidoptera:Crambidae

    Directory of Open Access Journals (Sweden)

    R. F. Amatuzzi

    2017-11-01

    Full Text Available Abstract This study reports the first assessment of endophytic fungi isolated from strawberry leaves and selection of isolates for the control of Duponchelia fovealis, a new pest of strawberries. A total of 400 strawberry leaves of the cultivar ‘Albion’ were collected in four commercial farms. Leaves were disinfected, cut in fragments, and placed on Petri dishes containing potato dextrose agar media with tetracycline and incubated for 30 days. Following this time, 517 fungal colonies were isolated, and thirteen genera were identified: Cladosporium, Aspergillus, Nigrospora, Fusarium, Trichoderma, Chaetomium, Alternaria, Paecilomyces, Penicillium, Ulocladium, Bipolaris, Diaporthe, and Phoma. Eight isolates belonging to the genera Aspergillus, Diaporthe, Paecilomyces, and Cladosporium were selected for pathogenicity bioassays against third instar larvae of D. fovealis. Isolates of Paecilomyces induced the highest mortality rates.

  3. Field Surveys to Identify Biocontrol Agents of Hydrilla verticillata from June - September 2012

    Science.gov (United States)

    2015-07-01

    herbivory by Hydrellia pakistanae (Diptera: Ephydridae) on growth and photosynthesis potential of Hydrilla verticillata. Biological Control 24:221– 229...Jr. 2000. Evaluation of macrophyte control in 38 Florida lakes using triploid grass carp. Journal of Aquatic Plant Management 38:48–54. Michel, A...and J. M. Nachtrieb. 2006. Viability of hydrilla fragments exposed to different levels of insect herbivory. Journal of Aquatic Plant Management 44

  4. Effect of formulation on the viabilıty of biocontrol agent, Trıchoderma ...

    African Journals Online (AJOL)

    A zeolite-water heterogeneous mixture (1:2 w/v) was found suitable medium for growing Turkish isolate of Trichoderma harzianum T1. Pelletized formulations of zeolite containing conidia of Turkish isolate of Trichoderma harzianum T1 in alginate were prepared. Formulations were more viable at 4°C than at 30°C.

  5. Exploiting the behaviour of wild malaria vectors to achieve high infection with fungal biocontrol agents

    NARCIS (Netherlands)

    Mnyone, L.L.; Lyimo, I.N.; Lwetoijera, D.W.; Mpingwa, M.W.; Nchimbi, N.; Hancock, P.A.; Russell, T.L.; Kirby, M.J.; Takken, W.; Koenraadt, C.J.M.

    2012-01-01

    Background Control of mosquitoes that transmit malaria has been the mainstay in the fight against the disease, but alternative methods are required in view of emerging insecticide resistance. Entomopathogenic fungi are candidate alternatives, but to date, few trials have translated the use of these

  6. Biocontrol and Rapid Detection of Food-Borne Pathogens Using Bacteriophages and Endolysins

    Science.gov (United States)

    Bai, Jaewoo; Kim, You-Tae; Ryu, Sangryeol; Lee, Ju-Hoon

    2016-01-01

    Bacteriophages have been suggested as natural food preservatives as well as rapid detection materials for food-borne pathogens in various foods. Since Listeria monocytogenes-targeting phage cocktail (ListShield) was approved for applications in foods, numerous phages have been screened and experimentally characterized for phage applications in foods. A single phage and phage cocktail treatments to various foods contaminated with food-borne pathogens including E. coli O157:H7, Salmonella enterica, Campylobacter jejuni, Listeria monocytogenes, Staphylococcus aureus, Cronobacter sakazakii, and Vibrio spp. revealed that they have great potential to control various food-borne pathogens and may be alternative for conventional food preservatives. In addition, phage-derived endolysins with high host specificity and host lysis activities may be preferred to food applications rather than phages. For rapid detection of food-borne pathogens, cell-wall binding domains (CBDs) from endolysins have been suggested due to their high host-specific binding. Fluorescence-tagged CBDs have been successfully evaluated and suggested to be alternative materials of expensive antibodies for various detection applications. Most recently, reporter phage systems have been developed and tested to confirm their usability and accuracy for specific detection. These systems revealed some advantages like rapid detection of only viable pathogenic cells without interference by food components in a very short reaction time, suggesting that these systems may be suitable for monitoring of pathogens in foods. Consequently, phage is the next-generation biocontrol agent as well as rapid detection tool to confirm and even identify the food-borne pathogens present in various foods. PMID:27092128

  7. Biocontrol and Rapid Detection of Food-borne Pathogens Using Bacteriophages and Endolysins

    Directory of Open Access Journals (Sweden)

    Jaewoo eBai

    2016-04-01

    Full Text Available Bacteriophages have been suggested as natural food preservatives as well as rapid detection materials for food-borne pathogens in various foods. Since Listeria monocytogenes-targeting phage cocktail (ListShield was approved for applications in foods, numerous phages have been screened and experimentally characterized for phage applications in foods. A single phage and phage cocktail treatments to various foods contaminated with food-borne pathogens including E. coli O157:H7, Salmonella enterica, Campylobacter jejuni, Listeria monocytogenes, Staphylococcus aureus, Cronobacter sakazakii, and Vibrio spp. revealed that they have great potential to control various food-borne pathogens and may be alternative for conventional food preservatives. In addition, phage-derived endolysins with high host specificity and host lysis activities may be preferred to food applications rather than phages. For rapid detection of food-borne pathogens, cell-wall binding domains (CBDs from endolysins have been suggested due to their high host-specific binding. Fluorescence-tagged CBDs have been successfully evaluated and suggested to be alternative materials of expensive antibodies for various detection applications. Most recently, reporter phage systems have been developed and tested to confirm their usability and accuracy for specific detection. These systems revealed some advantages like rapid detection of only viable pathogenic cells without interference by food components in a very short reaction time, suggesting that these systems may be suitable for monitoring of pathogens in foods. Consequently, phage is the next-generation biocontrol agent as well as rapid detection tool to confirm and even identify the food-borne pathogens present in various foods.

  8. Assessment of virally vectored autoimmunity as a biocontrol strategy for cane toads.

    Directory of Open Access Journals (Sweden)

    Jackie A Pallister

    Full Text Available BACKGROUND: The cane toad, Bufo (Chaunus marinus, is one of the most notorious vertebrate pests introduced into Australia over the last 200 years and, so far, efforts to identify a naturally occurring B. marinus-specific pathogen for use as a biological control agent have been unsuccessful. We explored an alternative approach that entailed genetically modifying a pathogen with broad host specificity so that it no longer caused disease, but carried a gene to disrupt the cane toad life cycle in a species specific manner. METHODOLOGY/PRINCIPAL FINDINGS: The adult beta globin gene was selected as the model gene for proof of concept of autoimmunity as a biocontrol method for cane toads. A previous report showed injection of bullfrog tadpoles with adult beta globin resulted in an alteration in the form of beta globin expressed in metamorphs as well as reduced survival. In B. marinus we established for the first time that the switch from tadpole to adult globin exists. The effect of injecting B. marinus tadpoles with purified recombinant adult globin protein was then assessed using behavioural (swim speed in tadpoles and jump length in metamorphs, developmental (time to metamorphosis, weight and length at various developmental stages, protein profile of adult globin and genetic (adult globin mRNA levels measures. However, we were unable to detect any differences between treated and control animals. Further, globin delivery using Bohle iridovirus, an Australian ranavirus isolate belonging to the Iridovirus family, did not reduce the survival of metamorphs or alter the form of beta globin expressed in metamorphs. CONCLUSIONS/SIGNIFICANCE: While we were able to show for the first time that the switch from tadpole to adult globin does occur in B. marinus, we were not able to induce autoimmunity and disrupt metamorphosis. The short development time of B. marinus tadpoles may preclude this approach.

  9. Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici.

    Science.gov (United States)

    Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok

    2013-06-01

    We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.

  10. Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici

    Science.gov (United States)

    Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok

    2013-01-01

    We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05) reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit. PMID:25288942

  11. Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici

    Directory of Open Access Journals (Sweden)

    Mee Kyung Sang

    2013-06-01

    Full Text Available We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107 among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05 reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05 reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.

  12. Ochratoxin A Management in Vineyards by Lobesia botrana Biocontrol

    Directory of Open Access Journals (Sweden)

    Giuseppe Cozzi

    2013-01-01

    Full Text Available Grape berries attacked by Lobesia botrana larvae are more easily infected by Aspergillus section Nigri (black aspergilli ochratoxigenic species. Two-year field trials were carried out in Apulia (Italy to evaluate a bioinsecticide control strategy against L. botrana and the indirect effect on reducing ochratoxin A (OTA contamination in vineyards. A commercial Bacillus thuringiensis formulate and an experimental Beauveria bassiana (ITEM-1559 formulate were tested in two vineyards cultivated with the same grape variety, Negroamaro, but with two different training systems (espalier and little-arbor techniques. In both years and training systems the treatments by B. bassiana ITEM-1559 significantly controlled L. botrana larvae attacks with effectiveness similar to B. thuringensis (more than 20%. A significant reduction of OTA concentrations (up to 80% compared to untreated controls was observed only in the first year in both training systems, when the metereological parameters prior to harvest were more favorable to the insect attack. Results of field trials showed that B. bassiana ITEM-1559 is a valid bioinsecticide against L. botrana and that grape moth biocontrol is a strategy to reduce OTA contamination in vineyard in seasons with heavy natural infestation.

  13. Three encochitinase-encoding genes identified in the biocontrol fungus Clonostachys rosea are differentially expressed

    DEFF Research Database (Denmark)

    Mamarabadi, Mojtaba; Jensen, Birgit; Lübeck, Mette

    2008-01-01

    . rosea were made by disruption of the endochitinase genes via Agrobacterium-mediated transformation and their biocontrol activity was evaluated. While in planta bioassays showed no significant difference in biocontrol efficacy between the disruptants and the wildtype, the real time RT-PCR analysis showed...

  14. Draft Genome Sequence of Chryseobacterium sp. Strain GSE06, a Biocontrol Endophytic Bacterium Isolated from Cucumber (Cucumis sativus)

    Science.gov (United States)

    Jeong, Jin-Ju; Park, Byeong Hyeok; Park, Hongjae

    2016-01-01

    Chryseobacterium sp. strain GSE06 is a biocontrol endophytic bacterium against the destructive soilborne oomycete Phytophthora capsici, which causes Phytophthora blight of pepper. Here, we present its draft genome sequence, which contains genes related to biocontrol traits, such as colonization, antimicrobial activity, plant growth promotion, and abiotic or biotic stress adaptation. PMID:27313310

  15. Evaluation of recycled bioplastic pellets and a sprayable formulation for application of an Aspergillus flavus biocontrol strain

    Science.gov (United States)

    Biocontrol of Aspergillus flavus using inoculated bioplastic granules has been proven to be effective under laboratory and field conditions. In the present study, the use of low-density pellets from recycled bioplastic as a biocontrol strain carrier was evaluated. Applying recycled bioplastic pell...

  16. A phenazine-1-carboxylic acid producing polyextremophilic Pseudomonas chlororaphis (MCC2693) strain, isolated from mountain ecosystem, possesses biocontrol and plant growth promotion abilities.

    Science.gov (United States)

    Jain, Rahul; Pandey, Anita

    2016-09-01

    The genus Pseudomonas is known to comprise a huge diversity of species with the ability to thrive in different habitats, including those considered as extreme environments. In the present study, a psychrotolerant, wide pH tolerant and halotolerant strain of Pseudomonas chlororaphis GBPI_507 (MCC2693), isolated from the wheat rhizosphere growing in a mountain location in Indian Himalayan Region (IHR), has been investigated for its antimicrobial potential with particular reference to phenazine production and plant growth promoting traits. GBPI_507 showed phenazine production at the temperatures ranged from 14 to 25°C. The benzene extracted compound identified as phenazine-1-carboxylic acid (PCA) through GC-MS exhibited antimicrobial properties against Gram positive bacteria and actinomycetes. The inhibition of phytopathogens in diffusible biocontrol assays was recorded in an order: Alternaria alternata>Phytophthora sp.>Fusarium solani>F. oxysporum. In volatile metabolite assays, all the pathogens, except Phytophthora sp. produced distorted colonies, characterized by restricted sporulation. The isolate also possessed other growth promoting and biocontrol traits including phosphate solubilization and production of siderophores, HCN, ammonia, and lytic enzymes (lipase and protease). Molecular studies confirmed production of PCA by the bacterium GBPI_507 through presence of phzCD and phzE genes in its genome. The polyextremophilic bacterial strain possesses various important characters to consider it as a potential agent for field applications, especially in mountain ecosystem, for sustainable and eco-friendly crop production. Copyright © 2016 Elsevier GmbH. All rights reserved.

  17. Gadolinium released from MR contrast agents is deposited in brain tumors: in situ demonstration using scanning electron microscopy with energy dispersive X-ray spectroscopy

    International Nuclear Information System (INIS)

    Xia, Daniel; Davis, Richard L.; Crawford, Judith A.; Abraham, Jerrold L.

    2010-01-01

    Background: Gadolinium (Gd)-containing MRI contrast agents (GdCA) are widely used in studies of brain tumors, and a number of reports suggest that under certain conditions, such as renal failure, Gd may be released from GdCA into patient's tissues. Whether this may happen in abnormal tissues in the absence of renal failure has not been studied. Purpose: To test the hypothesis that the local retention of GdCA resulting from brain tumor-associated alterations in the blood-brain barrier (BBB) may result in the deposition of Gd released from the GdCA, depending on stability. Material and Methods: In this retrospective study, 30 selected brain tumor biopsies from 28 patients (taken before and after an institutional switch from a less stable to an intermediate stable GdCA) were searched for Gd-containing deposits using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Relevant histories and laboratory results were obtained through institutional electronic records. Associations between the presence of deposits and other variables were tested for statistical significance using the two-tailed Fisher's exact test. Results: Insoluble deposits containing Gd associated with phosphorus and calcium were found in seven biopsies from five patients. These deposits were found in patients with estimated GFRs above 53 ml/min, and were detected more often in those receiving GdCA before the switch from a less stable to an intermediate stable GdCA (P = 0.04), and may be more frequent in patients receiving more than one contrast-enhanced MR scan (P = 0.15). Conclusion: Gd-containing deposits are present in brain tumors following contrast-enhanced MR scans in patients without severe renal disease. Further studies are needed to assess the clinical importance of the deposits we observed and to determine whether they are also found in other conditions that alter the integrity of the BBB

  18. Biocontrol bacteria selected by a direct plant protection strategy against avocado white root rot show antagonism as a prevalent trait.

    Science.gov (United States)

    González-Sánchez, M Á; Pérez-Jiménez, R M; Pliego, C; Ramos, C; de Vicente, A; Cazorla, F M

    2010-07-01

    This study was undertaken to study bacterial strains obtained directly for their efficient direct control of the avocado white root rot, thus avoiding prescreening by any other possible mechanism of biocontrol which could bias the selection. A collection of 330 bacterial isolates was obtained from the roots and soil of healthy avocado trees. One hundred and forty-three representative bacterial isolates were tested in an avocado/Rosellinia test system, resulting in 22 presumptive protective strains, all of them identified mainly as Pseudomonas and Bacillus species. These 22 candidate strains were screened in a more accurate biocontrol trial, confirming protection of some strains (4 out of the 22). Analyses of the potential bacterial traits involved in the biocontrol activity suggest that different traits could act jointly in the final biocontrol response, but any of these traits were neither sufficient nor generalized for all the active bacteria. All the protective strains selected were antagonistic against some fungal root pathogens. Diverse bacteria with biocontrol activity could be obtained by a direct plant protection strategy of selection. All the biocontrol strains finally selected in this work were antagonistic, showing that antagonism is a prevalent trait in the biocontrol bacteria selected by a direct plant protection strategy. This is the first report on the isolation of biocontrol bacterial strains using direct plant protection strategy in the system avocado/Rosellinia. Characterization of selected biocontrol bacterial strains obtained by a direct plant protection strategy showed that antagonism is a prevalent trait in the selected strains in this experimental system. This suggests that antagonism could be used as useful strategy to select biocontrol strains. © 2009 The Authors. Journal compilation © 2009 The Society for Applied Microbiology.

  19. Biocontrol of Aspergillus species on peanut kernels by antifungal diketopiperazine producing Bacillus cereus associated with entomopathogenic nematode.

    Directory of Open Access Journals (Sweden)

    Sasidharan Nishanth Kumar

    Full Text Available The rhabditid entomopathogenic nematode associated Bacillus cereus and the antifungal compounds produced by this bacterium were evaluated for their activity in reducing postharvest decay of peanut kernels caused by Aspergillus species in in vitro and in vivo tests. The results showed that B. cereus had a significant effect on biocontrol effectiveness in in vitro and in vivo conditions. The antifungal compounds produced by the B. cereus were purified using silica gel column chromatography and their structure was elucidated using extensive spectral analyses. The compounds were identified as diketopiperazines (DKPs [cyclo-(L-Pro-Gly, cyclo(L-Tyr-L-Tyr, cyclo-(L-Phe-Gly and cyclo(4-hydroxy-L-Pro-L-Trp]. The antifungal activities of diketopiperazines were studied against five Aspergillus species and best MIC of 2 µg/ml was recorded against A. flavus by cyclo(4-hydroxy-L-Pro-L-Trp. To investigate the potential application of cyclo(4-hydroxy-L-Pro-L-Trp to eliminate fungal spoilage in food and feed, peanut kernels was used as a food model system. White mycelia and dark/pale green spores of Aspergillus species were observed in the control peanut kernels after 2 days incubation. However the fungal growth was not observed in peanut kernels treated with cyclo(4-hydroxy-L-Pro-L-Trp. The cyclo(4-hydroxy-L-Pro-L-Trp was nontoxic to two normal cell lines [fore skin (FS normal fibroblast and African green monkey kidney (VERO] up to 200 µg/ml in MTT assay. Thus the cyclo(4-hydroxy-L-Pro-L-Trp identified in this study may be a promising alternative to chemical preservatives as a potential biopreservative agent which prevent fungal growth in food and feed. To the best of our knowledge, this is the first report demonstrating that the entomopathogenic nematode associated B. cereus and cyclo(4-hydroxy-L-Pro-L-Trp could be used as a biocontrol agents against postharvest fungal disease caused by Aspergillus species.

  20. DNA barcodes, expanded distribution, and redescription of Apanteles hemara Nixon, 1965 (Hymenoptera, Braconidae, Microgastrinae, a potential biocontrol species against amaranth leaf-webbers in Africa

    Directory of Open Access Journals (Sweden)

    Jose Fernandez-Triana

    2017-08-01

    Full Text Available The microgastrine parasitoid wasp Apanteles hemara Nixon, 1965, is currently being considered as a potential biocontrol agent of amaranth leaf-webber pests in Africa. To facilitate future research and identification of the species, we characterize it from an integrative taxonomy perspective by providing a comprehensive morphological redescription, extensive illustrations (including the first images of the holotype, DNA barcodes, wasp biology, host data (Choreutidae and Crambidae caterpillars, and updated geographical distribution of the species (including eight new country records. Despite a wide distribution across four major biogeographical regions (mostly within the Old World tropics, the species seems to be relatively uniform from a molecular and morphological perspective, based on studied specimens from Africa and Asia.

  1. Yeast Biocontrol of a Fungal Plant Disease: A Model for Studying Organism Interrelationships

    Science.gov (United States)

    Chanchaichaovivat, Arun; Panijpan, Bhinyo; Ruenwongsa, Pintip

    2008-01-01

    An experiment on the action of the yeast, "Saccharomyces cerevisiae", against a fungal plant disease is proposed for secondary students (Grade 11) to support their study of organism interrelationship. This biocontrol experiment serves as the basis for discussing relationships among three organisms (red chilli fruit, "Saccharomyces cerevisiae," and…

  2. Heat shock improves stress tolerance and biocontrol performance of Rhodotorula mucilaginosa

    Science.gov (United States)

    Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeasts, is a research topic and eco-friendly management approach that has received considerable attention. A few yeast-based biocontrol products are available in the market. Ecological fitness, stress to...

  3. Biocontrol of charcoal-rot of sorghum by actinomycetes isolated from ...

    African Journals Online (AJOL)

    use

    2011-12-12

    Dec 12, 2011 ... Streptomyces but with different species in BLAST analysis. This study indicates that the selected actinomycetes have the potential for PGP and control of charcoal-rot disease in sorghum. Key words: Antagonistic actinomycetes, biocontrol, charcoal-rot, Macrophomina phaseolina. INTRODUCTION.

  4. Fungal root endophytes of tomato from Kenya and their nematode biocontrol potential

    NARCIS (Netherlands)

    Bogner, C.W.; Kariuki, George M.; Elashry, A.; Sichtermann, Gisela; Buch, Ann-Katrin; Mishra, Bagdevi; Thines, M.; Grundler, F.M.W.; Schouten, A.

    2016-01-01

    The significance of fungal endophytes in African agriculture, particularly Kenya, has not been well investigated. Therefore, the objective of the present work was isolation, multi-gene phylogenetic characterization and biocontrol assessment of endophytic fungi harbored in tomato roots for nematode

  5. Transcriptomic responses of the biocontrol yeast Pichia anomala to aflatoxigenic Aspergillus flavus

    Science.gov (United States)

    Pichia anomala (Wickerhamomyces anomalus) WRL-076 is a biocontrol yeast which has been shown to inhibit growth and aflatoxin production of Aspergillus flavus. The molecular mechanism of biological control was further characterized by the temporal transcriptome response of P. anomala to A. flavus in...

  6. Biocontrol of tomato foot and root rot by Pseudomonas bacteria in stonewool

    NARCIS (Netherlands)

    Validov, Shamil

    2007-01-01

    The research described in this thesis shows that the enrichment technique based on competitive root tip colonization allows the isolation of bacteria which can protect plants from TFRR through the mechanism competition for nutrients (and niches). The efficacy of biocontrol of one of these strains,

  7. Differential effects of organic compounds on cucumber damping-off and biocontrol activity of antagonistic bacteria

    DEFF Research Database (Denmark)

    Li, Bin; Ravnskov, Sabine; Guanlin, X.

    2011-01-01

    showed that the organic compounds differentially affected both pathogen and BCAs. Tryptic soy broth, glucose and chitosan increased Pythium damping-off of cucumber, compared to the control treatment without organic compounds, whereas cellulose had no effect. Both Paenibacillus species had biocontrol...

  8. Potential of bulb-associated bacteria for biocontrol of hyacinth soft rot caused by Dickeya zeae

    NARCIS (Netherlands)

    Jafra, S.; Przysowa, J.; Gwizdek-Wisniewska, A.; Wolf, van der J.M.

    2009-01-01

    Dickeya zeae is a pectinolytic bacterium responsible for soft rot disease in flower bulb crops. In this study, the possibility of controlling soft rot disease in hyacinth by using antagonistic bacteria isolated from hyacinth bulbs was explored. Bacterial isolates with potential for biocontrol were

  9. Biocontrol and population dynamics of Fusarium spp. on wheat stubble in Argentina

    NARCIS (Netherlands)

    Palazzini, J.M.; Groenenboom-de Haas, de B.H.; Torres, A.M.; Köhl, J.; Chulze, S.N.

    2013-01-01

    The biocontrol effect of Clonostachys rosea (strains 016 and 1457) on Fusarium graminearum, F. avenaceum, F. verticillioides, F. langsethiae, F. poae, F. sporotrichioides, F. culmorum and Microdochium nivale was evaluated on naturally infected wheat stalks exposed to field conditions for 180 days.

  10. Pantoea applied genomics to understand and improve biocontrol activity against fire blight

    Science.gov (United States)

    Pantoea agglomerans and P. vagans (ex. Erwinia herbicola) are common epiphytes of pome fruit flowers and three strains (E325, P10c, C9-1) have been commercially developed as effective biocontrol products for managing fire blight (Erwinia amylovora). Antibiotics as a standard, reliable chemical optio...

  11. Remote sensing bio-control damage on aquatic invasive alien plant ...

    African Journals Online (AJOL)

    Naeem

    Abstract. Aquatic Invasive Alien Plant (AIAP) species are a major threat to freshwater ecosystems, placing great strain on South Africa's limited water resources. Bio-control programmes have been initiated in an effort to mitigate the negative environmental impacts associated with their presence in non-native areas. Remote ...

  12. Stress tolerance and biocontrol performance of the yeast antagonist, Candida diversa, change with morphology transition.

    Science.gov (United States)

    Li, Guangkun; Chi, Mengshan; Chen, Huizhen; Sui, Yuan; Li, Yan; Liu, Yongsheng; Zhang, Xiaojing; Sun, Zhiqiang; Liu, Guoqing; Wang, Qi; Liu, Jia

    2016-02-01

    As an eco-friendly management method, biological control of postharvest diseases, utilizing antagonistic yeasts, is a research topic receiving considerable attention. Detailed knowledge on the biology of yeast antagonists is crucial when considering their potential application and development as biocontrol products. Changes in the growth form, such as single-cell to pseudohyphae, have been associated with the mode of action in postharvest biocontrol yeasts. In this study, the antagonistic yeast, Candida diversa, reversibly shifted from a single-cell morphology on yeast peptone dextrose (YPD) medium with 2 % agar to a pseudohyphal morphology on YPD with 0.3 % agar. The tolerance of the pseudohyphal form to heat and oxidative stresses, as well as the biocontrol efficacy against Botrytis cinerea on apple and kiwifruit stored at 25 and 4 °C, was significantly higher as compared to the single-cell form. This study provides new information on the ability of C. diversa to change its morphology and the impact of the morphology shift on stress tolerance and biocontrol performance.

  13. Agar composition affects in vitro screening of biocontrol activity of antagonistic microorganisms

    NARCIS (Netherlands)

    Bosmans, Lien; De Bruijn, I.; de Mot, Rene; Readers, Hans; Lievens, Bart

    2016-01-01

    Agar-based screening assays are the method of choice when evaluating antagonistic potential of bacterial biocontrol-candidates against pathogens.Weshowed thatwhen using the samemedium, but different agar compositions, the activity of a bacterial antagonist against Agrobacteriumwas strongly affected.

  14. Biocontrol Potential ofStreptomyces hydrogenansStrain DH16 towardAlternaria brassicicolato Control Damping Off and Black Leaf Spot ofRaphanus sativus.

    Science.gov (United States)

    Manhas, Rajesh K; Kaur, Talwinder

    2016-01-01

    Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola , causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v) of S. hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10%) and streptomycete cells significantly improved seed germination (75-80%) and vigor index (1167-1538). Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers.

  15. Biocontrol Potential of Streptomyces hydrogenans strain DH16 Towards Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus

    Directory of Open Access Journals (Sweden)

    Rajesh Kumari Manhas

    2016-12-01

    Full Text Available Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v of Streptomyces hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10% and streptomycete cells significantly improved seed germination (75-80% and vigour index (1167-1538. Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers.

  16. Efficacy of Eucalyptus cinerea as a Source of Bioactive Compounds for Curative Biocontrol of Crown Gall Caused by Agrobacterium tumefaciens Strain B6

    Directory of Open Access Journals (Sweden)

    Yosra Kahla

    2017-01-01

    Full Text Available This research investigated the Eucalyptus cinerea leaves efficiency in the Agrobacterium tumefaciens biocontrol, the causative agent of crown gall. GC-MS analysis of the essential oil (EO showed that the main components were 1,8-cineole (61% and camphene (15.13%. Thanks to its polyphenols, flavonoids, quinones, terpenoids, alkaloids, and tannins richness, the EtOAc-F exhibited the most potent antibacterial activity in vitro. Indeed, compared to the other fractions, it has the lowest MIC and MBC values of 0.312 mg/mL and 2.5 mg/mL, respectively. The GC-MS analysis of EtOAc-F confirmed its richness in antibacterial compounds including gallic acid (7.18%, shikimic acid (5.07%, and catechin (3.12%. The time-kill curve assay of EtOAc-F (2.5 mg/mL showed a potent bactericidal effect after 20 min of direct contact with A. tumefaciens. In planta experiments, gall weights were significantly reduced when EtOAc-F was applied at 0.625 and 2.5 mg/wounds. Besides, the disease reduction rates in gall weight were 95% and 97.5%, respectively. Interestingly, no phytotoxic effect was observed since tomato seeds germinated in the presence of the different concentrations of EtOAc-F. These results suggest that EtOAc-F has a good potential to be a curative biocontrol agent for crown gall disease.

  17. Silver nanoparticles from Prosopis glandulosa and their potential application as biocontrol of Acinetobacter calcoaceticus and Bacillus cereus

    Directory of Open Access Journals (Sweden)

    Ali Abdelmoteleb

    2017-01-01

    Full Text Available In the present study the characterization and properties of silver nanoparticles from Prosopis glandulosa leaf extract (AgNPs were investigated using UV–Vis spectroscopic techniques, energy dispersive X-ray spectrometers (EDS, zeta potential and dynamic light scattering. The UV–Vis spectroscopic analysis showed the absorbance peaked at 487 nm, which indicated the synthesis of silver nanoparticles. The experimental results showed silver nanoparticles had Z-average diameter of 421 nm with higher stability (−200 mV. The EDS analysis also exhibited presentation of silver element. Additionally, the different concentrations of AgNPs (25, 50, 75 and 100 mg/mL showed antibacterial activity against Acinetobacter calcoaceticus and Bacillus cereus. Finally, AgNPs from leaf extracts of P. glandulosa may be used as an agent of biocontrol of microorganism of importance medical. However, further studies will be needed to fully understand the antimicrobial activity of silver nanoparticles obtain from P. glandulosa.

  18. Yeasts from native Brazilian Cerrado plants: Occurrence, diversity and use in the biocontrol of citrus green mould.

    Science.gov (United States)

    Sperandio, Eugenio Miranda; Martins do Vale, Helson Mario; Moreira, Geisianny Augusta Monteiro

    2015-11-01

    Yeasts are some of the most important postharvest biocontrol agents. Postharvest oranges frequently deteriorate due to green mould (Penicillium digitatum), which causes significant losses. The aims of this study were to determine the composition and diversity of yeasts on plants of the Brazilian Cerrado and to explore their potential for inhibiting citrus green mould. Leaves and fruit of Byrsonima crassifolia and Eugenia dysenterica were collected from Cerrado conservation areas, and thirty-five yeasts were isolated and identified by sequencing the D1-D2 domain of the rDNA large subunit (26S). The isolates represented the Aureobasidium, Meyerozyma, Candida, and Pichia genera. Three isolates identified as Aureobasidium pullulans exhibited potential for the control of P. digitatum in both in vitro and in vivo tests; these isolates reduced the incidence of disease and increased the storage time of fruit. Aureobasidium. pullulans has immense potential for the biological control of filamentous fungi. Copyright © 2015 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  19. Biocontrol of Late Blight (Phytophthora capsici Disease and Growth Promotion of Pepper by Burkholderia cepacia MPC-7

    Directory of Open Access Journals (Sweden)

    Mao Sopheareth

    2013-03-01

    Full Text Available A chitinolytic bacterial strain having strong antifungal activity was isolated and identified as Burkholderia cepacia MPC-7 based on 16S rRNA gene analysis. MPC-7 solubilized insoluble phosphorous in hydroxyapatite agar media. It produced gluconic acid and 2-ketogluconic acid related to the decrease in pH of broth culture. The antagonist produced benzoic acid (BA and phenylacetic acid (PA. The authentic compounds, BA and PA, showed a broad spectrum of antimicrobial activity against yeast, several bacterial and fungal pathogens in vitro. To demonstrate the biocontrol efficiency of MPC-7 on late blight disease caused by Phytophthora capsici, pepper plants in pot trials were treated with modified medium only (M, M plus zoospore inoculation (MP, MPC-7 cultured broth (B and B plus zoospore inoculation (BP. With the sudden increase in root mortality, plants in MP wilted as early as five days after pathogen inoculation. However, plant in BP did not show any symptom of wilting until five days. Root mortality in BP was markedly reduced for as much as 50%. Plants in B had higher dry weight, P concentration in root, and larger leaf area compared to those in M and MP. These results suggested that B. cepacia MPC-7 should be considered as a candidate for the biological fertilizer as well as antimicrobial agent for pepper plants.

  20. Attachment Capability of Antagonistic Yeast Rhodotorula glutinis to Botrytis cinerea Contributes to Biocontrol Efficacy.

    Science.gov (United States)

    Li, Boqiang; Peng, Huaimin; Tian, Shiping

    2016-01-01

    Rhodotorula glutinis as an antagonism show good biocontrol performance against various post-harvest diseases in fruits. In the present study, strong attachment capability of R. glutinis to spores and hyphae of Botrytis cinerea was observed. Further analysis showed that certain protein components on the yeast cell surface played critical role during the interaction between R. glutinis and B. cinerea. The components mainly distributed at the poles of yeast cells and might contain glycosylation modification, as tunicamycin treated yeast cells lost attachment capability to B. cinerea. To investigate contributions of attachment capability of R. glutinis to its biocontrol efficacy, yeast cells were mutagenized with 3% methane-sulfonic acid ethyl ester (EMS), and a mutant CE4 with stable non-attaching phenotype was obtained. No significant difference was found on colony, cell morphology, reproductive ability, and capsule formation between the mutant and wild-type. However, there was a distinct difference in India ink positive staining patterns between the two strains. Moreover, wild-type strain of R. glutinis showed better performance on inhibiting spore germination and mycelial growth of B. cinerea than CE4 strain when yeast cells and B. cinerea were co-cultured in vitro. In biocontrol assay, both wild-type and CE4 strains showed significant biocontrol efficacy against gray mold caused by B. cinerea in apple fruit, whereas, control effect of CE4 strain was lower than that of wild-type. Our findings provided new evidences that attachment capability of R. glutinis to B. cinerea contributed to its biocontrol efficacy.

  1. Biocontrol of the internalization of Salmonella enterica and Enterohaemorrhagic Escherichia coli in mung bean sprouts with an endophytic Bacillus subtilis.

    Science.gov (United States)

    Shen, Zhenyu; Mustapha, Azlin; Lin, Mengshi; Zheng, Guolu

    2017-06-05

    inhibition against the S. enterica cocktails by a reduction of about 1.1-1.4lg CFU/g of seeds by day 5. Results of this study suggest that the source (native vs. alien) of B. subtilis isolates may not affect the efficacy of the inhibition, but it might be affected by the production of antimicrobial substance and/or nutrition/space competition. The results also indicate that strain LCA1 may be useful as a biocontrol agent to reduce Salmonella and EHEC contamination in seed sprouts. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Biocontrol of potato wilt by selective rhizospheric and endophytic ...

    African Journals Online (AJOL)

    Ralstonia solanacearum is the causative agent of wilt disease in plants, which constitutes a severe problem to agricultural crops, particularly for potato production in Madagascar. The present study focuses on the isolation, in vitro and in vivo assays of potential rhizospheric and endophytic bacteria associated with healthy ...

  3. After biocontrol: assessing indirect effects of insect releases

    Science.gov (United States)

    Julie S. Denslow; Carla M. D' Antonio

    2005-01-01

    Development of biological control agents for weeds has been motivated by the need to reduce the abundance and distribution of a pest plant where chemical and mechanical control were not cost effective. Primary objectives have been direct reduction in abundance of the target and, secondarily, the increase of desirable species. Recently, wildland weeds have become a...

  4. A socioeconomic analysis of biocontrol in integrated pest management

    NARCIS (Netherlands)

    Benjamin, Emmanuel O.; Wesseler, Justus H.H.

    2016-01-01

    European regulations on the sustainable use of pesticides aim to promote integrated pest management (IPM) strategy and the use of biological control agents. However, uncertainty over benefits and costs, irreversibility effects as well as flexibility in adoption of this technology needs to be

  5. Biocontrol evaluation of wheat take-all disease by Trichoderma ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-10-20

    Oct 20, 2008 ... operculum. i: Growth reduction, overgrowth, and abnormal production of yellow pigment. g: The height of control and healthy plant. k, i: Root necrosis of control and healthy plant. nated with 1600 propagules (infested millet seeds) of take-all agent per 1 kg soil. Wheat seeds were coated with Trichoderma at ...

  6. Biocontrole de Listeria monocytogenes por Pediococcus acidilactici em couve minimamente processada Biocontrol of Listeria monocytogenes by Pediococcus acidilactici in fresh-cut kale

    OpenAIRE

    Wanessa Altimiras Costa; Maria Cristina Dantas Vanetti; Rolf Puschamann

    2009-01-01

    Este estudo avaliou um sistema de biocontrole para inibição de Listeria monocytogenes em couve minimamente processada, objetivando sua segurança durante estocagem sob refrigeração e em condições de abuso de temperatura. O potencial inibitório de bactérias láticas tolerantes ao sal e psicrotróficas contaminantes naturais da couve e Lactobacillus plantarum, Lactobacillus delbrueckii ATCC 9649 e Lactobacillus casei CCT 1465 foram avaliadas contra L. monocytogenes. O isolado de couve identificado...

  7. ADHERENCE AND PA THOGENICITY ASSA Y OF VIBRIO HARVE YI IN TIGER SHRIMP (PENAEUS MONODON LARVAE FOR SC REENING BIOCONTROL AGE NT

    Directory of Open Access Journals (Sweden)

    YUSMINAH H ALA

    2002-01-01

    Full Text Available Rifampicin-resistant marker w as empl oyed as a repor ter t o detect the ad here nce and colonization of V. harve yi in s hrimp larvae. Vibri o h arve yi P1B and YA3 2. 2 were isolated f rom dead s hrimp la rv ae i n Besuki, Norther n C oast of East Jav a, while V. harveyi HB3, was isolated from pris tine sea water in Pacita n, S outhe rn Coast of E ast Ja va . Vi brio metsc hnikovii used a s bioc ontr ol a gent was i solated fr om healthy shrimp larvae in Serang, We st Java. Spontane ous mutation was c onducted to generate V. harveyi P1B, YA32.2 and HB3 resistant to rifampi cin. These mutants exhibit ed similar survival ability to t heir parent al (wild type strai ns. Signifi cant larval mortalit y was o bserv ed i n s hrimp l arv ae i noculated with YA32.2 than that of larvae ino culated with P1B. Larvae inoculated with H B 3 showed the lo w est mortality. Bacterial cell c ount of Vi brio Rf* in dead larvae w ere 103-104 cells/larvae. Isolates of Vi brio metschnikovii Z an d M as biocontrol candid ates effectively r educed the growth a nd a dherence ability of YA32.2 t o shrimp larvae. Larval mort ality in rearing water inoculat ed simultaneousl y w ith YA32.2 and V. metschnikovii was lower than the one inoculated with YA32.2 alone. Therefore, Vibrio metschnikovii Z or M could be develope d as an effective pro biotic or biocontrol agent for V. harvey i in shrimp hatcheri es.

  8. Optimization and biochemical characterization of a bacteriocin from a newly isolated Bacillus subtilis strain 14B for biocontrol of Agrobacterium spp. strains.

    Science.gov (United States)

    Hammami, I; Rhouma, A; Jaouadi, B; Rebai, A; Nesme, X

    2009-02-01

    The identification of a new compound active against Agrobacterium tumefaciens. The culture conditions of a newly isolated Bacillus subtilis strain, designed 14B, were optimized, as a first step, to produce its bacteriocin (termed Bac 14B) for the biocontrol of Agrobacterium spp., the causal agents of the crown gall disease. Bac 14B was then partially purified and biochemically characterized. Bacillus subtilis 14B was observed to produce an antibacterial compound having a protinaceous nature. As estimated by sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE), the semi-purified bacteriocin substance was found to be a monomeric protein with a molecular weight of 21 kDa. While the latter's antimicrobial activity was completely stable during exposure to a temperature range of up to 100 degrees C for 2 h, its initial activity was totally lost at 121 degrees C for 20 min. The maximum bacteriocin production (4096 AU ml(-1)) was recorded after 96 h-incubation in an optimized Luria Bertani medium supplemented with 10 g l(-1) glucose, 15 g l(-1) K(2)HPO(4) and 5 g l(-1) MgSO(4) 7H(2)O at 30 degrees C in a shaking flask culture. Interestingly, the B. subtilis 14B culture supernatant that contained the bacteriocin under study was proved efficient in reducing both the percentage of galled plants and the number of galls in tomato. The findings revealed that B. subtilis 14B and its bacteriocin are efficient in reducing the percentage of infections in plants caused by Ag. tumefaciens. The results could be useful for the nurserymen who are particularly interested in the biocontrol of the crown gall disease.

  9. Novel Biocontrol Methods for Listeria monocytogenes Biofilms in Food Production Facilities

    Directory of Open Access Journals (Sweden)

    Jessica A. Gray

    2018-04-01

    Full Text Available High mortality and hospitalization rates have seen Listeria monocytogenes as a foodborne pathogen of public health importance for many years and of particular concern for high-risk population groups. Food manufactures face an ongoing challenge in preventing the entry of L. monocytogenes into food production environments (FPEs due to its ubiquitous nature. In addition to this, the capacity of L. monocytogenes strains to colonize FPEs can lead to repeated identification of L. monocytogenes in FPE surveillance. The contamination of food products requiring product recall presents large economic burden to industry and is further exacerbated by damage to the brand. Poor equipment design, facility layout, and worn or damaged equipment can result in Listeria hotspots and biofilms where traditional cleaning and disinfecting procedures may be inadequate. Novel biocontrol methods may offer FPEs effective means to help improve control of L. monocytogenes and decrease cross contamination of food. Bacteriophages have been used as a medical treatment for many years for their ability to infect and lyse specific bacteria. Endolysins, the hydrolytic enzymes of bacteriophages responsible for breaking the cell wall of Gram-positive bacteria, are being explored as a biocontrol method for food preservation and in nanotechnology and medical applications. Antibacterial proteins known as bacteriocins have been used as alternatives to antibiotics for biopreservation and food product shelf life extension. Essential oils are natural antimicrobials formed by plants and have been used as food additives and preservatives for many years and more recently as a method to prevent food spoilage by microorganisms. Competitive exclusion occurs naturally among bacteria in the environment. However, intentionally selecting and applying bacteria to effect competitive exclusion of food borne pathogens has potential as a biocontrol application. This review discusses these novel biocontrol

  10. Cannibalism in invasive, native and biocontrol populations of the harlequin ladybird

    Science.gov (United States)

    2014-01-01

    Background Cannibalism is widespread in both vertebrates and invertebrates but its extent is variable between and within species. Cannibalism depends on population density and nutritional conditions, and could be beneficial during colonisation of new environments. Empirical studies are needed to determine whether this trait might facilitate invasion of a new area in natural systems. We investigated whether the propensity for cannibalism in H. axyridis differs both between native and invasive populations and between invasive populations from the core and from the front of the invasive area in Western Europe. We also compared the propensity for cannibalism of these natural populations with that of laboratory-reared biocontrol populations. We measured the cannibalism rates of eggs by first instar larvae and adult females at two different individual densities of ladybirds from three types of population (invasive, native and biocontrol), in laboratory-controlled conditions. Results Cannibalism was significantly greater in larvae from invasive populations compared to native or biocontrol populations, but there was no difference in cannibalism rates between populations from the core or front of the invaded range. Cannibalism was significantly lower in larvae from biocontrol populations compared to wild (invasive and native) populations. No differences in cannibalism rates of adult females were found between any populations. While high population density significantly increased cannibalism in both larvae and adults, the norm of reaction of cannibalism to individual density did not change significantly during the invasion and/or laboratory rearing processes. Conclusion This study is the first to provide evidence for a higher propensity for cannibalism in invasive populations compared to native ones. Our experiments also shed light on the difference in cannibalism evolution with respect to life stages. However, we are still at an early stage in understanding the underlying

  11. Identification of Quorum Quenching Bacteria and Its Biocontrol Potential Against Soft Rot Disease Bacteria, Dickeya Dadantii

    OpenAIRE

    Khoiri, Syaiful; Damayanti, Tri Asmira; Giyanto, Giyanto

    2017-01-01

    Dickeya dadantii is one of newly found bacteria causing soft rot on orchids in Indonesia. Infected plants showed severe rot rapidly only in few days. An effort to control the bacteria was conducted by utilizing selected quorum quenching (QQ) inducer bacteria which produce AHL-lactonase by aiiA gene. The aims of this research were to screen and identify of quorum quenching bacteria, and also assayed their biocontrol potential ability against D. dadantii in laboratory. The screening of QQ bacte...

  12. Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture

    OpenAIRE

    ?lvarez, Bel?n; Biosca, Elena G.

    2017-01-01

    Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum, and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the a...

  13. Complete Genome Sequence of the Endophytic Biocontrol Strain Bacillus velezensis CC09

    OpenAIRE

    Cai, Xunchao; Kang, Xingxing; Xi, Huan; Liu, Changhong; Xue, Yarong

    2016-01-01

    Bacillus velezensis is a heterotypic synonym of B. methylotrophicus, B. amyloliquefaciens subsp. plantarum, and Bacillus oryzicola, and has been used to control plant fungal diseases. In order to fully understand the genetic basis of antimicrobial capacities, we did a complete genome sequencing of the endophytic B.?velezensis strain CC09. Genes tightly associated with biocontrol ability, including nonribosomal peptide synthetases, polyketide synthetases, iron acquisition, colonization, and vo...

  14. Complete Genome Sequence of the Endophytic Biocontrol Strain Bacillus velezensis CC09.

    Science.gov (United States)

    Cai, Xunchao; Kang, Xingxing; Xi, Huan; Liu, Changhong; Xue, Yarong

    2016-09-29

    Bacillus velezensis is a heterotypic synonym of B. methylotrophicus, B. amyloliquefaciens subsp. plantarum, and Bacillus oryzicola, and has been used to control plant fungal diseases. In order to fully understand the genetic basis of antimicrobial capacities, we did a complete genome sequencing of the endophytic B. velezensis strain CC09. Genes tightly associated with biocontrol ability, including nonribosomal peptide synthetases, polyketide synthetases, iron acquisition, colonization, and volatile organic compound synthesis were identified in the genome. Copyright © 2016 Cai et al.

  15. Identification of a novel fungus, Trichoderma asperellum GDFS1009, and comprehensive evaluation of its biocontrol efficacy

    OpenAIRE

    Wu, Qiong; Sun, Ruiyan; Ni, Mi; Yu, Jia; Li, Yaqian; Yu, Chuanjin; Dou, Kai; Ren, Jianhong; Chen, Jie

    2017-01-01

    Due to its efficient broad-spectrum antimicrobial activity, Trichoderma has been established as an internationally recognized biocontrol fungus. In this study, we found and identified a novel strain of Trichoderma asperellum, named GDFS1009. The mycelium of T. asperellum GDFS1009 exhibits a high growth rate, high sporulation capacity, and strong inhibitory effects against pathogens that cause cucumber fusarium wilt and corn stalk rot. T. asperellum GDFS1009 secretes chitinase, glucanase, and ...

  16. Mechanism of H₂O₂-induced oxidative stress regulating viability and biocontrol ability of Rhodotorula glutinis.

    Science.gov (United States)

    Chen, Jian; Li, Boqiang; Qin, Guozheng; Tian, Shiping

    2015-01-16

    The use of antagonistic yeasts to control postharvest pathogens is a promising alternative to fungicides. The effectiveness of the antagonists against fungal pathogens is greatly dependent on their viability, which is usually mediated by reactive oxygen species (ROS). Here, we investigated the effects of H₂O₂-induced oxidative stress on the viability and biocontrol efficacy of Rhodotorula glutinis and, using flow cytometric analysis, observed the changes of ROS accumulation and apoptosis in the yeast cells with or without H₂O₂ treatment. We found that the viability of R. glutinis decreased in a time- and dose-dependent manner under H₂O₂-induced oxidative stress. Compared to the control, yeast cells exposed to oxidative stress exhibited more accumulation of ROS and higher levels of protein oxidative damage, but showed lower efficacy for biocontrol of Penicillium expansum causing blue mold rot on peach fruit. The results indicate that apoptosis is a main cause of the cell viability loss in R. glutinis, which is attributed to ROS accumulation under oxidative stress. These findings offer a plausible explanation that oxidative stress affects biocontrol efficacy of R. glutinis via regulating its viability and cell apoptosis. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Plant microbial diversity is suggested as the key to future biocontrol and health trends.

    Science.gov (United States)

    Berg, Gabriele; Köberl, Martina; Rybakova, Daria; Müller, Henry; Grosch, Rita; Smalla, Kornelia

    2017-05-01

    The microbiome of plants plays a crucial role in both plant and ecosystem health. Rapid advances in multi-omics tools are dramatically increasing access to the plant microbiome and consequently to the identification of its links with diseases and to the control of those diseases. Recent insights reveal a close, often symbiotic relationship between microorganisms and plants. Microorganisms can stimulate germination and plant growth, prevent diseases, and promote stress resistance and general fitness. Plants and their associated microorganisms form a holobiont and have to be considered as co-evolved species assemblages consisting of bacterial, archaeal and diverse eukaryotic species. The beneficial interplay of the host and its microbiome is responsible for maintaining the health of the holobiont, while diseases are often correlated with microbial dysbioses. Microbial diversity was identified as a key factor in preventing diseases and can be implemented as a biomarker in plant protection strategies. Targeted and predictive biocontrol approaches are possible by developing microbiome-based solutions. Moreover, combined breeding and biocontrol strategies maintaining diversity and ecosystem health are required. The analysis of plant microbiome data has brought about a paradigm shift in our understanding of its role in health and disease and has substantial consequences for biocontrol and health issues. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture

    Science.gov (United States)

    Álvarez, Belén; Biosca, Elena G.

    2017-01-01

    Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum, and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis, not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta. Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field. PMID:28769942

  19. Influence of Oxidative Stress on Biocontrol Activity ofCryptococcus laurentiiagainst Blue Mold on Peach Fruit.

    Science.gov (United States)

    Zhang, Zhanquan; Chen, Jian; Li, Boqiang; He, Chang; Chen, Yong; Tian, Shiping

    2017-01-01

    The limitations of chemical fungicides for the control of postharvest diseases have recently become more apparent. The utilization of antagonistic microorganisms is a promising alternative to that of fungicides to control postharvest decay. In previous studies, the antagonistic yeast Cryptococcus laurentii has shown excellent effects of biocontrol and great potential for practical application. Adverse conditions, such as oxidative stress, limit the practical application of antagonistic yeast. In this study, we investigated the oxidative stress tolerance of C. laurentii and the associated mechanisms. The results indicated that exogenous oxidative stress has a significant effect on the viability and biocontrol efficiency of C. laurentii . H 2 O 2 -induced oxidative stress led to the accumulation of reactive oxygen species. The results of flow cytometric analysis suggested that apoptosis is responsible for the reduced survival rate of C. laurentii under oxidative stress. Using tests of antioxidant activity, we found that C. laurentii could employ enzymatic systems to resist exogenous oxidative stress. The addition of exogenous glutathione, a non-enzymatic antioxidant, to the media can significantly enhance oxidative tolerance and biocontrol efficiency of C. laurentii .

  20. Importance of prumycin produced by Bacillus amyloliquefaciens SD-32 in biocontrol against cucumber powdery mildew disease.

    Science.gov (United States)

    Tanaka, Keijitsu; Fukuda, Mutsumi; Amaki, Yusuke; Sakaguchi, Takatoshi; Inai, Koji; Ishihara, Atsushi; Nakajima, Hiromitsu

    2017-12-01

    Powdery mildew disease of cucurbits is caused mainly by Podosphaera fusca, which is one of the most important limiting factors in cucurbit production worldwide. Previously we reported that Bacillus amyloliquefaciens biocontrol strain SD-32 produces C 17 bacillomycin D and [Ile 2002]surfactin, and that these metabolites play important roles in SD-32's biocontrol over cucumber gray mold disease. Our further investigation demonstrated that the culture broth and its supernatant suppressed cucumber powdery mildew disease in greenhouse experiments. However, the active principle(s) remained unknown. The active compound was isolated from the culture supernatant after anti-powdery mildew disease activity-guided purification and identified as prumycin. Prumycin significantly suppressed the disease, whereas bacillomycin D and [Ile 2002]surfactin did not. Prumycin did not induce the expression of plant defense genes (PR1a and VSP1), suggesting that it does not act via plant defense response. Light microscopic observations of prumycin-treated cucumber cotyledon suggested that prumycin inhibits the conidial germination of P. fusca. This study demonstrates that prumycin is a major factor in SD-32's suppression of cucumber powdery mildew disease. Our findings shed light for the first time on prumycin's role in biocontrol by Bacillus against this disease. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  1. Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture

    Directory of Open Access Journals (Sweden)

    Belén Álvarez

    2017-07-01

    Full Text Available Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum, and R. syzygii subsp. indonesiensis (former R. solanacearum species complex are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis, not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta. Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field.

  2. Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture.

    Science.gov (United States)

    Álvarez, Belén; Biosca, Elena G

    2017-01-01

    Bacterial wilt diseases caused by Ralstonia solanacearum , R. pseudosolanacearum , and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis , not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta . Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field.

  3. Investigating Biological Control Agents for Controlling Invasive Populations of the Mealybug Pseudococcus comstocki in France.

    Science.gov (United States)

    Malausa, Thibaut; Delaunay, Mathilde; Fleisch, Alexandre; Groussier-Bout, Géraldine; Warot, Sylvie; Crochard, Didier; Guerrieri, Emilio; Delvare, Gérard; Pellizzari, Giuseppina; Kaydan, M Bora; Al-Khateeb, Nadia; Germain, Jean-François; Brancaccio, Lisa; Le Goff, Isabelle; Bessac, Melissa; Ris, Nicolas; Kreiter, Philippe

    2016-01-01

    Pseudococcus comstocki (Hemiptera: Pseudococcidae) is a mealybug species native to Eastern Asia and present as an invasive pest in northern Italy and southern France since the start of the century. It infests apple and pear trees, grapevines and some ornamental trees. Biocontrol programmes against this pest proved successful in central Asia and North America in the second half of the 20th century. In this study, we investigated possible biocontrol agents against P. comstocki, with the aim of developing a biocontrol programme in France. We carried out systematic DNA-barcoding at each step in the search for a specialist parasitoid. First we characterised the French target populations of P. comstocki. We then identified the parasitoids attacking P. comstocki in France. Finally, we searched for foreign mealybug populations identified a priori as P. comstocki and surveyed their hymenopteran parasitoids. Three mealybug species (P. comstocki, P. viburni and P. cryptus) were identified during the survey, together with at least 16 different parasitoid taxa. We selected candidate biological control agent populations for use against P. comstocki in France, from the species Allotropa burrelli (Hymenoptera: Platygastridae) and Acerophagus malinus (Hymenoptera: Encyrtidae). The coupling of molecular and morphological characterisation for both pests and natural enemies facilitated the programme development and the rejection of unsuitable or generalist parasitoids.

  4. Investigating Biological Control Agents for Controlling Invasive Populations of the Mealybug Pseudococcus comstocki in France.

    Directory of Open Access Journals (Sweden)

    Thibaut Malausa

    Full Text Available Pseudococcus comstocki (Hemiptera: Pseudococcidae is a mealybug species native to Eastern Asia and present as an invasive pest in northern Italy and southern France since the start of the century. It infests apple and pear trees, grapevines and some ornamental trees. Biocontrol programmes against this pest proved successful in central Asia and North America in the second half of the 20th century. In this study, we investigated possible biocontrol agents against P. comstocki, with the aim of developing a biocontrol programme in France. We carried out systematic DNA-barcoding at each step in the search for a specialist parasitoid. First we characterised the French target populations of P. comstocki. We then identified the parasitoids attacking P. comstocki in France. Finally, we searched for foreign mealybug populations identified a priori as P. comstocki and surveyed their hymenopteran parasitoids. Three mealybug species (P. comstocki, P. viburni and P. cryptus were identified during the survey, together with at least 16 different parasitoid taxa. We selected candidate biological control agent populations for use against P. comstocki in France, from the species Allotropa burrelli (Hymenoptera: Platygastridae and Acerophagus malinus (Hymenoptera: Encyrtidae. The coupling of molecular and morphological characterisation for both pests and natural enemies facilitated the programme development and the rejection of unsuitable or generalist parasitoids.

  5. Antagonismo direto e biocontrole da podridão-mole-do-tomateiro pelo uso de procariotas Direct antagonism and biocontrol of tomato soft rot using prokaryotes

    Directory of Open Access Journals (Sweden)

    Victor Rafael Barra

    2009-03-01

    Full Text Available O objetivo deste trabalho foi avaliar procariotas quanto ao potencial de antagonismo direto para o biocontrole da podridão-mole-do-tomateiro (Pectobacterium carotovorum subsp. carotovorum. Avaliaram-se 45 isolados bacterianos pelo teste de antibiose contra o patógeno. Foram feitos dois ensaios em que sementes de tomate (Lycopersicon esculentum Mill. cv. Santa Clara foram infectadas com isolados antagônicos. As mudas foram transplantadas para solos infestados com suspensões de propágulos P. carotovorum com OD540 de 0,45 e 0,65. Os antagonistas UFV-0005, UFV-043, UFV-BF112 e UFV-0006 foram eficientes em proteger plantas de tomateiro contra a podridão-mole.This work aimed to evaluate prokaryotes to provide direct antagonism and biocontrol of tomato soft rot (Pectobacterium carotovorum subsp. carotovorum. Forty-five bacterial isolates previously selected for biological control of several tomato (Lycopersicon esculentum Mill. diseases were evaluated using an antibiosis test. 'Santa Clara' tomato seeds were inoculated with potential antagonist isolates and transplanted to a soil infested with the pathogen, in two asseys, at a propagule concentration of OD540 0.45 and 0.65. Antagonists UFV-0005, UFV-043, UFV-BF112, and UFV-0006 protected tomato plants against soft rot disease.

  6. Isolation and characterization of soil Streptomyces species as potential biological control agents against fungal plant pathogens.

    Science.gov (United States)

    Evangelista-Martínez, Zahaed

    2014-05-01

    The use of antagonist microorganisms against fungal plant pathogens is an attractive and ecologically alternative to the use of chemical pesticides. Streptomyces are beneficial soil bacteria and potential candidates for biocontrol agents. This study reports the isolation, characterization and antagonist activity of soil streptomycetes from the Los Petenes Biosphere Reserve, a Natural protected area in Campeche, Mexico. The results showed morphological, physiological and biochemical characterization of six actinomycetes and their inhibitory activity against Curvularia sp., Aspergillus niger, Helminthosporium sp. and Fusarium sp. One isolate, identified as Streptomyces sp. CACIS-1.16CA showed the potential to inhibit additional pathogens as Alternaria sp., Phytophthora capsici, Colletotrichum sp. and Rhizoctonia sp. with percentages ranging from 47 to 90 %. This study identified a streptomycete strain with a broad antagonist activity that could be used for biocontrol of plant pathogenic fungi.

  7. Nonribosomal peptides, key biocontrol components for Pseudomonas fluorescens In5, isolated from a Greenlandic suppressive soil.

    Science.gov (United States)

    Michelsen, Charlotte F; Watrous, Jeramie; Glaring, Mikkel A; Kersten, Roland; Koyama, Nobuhiro; Dorrestein, Pieter C; Stougaard, Peter

    2015-03-17

    Potatoes are cultivated in southwest Greenland without the use of pesticides and with limited crop rotation. Despite the fact that plant-pathogenic fungi are present, no severe-disease outbreaks have yet been observed. In this report, we document that a potato soil at Inneruulalik in southern Greenland is suppressive against Rhizoctonia solani Ag3 and uncover the suppressive antifungal mechanism of a highly potent biocontrol bacterium, Pseudomonas fluorescens In5, isolated from the suppressive potato soil. A combination of molecular genetics, genomics, and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) imaging mass spectrometry (IMS) revealed an antifungal genomic island in P. fluorescens In5 encoding two nonribosomal peptides, nunamycin and nunapeptin, which are key components for the biocontrol activity by strain In5 in vitro and in soil microcosm experiments. Furthermore, complex microbial behaviors were highlighted. Whereas nunamycin was demonstrated to inhibit the mycelial growth of R. solani Ag3, but not that of Pythium aphanidermatum, nunapeptin instead inhibited P. aphanidermatum but not R. solani Ag3. Moreover, the synthesis of nunamycin by P. fluorescens In5 was inhibited in the presence of P. aphanidermatum. Further characterization of the two peptides revealed nunamycin to be a monochlorinated 9-amino-acid cyclic lipopeptide with similarity to members of the syringomycin group, whereas nunapeptin was a 22-amino-acid cyclic lipopeptide with similarity to corpeptin and syringopeptin. Crop rotation and systematic pest management are used to only a limited extent in Greenlandic potato farming. Nonetheless, although plant-pathogenic fungi are present in the soil, the farmers do not experience major plant disease outbreaks. Here, we show that a Greenlandic potato soil is suppressive against Rhizoctonia solani, and we unravel the key biocontrol components for Pseudomonas fluorescens In5, one of the potent biocontrol bacteria

  8. Transcriptional and Antagonistic Responses of Biocontrol Strain Lysobacter enzymogenes OH11 to the Plant Pathogenic Oomycete Pythium aphanidermatum

    Directory of Open Access Journals (Sweden)

    Yangyang Zhao

    2017-06-01

    Full Text Available Lysobacter enzymogenes is a ubiquitous, beneficial, plant-associated bacterium emerging as a novel biological control agent. It has the potential to become a new source of antimicrobial secondary metabolites such as the Heat-Stable Antifungal Factor (HSAF, which is a broad-spectrum antimycotic with a novel mode of action. However, very little information about how L. enzymogenes detects and responds to fungi or oomycetes has been reported. An in vitro confrontation bioassay between the pathogenic oomycete Pythium aphanidermatum and the biocontrol bacterial strain L. enzymogenes OH11 was used to analyze the transcriptional changes in the bacteria that were induced by the oomycetes. Analysis was performed at three time points of the interaction, starting before inhibition zone formation until inhibition zone formation. A L. enzymogenes OH11 DNA microarray was constructed for the analysis. Microarray analysis indicated that a wide range of genes belonging to 14 diverse functions in L. enzymogenes were affected by P. aphanidermatum as critical antagonistic effects occurred. L. enzymogenes detected and responded to the presence of P. aphanidermatum early, but alteration of gene expression typically occurred after inhibition zone formation. The presence of P. aphanidermatum increased the twitching motility and HSAF production in L. enzymogenes. We also performed a contact interaction between L. enzymogenes and P. aphanidermatum, and found that HSAF played a critical role in the interaction. Our experiments demonstrated that L. enzymogenes displayed transcriptional and antagonistic responses to P. aphanidermatum in order to gain advantages in the competition with this oomycete. This study revealed new insights into the interactions between bacteria and oomycete.

  9. Fungal endophytes of turmeric (Curcuma longa L.) and their biocontrol potential against pathogens Pythium aphanidermatum and Rhizoctonia solani.

    Science.gov (United States)

    Vinayarani, G; Prakash, H S

    2018-03-14

    Endophytic fungi have been isolated from the healthy turmeric (Curcuma longa L.) rhizomes from South India. Thirty-one endophytes were identified based on morphological and ITS-rDNA sequence analysis. The isolated endophytes were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric respectively. Results revealed that only six endophytes showed > 70% suppression of test pathogens in antagonistic dual culture assays. The endophyte T. harzianum TharDOB-31 showed significant in vitro mycelial growth inhibition of P. aphanidermatum (76.0%) and R. solani (76.9%) when tested by dual culture method. The SEM studies of interaction zone showed morphological abnormalities like parasitism, shriveling, breakage and lysis of hyphae of the pathogens by endophyte TharDOB-31. Selected endophytic isolates recorded multiple plant growth promoting traits in in vitro studies. The rhizome bacterization followed by soil application of endophyte TharDOB-31 showed lowest Percent Disease Incidence of rhizome rot and leaf blight, 13.8 and 11.6% respectively. The treatment of TharDOB-31 exhibited significant increase in plant height (85 cm) and fresh rhizome yield/plant (425 g) in comparison with untreated control under greenhouse condition. The confocal microscopy validates the colonization of the TharDOB-31 in turmeric rhizomes. The secondary metabolites in ethyl acetate extract of TharDOB-31 were found to contain higher number of antifungal compounds by high resolution liquid chromatograph mass spectrometer analysis. Thereby, endophyte T. harzianum isolate can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

  10. DNA polymorphisms and biocontrol of Bacillus antagonistic to citrus bacterial canker with indication of the interference of phyllosphere biofilms.

    Directory of Open Access Journals (Sweden)

    Tzu-Pi Huang

    Full Text Available Citrus bacterial canker caused by Xanthomonas axonopodis pv. citri is a devastating disease resulting in significant crop losses in various citrus cultivars worldwide. A biocontrol agent has not been recommended for this disease. To explore the potential of bacilli native to Taiwan to control this disease, Bacillus species with a broad spectrum of antagonistic activity against various phytopathogens were isolated from plant potting mixes, organic compost and the rhizosphere soil. Seven strains TKS1-1, OF3-16, SP4-17, HSP1, WG6-14, TLB7-7, and WP8-12 showing superior antagonistic activity were chosen for biopesticide development. The genetic identity based on 16S rDNA sequences indicated that all seven native strains were close relatives of the B. subtilis group and appeared to be discrete from the B. cereus group. DNA polymorphisms in strains WG6-14, SP4-17, TKS1-1, and WP8-12, as revealed by repetitive sequence-based PCR with the BOXA1R primers were similar to each other, but different from those of the respective Bacillus type strains. However, molecular typing of the strains using either tDNA-intergenic spacer regions or 16S-23S intergenic transcribed spacer regions was unable to differentiate the strains at the species level. Strains TKS1-1 and WG6-14 attenuated symptom development of citrus bacterial canker, which was found to be correlated with a reduction in colonization and biofilm formation by X. axonopodis pv. citri on leaf surfaces. The application of a Bacillus strain TKS1-1 endospore formulation to the leaf surfaces of citrus reduced the incidence of citrus bacterial canker and could prevent development of the disease.

  11. Fengycin produced by Bacillus subtilis 9407 plays a major role in the biocontrol of apple ring rot disease.

    Science.gov (United States)

    Fan, Haiyan; Ru, Jinjiang; Zhang, Yuanyuan; Wang, Qi; Li, Yan

    2017-06-01

    Apple ring rot, caused by Botryosphaeria dothidea, is a serious apple disease in China. Bacillus subtilis 9407 was isolated from healthy apples and showed strong antifungal activity against B. dothidea. To identify the primary antifungal compound of B. subtilis 9407 and determine its role in controlling apple ring rot, a transposon mutant library was constructed using TnYLB-1, and a mutant completely defective in antifungal activity was obtained. The gene inactivated in the antifungal activity mutant had 98.5% similarity to ppsB in B. subtilis subsp. subtilis str. 168, which encodes one of the five synthetases responsible for synthesizing fengycin. A markerless ppsB deletion mutant was constructed. Compared with the wild-type strain, lipopeptide crude extracts from ΔppsB showed almost no inhibition of B. dothidea mycelial growth. Furthermore, fengycin-like lipopeptides (retention factor 0.1-0.2) that exhibited antifungal activity against B. dothidea were observed in the wild-type strain by thin-layer chromatography (TLC)-bioautography analysis, but not in ΔppsB. Semipreparative reverse-phase high performance liquid chromatography (RP-HPLC) detection revealed that ΔppsB lost the ability to synthesize fengycin. These results suggest that ppsB is responsible for synthesizing fengycin and that fengycin is the major antifungal compound produced by B. subtilis 9407 against B. dothidea. Moreover, a biocontrol assay showed that the control efficacy of ΔppsB was reduced by half compared with the wild-type strain, indicating that fengycin plays a major role in controlling apple ring rot disease. This is the first report on the use of a B. subtilis strain as a potential biological control agent to control apple ring rot disease by the production of fengycin. Copyright © 2017 Elsevier GmbH. All rights reserved.

  12. Evaluation of the biocontrol efficacy of a Serratia marcescens strain indigenous to tea rhizosphere for the management of root rot disease in tea.

    Science.gov (United States)

    Dhar Purkayastha, Gargee; Mangar, Preeti; Saha, Aniruddha; Saha, Dipanwita

    2018-01-01

    The aim of the present study is to evaluate plant growth promoting and biocontrol efficacy of a Serratia marcescens strain ETR17 isolated from tea rhizosphere for the effective management of root rot disease in tea. Isolated bacterial culture ETR17 showed significant level of in vitro antagonism against nine different foliar and root pathogens of tea. The phenotypic and molecular characterization of ETR17 revealed the identity of the bacterium as Serratia marcescens. The bacterium was found to produce several hydrolytic enzymes like chitinase, protease, lipase, cellulase and plant growth promoting metabolites like IAA and siderophore. Scanning electron microscopic studies on the interaction zone between pathogen and antagonistic bacterial isolate revealed severe deformities in the fungal mycelia. Spectral analyses (LC-ESI-MS, UV-VIS spectrophotometry and HPLC) and TLC indicated the presence of the antibiotics pyrrolnitrin and prodigiosin in the extracellular bacterial culture extracts. Biofilm formation by ETR17 on polystyrene surface was also observed. In vivo application of talc-based formulations prepared with the isolate ETR17 in tea plantlets under green house conditions revealed effective reduction of root-rot disease as well as plant growth promotion to a considerable extent. Viability studies with the ETR17 talc formulation showed the survivability of the isolate up to six months at room temperature. The sustenance of ETR17 (concentration of 8-9x108 cfu g-1) in the soil after the application of talc formulation was recorded by ELISA. Safety studies revealed that ETR17 did not produce hemolysin as observed in pathogenic Serratia strains. The biocontrol strain reported in this study can be used for field application in order to minimize the use of chemical fungicides for disease control in tea gardens.

  13. Evaluation of the biocontrol efficacy of a Serratia marcescens strain indigenous to tea rhizosphere for the management of root rot disease in tea.

    Directory of Open Access Journals (Sweden)

    Gargee Dhar Purkayastha

    Full Text Available The aim of the present study is to evaluate plant growth promoting and biocontrol efficacy of a Serratia marcescens strain ETR17 isolated from tea rhizosphere for the effective management of root rot disease in tea. Isolated bacterial culture ETR17 showed significant level of in vitro antagonism against nine different foliar and root pathogens of tea. The phenotypic and molecular characterization of ETR17 revealed the identity of the bacterium as Serratia marcescens. The bacterium was found to produce several hydrolytic enzymes like chitinase, protease, lipase, cellulase and plant growth promoting metabolites like IAA and siderophore. Scanning electron microscopic studies on the interaction zone between pathogen and antagonistic bacterial isolate revealed severe deformities in the fungal mycelia. Spectral analyses (LC-ESI-MS, UV-VIS spectrophotometry and HPLC and TLC indicated the presence of the antibiotics pyrrolnitrin and prodigiosin in the extracellular bacterial culture extracts. Biofilm formation by ETR17 on polystyrene surface was also observed. In vivo application of talc-based formulations prepared with the isolate ETR17 in tea plantlets under green house conditions revealed effective reduction of root-rot disease as well as plant growth promotion to a considerable extent. Viability studies with the ETR17 talc formulation showed the survivability of the isolate up to six months at room temperature. The sustenance of ETR17 (concentration of 8-9x108 cfu g-1 in the soil after the application of talc formulation was recorded by ELISA. Safety studies revealed that ETR17 did not produce hemolysin as observed in pathogenic Serratia strains. The biocontrol strain reported in this study can be used for field application in order to minimize the use of chemical fungicides for disease control in tea gardens.

  14. Evaluation of the biocontrol efficacy of a Serratia marcescens strain indigenous to tea rhizosphere for the management of root rot disease in tea

    Science.gov (United States)

    Mangar, Preeti; Saha, Aniruddha

    2018-01-01

    The aim of the present study is to evaluate plant growth promoting and biocontrol efficacy of a Serratia marcescens strain ETR17 isolated from tea rhizosphere for the effective management of root rot disease in tea. Isolated bacterial culture ETR17 showed significant level of in vitro antagonism against nine different foliar and root pathogens of tea. The phenotypic and molecular characterization of ETR17 revealed the identity of the bacterium as Serratia marcescens. The bacterium was found to produce several hydrolytic enzymes like chitinase, protease, lipase, cellulase and plant growth promoting metabolites like IAA and siderophore. Scanning electron microscopic studies on the interaction zone between pathogen and antagonistic bacterial isolate revealed severe deformities in the fungal mycelia. Spectral analyses (LC-ESI-MS, UV-VIS spectrophotometry and HPLC) and TLC indicated the presence of the antibiotics pyrrolnitrin and prodigiosin in the extracellular bacterial culture extracts. Biofilm formation by ETR17 on polystyrene surface was also observed. In vivo application of talc-based formulations prepared with the isolate ETR17 in tea plantlets under green house conditions revealed effective reduction of root-rot disease as well as plant growth promotion to a considerable extent. Viability studies with the ETR17 talc formulation showed the survivability of the isolate up to six months at room temperature. The sustenance of ETR17 (concentration of 8-9x108 cfu g-1) in the soil after the application of talc formulation was recorded by ELISA. Safety studies revealed that ETR17 did not produce hemolysin as observed in pathogenic Serratia strains. The biocontrol strain reported in this study can be used for field application in order to minimize the use of chemical fungicides for disease control in tea gardens. PMID:29466418

  15. Biocontrol activity of a cold-adapted yeast from Tibet against gray mold in cherry tomato and its action mechanism.

    Science.gov (United States)

    Hu, Hao; Wisniewski, Michael E; Abdelfattah, Ahmed; Zheng, Xiaodong

    2017-07-01

    Cold-adapted biocontrol yeast was selected from four yeast isolates from Tibet against gray mold of cherry tomato in cold storage. The strain numbered LB2 showed the best biocontrol activity and identified as Cryptococcus laurentii. Competition for nutrient, space, and induced fruit resistance was also its antagonistic mechanism. Compared with C. laurentii from sea-level place, the reason why LB2 had a better biocontrol activity was studied. More trehalose and proline in cell of LB2 made it exhibit a better cellular activity at low temperature, such as higher population dynamics in the wounds of cherry tomato and more biocontrol-related enzyme secretion, chitinase and β-glucanase. The better oxidative stress tolerance was another characteristic of LB2. Maybe because of the ideal culture condition, there was no obvious difference between these two yeasts in the growth in vitro test at low temperature. Although the same phenomenon existed in the low pH stress test, LB2 still had higher cell concentration under this stress. Comparative transcriptomics method was also applied to analyze the cell activity of LB2 and C. laurentii at different temperatures. The results showed that more active response in the intracellular structure and intracellular metabolic process to cold temperature made LB2 had a better activity. The present study indicated a possibility to select cold-adapted biocontrol yeast from Tibet and also showed its primary action mechanism.

  16. Antibiotic Agents

    Science.gov (United States)

    ... Superbugs and Drugs" Home | Contact Us General Background: Antibiotic Agents What is an antibacterial and how are ... with the growth and reproduction of bacteria. While antibiotics and antibacterials both attack bacteria, these terms have ...

  17. Isolation, identification, and biocontrol of antagonistic bacterium against Botrytis cinerea after tomato harvest

    Directory of Open Access Journals (Sweden)

    Jun-Feng Shi

    Full Text Available ABSTRACT Tomato is one of the most important vegetables in the world. Decay after harvest is a major issue in the development of tomato industry. Currently, the most effective method for controlling decay after harvest is storage of tomato at low temperature combined with usage of chemical bactericide; however, long-term usage of chemical bactericide not only causes pathogen resistance but also is harmful for human health and environment. Biocontrol method for the management of disease after tomato harvest has great practical significance. In this study, antagonistic bacterium B-6-1 strain was isolated from the surface of tomato and identified as Enterobacter cowanii based on morphological characteristics and physiological and biochemical features combined with sequence analysis of 16SrDNA and ropB gene and construction of dendrogram. Effects of different concentrations of antagonistic bacterium E. cowanii suspension on antifungal activity after tomato harvest were analyzed by mycelium growth rate method. Results revealed that antifungal activity was also enhanced with increasing concentrations of antagonistic bacterium; inhibitory rates of 1 × 105 colony-forming units (cfu/mL antagonistic bacterial solution on Fusarium verticillioides, Alternaria tenuissima, and Botrytis cinerea were 46.31%, 67.48%, and 75.67%, respectively. By using in vivo inoculation method, it was further confirmed that antagonistic bacterium could effectively inhibit the occurrence of B. cinerae after tomato harvest, biocontrol effect of 1 × 109 cfu/mL zymotic fluid reached up to 95.24%, and antagonistic bacterium E. cowanii has biocontrol potential against B. cinerea after harvest of fruits and vegetables.

  18. Characterization of the biocontrol activity of pseudomonas fluorescens strain X reveals novel genes regulated by glucose.

    Directory of Open Access Journals (Sweden)

    Gerasimos F Kremmydas

    Full Text Available Pseudomonas fluorescens strain X, a bacterial isolate from the rhizosphere of bean seedlings, has the ability to suppress damping-off caused by the oomycete Pythium ultimum. To determine the genes controlling the biocontrol activity of strain X, transposon mutagenesis, sequencing and complementation was performed. Results indicate that, biocontrol ability of this isolate is attributed to gcd gene encoding glucose dehydrogenase, genes encoding its co-enzyme pyrroloquinoline quinone (PQQ, and two genes (sup5 and sup6 which seem to be organized in a putative operon. This operon (named supX consists of five genes, one of which encodes a non-ribosomal peptide synthase. A unique binding site for a GntR-type transcriptional factor is localized upstream of the supX putative operon. Synteny comparison of the genes in supX revealed that they are common in the genus Pseudomonas, but with a low degree of similarity. supX shows high similarity only to the mangotoxin operon of Ps. syringae pv. syringae UMAF0158. Quantitative real-time PCR analysis indicated that transcription of supX is strongly reduced in the gcd and PQQ-minus mutants of Ps. fluorescens strain X. On the contrary, transcription of supX in the wild type is enhanced by glucose and transcription levels that appear to be higher during the stationary phase. Gcd, which uses PQQ as a cofactor, catalyses the oxidation of glucose to gluconic acid, which controls the activity of the GntR family of transcriptional factors. The genes in the supX putative operon have not been implicated before in the biocontrol of plant pathogens by pseudomonads. They are involved in the biosynthesis of an antimicrobial compound by Ps. fluorescens strain X and their transcription is controlled by glucose, possibly through the activity of a GntR-type transcriptional factor binding upstream of this putative operon.

  19. Small RNAs regulate the biocontrol property of fluorescent Pseudomonas strain Psd.

    Science.gov (United States)

    Upadhyay, Anamika; Kochar, Mandira; Upadhyay, Ashutosh; Tripathy, Soumya; Rajam, Manchikatla Venkat; Srivastava, Sheela

    2017-03-01

    The production of biocontrol factors by Pseudomonads is reported to be controlled at the post-transcriptional level by the GacS/GacA signal transduction pathway. This involves RNA-binding translational repressor proteins, RsmA and RsmE, and the small regulatory RNAs (sRNAs) RsmX, RsmY, and RsmZ. While the former represses genes involved in secondary metabolite production, the latter relieves this repression at the end of exponential growth. We have studied the fluorescent Pseudomonas strain Psd, possessing good biocontrol potential, and confirmed the presence of rsmY and rsmZ by PCR amplification. Gene constructs for all the three small RNAs (RsmX, RsmY and RsmZ) carried on broad host-range plasmid, pME6032 were mobilized into strain Psd. Expression analysis of gacA in the recombinant strains over-expressing rsmX (Psd-pME7320), rsmY (Psd-pME6359) and rsmZ (Psd-pME6918) revealed a significant upregulation of the response regulator. Besides, a remarkable down-regulation of rsmA was also reported in all the strains. The variant strains were found to produce comparatively higher levels of phenazines. Indole acetic acid levels were higher to some extent, and strain Psd-pME6918 also showed elevated production of HCN. The tomato seedlings infected with Fusarium oxysporum and Verticillium dahliae in the presence of culture filtrate of the recombinant strains showed better plant protection response in comparison to the wild-type strain Psd. These results suggest that small RNAs are important determinants in regulation of the biocontrol property of strain Psd. Copyright © 2016 Elsevier GmbH. All rights reserved.

  20. Extracellular Protease of Pseudomonas fluorescens CHA0, a Biocontrol Factor with Activity against the Root-Knot Nematode Meloidogyne incognita

    Science.gov (United States)

    Siddiqui, Imran Ali; Haas, Dieter; Heeb, Stephan

    2005-01-01

    In Pseudomonas fluorescens CHA0, mutation of the GacA-controlled aprA gene (encoding the major extracellular protease) or the gacA regulatory gene resulted in reduced biocontrol activity against the root-knot nematode Meloidogyne incognita during tomato and soybean infection. Culture supernatants of strain CHA0 inhibited egg hatching and induced mortality of M. incognita juveniles more strongly than did supernatants of aprA and gacA mutants, suggesting that AprA protease contributes to biocontrol. PMID:16151170

  1. Significance of phage-host interactions for biocontrol of Campylobacter jejuni in food

    DEFF Research Database (Denmark)

    Athina, Zampara; Sørensen, Martine Camilla Holst; Elsser-Gravesen, Anne

    2017-01-01

    Poultry meat is the main source of Campylobacter jejuni foodborne disease. Currently, no effective control measures prevent C. jejuni from contaminating poultry meat. However, post-harvest phage treatment is a promising biocontrol strategy that has not yet been explored. Here we identified phages...... most effective phages (F356 showing 0.49 and F357 showing 0.55 log reductions, respectively) led to a 0.73 log reduction of C. jejuni on artificially contaminated chicken skin. Our study shows that poly-phage treatment at 5 °C can be more effective against C. jejuni compared to single phage application...

  2. Biocontrole de Listeria monocytogenes por Pediococcus acidilactici em couve minimamente processada

    OpenAIRE

    Costa,Wanessa Altimiras; Vanetti,Maria Cristina Dantas; Puschamann,Rolf

    2009-01-01

    Este estudo avaliou um sistema de biocontrole para inibição de Listeria monocytogenes em couve minimamente processada, objetivando sua segurança durante estocagem sob refrigeração e em condições de abuso de temperatura. O potencial inibitório de bactérias láticas tolerantes ao sal e psicrotróficas contaminantes naturais da couve e Lactobacillus plantarum, Lactobacillus delbrueckii ATCC 9649 e Lactobacillus casei CCT 1465 foram avaliadas contra L. monocytogenes. O isolado de couve identificado...

  3. Biocontrol of Pectobacterium carotovorum subsp. carotovorum using bacteriophage PP1.

    Science.gov (United States)

    Lim, Jeong-A; Jee, Samnyu; Lee, Dong Hwan; Roh, Eunjung; Jung, Kyusuk; Oh, Changsik; Heu, Sunggi

    2013-08-01

    Pectobacterium carotovorum subsp. carotovorum (formerly Erwinia carotovora subsp. carotovora) is a plant pathogen that causes soft rot and stem rot diseases in several crops, including Chinese cabbage, potato, and tomato. To control this bacterium, we isolated a bacteriophage, PP1, with lytic activity against P. carotovorum subsp. carotovorum. Transmission electron microscopy revealed that the PP1 phage belongs to the Podoviridae family of the order Caudovirales, which exhibit icosahedral heads and short non-contractile tails. PP1 phage showed high specificity for P. carotovorum subsp. carotovorum, and several bacteria belonging to different species and phyla were resistant to PP1. This phage showed rapid and strong lytic activity against its host bacteria in liquid medium and was stable over a broad range of pH values. Disease caused by P. carotovorum subsp. carotovorum was significantly reduced by PP1 treatment. Overall, PP1 bacteriophage effectively controls P. carotovorum subsp. carotovorum.

  4. 3,4-Dihydro-1,3-2H-benzoxazines: Novel reducing agents through one electron donation mechanism and their application as the formation of nano-metallic silver coating

    Energy Technology Data Exchange (ETDEWEB)

    Kaewvilai, Attaphon [Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Wattanathana, Worawat [Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Jongrungruangchok, Suchada [Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Rangsit University, Pathumthani, 12000 (Thailand); Veranitisagul, Chatchai [Department of Material and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Klong 6, Thanyaburi, Pathumthani, 12110 (Thailand); Koonsaeng, Nattamon [Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Laobuthee, Apirat, E-mail: fengapl@ku.ac.th [Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand)

    2015-11-01

    3,4-dihydro-1,3-2H-benzoxazines as novel one-electron donators for silver(I) ion into nano-metallic silver was firstly found and reported. The silver formation from nano-spherical particles to coral-like and dendrite-like structures was presented. With respect to the characterization results, the feasible reaction mechanism of the silver formation was proposed as an electron donated from benzoxazine to silver(I) ion, resulting in a radical cationic species of benzoxazine and silver(0). Based on this reduction process, a new approach for nano-silver coating on various surfaces such as fumed silica (SiO{sub 2}), titanium dioxide (TiO{sub 2}), carbon black (CB), chitosan (CS) including plastic sheet (polycarbonate, PC) and pellet (polyvinyl alcohol, PVA), was also revealed. Besides the nano-silver coated products were applied as antimicrobials fillers for Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 2785 and Candida albicans ATCC 10231. - Highlights: • Benzoxazines were discovered to be novel reducing agents for silver(I) ion. • The speculated mechanism of the one electron donation process was investigated. • Dendrite structure of silver was formed from spherical silver nanoparticles. • A new approach for nano metallic-silver coating on various surfaces was revealed. • The nano-silver coated products were applied as antimicrobials fillers.

  5. 3,4-Dihydro-1,3-2H-benzoxazines: Novel reducing agents through one electron donation mechanism and their application as the formation of nano-metallic silver coating

    International Nuclear Information System (INIS)

    Kaewvilai, Attaphon; Wattanathana, Worawat; Jongrungruangchok, Suchada; Veranitisagul, Chatchai; Koonsaeng, Nattamon; Laobuthee, Apirat

    2015-01-01

    3,4-dihydro-1,3-2H-benzoxazines as novel one-electron donators for silver(I) ion into nano-metallic silver was firstly found and reported. The silver formation from nano-spherical particles to coral-like and dendrite-like structures was presented. With respect to the characterization results, the feasible reaction mechanism of the silver formation was proposed as an electron donated from benzoxazine to silver(I) ion, resulting in a radical cationic species of benzoxazine and silver(0). Based on this reduction process, a new approach for nano-silver coating on various surfaces such as fumed silica (SiO 2 ), titanium dioxide (TiO 2 ), carbon black (CB), chitosan (CS) including plastic sheet (polycarbonate, PC) and pellet (polyvinyl alcohol, PVA), was also revealed. Besides the nano-silver coated products were applied as antimicrobials fillers for Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 2785 and Candida albicans ATCC 10231. - Highlights: • Benzoxazines were discovered to be novel reducing agents for silver(I) ion. • The speculated mechanism of the one electron donation process was investigated. • Dendrite structure of silver was formed from spherical silver nanoparticles. • A new approach for nano metallic-silver coating on various surfaces was revealed. • The nano-silver coated products were applied as antimicrobials fillers.

  6. Adjuvantes e herbicidas e a infectividade de Fusarium graminearum, agente potencial de biocontrole de Egeria densa e Egeria najas Adjuvants and herbicides and the infectivity of Fusarium graminearum, a potential biocontrol agent of Egeria densa and Egeria najas

    Directory of Open Access Journals (Sweden)

    C.R. Borges Neto

    2004-03-01

    Full Text Available Foram estudados os efeitos da adição de adjuvantes e a associação com herbicidas na infectividade do fungo dentro do patossistema Fusarium graminearum x Egeria spp. Foram utilizadas plantas sadias de Egeria densa e E. najas inoculadas com uma suspensão de arroz moído colonizado por F. graminearum, na concentração de 0,7 g L-1. Os tubos de ensaio contendo as plantas imersas na referida suspensão foram mantidos em incubadora à temperatura de 25 ºC e fotoperíodo de 12 horas diárias de luz, por oito dias, durante os quais foram avaliados os sintomas nas plantas a cada dois dias e o crescimento destas através do incremento de matéria fresca ao final do experimento. O efeito de 14 adjuvantes e 6 herbicidas, adicionados à suspensão de inóculo, sobre a ação de F. graminearum em E. densa e E. najas foi avaliado. De modo geral, os adjuvantes melhoraram a eficiência do bioerbicida e a associação herbicida + fungo proporcionou maior severidade de doença e controle do crescimento das plantas.The effects of adding adjuvants and their association with herbicides on fungus infectivity were studied in the Fusarium graminearum x Egeria spp. pathosystem. Healthy Egeria densa and E. naja plants were inoculated with suspension of ground rice with F. graminearum, at a concentration of 0.7 g L-1. The assay tubes with the plants immersed in the suspension were kept in the incubator at the temperature of 25 ºC and photoperiod of 12 hours daily, with plant symptoms being evaluated every two hours and plant growth monitored based on fresh matter increase at the end of the experiment. The effect of 14 adjuvants and 6 herbicides added to the inoculum on the action of F. graminearum against E. densa and E. najas was evaluated. In general, the adjuvants improved bioherbicide efficiency and the herbicide + fungus association increased disease severity and plant growth control.

  7. Information brokering agents in intelligent Websites

    NARCIS (Netherlands)

    Jonker, Catholijn M.; Treur, J.

    1999-01-01

    In this paper a generic information broker agent for intelligent Websites is introduced. The agent architecture has been designed using the compositional development method for multi-agent systems Desire. The use of the architecture is illustrated in an Electronic Commerce application for a

  8. Implications of European corn borer, Ostrinia nubilalis, infestation in an Aspergillus flavus-biocontrolled corn agroecosystem.

    Science.gov (United States)

    Mencarelli, Mariangela; Accinelli, Cesare; Vicari, Alberto

    2013-09-01

    A novel biocontrol strategy consisting of field application of bioplastic-based granules inoculated with a non-toxigenic Aspergillus flavus L. strain has recently been shown to be effective for reducing aflatoxin contamination in corn. This study focused on other factors that may affect the feasibility of this biocontrol technique, and more specifically the role of the European corn borer (ECB), Ostrinia nubilalis H., in the dispersal and infestation of A. flavus in corn and its impact on crop yield. In spite of the high percentage of corn ears showing larval feeding damage, ECB-bored kernels accounted for only 3 and 4% in 2009 and 2010 respectively. Most of the damaged kernels were localised in the ear tip or immediately below. More precisely, the average incidence of ECB-bored kernels in the upper end of the ear was 32%. However, less than 5% of kernels from the central body of the ear, which includes the majority of kernels, were injured by ECB. Although ECB larvae showed a high tolerance to aflatoxin B1 and thus had the potential to serve as vectors of the mould, fungal infection of kernels was poorly associated with insect damage. ECB infestation resulted in grain yield losses not exceeding 2.5%. © 2012 Society of Chemical Industry.

  9. Identification and evaluation of potential bio-control fungal endophytes against Ustilagonoidea virens on rice plants.

    Science.gov (United States)

    Andargie, Mebeaselassie; Congyi, Zhu; Yun, Yun; Li, Jianxiong

    2017-06-01

    False smut disease of rice is posing an increasing concern for production, not only because of the hiking epidemic occurrence in rice production, but also because of the challenging specific pathogenesis of the disease. The aim of this work was to evaluate the potential of five fungal endophytes to reduce negative effects of rice false smut fungus (Ustilagonoidea virens) on rice plants, in both the laboratory and greenhouse. Though all the fungal isolates showed the ability to inhibit the growth of U. virens with varying degrees, isolate E337 showed significant antagonistic activity against the pathogenic fungi. The isolate E337 was identified as Antennariella placitae by molecular and morphological data analysis including 18S rDNA sequence analysis. This isolate showed a significant in vitro inhibition of mycelial growth of U. virens by dual culture method and it was subsequently tested for its in vivo biocontrol potential on false smut disease on rice plants. Greenhouse experiments confirmed that applications of conidia of A. placitae protected rice plants by improving rice yield and by decreasing the severity of false smut disease on susceptible rice plants. This is the first report where A. placitae has been identified as a biocontrol organism.

  10. Diversity, Biocontrol, and Plant Growth Promoting Abilities of Xylem Residing Bacteria from Solanaceous Crops

    Directory of Open Access Journals (Sweden)

    Gauri A. Achari

    2014-01-01

    Full Text Available Eggplant (Solanum melongena L. is one of the solanaceous crops of economic and cultural importance and is widely cultivated in the state of Goa, India. Eggplant cultivation is severely affected by bacterial wilt caused by Ralstonia solanacearum that colonizes the xylem tissue. In this study, 167 bacteria were isolated from the xylem of healthy eggplant, chilli, and Solanum torvum Sw. by vacuum infiltration and maceration. Amplified rDNA restriction analysis (ARDRA grouped these xylem residing bacteria (XRB into 38 haplotypes. Twenty-eight strains inhibited growth of R. solanacearum and produced volatile and diffusible antagonistic compounds and plant growth promoting substances in vitro. Antagonistic strains XB86, XB169, XB177, and XB200 recorded a biocontrol efficacy greater than 85% against BW and exhibited 12%–22 % increase in shoot length in eggplant in the greenhouse screening. 16S rRNA based identification revealed the presence of 23 different bacterial genera. XRB with high biocontrol and plant growth promoting activities were identified as strains of Staphylococcus sp., Bacillus sp., Streptomyces sp., Enterobacter sp., and Agrobacterium sp. This study is the first report on identity of bacteria from the xylem of solanaceous crops having traits useful in cultivation of eggplant.

  11. Biocontrol activity of effusol from the extremophile plant, Juncus maritimus, against the wheat pathogen Zymoseptoria tritici.

    Science.gov (United States)

    Sahli, Ramla; Rivière, Céline; Siah, Ali; Smaoui, Abderrazak; Samaillie, Jennifer; Hennebelle, Thierry; Roumy, Vincent; Ksouri, Riadh; Halama, Patrice; Sahpaz, Sevser

    2017-05-08

    Zymoseptoria tritici, responsible for Septoria tritici blotch, is the most important pathogen of wheat. The control of this parasite relies mainly on synthetic fungicides, but their use is increasingly controversial and searching for alternative management strategies is encouraged. In this context, the biocontrol potential of crude methanolic extracts of eight extremophile plant species from Tunisia, including three xerophytes and five halophytes, against Z. tritici was assessed. Only the extract of Juncus maritimus rhizomes showed significant in vitro antifungal activity. In extremophile plants, the production of secondary metabolites is often influenced by abiotic conditions. Thus, we collected several samples of J. maritimus rhizomes at different vegetative stages, at different periods, and from different substrates to compare their antifungal activities. Our results suggest that the plant environment, especially the substrate of the soil, should be taken into account to identify great sources of natural antifungal products. From the most active sample, a 9,10-dehydrophenanthrene derivative, effusol, absent from other J. maritimus rhizomes extracts, was purified. This product showed a strong antifungal activity against the pathogen, with a minimal inhibitory concentration of 19 μg mL -1 and an half-maximal inhibitory concentration of 9.98 μg mL -1 . This phenanthrene derivative could be a promising biocontrol molecule against Z. tritici.

  12. Biocontrol of the wheat pathogen Zymoseptoria tritici using cyclic lipopeptides from Bacillus subtilis.

    Science.gov (United States)

    Mejri, Samara; Siah, Ali; Coutte, François; Magnin-Robert, Maryline; Randoux, Béatrice; Tisserant, Benoit; Krier, François; Jacques, Philippe; Reignault, Philippe; Halama, Patrice

    2017-06-21

    Innovation toward ecofriendly plant protection products compatible with sustainable agriculture and healthy food is today strongly encouraged. Here, we assessed the biocontrol activity of three cyclic lipopeptides from Bacillus subtilis (mycosubtilin, M; surfactin, S; fengycin, F) and two mixtures (M + S and M + S + F) on wheat against Zymoseptoria tritici, the main pathogen on this crop. Foliar application of these biomolecules at a 100-mg L -1 concentration on the wheat cultivars Dinosor and Alixan, 2 days before fungal inoculation, provided significant reductions of disease severity. The best protection levels were recorded with the M-containing formulations (up to 82% disease reduction with M + S on Dinosor), while S and F treatments resulted in lower but significant disease reductions. In vitro and in planta investigations revealed that M-based formulations inhibit fungal growth, with half-maximal inhibitory concentrations of 1.4 mg L -1 for both M and M + S and 4.5 mg L -1 for M + S + F, thus revealing that the observed efficacy of these products may rely mainly on antifungal property. By contrast, S and F had no direct activity on the pathogen, hence suggesting that these lipopeptides act on wheat against Z. tritici as resistance inducers rather than as biofungicides. This study highlighted the efficacy of several lipopeptides from B. subtilis to biocontrol Z. tritici through likely distinct and biomolecule-dependent modes of action.

  13. Nonribosomal peptides and polyketides of Burkholderia: new compounds potentially implicated in biocontrol and pharmaceuticals.

    Science.gov (United States)

    Esmaeel, Qassim; Pupin, Maude; Jacques, Philippe; Leclère, Valérie

    2017-05-25

    Bacteria belonging to the genus Burkholderia live in various ecological niches and present a significant role in the environments through the excretion of a wide variety of secondary metabolites including modular nonribosomal peptides (NRPs) and polyketides (PKs). These metabolites represent a widely distributed biomedically and biocontrol important class of natural products including antibiotics, siderophores, and anticancers as well as biopesticides that are considered as a novel source that can be used to defend ecological niche from competitors and to promote plant growth. The aim of this review is to present all NRPs produced or potentially produced by strains of Burkholderia, as NRPs represent a major source of active compounds implicated in biocontrol. The review is a compilation of results from a large screening we have performed on 48 complete sequenced genomes available in NCBI to identify NRPS gene clusters, and data found in the literature mainly because some interesting compounds are produced by strains not yet sequenced. In addition to NRPs, hybrids NRPs/PKs are also included. Specific features about biosynthetic gene clusters and structures of the modular enzymes responsible for the synthesis, the biological activities, and the potential uses in agriculture and pharmaceutical of NRPs and hybrids NRPs/PKs will also be discussed.

  14. SCREENING OF FLUORESCENT RHIZOBACTERIA FOR THE BIOCONTROL OF SOILBORNE PLANT PATHOGENIC FUNGI

    Directory of Open Access Journals (Sweden)

    ANELISE DIAS

    2014-01-01

    Full Text Available The biocontrol of soilborne plant pathogens represents a promising approach from the environ- mental and practical points of view. Fluorescent pseudomonad rhizobacteria are well known by their antagonis- tic capacity towards several plant pathogens due to a diversity of antimicrobial metabolites they produce. This study was conceived to select and characterize rhizobacteria having antagonistic potential towards the patho- genic fungi Rhizoctonia solani and Sclerotium rolfsii. A total of 94 bacterial strains isolated from the rhizospheres of four vegetable species under organic cultivation were evaluated. Twenty-two strains which predominate in lettuce and rudbeckia rhizospheres showed identical biochemical profiles to Pseudomonas fluo- rescens, while in kale and parsley rhizospheres identical profiles to Pseudomonas putida (subgroups A and B strains prevailed. Two types of antagonism were verified in vitro and defined as competition and inhibition of mycelial growth. Sixty percent of the evaluated strains showed antagonistic potential and, among those, 24 strains expressed antagonism to both target fungi, with P. fluorescens being the most representative bacterial species. This work clearly identified a number of strains with potential for use as plant growth-promoting and biocontrol of the two soilborne fungal pathogens in vegetable crops production systems.

  15. Identification of a novel fungus, Trichoderma asperellum GDFS1009, and comprehensive evaluation of its biocontrol efficacy.

    Science.gov (United States)

    Wu, Qiong; Sun, Ruiyan; Ni, Mi; Yu, Jia; Li, Yaqian; Yu, Chuanjin; Dou, Kai; Ren, Jianhong; Chen, Jie

    2017-01-01

    Due to its efficient broad-spectrum antimicrobial activity, Trichoderma has been established as an internationally recognized biocontrol fungus. In this study, we found and identified a novel strain of Trichoderma asperellum, named GDFS1009. The mycelium of T. asperellum GDFS1009 exhibits a high growth rate, high sporulation capacity, and strong inhibitory effects against pathogens that cause cucumber fusarium wilt and corn stalk rot. T. asperellum GDFS1009 secretes chitinase, glucanase, and protease, which can degrade the cell walls of fungi and contribute to mycoparasitism. The secreted xylanases are good candidates for inducing plant resistance and enhancing plant immunity against pathogens. RNA sequencing (RNA-seq) and gas chromatography-mass spectrometry (GC-MS) showed that T. asperellum GDFS1009 produces primary metabolites that are precursors of antimicrobial compounds; it also produces a variety of antimicrobial secondary metabolites, including polyketides and alkanes. In addition, this study speculated the presence of six antimicrobial peptides via ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-QTOF-MS/MS). Future studies should focus on these antimicrobial metabolites for facilitating widespread application in the field of agricultural bio-control.

  16. Lower resistance and higher tolerance of invasive host plants: biocontrol agents reach high densities but exert weak control

    Science.gov (United States)

    1. Invasive plants often have novel biotic interactions in their introduced ranges. Changes in herbivore defense traits are important for the effectiveness of biological control, because insect natural enemies may rapidly build up their populations on invasive plants due to decreased resistance but...

  17. Development of Colletotrichum gloeosporioides Restriction Enzyme-Mediated Integration Mutants as Biocontrol Agents Against Anthracnose Disease in Avocado Fruits.

    Science.gov (United States)

    Yakoby, N; Zhou, R; Kobiler, I; Dinoor, A; Prusky, D

    2001-02-01

    ABSTRACT Reduced-pathogenicity mutants of the avocado fruit pathogen Colletotrichum gloeosporioides isolate Cg-14 (teleomorph: Glomerella cingulata) were generated by insertional mutagenesis by restriction enzyme-mediated integration (REMI) transformation. Following seven transformations, 3,500 hygromycin-resistant isolates were subjected to a virulence assay by inoculation on mesocarp and pericarp of cv. Fuerte avocado fruits. Fourteen isolates showed a reduced degree of virulence relative compared with wild-type Cg-14. Two isolates, Cg-M-142 and Cg-M-1150, were further characterized. Cg-M-142 produced appressoria on avocado pericarp similar to Cg-14, but caused reduced symptom development on the fruit's pericarp and mesocarp. Isolate Cg-M-1150 did not produce appressoria; it caused much reduced maceration on the mesocarp and no symptoms on the pericarp. Southern blot analysis of Cg-M-142 and Cg-M-1150 showed REMI at different XbaI sites of the fungal genome. Pre-inoculation of avocado fruit with Cg-M-142 delayed symptom development by the wild-type isolate. Induced resistance was accompanied by an increase in the levels of preformed antifungal diene, from 760 to 1,200 mug/g fresh weight 9 days after inoculation, whereas pre-inoculation with Cg-M-1150 did not affect the level of antifungal diene, nor did it delay the appearance of decay symptoms. The results presented here show that reduced-pathogenicity isolates can be used for the biological control of anthracnose caused by C. gloeosporioides attack.

  18. Ecohydrology of saltcedar (Tamarix spp.) in the western United States and implications of water balance following a biocontrol agent introduction

    Science.gov (United States)

    Nagler, P. L.; Glenn, E. P.

    2012-12-01

    With increased demand on water sources for human use and likely diminished supplies due to climate change, it is important to understand the variation in evapotranspiration (ET) and vegetation water use by transpiration (T) in arid and semi-arid zone riparian areas in the western U.S. Understanding riparian plant water use is critical for accuracy of climate models, predictions used in water resources management, and assessment of land use change impacts on the water balance of ecosystems. Moore and Heilman (2011) suggested the following three principles for predicting when vegetation changes will impact the local or regional water budget: (i) variation will result if energy balance partitioning has been altered, (ii) if deeper or shallower active rooting depth has changed the amount of soil moisture accessible to plants, or (iii) if temporary changes in water use add up over longer time scales. They note that large changes in vegetation types do not necessarily result in changes in water discharge. We will use these principles to consider the case of saltcedar (Tamarix spp.) on western U.S. rivers. Once considered a high-water-use plant that out-competed native trees, research over the past two decades has shown that saltcedar water use is low to moderate, and less than native trees. Consequently, the prospects of salvaging water for human use by replacing saltcedar with native trees, once thought to be bright, now appear questionable. Furthermore, saltcedar has come to occupy ecohydrological niches on altered river systems that are no longer available to native plants. However, with the widespread introduction and spread of saltcedar leaf beetles (Diorhabda carinulata) on western rivers, introduced in part to reduce riparian water use through reduction of saltcedar abundance, saltcedar ecology has now entered a new phase. The talk will present a synthesis of the recent literature on saltcedar water use and provide an overview of saltcedar ecohydrology in terms of the principles set forth in Moore and Heilman for determining when vegetation changes will lead to changes in the local water balance. Such an analysis is needed to develop adaptive management practices for maintaining riparian ecological values while providing water for human and ecosystem needs over the next 50 years. So far, none of the three principles for change in the riparian water balance through reduction of saltcedar cover has been fulfilled, and riparian water use is relatively unchanged following introduction of saltcedar leaf beetles.

  19. Optimized fluorescent proteins for the rhizosphere-associated bacterium Bacillus mycoides with endophytic and biocontrol agent potential

    NARCIS (Netherlands)

    Yi, Yanglei; Frenzel, Elrike; Spoelder, Jan; Elzenga, J Theo M; van Elsas, Jan Dirk; Kuipers, Oscar P

    2017-01-01

    Tracking of fluorescent protein (FP)-labeled rhizobacteria is a key prerequisite to gain insights into plant-bacteria interaction mechanisms. However, the performance of FPs mostly has to be optimized for the bacterial host and for the environment of intended application. We report on the

  20. Hot-spot application of biocontrol agents to replace pesticides in large scale commercial rose farms in Kenya

    DEFF Research Database (Denmark)

    Gacheri, Catherine; Kigen, Thomas; Sigsgaard, Lene

    2015-01-01

    of the predatory mite Phytoseiulus persimilis (Acari: Phytoseidae) in large commercial rose greenhouses. Hot-spot treatments replaced acaricides except at high infestations and the two treatments were applied in seven greenhouses each. With the conventional treatment, acaricides were applied when T. urticae...

  1. Corynespora cassiicola f. sp. schinii, a potential biocontrol agent for the weed Schinus terebinthifolius in the United States

    Science.gov (United States)

    An isolate of Corynespora cassiicola was found in Brazil (state of Espírito Santo) causing a severe leaf spot and foliage blight on Schinus terebinthifolius (Anacardiaceae, Brazilian peppertree or ‘aroeira’) which is a major environmental weed in many tropical and sub-tropical areas of the globe, in...

  2. Microbial synthesis of chitinase in solid cultures and its potential as a biocontrol agent against phytopathogenic fungus Colletotrichum gloeosporioides.

    Science.gov (United States)

    Sandhya, Chandran; Binod, Parameswaran; Nampoothiri, K Madhavan; Szakacs, George; Pandey, Ashok

    2005-10-01

    Antifungal activity of chitinase can be effectively utilized in biologic pest control strategies. Because solid-state cultivation has been termed a cost-effective means for fungal growth and metabolite production, chitinase production by Trichoderma harzianum was studied using wheat bran-based solid medium containing 1% colloidal chitin. Chitinase synthesis was found to be growth associated because maximum enzyme (5.4 U/g of dry substrate) and biomass production occurred at 72 h. Substrate moisture had a critical impact on chitinase production; five grams of medium having an initial moisture content of 68.4% when incubated for 72 h increased the enzyme yield to 9.3 U/g of dry substrate. Optimization of colloidal chitin concentration showed that improvements in chitinase yield and maximum activity were attained with a 2% (w/w) concentration. Supplementation of additional nitrogen sources also influenced enzyme production, and the best yield was obtained with yeast extract. The effect of crude chitinase on hyphal morphology of the phytopathogenic fungus Colletotrichum gloeosporioides was swelling as well as lysis of hyphal wall, depending on the age of the mycelium. Studies of pH and thermal stability showed that crude culture filtrate was active over pH 4.0-6.0 and retained about 48.2% activity after 40 min of incubation at 40 degrees C.

  3. Biology and host preferences of Cryptorhynchus melastomae (Coleoptera: Curculionidae), a possible biocontrol agent for Miconia calvescens (Melastomataceae) in Hawaii

    Science.gov (United States)

    E. Reichert; M.T. Johnson; E. Chacon; R.S. Anderson; T.A. Wheeler

    2010-01-01

    The introduced plant Miconia calvescens (Melastomataceae) poses a grave threat to Hawaii's native ecosystems and biodiversity. One potential candidate for classical biological control is Cryptorhynchus melastomae (Coleoptera: Curculionidae: Cryptorhynchinae), a stem-boring weevil from Central and South America. This weevil...

  4. Potential for using Verticillium albo-atrum as a biocontrol agent for tree-of-heaven (Ailanthus altissima)

    Science.gov (United States)

    Donald D. Davis; Matthew Kasson; Mark. Schall

    2011-01-01

    Extensive, unprecedented wilt and mortality of the highly invasive, exotic tree-of-heaven (Ailanthus altissima) occurred recently within mixed hardwood forests in south-central Pennsylvania. Until this study, the cause of the epidemic was unknown.

  5. Effect of fungicides and biocontrol agents on inoculum production and persistence of Phytophthora ramorum on nursery hosts

    Science.gov (United States)

    Steve Tjosvold; David Chambers; Gary Chastagner; Marianne. Elliott

    2013-01-01

    Once Phytophthora ramorum is introduced into a nursery on a host, its local spread and establishment is primarily dependent on sporangia and zoospore production. Nursery operators commonly use fungicides to prevent the establishment of Phytophthora –caused diseases, although current research only supports the use of fungicides...

  6. The Use of Megamelus scutellaris Berg in the Southern United States as a Biocontrol Agent of Waterhyacinth (Eichhornia crassipes (Mart.))

    Science.gov (United States)

    2014-07-01

    flooded rice ( Oryza sativa ) and wild rice (Zizania spp.) to control several pest species, including rice weevils. ERDC/TN APCRP-BC-33 July 2014 7...multiple life stages (adult and various nymph instars). This information was combined with visual assessments of general condition of the

  7. Microflora of Meloidogyne egg masses: species composition, population density and effect on the biocontrol agent Verticillium chlamudosporium (Goddard)

    NARCIS (Netherlands)

    Kok, C.J.; Papert, A.; Hok-A-Hin, C.H.

    2001-01-01

    Egg masses of Meloidogyne fallax from tomato and potato growing in soil from a nematode suppressive and a nonsuppressive field sustained bacterial population densities two to three orders of magnitude higher than those of the rhizosphere soil. BIOLOG metabolic profiling identified 16 bacterial

  8. Survival of Pantoea agglomerans E325 as fire blight biocontrol agent when osmoadapted in high-saline medium

    Science.gov (United States)

    Pantoea agglomerans strain E325 is available commercially as the active ingredient in a freeze-dried product (Bloomtime FDTM) of Northwest Agricultural Products (NAP) for biological control of fire blight. Osmoadaptation, which involves the combination of Pantoea agglomerans strain E325 is available...

  9. Effects of compost amendment and the biocontrol agent Clonostachys rosea on the development of charcoal rot (Macrophomina phaseolina) on cowpea

    NARCIS (Netherlands)

    Ndiaye, M.; Termorshuizen, A.J.; Bruggen, van A.H.C.

    2010-01-01

    Macrophomina phaseolina is a destructive pathogen causing charcoal rot of cowpea and other crops in the semi- arid areas of the Sahel (north-west Africa). Chemical management is not feasible in conditions of subsistence farming, and the plurivorous nature of the fungus limits the effectiveness of

  10. Abrostola clarissa (Lepidoptera, Noctuidae), a new potential biocontrol agent for invasive swallow-worts, Vincetoxicum rossicum and V. nigrum

    Science.gov (United States)

    Pale and black swallow-worts (Vincetoxicum rossicum and V. nigrum; Apocynaceae, subfamily Asclepiadoideae), perennial vines native to Eurasia, are now invading natural and anthropogenic habitats in the northeastern U.S.A. and southeastern Canada, threatening natural biodiversity and increasing contr...

  11. The tick biocontrol agent Metarhizium brunneum (= M. anisopliae) (strain F52) does not reduce non-target arthropods

    Science.gov (United States)

    Keesing, Felicia; Ostfeld, Richard S.

    2017-01-01

    Previous studies have found that Met52®, which contains the entomopathogenic fungus Metarhizium brunneum, is effective in reducing the abundance of Ixodes scapularis, the tick vector for the bacterium causing Lyme disease and for other tick-borne pathogens. Given widespread interest in effective, safe methods for controlling ticks, Met52 has the potential to be used at increasing scales. The non-target impacts of Met52, as applied for tick control, have not yet been assessed. A Before-After-Control-Impact experiment was conducted to assess the effects of Met52 on non-target arthropods in lawn and forest habitats typical of residential yards. Ground-dwelling arthropods were collected using bulk sampling of soil and litter, and pitfall sampling. Arthropods were sampled once before and twice after treatment of plots with either Met52 or water (control). Multivariate general linear models were used to jointly model the abundance of arthropod orders. For each sampling method and post-spray sampling occasion, Akaike Information Criterion values were used to compare the fits of two alternative models: one that included effects of period (before vs. after spray), habitat (lawn vs. forest), and treatment (Met52 vs. control), versus a nested null model that included effects of period, and habitat, but no treatment effect. The null model was consistently better supported by the data. Significant effects were found of period and habitat but not treatment. Retrospective power analysis indicated the study had 80% power to detect a 50% reduction in arthropod abundance, as measured by bulk samples taken before versus one week after treatment. The deployment of Met52 in suburban settings is unlikely to cause meaningful reductions in the abundance of non-target arthropods. PMID:29155838

  12. The tick biocontrol agent Metarhizium brunneum (= M. anisopliae (strain F52 does not reduce non-target arthropods.

    Directory of Open Access Journals (Sweden)

    Ilya R Fischhoff

    Full Text Available Previous studies have found that Met52®, which contains the entomopathogenic fungus Metarhizium brunneum, is effective in reducing the abundance of Ixodes scapularis, the tick vector for the bacterium causing Lyme disease and for other tick-borne pathogens. Given widespread interest in effective, safe methods for controlling ticks, Met52 has the potential to be used at increasing scales. The non-target impacts of Met52, as applied for tick control, have not yet been assessed. A Before-After-Control-Impact experiment was conducted to assess the effects of Met52 on non-target arthropods in lawn and forest habitats typical of residential yards. Ground-dwelling arthropods were collected using bulk sampling of soil and litter, and pitfall sampling. Arthropods were sampled once before and twice after treatment of plots with either Met52 or water (control. Multivariate general linear models were used to jointly model the abundance of arthropod orders. For each sampling method and post-spray sampling occasion, Akaike Information Criterion values were used to compare the fits of two alternative models: one that included effects of period (before vs. after spray, habitat (lawn vs. forest, and treatment (Met52 vs. control, versus a nested null model that included effects of period, and habitat, but no treatment effect. The null model was consistently better supported by the data. Significant effects were found of period and habitat but not treatment. Retrospective power analysis indicated the study had 80% power to detect a 50% reduction in arthropod abundance, as measured by bulk samples taken before versus one week after treatment. The deployment of Met52 in suburban settings is unlikely to cause meaningful reductions in the abundance of non-target arthropods.

  13. The tick biocontrol agent Metarhizium brunneum (= M. anisopliae) (strain F52) does not reduce non-target arthropods.

    Science.gov (United States)

    Fischhoff, Ilya R; Keesing, Felicia; Ostfeld, Richard S

    2017-01-01

    Previous studies have found that Met52®, which contains the entomopathogenic fungus Metarhizium brunneum, is effective in reducing the abundance of Ixodes scapularis, the tick vector for the bacterium causing Lyme disease and for other tick-borne pathogens. Given widespread interest in effective, safe methods for controlling ticks, Met52 has the potential to be used at increasing scales. The non-target impacts of Met52, as applied for tick control, have not yet been assessed. A Before-After-Control-Impact experiment was conducted to assess the effects of Met52 on non-target arthropods in lawn and forest habitats typical of residential yards. Ground-dwelling arthropods were collected using bulk sampling of soil and litter, and pitfall sampling. Arthropods were sampled once before and twice after treatment of plots with either Met52 or water (control). Multivariate general linear models were used to jointly model the abundance of arthropod orders. For each sampling method and post-spray sampling occasion, Akaike Information Criterion values were used to compare the fits of two alternative models: one that included effects of period (before vs. after spray), habitat (lawn vs. forest), and treatment (Met52 vs. control), versus a nested null model that included effects of period, and habitat, but no treatment effect. The null model was consistently better supported by the data. Significant effects were found of period and habitat but not treatment. Retrospective power analysis indicated the study had 80% power to detect a 50% reduction in arthropod abundance, as measured by bulk samples taken before versus one week after treatment. The deployment of Met52 in suburban settings is unlikely to cause meaningful reductions in the abundance of non-target arthropods.

  14. Influence of introduced potential biocontrol agents on maize seedling growth and bacterial community structure in the rhizosphere

    NARCIS (Netherlands)

    Kozdroj, J; Trevors, JT; van Elsas, JD

    2004-01-01

    Two species of Pseudomonas chromosomally tagged with gfp, which had shown antagonistic activity against the tomato pathogen Ralstonia solanacearum in a previous study, were assessed for their impact in the rhizosphere of maize. Plant growth characteristics, numbers of indigenous heterotrophic

  15. Contribution of biocontrol agents to sustainable agriculture: do insights from microbiome research and BCA “omics” pay off

    Science.gov (United States)

    By the year 2050 there will be 9 to 11 billion people on earth to feed using the same amount or less land and water as is currently available for agricultural production. The United Nations estimated that global food production will need to increase by 70% by 2050. Currently, about one-third of all ...

  16. Leaf application of a sprayable bioplastic-based formulation of biocontrol Aspergillus flavus strains for reduction of aflatoxins in corn.

    Science.gov (United States)

    Accinelli, Cesare; Abbas, Hamed K; Vicari, Alberto; Shier, W Thomas

    2016-08-01

    Applying non-aflatoxin-producing Aspergillus flavus isolates to the soil has been shown to be effective in reducing aflatoxin levels in harvested crops, including peanuts, cotton and corn. The aim of this study was to evaluate the possibility of controlling aflatoxin contamination using a novel sprayable formulation consisting of a partially gelatinized starch-based bioplastic dispersion embedded with spores of biocontrol A. flavus strains, which is applied to the leaf surfaces of corn plants. The formulation was shown to be adherent, resulting in colonization of leaf surfaces with the biocontrol strain of A. flavus, and to reduce aflatoxin contamination of harvested kernels by up to 80% in Northern Italy and by up to 89% in the Mississippi Delta. The percentage of aflatoxin-producing isolates in the soil reservoir under leaf-treated corn was not significantly changed, even when the soil was amended with additional A. flavus as a model of changes to the soil reservoir that occur in no-till agriculture. This study indicated that it is not necessary to treat the soil reservoir in order to achieve effective biocontrol of aflatoxin contamination in kernel corn. Spraying this novel bioplastic-based formulation to leaves can be an effective alternative in the biocontrol of A. flavus in corn. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  17. Phytohormone profiles induced by Trichoderma isolates correspond with their biocontrol and plant growth-promoting activity on melon plants

    NARCIS (Netherlands)

    Martínez-Medina, Ainhoa; Del Mar Alguacil, Maria; Pascual, Jose A.; van Wees, Saskia C M

    2014-01-01

    The application of Trichoderma strains with biocontrol and plant growth-promoting capacities to plant substrates can help reduce the input of chemical pesticides and fertilizers in agriculture. Some Trichoderma isolates can directly affect plant pathogens, but they also are known to influence the

  18. Quorum signaling mycotoxins: A new risk strategy for bacterial biocontrol of Fusarium verticillioides and other endophytic fungal species?

    Science.gov (United States)

    Bacterial endophytes are used as biocontrol organisms for plant pathogens such as the maize endophyte Fusarium verticillioides and its production of fumonisin mycotoxins. However, such applications are not always predictable and efficient. All bacteria communicate via cell-dependent signals, which...

  19. Survival of Salmonella enterica on soybean sprouts following treatments with gaseous chlorine dioxide and biocontrol Pseudomonas bacteria

    Science.gov (United States)

    Control of Salmonella enterica on sprouts and minimally processed, ready-to-eat fruits and vegetables is important for food and consumer safety. The aim of this research was to assess the effects of gaseous chlorine dioxide(ClO2)and biocontrol microorganisms (Pseudomonas chlororaphis and P. fluoresc...

  20. Survival of Salmonella Typhimurium on soybean sprouts after treatment with gaseous chlorine dioxide and biocontrol Pseudomonas bacteria

    Science.gov (United States)

    Control of Salmonella Typhimurium on sprouts and minimally processed produce is crucial for food and consumer safety. The aim of this research was to assess natural microflora populations on soybean and evaluate the effects of gaseous chlorine dioxide (ClO2) and biocontrol Pseudomonas on the surviva...

  1. Seasonal variation in the biocontrol efficiency of bacterial wilt is driven by temperature-mediated changes in bacterial competitive interactions

    NARCIS (Netherlands)

    Wei, Zhong; Huang, Jianfeng; Yang, Tianjie|info:eu-repo/dai/nl/413576965; Jousset, Alexandre|info:eu-repo/dai/nl/370632656; Xu, Yangchun; Shen, Qirong; Friman, Ville Petri

    2017-01-01

    Microbe-based biocontrol applications hold the potential to become an efficient way to control plant pathogen disease outbreaks in the future. However, their efficiency is still very variable, which could be due to their sensitivity to the abiotic environmental conditions. Here, we assessed how

  2. Novel components of leaf bacterial communities of field-grown tomato plants and their potential for plant growth promotion and biocontrol of tomato diseases.

    Science.gov (United States)

    Romero, Fernando M; Marina, María; Pieckenstain, Fernando L

    2016-04-01

    This work aimed to characterize potentially endophytic culturable bacteria from leaves of cultivated tomato and analyze their potential for growth promotion and biocontrol of diseases caused by Botrytis cinerea and Pseudomonas syringae. Bacteria were obtained from inner tissues of surface-disinfected tomato leaves of field-grown plants. Analysis of 16S rRNA gene sequences identified bacterial isolates related to Exiguobacterium aurantiacum (isolates BT3 and MT8), Exiguobacterium spp. (isolate GT4), Staphylococcus xylosus (isolate BT5), Pantoea eucalypti (isolate NT6), Bacillus methylotrophicus (isolate MT3), Pseudomonas veronii (isolates BT4 and NT2), Pseudomonas rhodesiae (isolate BT2) and Pseudomonas cichorii (isolate NT3). After seed inoculation, BT2, BT4, MT3, MT8, NT2 and NT6 were re-isolated from leaf extracts. NT2, BT2, MT3 and NT6 inhibited growth of Botrytis cinerea and Pseudomonas syringae pv. tomato in vitro, produced antimicrobial compounds and reduced leaf damage caused by B. cinerea. Some of these isolates also promoted growth of tomato plants, produced siderophores, the auxin indole-3-acetic and solubilized inorganic phosphate. Thus, bacterial communities of leaves from field-grown tomato plants were found to harbor potentially endophytic culturable beneficial bacteria capable of antagonizing pathogenic microorganisms and promoting plant growth, which could be used as biological control agents and biofertilizers/biostimulators for promotion of tomato plant growth. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  3. Bioproduction of hydrolytic enzymes using apple pomace waste by A. niger: applications in biocontrol formulations and hydrolysis of chitin/chitosan.

    Science.gov (United States)

    Dhillon, G S; Brar, S K; Valero, J R; Verma, Mausam

    2011-10-01

    Studies were carried out for β-glucosidase production using apple pomace (AP) in solid-state fermentation using 2(4) factorial design and response surface methodology. The influence of four independent variables including initial moisture level and inducers [veratryl alcohol (VA), lactose (LAC) and copper sulfate (CS)] was studied. The experimental design showed that initial moisture level had significant negative effect on the response. Higher β-glucosidase activity of 64.18 IU/gram fermented substrate (gfs) was achieved in solid-state tray fermentation with optimum conditions having initial moisture level 55% (v/w), pH 4.5, 2 mM/kg VA, 2% (w/w) LAC and 1.5 mM/kg CS concentration, respectively,. The non-specific chitinase 70.28 ± 6.34 IU/gfs and chitosanase activities 60.18 ± 6.82 to 64.20 ± 7.12 IU/gfs were observed. The study demonstrated that AP can be potentially used for the β-glucosidase production by Aspergillus niger. Moreover, β-glucosidase can be used for the hydrolysis of chitin/chitosan to depolymerized products and in the formulation of biocontrol agents for enhanced entomotoxicity levels.

  4. Biocontrol Activity of Volatile-Producing Bacillus megaterium and Pseudomonas protegens against Aspergillus flavus and Aflatoxin Production on Stored Rice Grains

    Science.gov (United States)

    Mannaa, Mohamed; Oh, Ji Yeon

    2017-01-01

    In our previous study, three bacterial strains, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15, were selected as effective biocontrol agents against Aspergillus flavus on stored rice grains. In this study, we evaluated the inhibitory effects of the volatiles produced by the strains on A. flavus growth and aflatoxin production on stored rice grains. The three strains significantly reduced mycelial growth of A. flavus in dual-culture assays compared with the negative control strain, Sphingomonas aquatilis KU408, and an untreated control. Of these tested strains, volatiles produced by B. megaterium KU143 and P. protegens AS15 markedly inhibited mycelial growth, sporulation, and conidial germination of A. flavus on agar medium and suppressed the fungal populations in rice grains. Moreover, volatiles produced by these two strains significantly reduced aflatoxin production in the rice grains by A. flavus. To our knowledge, this is the first report of the suppression of A. flavus aflatoxin production in rice grains using B. megaterium and P. protegens volatiles. PMID:29138628

  5. Biocontrol Potential of Lariophagus distinguendus (Hymenoptera: Pteromalidae) Against Sitophilus granarius (Coleoptera: Curculionidae) at Low Temperatures: Reproduction and Parasitoid-Induced Mortality

    DEFF Research Database (Denmark)

    Hansen, Lise Stengård

    2007-01-01

    the potential of this parasitoid against S. granarius in temperate regions, where grain is cooled with ambient air to achieve safe storage conditions. The influence of constant temperatures of 16, 18, and 20°C on life table parameters and parasitoid-induced mortality (PIM) was investigated in the laboratory. L....... distinguendus is able to develop and reproduce at temperatures as low as 16°C. The intrinsic rate of natural increase, r m , was 0.0182, 0.0222, and 0.0792 d -1 at 16, 18, and 20°C, respectively. The proportion of hosts killed due to parasitoid-induced mortality was highest at 20°C. At this temperature......, it amounted to 70% of the total mortality exerted by the parasitoid; at 18 and 16°C, it was 57 and 42% of the total, respectively. L. distinguendus is a promising biocontrol agent for grain stores in temperate regions because it is able to develop and reproduce at temperatures down to 16°C; its development...

  6. Effects of a non-native biocontrol weevil, Larinus planus, and other emerging threats on populations of the federally threatened Pitcher's thistle, Cirsium pitcheri

    Science.gov (United States)

    Havens, Kayri; Jolls, Claudia L.; Marik, Julie E.; Vitt, Pati; McEachern, A. Kathryn; Kind, Darcy

    2012-01-01

    Larinus planus Frabicius (Curculionidae), is a seed-eating weevil that was inadvertently introduced into the US and was subsequently distributed in the US and Canada for the control of noxious thistle species of rangelands. It has been detected recently in the federally threatened Pitcher's thistle (Cirsium pitcheri). We assayed weevil damage in a natural population of Pitcher's thistle at Whitefish Dunes State Park, Door County, WI and quantified the impact on fecundity. We then estimated the impact of this introduced weevil and other emerging threats on two natural, uninvaded populations of Pitcher's thistle for which we have long-term demographic data for 16 yr (Wilderness State Park, Emmet County, MI) and 23 yr (Miller High Dunes, Indiana Dunes National Lakeshore, Porter County, IN). We used transition matrices to determine growth rates and project the potential effects of weevil damage, inbreeding, goldfinch predation, and vegetative succession on Pitcher's thistle population viability. Based on our models, weevil seed predation reduced population growth rate by 10–12%, but this reduction was enough to reduce time to extinction from 24 yr to 13 yr and 8 yr to 5 yr in the MI and IN population, respectively. This impact is particularly severe, given most populations of Pitcher's thistle throughout its range hover near or below replacement. This is the first report of unanticipated ecological impacts from a biocontrol agent on natural populations of Cirsium pitcheri.

  7. Biocontrol Potentials of Antimicrobial Peptide Producing Bacillus Species: Multifaceted Antagonists for the Management of Stem Rot of Carnation Caused by Sclerotinia sclerotiorum

    Science.gov (United States)

    Vinodkumar, S.; Nakkeeran, S.; Renukadevi, P.; Malathi, V. G.

    2017-01-01

    Bacillus species are widely exploited as biocontrol agents because of their efficiency in impeding various plant pathogens with multifaceted approach. In this study, Bacillus species were isolated from rhizosphere of various plants viz., carnations, cotton, turmeric, and bananas in Tamil Nadu state of India. Their potential to control the mycelial growth of Sclerotinia sclerotiorum was assessed in vitro by dual plate and partition plate techniques. B. amyloliquefaciens strain VB7 was much effective in inhibiting mycelial growth (45% inhibition of over control) and sclerotial production (100%). PCR detection of AMP genes revealed that B. amyloliquefaciens (VB7) had a maximum of 10 diverse antibiotic biosynthesis genes, namely, ituD, ipa14, bacA, bacD, bamC, sfP, spaC, spaS, alba, and albF, that resulted in production of the antibiotics iturin, bacilysin, bacillomycin, surfactin, subtilin, and subtilosin. Further, metabolites from B. amyloliquefaciens strains VB2 and VB7, associated with inhibition of S. sclerotiorum, were identified as phenols and fatty acids by gas chromatography mass spectrometry (GC-MS). Delivery of bacterial suspension of the effective strains of Bacillus spp. as root dip was found promising for the management of stem rot of cultivated carnations. Minimal percent disease incidence (4.6%) and maximum plant growth promotion was observed in the plants treated with B. amyloliquefaciens (VB7). PMID:28392780

  8. Low-Dose Total Skin Electron Beam Therapy as a Debulking Agent for Cutaneous T-Cell Lymphoma: An open-label prospective phase II study

    DEFF Research Database (Denmark)

    Kamstrup, M R; Lindahl, Lise Maria; Gniadecki, R

    2012-01-01

    Background: Total skin electron beam therapy (TSEBT) is a powerful treatment for cutaneous T-cell lymphomas (CTCL). Based on the occurrence of relapses with low radiation doses, doses of 30-36 Gy are commonly used but most patients still eventually relapse and repeat treatment courses are limited...... due to the cumulative toxicity. Complete response rates are about 60-90% for T2-4 stages with a 5-year relapse-free survival of 10-25% for stages IB-III. Objectives: To evaluate prospectively the efficacy of low-dose TSEBT (10 Gy) in terms of complete cutaneous response rate, overall response rate...... and response duration in CTCL. Methods: Ten patients with stage IB-IV mycosis fungoides (MF) were treated in an open-label manner with 4 fractions of 1 Gy/week TSEB to a total skin dose of 10 Gy. Treatment responses were assessed at 1 and 3 months after treatment and subsequently at least every 6 months...

  9. Transcriptomic profiling of microbe-microbe interactions reveals the specific response of the biocontrol strain P. fluorescens In5 to the phytopathogen Rhizoctonia solani.

    Science.gov (United States)

    Hennessy, Rosanna C; Glaring, Mikkel A; Olsson, Stefan; Stougaard, Peter

    2017-08-10

    metabolite detoxification are highly upregulated in P. fluorescens In5 when co-cultured with plant pathogens and in particular the fungus R. solani. This highlights the importance of studying microbe-microbe interactions to gain a better understanding of how different systems function in vitro and ultimately in natural systems where biocontrol agents can be used for the sustainable management of plant diseases.

  10. In vivo coordination structural changes of a potent insulin-mimetic agent, bis(picolinato)oxovanadium(IV), studied by electron spin-echo envelope modulation spectroscopy.

    Science.gov (United States)

    Fukui, K; Fujisawa, Y; OhyaNishiguchi, H; Kamada, H; Sakurai, H

    1999-01-01

    Bis(picolinato)oxovanadium(IV) [VO(pic)2] is one of the most potent insulin-mimetic vanadium complexes. To probe coordination structural changes of this complex in vivo and provide insights into the origin of its high potency, an electron spin-echo envelope modulation (ESEEM) study was performed on organs (kidney, liver and bone) of VO(pic)2- and VOSO4-treated rats. Kidney and liver samples from both types of rats exhibited a 14N ESEEM signal that could be attributed to equatorially coordinating amine nitrogen. The relative intensity of the amine signal was larger for the organs of the rat treated with the less potent VOSO4, suggesting that this amine coordination inhibits the insulin-mimetic activity. The spectra of kidney and liver from the VO(pic)2-treated rat contained a weak signal due to the picolinate imine nitrogen. This suggests that some picolinato species (including both the bispicolinato and a partially decomposed monopicolinato species) still exist in the organs as a minor species, where the proportions of the picolinato species to the total amount of the EPR-detectable VIVO species are estimated as 8-16% in the kidney and 12-24% in the liver. The picolinate ligand presumably serves to prevent VO2+ from being converted into the inactive amine-coordinated species. Bone samples from both types of rats exhibited an ESEEM signal due to 31P nuclei. The VO2+ in bone is therefore most likely incorporated into the hydroxyapatite Ca10(PO4)6(OH)2 matrix, which is consistent with the hypothesis that the bone-accumulated VO2+ is gradually released and transported to other organs as is Ca2+. No 14N signals were observed, even in the bone samples of the VO(pic)2-treated rats, indicating that vanadium uptake by bone requires complete decomposition of the complex.

  11. Using Citrus aurantifolia essential oil for the potential biocontrol of Colocasia esculenta (taro) leaf blight caused by Phytophthora colocasiae.

    Science.gov (United States)

    Tchameni, Séverin Nguemezi; Mbiakeu, Staelle Njamou; Sameza, Modeste Lambert; Jazet, Pierre Michel Dongmo; Tchoumbougnang, François

    2017-11-17

    The aim of this work was to evaluate the antimicrobial activities of leaves and epicarp of Citrus aurantifolia essential oil against Phytophthora colocasiae, the causative agent of taro leaf blight. Oils were extracted by hydrodistillation, and their chemical composition was determined by gas chromatography and gas chromatography coupled with mass spectrometry. Antimicrobial activities of oils were tested in vitro against mycelium growth and sporangium production. In situ tests were done on healthy taro leaves, and the necrosis symptoms were evaluated. Results showed that the essential oil extraction yields from leaves and epicarp were 0.61 and 0.36%, respectively. Limonene (48.96%), bornyl acetate (14.18%), geraniol (10.53%), geranial (3.93%), and myrcene (3.14%) were the main components in leaf oil, while limonene (59.09%), cis-hydrate sabinene (7.53%), geranial (5.61%), myrtenol (5.02%), and terpinen-4-ol (3.48%) were the main components in epicarp oil. Both oils exhibited antimicrobial activities with total inhibition of the mycelium growth at 500 and 900 ppm for leaf and epicarp, respectively. The highest inhibitory concentration of sporangium production was 400 (72.84%) and 800 ppm (80.65%) for leaf and epicarp oil, respectively. For the standard fungicide (metalaxyl), the total inhibition value of mycelial growth and sporangium production was 750 ppm. In situ tests showed that, at 5000 ppm, total inhibition (100%) was obtained for a preventive test, while 50% of the inhibition was observed for a curative test when leaf oil was applied. When epicarp essential oil was applied at 5000 ppm, 47.5 and 16.66% of the reduction of leaf necrosis were observed for the preventive and curative test, respectively. There were positive correlations between both the oil concentration and the reduction of necrosis caused by P. colocasiae. These findings suggest that the C. aurantifolia essential oil could serve as an eco-friendly biocontrol for the management of taro

  12. Biocontrol of Bacterial Leaf Blight of Rice and Profiling of Secondary Metabolites Produced by Rhizospheric Pseudomonas aeruginosa BRp3

    Science.gov (United States)

    Yasmin, Sumera; Hafeez, Fauzia Y.; Mirza, Muhammad S.; Rasul, Maria; Arshad, Hafiz M. I.; Zubair, Muhammad; Iqbal, Mazhar

    2017-01-01

    Xanthomonas oryzae pv. oryzae (Xoo) is widely prevalent and causes Bacterial Leaf Blight (BLB) in Basmati rice grown in different areas of Pakistan. There is a need to use environmentally safe approaches to overcome the loss of grain yield in rice due to this disease. The present study aimed to develop inocula, based on native antagonistic bacteria for biocontrol of BLB and to increase the yield of Super Basmati rice variety. Out of 512 bacteria isolated from the rice rhizosphere and screened for plant growth promoting determinants, the isolate BRp3 was found to be the best as it solubilized 97 μg/ mL phosphorus, produced 30 μg/mL phytohormone indole acetic acid and 15 mg/ L siderophores in vitro. The isolate BRp3 was found to be a Pseudomonas aeruginosa based on 16S rRNA gene sequencing (accession no. HQ840693). This bacterium showed antagonism in vitro against different phytopathogens including Xoo and Fusarium spp. Strain BRp3 showed consistent pathogen suppression of different strains of BLB pathogen in rice. Mass spectrometric analysis detected the production of siderophores (1-hydroxy-phenazine, pyocyanin, and pyochellin), rhamnolipids and a series of already characterized 4-hydroxy-2-alkylquinolines (HAQs) as well as novel 2,3,4-trihydroxy-2-alkylquinolines and 1,2,3,4-tetrahydroxy-2-alkylquinolines in crude extract of BRp3. These secondary metabolites might be responsible for the profound antibacterial activity of BRp3 against Xoo pathogen. Another contributing factor toward the suppression of the pathogen was the induction of defense related enzymes in the rice plant by the inoculated strain BRp3. When used as an inoculant in a field trial, this strain enhanced the grain and straw yields by 51 and 55%, respectively, over non-inoculated control. Confocal Laser Scanning Microscopy (CLSM) used in combination with immunofluorescence marker confirmed P. aeruginosa BRp3 in the rice rhizosphere under sterilized as well as field conditions. The results provide

  13. Biocontrol of Bacterial Leaf Blight of Rice and Profiling of Secondary Metabolites Produced by Rhizospheric Pseudomonas aeruginosa BRp3

    Directory of Open Access Journals (Sweden)

    Sumera Yasmin

    2017-09-01

    Full Text Available Xanthomonas oryzae pv. oryzae (Xoo is widely prevalent and causes Bacterial Leaf Blight (BLB in Basmati rice grown in different areas of Pakistan. There is a need to use environmentally safe approaches to overcome the loss of grain yield in rice due to this disease. The present study aimed to develop inocula, based on native antagonistic bacteria for biocontrol of BLB and to increase the yield of Super Basmati rice variety. Out of 512 bacteria isolated from the rice rhizosphere and screened for plant growth promoting determinants, the isolate BRp3 was found to be the best as it solubilized 97 μg/ mL phosphorus, produced 30 μg/mL phytohormone indole acetic acid and 15 mg/ L siderophores in vitro. The isolate BRp3 was found to be a Pseudomonas aeruginosa based on 16S rRNA gene sequencing (accession no. HQ840693. This bacterium showed antagonism in vitro against different phytopathogens including Xoo and Fusarium spp. Strain BRp3 showed consistent pathogen suppression of different strains of BLB pathogen in rice. Mass spectrometric analysis detected the production of siderophores (1-hydroxy-phenazine, pyocyanin, and pyochellin, rhamnolipids and a series of already characterized 4-hydroxy-2-alkylquinolines (HAQs as well as novel 2,3,4-trihydroxy-2-alkylquinolines and 1,2,3,4-tetrahydroxy-2-alkylquinolines in crude extract of BRp3. These secondary metabolites might be responsible for the profound antibacterial activity of BRp3 against Xoo pathogen. Another contributing factor toward the suppression of the pathogen was the induction of defense related enzymes in the rice plant by the inoculated strain BRp3. When used as an inoculant in a field trial, this strain enhanced the grain and straw yields by 51 and 55%, respectively, over non-inoculated control. Confocal Laser Scanning Microscopy (CLSM used in combination with immunofluorescence marker confirmed P. aeruginosa BRp3 in the rice rhizosphere under sterilized as well as field conditions. The

  14. Application of electron beam radiation for peat sterilization and suppression of microbe contaminants; Aplicacao da radiacao por feixe de eletrons como agente esterilizante de microorganismos em substrato turfoso

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, David

    2006-07-01

    Inoculation of root nodule bacteria into legume seeds such as soybean [Glycine max. (L.)], common bean (Phaseolus vulgaris L.) and forage pasture has been effective and convenient as this simple procedure may introduce effective strains of Bradyrhizobium/Rhizobium into agricultural soils without a past history of successful cropping systems with the legume hosts. Peat-based substrates previously sterilized have been used for decades as bacteria carrier, protecting them from the prevailing harsh conditions in tropical soils and ensuring their survival with nutrient and protection against the soil antagonists. The Brazilian Government requires that all peat-based substrates must be gamma-sterilized from a cobalt-60 ({sup 60}Co) source, prior the introduction of the root nodule bacteria into the package. The recommendation is for a dose up to 50 kGy for an effective suppression of pathogens and saprophytes, in order to avoid competition among the substrate microbiota. Recently, the use of the electron beam (EB) accelerator has shown to be a new alternative for peat pre-sterilization, as this technique may promote reactive free-radicals which are efficient to suppress microbial contaminants. This fast technology is considered more environment and ecology friendly-sound than gamma radiation ({gamma}). The disadvantage of not reaching higher depth than gamma rays from {sup 60}Co must be considered, and attempts of optimizing the technique are crucial. This study compared both methods by using increasing rates of radiation by {sup 60}Co by the EB method - O, 10, 20, 30, 40 e 50 kGy in a commercial peat used for inoculants. Experimental data from days 7, 14, 21 and 28 days (growth period) and 150, 180 and 210 days (storage period) indicated high numbers of the strain Rhizobium tropici CM-01, labelled with gusA{sup +} (Study 1) and celB{sup +} (Study 2) from both eat-sterilizing techniques, reaching values above the minimum of 1x10{sup 8} cells g{sup -1} peat. At high rates

  15. Efficiency of a yeast-based formulation for the biocontrol of postharvest anthracnose of papayas

    Directory of Open Access Journals (Sweden)

    Jaqueline Rabelo de Lima

    2014-09-01

    Full Text Available To identify formulations of biological agents that enable survival, stability and a good surface distribution of the antagonistic agent, studies that test different application vehicles are necessary. The efficiency of two killer yeasts, Wickerhamomyces anomalus (strain 422 and Meyerozyma guilliermondii (strain 443, associated with five different application vehicles, was assessed for the protection of postharvest papayas. In this study, after 90 days of incubation at 4ºC, W. anomalus (strain 422 and M. guilliermondii (strain 443 were viable with all application vehicles tested. Fruits treated with different formulations (yeasts + application vehicles had a decreased severity of disease (by at least 30% compared with untreated fruits. The treatment with W. anomalus (strain 422 + 2% starch lowered disease occurrence by 48.3%. The most efficient treatments using M. guilliermondii (strain 443 were those with 2% gelatin or 2% liquid carnauba wax, both of which reduced anthracnose by 50% in postharvest papayas. Electron micrographs of the surface tissues of the treated fruits showed that all application vehicles provided excellent adhesion of the yeast to the surface. Formulations based on starch (2%, gelatin (2% and carnauba wax (2% were the most efficient at controlling fungal diseases in postharvest papayas.

  16. Three-way interactions between Fusarium species, their plant hosts and biocontrol organisms

    DEFF Research Database (Denmark)

    Kosawang, Chatchai

    of the mycoparasitic fungus Clonostachys rosea IK726, which is effective in controlling mycotoxin-producing Fusarium species. This thesis reports on aspects regarding (I) detoxification of ZEA in connection to biocontrol activities of the IK726, (II) mechanisms conferring resistance to DON and ZEA and (III) evolution...... in metabolic processes, e.g., Cytochome P450 55A3, Cytochrome C oxidase and ATP synthase. This provided evidence that metabolic adjustment is a major component contributing to tolerance to DON in C. rosea. On the other hand, substantial upregulation of transcripts encoding ABC transporter species was observed...... are responsible for xenobiotic transport in many organisms, suggesting that the expansion of ABC transporters might be reflected in resistance to broad xenobiotics in C. rosea, while the contraction of subfamily C in T. reesei and T. atroviridae may be reflected in distinct lifestyles in these latter species....

  17. Shallot aphids, Myzus ascalonicus, in strawberry: biocontrol potential of three predators and three parasitoids.

    Science.gov (United States)

    Enkegaard, Annie; Sigsgaard, Lene; Kristensen, Kristian

    2013-01-01

    The parasitization capacity of 3 parasitoids and the predation capacity of 3 predators towards the shallot aphid, Myzus ascalonicus Doncaster (Homoptera: Aphididae), on strawberry, Fragaria x ananassa Duchesne (Rosales: Rosaceae) cv. Honeoye, were examined in laboratory experiments. In Petri dish assays, both Aphidius colemani Viereck (Hymenoptera: Aphidiidae) and A. ervi Haliday readily stung shallot aphids, with no significant difference in stinging frequency between the two species. A. ervi induced a significantly higher mortality (79.0 ± 7.2%) in terms of stung aphids compared with A. colemani (55.3 ± 4.1%); however, only a minor fraction (2.7 ± 1.8% and 7.1 ± 3.1%, respectively) of the killed aphids resulted in formation of mummies, presumably due to a physiological response to parasitism. The low percentage of mummification precludes the use of either Aphidius species in anything but inundative biocontrol. In similar set-ups, Aphelinus abdominalis (Dalman) (Hymenoptera: Aphelinidae) killed almost half (49.6 ± 5.3%) of the exposed aphids through host feeding. In addition, 23.2 ± 7.3% of non-host-fed aphids developed into mummified aphids, and 38.1 ± 13.2% of non-host-fed aphids died from other parasitoid-induced causes. However, the host feeding rate was reduced to only 1.2 ± 0.8%, and no significant parasitization mortality was observed on strawberry plants, suggesting that host plants interfered with A. abdominalis activity. This parasitoid does not, therefore, seem to be suited to either inoculative or inundative biocontrol of shallot aphids in strawberry. The three predators studied were the green lacewing, Chrysoperla carnea Steph. (Neuroptera: Chrysopidae), the two-spotted lady beetle, Adalia bipunctata L. (Coleoptera: Coccinellidae), and the gall midge Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae). Third instars of all 3 predators readily preyed upon the shallot aphid in Petri dish set-ups with significant differences in daily

  18. Radioprotective Agents

    Directory of Open Access Journals (Sweden)

    Ilker Kelle

    2008-01-01

    Full Text Available Since1949, a great deal of research has been carried out on the radioprotective activity of various chemical substances. Thiol compounds, compounds which contain –SH radical, different classes of pharmacological agents and other compounds such as vitamine C and WR-2721 have been shown to reduce mortality when administered prior to exposure to a lethal dose of radiation. Recently, honey bee venom as well as that of its components melittin and histamine have shown to be valuable in reduction of radiation-induced damage and also provide prophylactic alternative treatment for serious side effects related with radiotherapy. It has been suggested that the radioprotective activity of bee venom components is related with the stimulation of the hematopoetic system.

  19. Strategic Design of Mobile Agents

    OpenAIRE

    Vulkan, Nir

    2002-01-01

    Much of the economic value of electronic commerce comes from the automation of interactions between businesses and individuals. Game theory is a useful set of tools that can be used by designers of electronic-commerce applications in analyzing and engineering of automated agents and communication protocols. The central theoretical concept used in game theory is the Nash equilibrium. In this article, I show how the outcomes supported by a Nash equilibrium can positively be enlarged using autom...

  20. Hard surface biocontrol in hospitals using microbial-based cleaning products.

    Directory of Open Access Journals (Sweden)

    Alberta Vandini

    Full Text Available Healthcare-Associated Infections (HAIs are one of the most frequent complications occurring in healthcare facilities. Contaminated environmental surfaces provide an important potential source for transmission of many healthcare-associated pathogens, thus indicating the need for new and sustainable strategies.This study aims to evaluate the effect of a novel cleaning procedure based on the mechanism of biocontrol, on the presence and survival of several microorganisms responsible for HAIs (i.e. coliforms, Staphyloccus aureus, Clostridium difficile, and Candida albicans on hard surfaces in a hospital setting.The effect of microbial cleaning, containing spores of food grade Bacillus subtilis, Bacillus pumilus and Bacillus megaterium, in comparison with conventional cleaning protocols, was evaluated for 24 weeks in three independent hospitals (one in Belgium and two in Italy and approximately 20000 microbial surface samples were collected.Microbial cleaning, as part of the daily cleaning protocol, resulted in a reduction of HAI-related pathogens by 50 to 89%. This effect was achieved after 3-4 weeks and the reduction in the pathogen load was stable over time. Moreover, by using microbial or conventional cleaning alternatively, we found that this effect was directly related to the new procedure, as indicated by the raise in CFU/m2 when microbial cleaning was replaced by the conventional procedure. Although many questions remain regarding the actual mechanisms involved, this study demonstrates that microbial cleaning is a more effective and sustainable alternative to chemical cleaning and non-specific disinfection in healthcare facilities.This study indicates microbial cleaning as an effective strategy in continuously lowering the number of HAI-related microorganisms on surfaces. The first indications on the actual level of HAIs in the trial hospitals monitored on a continuous basis are very promising, and may pave the way for a novel and cost