WorldWideScience

Sample records for biocontrol agent pseudozyma

  1. 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.

  2. 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.

  3. 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

  4. Environmental impact assessment of genetically modified biocontrol agents

    International Nuclear Information System (INIS)

    This review summarises the theoretical basis of risk analysis, and the political and social implications of introducing new biotechnology products in agricultural environments. The main factors to be considered under the present European regulation in the environmental impact assessment of genetically modified biocontrol agents are briefly discussed. Finally, an alternative risk assessment paradigm is proposed for genetically modified microorganisms, which shall consider the intrinsic properties of each antagonist, rather than the method used for generating it

  5. Potencialidade antagonística detectada em alguns procariotas agentes de biocontrole de enfermidades de plantas Antagonistic potentiality in prokaryotic biocontrol agents for plant diseases

    Directory of Open Access Journals (Sweden)

    Victor Rafael Barra

    2008-06-01

    Full Text Available Ao longo de vários anos, no Laboratório de Bacteriologia de Plantas e Controle Biológico (LBPCB do Departamento de Fitopatologia da Universidade Federal de Viçosa têm-se, sistematicamente, isolado, de rizosfera, rizoplano e filoplano de plantas cultivadas de importância econômica, milhares de procariotas os quais são testados, um a um, como agentes de biocontrole de enfermidades. A grande maioria deles, como esperado, não exibe qualquer potencialidade como agente de biocontrole e é descartada. Alguns poucos são selecionados, através de demorados ensaios de biocontrole experimental tanto em casa de vegetação como em campo. Neste trabalho, mostra-se que muitos dos organismos em estudo, mesmo havendo sido selecionados, principalmente, por induzirem resistência sistêmica na planta alvo, expressam constitutivamente mecanismos de antagonismo microbiano que parecem fazer parte de seu perfil enquanto agentes de biocontrole.Along several years, at the Laboratory of Plant Bacteriology and Biological Control of the Department of Plant Pathology of the Federal University of Viçosa, thousands of prokaryote isolates have been obtained from the rhizosphere, rhizoplane and phylloplane of economically important plants. Every obtained isolate is tested as biocontrol agents. As expected, the majority does not show any biocontrol potentiality and is discarded. Few are selected through time-consuming experimental biocontrol trials in greenhouse and field. Even being selected mainly for their ability to induce resistance in target plants, many of them constitutively express mechanisms of antagonism against pathogens that seem to be part of their performance while biocontrol agents.

  6. Endophytic Bacteria as Biocontrol Agents of Tomato Bacterial Wilt Disease

    Directory of Open Access Journals (Sweden)

    Arika Purnawati

    2014-01-01

    Full Text Available Ralstonia solanacearum is a tomato pathogen causing wilt disease which can lose crop production up to 100%. This problem also has economical impact to Indonesia, though controlling this pathogen has been donebefore. Biological control using endophytic bacteria is one of alternative control methods to support agriculture sustainability. The objective of these experiments are isolating endophytic bacteria taken from healthy tomato stems and root as well as investigating patogens as biocontrol agents of tomato bacterial wilt disease. Among 10 isolates found, only Ps1 and Ps8 can inhibit R. solanacearum based on antagonistic test in vitro using seed coat method and 4-7 mm inhibition zone forming. In vivo test was applied in green house in 30 days old of tomatoes usingendophytic bacteria by theroot soak technique. The result shows Ps1 and Ps8 within 15-16 days incubation period have suppressed 8.07%-9.19% pathogen attack.

  7. 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. PMID:26845376

  8. Biosynthetic mechanism for sunscreens of the biocontrol agent Lysobacter enzymogenes.

    Directory of Open Access Journals (Sweden)

    Yan Wang

    Full Text Available Lysobacter are ubiquitous environmental bacteria emerging as novel biocontrol agents and new sources of anti-infectives. So far, very little effort has been invested in the study of the biology of these Gram-negative gliding bacteria. Many Lysobacter species are characterized by their yellow-orange appearance. Using transposon mutagenesis, we identified a stand-alone polyketide synthase (PKS gene cluster required for the pigment production in L. enzymogenes OH11. The yellow pigments were abolished in the "white" mutants generated by target-specific deletions of ketosynthase (KS, acyl carrier protein, or ketoreductase. Spectroscopic data suggested that the pigments belong to xanthomonadin-like aryl polyenes. Polyene-type polyketides are known to be biosynthesized by modular PKS (Type I, not by stand-alone PKS (Type II which always contain the heterodimer KS-CLF (chain-length factor as the key catalytic component. Remarkably, this aryl polyene PKS complex only contains the KS (ORF17, but not the CLF. Instead, a hypothetical protein (ORF16 is located immediately next to ORF17. ORF16-17 homologs are widespread in numerous uncharacterized microbial genomes, in which an ORF17 homolog is always accompanied by an ORF16 homolog. The deletion of ORF16 eliminated pigment production, and homology modeling suggested that ORF16 shares a structural similarity to the N-terminal half of CLF. A point-mutation of glutamine (Q166A that is the conserved active site of known CLF abolished pigment production. The "white" mutants are significantly more sensitive to UV/visible light radiation or H2O2 treatment than the wild type. These results unveil the first example of Type II PKS-synthesized polyene pigments and show that the metabolites serve as Lysobacter "sunscreens" that are important for the survival of these ubiquitous environmental organisms.

  9. Avaliação do potencial de leveduras dos géneros Pseudozyma e Rhodosporidium no controlo biológico pós-colheita de bolores

    OpenAIRE

    Alves, Maria Leonor Nobre

    2007-01-01

    Basidiomycetous yeasts belonging to the genera Pseudozyma and Rhodosporidium have been described as being able to act as biocontrol agents against different fungal pathogens. However, a detailed survey of the biological control potential of yeasts belonging to these genera has never been carried out. We tested the antagonistic activity of several species belonging to these genera, and other related species, against important postharvest fungal pathogens of the genus Penicillium. The potential...

  10. Incorporating Ecologically Relevant Measures of Pesticide Effect for Estimating the Compatibility of Pesticides and Biocontrol Agents

    Science.gov (United States)

    The compatibility of biological control agents with pesticides is a central concern in integrated pest management programs. The most common assessments of compatibility consist of simple comparisons of acute toxicity among pest species and select biocontrol agents. A more sophisticated approach, d...

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

    Institute of Scientific and Technical Information of China (English)

    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 v/ride 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 6.65×109 CFU/g initial dry substrate (IDS) after 10 d fermentation.As important enzymes for protecting plants from disease,ehitinase,β-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.

  12. 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)

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

    OpenAIRE

    Lihua Li; Jincai Ma; A. Mark Ibekwe; Qi Wang; Ching-Hong Yang

    2015-01-01

    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 determ...

  14. Lactic acid bacteria from fresh fruit and vegetables as biocontrol agents of phytopathogenic bacteria and fungi

    OpenAIRE

    Trias Mansilla, Rosalia; Bañeras Vives, Lluís; Montesinos Seguí, Emilio; Badosa Romañó, Esther

    2008-01-01

    This study evaluated the efficacy of lactic acid bacteria (LAB) isolated from fresh fruits and vegetables as biocontrol agents against the phytopathogenic and spoilage bacteria and fungi, Xanthomonas campestris, Erwinia carotovora, Penicillium expansum, Monilinia laxa, and Botrytis cinerea. The antagonistic activity of 496 LAB strains was tested in vitro and all tested microorganisms except P. expansum were inhibited by at least one isolate. The 496 isolates were also analyzed for the inhibit...

  15. 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.

  16. 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. PMID:26880001

  17. Evaluation of the sea anemone Anthothoe albocincta as an augmentative biocontrol agent for biofouling on artificial structures.

    Science.gov (United States)

    Atalah, Javier; Bennett, Holly; Hopkins, Grant A; Forrest, Barrie M

    2013-01-01

    Augmentative biocontrol, defined as the use of indigenous natural enemies to control pest populations, has not been explored extensively in marine systems. This study tested the potential of the anemone Anthothoe albocincta as a biocontrol agent for biofouling on submerged artificial structures. Biofouling biomass was negatively related to anemone cover. Treatments with high anemone cover (>35%) led to significant changes in biofouling assemblages compared to controls. Taxa that contributed to these changes differed among sites, but included reductions in cover of problematic fouling organisms, such as solitary ascidians and bryozoans. In laboratory trials, A. albocincta substantially prevented the settlement of larvae of the bryozoan Bugula neritina when exposed to three levels of larval dose, suggesting predation as an important biocontrol mechanism, in addition to space pre-emption. This study demonstrated that augmentative biocontrol using anemones has the potential to reduce biofouling on marine artificial structures, although considerable further work is required to refine this tool before its application.

  18. [Fungal bio-control agents against ixodid tick--a review].

    Science.gov (United States)

    Sun, Ming; Wang, Xiaoyan; Luo, Jianxun

    2012-08-01

    Entomopathogenic fungi as potential agents for bio-control have been widely applied in the control of insect pests in agriculture. However, the application remains in laboratory scale for the control of ectoparasites. Owing to the need to combat the short lasting period of chemical acaricides and reduction of pollution, it is urgent to develop sufficient, stable and safe measures for tick control. We reviewed the primary scientific achievements in utilization of environmental microbes for controlling of ticks. Studies conducted in this field may benefit to sustainable development, environmental protection, maintaining ecological balance and production of green products.

  19. 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...

  20. 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.

  1. Lactic acid bacteria from fresh fruit and vegetables as biocontrol agents of phytopathogenic bacteria and fungi.

    Science.gov (United States)

    Trias, Rosalia; Bañeras, Lluís; Montesinos, Emilio; Badosa, Esther

    2008-12-01

    This study evaluated the efficacy of lactic acid bacteria (LAB) isolated from fresh fruits and vegetables as biocontrol agents against the phytopathogenic and spoilage bacteria and fungi, Xanthomonas campestris, Erwinia carotovora, Penicillium expansum, Monilinia laxa, and Botrytis cinerea. The antagonistic activity of 496 LAB strains was tested in vitro and all tested microorganisms except P. expansum were inhibited by at least one isolate. The 496 isolates were also analyzed for the inhibition of P. expansum infection in wounds of Golden Delicious apples. Four strains (TC97, AC318, TM319, and FF441) reduced the fungal rot diameter of the apples by 20%; only Weissella cibaria strain TM128 decreased infection levels by 50%. Cell-free supernatants of selected antagonistic bacteria were studied to determine the nature of the antimicrobial compounds produced. Organic acids were the preferred mediators of inhibition but hydrogen peroxide was also detected when strains BC48, TM128, PM141 and FF441 were tested against E. carotovora. While previous reports of antifungal activity by LAB are scarce, our results support the potential of LAB as biocontrol agents against postharvest rot. PMID:19204894

  2. 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.

  3. Conidial quality of the biocontrol agent Coniothyrium minitans produced by solid-state cultivation in a packed-bed reactor

    NARCIS (Netherlands)

    Jones, E.E.; Weber, F.J.; Oostra, J.; Rinzema, A.; Mead, A.; Whipps, J.M.

    2004-01-01

    Conidial germination and novel sand- and soil-based sclerotial parasitism assays were used to test the quality of conidial inoculum of the biocontrol agent Coniothyrium minitans IVT1 produced in different packed bed reactor runs. The fermenter airflow rate was either kept constant, resulting in a tr

  4. 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...

  5. Hrp mutant bacteria as biocontrol agents: toward a sustainable approach in the fight against plant pathogenic bacteria.

    Science.gov (United States)

    Hanemian, Mathieu; Zhou, Binbin; Deslandes, Laurent; Marco, Yves; Trémousaygue, Dominique

    2013-10-01

    Sustainable agriculture necessitates development of environmentally safe methods to protect plants against pathogens. Among these methods, application of biocontrol agents has been efficiently used to minimize disease development. Here we review current understanding of mechanisms involved in biocontrol of the main Gram-phytopathogenic bacteria-induced diseases by plant inoculation with strains mutated in hrp (hypersensitive response and pathogenicity) genes. These mutants are able to penetrate plant tissues and to stimulate basal resistance of plants. Novel protection mechanisms involving the phytohormone abscisic acid appear to play key roles in the biocontrol of wilt disease induced by Ralstonia solanacearum in Arabidopsis thaliana. Fully understanding these mechanisms and extending the studies to other pathosystems are still required to evaluate their importance in disease protection.

  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)

    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. Production of a newly isolated Paenibacillus polymyxa biocontrol agent using monosodium glutamate wastewater and potato wastewater.

    Science.gov (United States)

    Gu, Likun; Bai, Zhihui; Jin, Bo; Zhang, Jianyun; Li, Wenying; Zhuang, Guoqiang; Zhang, Hongxun

    2010-01-01

    A phyllosphere bacterial strain EBL-06 was isolated from wheat leaves. The morphology, cultural characteristics, phospholipid fatty acids, physiological and antagonistic fungus activities of this strain were investigated. A phylogenetic tree was constructed by comparing with the published 16S rDNA sequences of the relevant bacteria. The results showed that the isolate EBL-06 was a strain of Paenibacillus polymyxa; this strain performed a high level of antagonistic fungus activity toward a broad spectrum of phytopathogens, such as Botrytis cinerea, Cladosporium cucumerinum, Fusarium spp. The isolate EBL-06 can grow well using monosodium glutamate wastewater (MGW) and potato wastewater (PW) as culture medium. The maximum yield of 6.5 x 10(9) CFU/mL of the isolate EBL-06 anti-fungus biocontrol agent was reached in 15 hr cultivation at 28 degrees C, pH 6.0-7.5 using the mixture of MGW and PW (1:9). PMID:21174972

  8. EFFICACY OF BIOCONTROL AGENTS IN CONTROLLING RHIZOCTONIA SOLANI ON NAGA KING CHILLI ( Capsicum chinense Jacq.

    Directory of Open Access Journals (Sweden)

    Marinus Ngullie

    2013-07-01

    Full Text Available Available biocontrol agents were evaluated either alone or in various combinations for finding out their efficacy in suppressing Rhizoctonia seedling rot incidence and promoting plant growth of Naga king chilli (Capsicum chinense Jacq. in green house as well field conditions. Among all tested combination, the treatment containing combination of T. viride +P. fluorescens was found most effective in reducing the incidence of seedling rot in both greenhouse and field condition. Highest per plant yield was also recorded from the same combination and it was followed by T. viride. However, the commercially available fungicide Copper oxychloride (0.1% showed 9.82 % and11.88% disease incidence in greenhouse and field condition respectively

  9. 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. PMID:27220011

  10. Preliminary in vitro insights into the use of natural fungal pathogens of leaf-cutting ants as biocontrol agents.

    Science.gov (United States)

    Folgarait, Patricia; Gorosito, Norma; Poulsen, Michael; Currie, Cameron R

    2011-09-01

    Leaf-cutting ants are one of the main herbivores of the Neotropics, where they represent an important agricultural pest. These ants are particularly difficult to control because of the complex network of microbial symbionts. Leaf-cutting ants have traditionally been controlled through pesticide application, but there is a need for alternative, more environmentally friendly, control methods such as biological control. Potential promising biocontrol candidates include the microfungi Escovopsis spp. (anamorphic Hypocreales), which are specialized pathogens of the fungi the ants cultivate for food. These pathogens are suppressed through ant behaviors and ant-associated antibiotic-producing Actinobacteria. In order to be an effective biocontrol agent, Escovopsis has to overcome these defenses. Here, we evaluate, using microbial in vitro assays, whether defenses in the ant-cultivated fungus strain (Leucoagaricus sp.) and Actinobacteria from the ant pest Acromyrmex lundii have the potential to limit the use of Escovopsis in biocontrol. We also explore, for the first time, possible synergistic biocontrol between Escovopsis and the entomopathogenic fungus Lecanicillium lecanii. All strains of Escovopsis proved to overgrow A. lundii cultivar in less than 7 days, with the Escovopsis strain isolated from a different leaf-cutting ant species being the most efficient. Escovopsis challenged with a Streptomyces strain isolated from A. lundii did not exhibit significant growth inhibition. Both results are encouraging for the use of Escovopsis as a biocontrol agent. Although we found that L. lecanii can suppress the growth of the cultivar, it also had a negative impact on Escovopsis, making the success of simultaneous use of these two fungi for biocontrol of A. lundii questionable. PMID:21739253

  11. Native isolate of Trichoderma: a biocontrol agent with unique stress tolerance properties.

    Science.gov (United States)

    Mishra, N; Khan, S S; Sundari, S Krishna

    2016-08-01

    Species of Trichoderma are widely recognized for their biocontrol abilities, but seldom studied collectively, for their plant growth promotion, abiotic stress tolerance and bioremediation properties. Our study is a concentrated effort to establish the potential of native isolate Trichoderma harzianum KSNM (T103) to tolerate biotic (root pathogens) and abiotic stresses [high salt (100-1000 mM); heavy metal (chromium, nickel and zinc: 1-10 mM); pesticides: malathion (100-600 ppm), carbofuran (100-600 ppb)], along with its ability to support plant growth. In vitro growth promotion assays with T103 treated Vigna radiata, Vigna mungo and Hordeum vulgare confirmed 'non-species specific' growth promotion effects of T103. At lower metal concentration, T103 treatment was found to completely negate the impact of metal stress [60 % increase in radicle length (RL) with no significant decrease in %germination (%G)]. Even at 10 mM metal, T103 inoculation gave 80 % increase in %G and >50 % increase in RL. In vitro experiments confirmed high metal reduction capacity (47 %-Cr, 35 %-Ni and 42 %-Zn) of T103 at concentrations as high as 4 mM. At maximum residual concentrations of malathion (440 ppm) and carbofuran (100 ppb) reported in agricultural soils, T103 maintained 80 and 100 % survivability, respectively. T103 treatment has improved %G and RL in all three hosts challenged with pesticide. Isolate T103 was found to effectively suppress growth of three major root pathogens: Macrophomina phaseolina (65.83 %) followed by Sclerotium rolfsii (19.33 %) and Fusarium oxysporum (19.18 %). In the light of these observations, native T. harzianum (T103) seems to be a competent biocontrol agent for tropical agricultural soils contaminated with residual pesticides and heavy metals. PMID:27339311

  12. 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

  13. 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

  14. 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

  15. 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.

  16. Purification of an antifungal endochitinase from a potential biocontrol Agent Streptomyces griseus.

    Science.gov (United States)

    Rabeeth, M; Anitha, A; Srikanth, Geetha

    2011-08-15

    Streptomyces griseus (MTCC 9723) is a chitinolytic bacterium isolated from prawn cultivated pond soil of Peddapuram Village; East Godavari District was studied in detailed. Chitinase (EC 3.2.1.14) was extracted from the culture filtrate of Streptomyces griseus and purified by ammonium sulfate precipitation, DEAE-cellulose ionexchange chromatography, Sephadex G-100 and Sephadex G-200 gel filtration chromatography. The molecular mass of the purified chitinase was estimated to be 34, 32 kDa by SDS gel electrophoresis and confirmed by activity staining with Calcofluor White M2R. Chitinase was optimally active at pH of 6.0 and at 40 degrees C. The enzyme was stable from pH 5-9 and up to 20-50 degrees C. The chitinase exhibited Km and Vmax values of 400 mg and 180 IU mL(-1) for colloidal chitin. Among the metals and inhibitors that were tested, the Hg+, Hg2+ and P-chloromercuribenzoic acid completely inhibited the chitinase activity at 1 mM concentration. The purified chitinase showed high activity on colloidal chitin, chitobiose, and chitooligosaccharide. An in vitro assay proved that the crude chitinase, actively growing cells of S. griseus having antifungal activity against all studied fungal pathogen. This result implies that characteristics of S. griseus producing endochitinase made them suitable for biotechnological purpose such as for degradation of chitin containing waste and it might be a promising biocontrol agent for plant pathogens. PMID:22545353

  17. 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.

  18. Candida parapsilosis as a Potent Biocontrol Agent against Growth and Aflatoxin Production by Aspergillus Species

    Science.gov (United States)

    Niknejad, F; Zaini, F; Faramarzi, MA; Amini, M; Kordbacheh, P; Mahmoudi, M; Safara, M

    2012-01-01

    Background: Aflatoxin contamination of food and feed stuff is a serious health problem and significant economic concerns. In the present study, the inhibitory effect of Candida parapsilosis IP1698 on mycelial growth and aflatoxin production in aflatoxigenic strains of Aspergillus species was investigated. Methods: Mycelial growth inhibitions of nine strains of aflatoxigenic and non-aflatoxigenic Aspergillus species in the presence of C. parapsilosis investigated by pour plate technique at different pH, temperature and time of incubation. Reduction of aflatoxin was evaluated in co-cultured fungi in yeast extract sucrose broth after seven days of incubation using HPLC method. The data were analyzed by SPSS 11.5. Results: The presence of the C. parapsilosis at different pH did not affect significantly the growth rate of Aspergillus isolates. On the other hand, temperature and time of incubation showed to be significantly effective when compared to controls without C. parapsilosis (P≤0.05). In aflatoxigenic strains, minimum percentage of reductions in total aflatoxin and B1, B2, G1, G2 fractions were 92.98, 92.54, 77.48, 54.54 and 72.22 and maximum percentage of reductions were 99.59, not detectable, 94.42, and not detectable in both G1 and G2, respectively. Conclusion: C. parapsilosis might employ as a good biocontrol agent against growth and aflatoxin production by aflatoxigenic Aspergillus species PMID:23308351

  19. Candida Parapsilosis as a Potent Biocontrol Agent against Growth and Aflatoxin Production by Aspergillus Species

    Directory of Open Access Journals (Sweden)

    F Niknejad

    2012-10-01

    Full Text Available Background: Aflatoxin contamination of food and feed stuff is a serious health problem and significant economic concerns. In the present study, the inhibitory effect of Candida parapsilosis IP1698 on mycelial growth and aflatoxin production in aflatoxigenic strains of Aspergillus species was investigated.Methods: Mycelial growth inhibitions of nine strains of aflatoxigenic and non-aflatoxigenic Aspergillus species in thepresence of C. parapsilosis investigated by pour plate technique at different pH, temperature and time of incubation.Reduction of aflatoxin was evaluated in co-cultured fungi in yeast extract sucrose broth after seven days of incubation using HPLC method. The data were analyzed by SPSS 11.5.Results: The presence of the C. parapsilosis at different pH did not affect significantly the growth rate of Aspergillus isolates. On the other hand, temperature and time of incubation showed to be significantly effective when compared to controls without C. parapsilosis (P≤0.05. In aflatoxigenic strains, minimum percentage of reductions in total aflatoxin and B1, B2, G1, G2 fractions were 92.98, 92.54, 77.48, 54.54 and 72.22 and maximum percentage ofreductions were 99.59, not detectable, 94.42, and not detectable in both G1 and G2, respectively.Conclusion: C. parapsilosis might employ as a good biocontrol agent against growth and aflatoxin production by aflatoxigenic Aspergillus species.

  20. Ecology of Anti-Biofilm Agents II: Bacteriophage Exploitation and Biocontrol of Biofilm Bacteria

    Directory of Open Access Journals (Sweden)

    Stephen T. Abedon

    2015-09-01

    Full Text Available Bacteriophages are the viruses of bacteria. In the guise of phage therapy they have been used for decades to successfully treat what are probable biofilm-containing chronic bacterial infections. More recently, phage treatment or biocontrol of biofilm bacteria has been brought back to the laboratory for more rigorous assessment as well as towards the use of phages to combat environmental biofilms, ones other than those directly associated with bacterial infections. Considered in a companion article is the inherent ecological utility of bacteriophages versus antibiotics as anti-biofilm agents. Discussed here is a model for phage ecological interaction with bacteria as they may occur across biofilm-containing ecosystems. Specifically, to the extent that individual bacterial types are not highly abundant within biofilm-containing environments, then phage exploitation of those bacteria may represent a “Feast-or-famine” existence in which infection of highly localized concentrations of phage-sensitive bacteria alternate with treacherous searches by the resulting phage progeny virions for new concentrations of phage-sensitive bacteria to infect. An updated synopsis of the literature concerning laboratory testing of phage use to combat bacterial biofilms is then provided along with tips on how “Ecologically” such phage-mediated biofilm control can be modified to more reliably achieve anti-biofilm efficacy.

  1. 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,

  2. 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

    2014-04-01

    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

  3. Amblyseius swirskii: what made this predatory mite such a successful biocontrol agent?

    Science.gov (United States)

    Calvo, F Javier; Knapp, Markus; van Houten, Yvonne M; Hoogerbrugge, Hans; Belda, José E

    2015-04-01

    The predatory mite Amblyseius swirskii quickly became one of the most successful biocontrol agents in protected cultivation after its introduction into the market in 2005 and is now released in more than 50 countries. There are several key factors contributing to this success: (1) it can control several major pests including the western flower thrips, Frankliniella occidentalis, the whiteflies Bemisia tabaci and Trialeurodes vaporariorum and the broad mite, Polyphagotarsonemus latus, simultaneously in vegetables and ornamental crops; (2) it can develop and reproduce feeding on non-prey food sources such as pollen, which allows populations of the predator to build up on plants before the pests are present and to persist in the crop during periods when prey is scarce or absent; and (3) it can be easily reared on factitious prey, which allows economic mass production. However, despite the fact that A. swirskii provides growers with a robust control method, external demands were initially a key factor in promoting the use of this predator, particularly in Spain. In 2006, when exports of fresh vegetables from Spain were stopped due to the presence of pesticide residues, growers were forced to look for alternatives to chemical control. This resulted in the massive adoption of biological control-based integrated pest management programmes based on the use of A. swirskii in sweet pepper. Biological control increased from 5 % in 2005, 1 year before A. swirskii was commercially released, to almost 100 % of a total 6,000 ha of protected sweet pepper in Spain within 3 years. Later, it was demonstrated that A. swirskii was equally effective in other crops and countries, resulting in extensive worldwide use of A. swirskii in greenhouses.

  4. Chitinases from the Plant Disease Biocontrol Agent, Stenotrophomonas maltophilia C3.

    Science.gov (United States)

    Zhang, Z; Yuen, G Y; Sarath, G; Penheiter, A R

    2001-02-01

    ABSTRACT Stenotrophomonas maltophilia strain C3, a biocontrol agent of Bipolaris sorokiniana in turfgrass, produced chitinases in broth media containing chitin. Chitinases were partially purified from culture fluid by ammonium sulfate precipitation and chitin affinity chromatography. The chromatography fraction with the highest specific chitinase activity was inhibitory to conidial germination and germ-tube elongation of B. sorokiniana, but it was less inhibitory than the protein fraction or the raw culture filtrate. The fraction exhibited strong exochitinase and weak endo-chitinase activity. Optimum temperature and pH for chitinase activity were 45 to 50 degrees C and 4.5 to 5.0, respectively. Chitinase activity was inhibited by Hg(2+) and Fe(3+), but not by other metal ions or enzyme inhibitors. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the chromatography fraction revealed the presence of five protein bands of 25, 32, 48, 65, and 75 kDa. Partial amino acid sequences of the 32-, 65-, and 75-kDa proteins indicated that they are homologous to known bacterial chitinases. There was no homology found in the partial amino acid sequences of the 25- and 48-kDa proteins to any known chitinases. Five chitinase-active proteins were detected in the protein and chromatography fractions by activity gels, but when each protein was extracted and re-electrophoresed separately under denaturing conditions, only 32- or 48-kDa proteins were revealed. It was concluded that strain C3 produces at least two chitinases that are antifungal.

  5. New solid-state fermentation chamber for bulk production of aerial conidia of fungal biocontrol agents on rice.

    Science.gov (United States)

    Ye, S D; Ying, S H; Chen, C; Feng, M G

    2006-06-01

    A novel solid-state fermentation apparatus, namely an upright multi-tray conidiation chamber, was developed to facilitate the production of aerial conidia of fungal biocontrol agents, such as Beauveria bassiana. The chamber with 25 bottom-meshed metal trays had a capacity of > or =50 kg rice with each tray holding > or =2 kg. In repeated trials, a mean yield of 2.4 (1.8-2.7) x 10(12) conidia kg(-1) rice was harvested from the 7-day cultures of B. bassiana in a fully loaded chamber. The new apparatus has a high potential for bulk production of fungal conidia. PMID:16786244

  6. Biological control of the cucurbit powdery mildew pathogen Podosphaera xanthii by means of the epiphytic fungus Pseudozyma aphidis and parasitism as a mode of action

    Directory of Open Access Journals (Sweden)

    Aviva eGafni

    2015-03-01

    Full Text Available Epiphytic yeasts, which colonize plant surfaces, may possess activity that can be harnessed to help plants defend themselves against various pathogens. Due to their unique characteristics, epiphytic yeasts belonging to the genus Pseudozyma hold great potential for use as biocontrol agents. We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis. Here, we show that strain L12 of P. aphidis can reduce the severity of powdery mildew caused by Podosphaera xanthii on cucumber plants with an efficacy of 75%. Confocal and scanning electron microscopy analyses demonstrated P. aphidis proliferation on infected tissue and its production of long hyphae that parasitize the powdery mildew hyphae and spores as an ectoparasite. We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta. Our results suggest that in addition to its antibiosis mode of action, P. aphidis may also act as an ectoparasite on P. xanthii. These results indicate that P. aphidis strain L12 has the potential to control powdery mildew.

  7. Biological control of the cucurbit powdery mildew pathogen Podosphaera xanthii by means of the epiphytic fungus Pseudozyma aphidis and parasitism as a mode of action.

    Science.gov (United States)

    Gafni, Aviva; Calderon, Claudia E; Harris, Raviv; Buxdorf, Kobi; Dafa-Berger, Avis; Zeilinger-Reichert, Einat; Levy, Maggie

    2015-01-01

    Epiphytic yeasts, which colonize plant surfaces, may possess activity that can be harnessed to help plants defend themselves against various pathogens. Due to their unique characteristics, epiphytic yeasts belonging to the genus Pseudozyma hold great potential for use as biocontrol agents. We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis. Here, we show that strain L12 of P. aphidis can reduce the severity of powdery mildew caused by Podosphaera xanthii on cucumber plants with an efficacy of 75%. Confocal and scanning electron microscopy analyses demonstrated P. aphidis proliferation on infected tissue and its production of long hyphae that parasitize the powdery mildew hyphae and spores as an ectoparasite. We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta. Our results suggest that in addition to its antibiosis as mode of action, P. aphidis may also act as an ectoparasite on P. xanthii. These results indicate that P. aphidis strain L12 has the potential to control powdery mildew. PMID:25814995

  8. Draft Whole-Genome Sequence of the Biocontrol Agent Trichoderma harzianum T6776.

    Science.gov (United States)

    Baroncelli, Riccardo; Piaggeschi, Giulia; Fiorini, Lisa; Bertolini, Edoardo; Zapparata, Antonio; Pè, Mario Enrico; Sarrocco, Sabrina; Vannacci, Giovanni

    2015-01-01

    Trichoderma harzianum T6776 is a promising beneficial isolate whose effects consist of growth promotion, positive response of photosynthetic activity, hormonal signaling, and carbon partitioning in tomato, coupled with biocontrol of plant pathogens. Here, we present the first genome assembly of T6776, providing a useful platform for the scientific community. PMID:26067977

  9. 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.

  10. Screening of Pseudomonas sp. Isolated from Rhizosphere of Soybean Plant as Plant Growth Promoter and Biocontrol Agent

    Directory of Open Access Journals (Sweden)

    Aris T. Wahyudi

    2011-01-01

    Full Text Available Problem statement: Pseudomonas spesies are one of the rihizobacterial group that have an important role in plant growth promoter and plant health. To prepare them as inoculants, they must have a range of characters as growth promoter such as Indole Acetic Acid (IAA producers which can promote the growth of plants and solubilize phosphates. In addition, they must also have the various characters that act as biocontrol agents such as siderofor, chitinase and anti-fungal compound producers. Approach: Pseudomonas sp isolated from soybeans rhizospere and identified based on physiological reactions and 16S rRNA gene sequences. Various tests for the determination of the growth promoter were based on IAA production, phosphate solubilization and growth promoter of length of root and stems and number of lateral roots of soybean sprouts. Test of siderophore, chitinase, as well as anti anti-fungal compounds productions to inhibit the growth of Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii, were used as a biocontrol agent determination. Hypersensitivity test was used to screen for Pseudomonas sp classified as non-pathogenic rhizobacteria. Results: Fourteen isolates identified as a non-pathogenic Pseudomonas sp that produced IAA and Promoted enhancement of root length, shoot length, or number of lateral root. Among those 14 isolates, 8 isolates showed phosphate solubilizing activity, 12 isolates capable of producing siderophore and six isolates were observed to have chitinolytic activity. Only three isolates were able to inhibit the growth of Fusarium oxysporum in high level. While one and two isolates inhibited Sclerotium rolfsii and Rhizoctonia solani in high level, respectively. Conclusion: On the basis of excellent growth promoter and biocontrol activities, we recommended 5 isolates of Pseudomonas sp which were Crb-3, Crb-16, Crb-17, Crb-44 and Crb-94 as potential isolates of Pseudomonas sp that could be applied as

  11. 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.

  12. A mutant of the nematophagous fungus Paecilomyces lilacinus (Thom) is a novel biocontrol agent for Sclerotinia sclerotiorum.

    Science.gov (United States)

    Yang, Fan; Abdelnabby, Hazem; Xiao, Yannong

    2015-12-01

    Sclerotinia sclerotiorum causes severe stem rot and yield loss in oilseed rape (Brassica napus L.) and other crops worldwide. Extensive studies have been conducted on Paecilomyces lilacinus as a nematophagous bioagent. However, no reports stated the effect of P. lilacinus as a biocontrol agent against oilseed rape rot S. sclerotiorum. This study describes such effect in lab and field trials using the new transformant pt361 derived from the wild strain P. lilacinus 36-1. Unlike the wild-type strain, the mutant pt361 showed high antagonistic effect against S. Sclerotiorum A. Under lab conditions, the pt361 inhibited (65%) radial mycelial growth of S. sclerotiorum in dual culture test producing 5.9 mm inhibition zone IZ in front of the S. sclerotiorum colony. Moreover, the cell-free filtrate of pt361 culture showed strong inhibitory effects (60.3-100%) on mycelial growth of S. sclerotiorum. In leaf detached assay, pt361 significantly (p rape stem rot, promoted growth and increased yield compared to the control and exceeded, at dose 100%, the action of the fungicide procymidone(®). In conclusion, the mutant pt361 of P. lilacinus is a novel and promising biocontrol agent against oilseed rape Sclerotinia stem rot. PMID:26521137

  13. Ecology of Anti-Biofilm Agents II: Bacteriophage Exploitation and Biocontrol of Biofilm Bacteria

    OpenAIRE

    Abedon, Stephen T.

    2015-01-01

    Bacteriophages are the viruses of bacteria. In the guise of phage therapy they have been used for decades to successfully treat what are probable biofilm-containing chronic bacterial infections. More recently, phage treatment or biocontrol of biofilm bacteria has been brought back to the laboratory for more rigorous assessment as well as towards the use of phages to combat environmental biofilms, ones other than those directly associated with bacterial infections. Considered in a companion ar...

  14. Polysaccharide Production Benefits Dry Storage Survival of the Biocontrol Agent Pseudomonas fluorescens S11:P:12 Effective Against Several Maladies of Stored Potatoes

    Science.gov (United States)

    Pseudomonas fluorescens S11:P:12 (NRRL B-21133) is a biological control agent able to suppress several potato diseases and sprouting. Notably, it produces a polysaccharide during liquid cultivation; and the objective of this work was to determine the role of this material in the bio-control process...

  15. Draft Genome Sequence of Cryptococcus flavescens Strain OH182.9_3C, a Biocontrol Agent against Fusarium Head Blight of Wheat

    OpenAIRE

    Rong, Xiaoqing; McSpadden Gardener, Brian B.

    2013-01-01

    Cryptococcus flavescens strain OH182.9_3C (3C) is a novel biopesticidal agent that can be used to control fusarium head blight of wheat. Here we present the draft genome sequence for 3C, the first for the species C. flavescens. Additionally, several genes that may contribute to the biocontrol activities of 3C were identified in silico.

  16. 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

    The production of bioactive polypeptides (peptaibiotics) in vivo is a sophisticated adaptation strategy of both mycoparasitic and saprotrophic Trichoderma species for colonizing and defending their natural habitats. This feature is of major practical importance, as the detection of peptaibiotics...... 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......®, Vitalin®, Promot® WP, and TrichoMax®, formulated with recently described species of the Trichoderma harzianum complex, viz. T. afroharzianum, T. simmonsii, and T. guizhouense. By using the well‐established, HPLC/MS‐based peptaibiomics approach, it could unequivocally be demonstrated that all...

  17. Potencial de la cepa CPA-8 de Bacillus subtilis como agente de biocontrol de enfermedades de postcosecha de fruta

    OpenAIRE

    Yánez Mandizábal, Viviana del Rocío

    2012-01-01

    La limitació en l’ús de fungicides per al control de malalties en postcollita de fruita és una problemàtica d’elevada magnitud en el sector fructícola actual. Degut a això l’ús d’estratègies alternatives com el control biològic microbià són fonamentals per a la producció de fruita de qualitat. Malgrat tot, el desenvolupament de programes de biocontrol eficaços requereix d’un coneixement profund de la capacitat de control i els mecanismes d’acció utilitzats per l’agent microbià ...

  18. In-vitro evaluation of fungicides, plant extracts and bio-control agents against rice blast pathogen magnaporthe oryzae couch

    International Nuclear Information System (INIS)

    Among 5 fungicides viz., Thiophanate-methyl, Carbendazim, Fosetyl-aluminium, Mancozeb and Copper oxychloride, used against the Magnaporthe oryzae, only Mancozeb appeared as the highly effective fungicide that completely inhibited the mycelial growth of the fungus. All other fungicides showed little effect at higher concentrations. The extracts of garlic (Allium sativum L.), neem (Azadirachta indica L.) and calatropis (Calotropis procera L.) when used against M. oryzae by food poisoning method, only higher dose of garlic completely inhibited the mycelial growth of the test fungus. Six bio-control agents viz., Trichoderma harzianum, Trichoderma polysporum, Trichoderma pseudokoningii, Gliocladium virens, Paecilomyces variotii and Paecilomyces lilacinus were used. Maximum mycelial inhibition of M. oryzae was provided by P. lilacinus followed by Trichoderma spp. (author)

  19. Isolation and identification of actinomycetes from a compost-amended soil with potential as biocontrol agents.

    Science.gov (United States)

    Cuesta, Gonzalo; García-de-la-Fuente, Rosana; Abad, Manuel; Fornes, Fernando

    2012-03-01

    The search for new biocontrol strategies to inhibit the growth of phytopathogenic microorganisms has become widely widespread due to environmental concerns. Among actinomycetes, Streptomyces species have been extensively studied since they have been recognized as important sources of antibiotics. Actinomycete strains were isolated from a calcareous soil, 2 two-phase olive mill waste ('alperujo') composts, and the compost-amended soil by using selective media, and they were then co-cultured with 5 phytopathogenic fungi and 1 bacterium to perform an in vitro antagonism assay. Forty-nine actinomycete strains were isolated, 12 of them showing a great antagonistic activity towards the phytopathogenic microorganisms tested. Isolated strains were identified by 16S rDNA sequence analysis and phenotypic procedures. Eleven isolates concerned the genus Streptomyces and 1 actinomycete with chitinolytic activity belonged to the genus Lechevalieria. PMID:21190787

  20. 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.

  1. 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

  2. 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.

  3. Seleção de bactérias endofíticas de tomateiro como potenciais agentes de biocontrole e de promoção de crescimento Screening of endophytic bacteria isolated from tomato plants as potencial biocontrol agents and growth promotion

    Directory of Open Access Journals (Sweden)

    Patrícia Baston Barretti

    2009-01-01

    Full Text Available Quarenta isolados bacterianos endofíticos de plantas sadias de tomateiro foram avaliados quanto à sua potencialidade como agentes de biocontrole de doenças do tomateiro. Foi realizada, em casa de vegetação, uma seleção massal utilizando-se Pseudomonas syringae pv. tomato e Alternaria solani, como patógenos desafiantes. Com base na média do número de lesões por planta, quatro isolados foram selecionados como potenciais agentes de biocontrole dessas enfermidades fúngica e bacteriana do tomateiro. Esses isolados foram identificados, por meio do sequenciamento do gene 16S do DNA ribossômico, como Acinetobacter johnsonii (UFV-E05, Serratia marcescens (UFV-E13, Sinorhizobium sp. (UFV-E25 e Bacillus megaterium (UFV-E26. Os mesmos isolados selecionados para o biocontrole também foram avaliados quanto à sua capacidade de promover o crescimento em plantas e somente S. marcescens (UFV-E13 proporcionou aumento na altura das plantas.Forty isolates of endophytic bacteria obtained from healthy tomato plants were tested for their potential as biocontrol agents of tomato diseases. A massal screening was performed at greenhouse using Pseudomonas syringae pv. tomato and Alternaria solani as challenging pathogens. Based on the average number of lesions per plant, four isolates were selected as potential agents of biocontrol of these tomato diseases caused by fungi and bacteria. These isolates were identified by 16S ribosomal DNA sequence analysis as Acinetobacter johnsonii (UFV-E05, Serratia marcescens (UFV-E13, Sinorhizobium sp. (UFV-E25 and Bacillus megaterium (UFV-E26. The four endophytes selected for biocontrol were also evaluated for their ability of promoting plant growth and only S. marcescens (UFV-E13 presented increase in the height of the plants.

  4. 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

  5. Novel Trichoderma polysporum Strain for the Biocontrol of Pseudogymnoascus destructans, the Fungal Etiologic Agent of Bat White Nose Syndrome.

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    Full Text Available White-nose syndrome (WNS, an emerging disease of hibernating bats, has rapidly spread across eastern North America killing millions of bats. Pseudogymnoascus destructans (Pd, the sole etiologic agent of WNS, is widespread and persistent in bat hibernacula. Control of Pd in the affected sites is urgently needed to break the transmission cycle while minimizing any adverse impact on the native organisms. We isolated a novel strain of Trichoderma polysporum (Tp from one of the caves at the epicenter of WNS zoonotic. Detailed experimental studies revealed: (1 Tp WPM 39143 was highly adapted to grow at temperatures simulating the cave environment (6°C-15°C, (2 Tp WPM 39143 restricted Pd colony growth in dual culture challenges, (3 Tp WPM 39143 caused four logs reduction of Pd colony forming units and genome copies in autoclaved soil samples from one of the WNS affected caves, (4 Tp WPM 39143 extract showed specific fungicidal activity against Pd in disk diffusion assay, but not against closely related fungus P. pannorum (Pp, (5 Tp WPM 39143 extract retained inhibitory activity after exposure to high temperatures, light and proteinase K, and (6 Inhibitory metabolites in Tp WPM 39143 extract comprised of water-soluble, high polarity compounds. These results suggest that Tp WPM 39143 is a promising candidate for further evaluation as a biocontrol agent of Pd in WNS affected sites.

  6. Complete genome sequence of Pseudomonas fluorescens strain PICF7, an indigenous root endophyte from olive (Olea europaea L.) and effective biocontrol agent against Verticillium dahliae.

    Science.gov (United States)

    Martínez-García, Pedro Manuel; Ruano-Rosa, David; Schilirò, Elisabetta; Prieto, Pilar; Ramos, Cayo; Rodríguez-Palenzuela, Pablo; Mercado-Blanco, Jesús

    2015-01-01

    Pseudomonas fluorescens strain PICF7 is a native endophyte of olive roots. Previous studies have shown this motile, Gram-negative, non-sporulating bacterium is an effective biocontrol agent against the soil-borne fungus Verticillium dahliae, the causal agent of one of the most devastating diseases for olive (Olea europaea L.) cultivation. Here, we announce and describe the complete genome sequence of Pseudomonas fluorescens strain PICF7 consisting of a circular chromosome of 6,136,735 bp that encodes 5,567 protein-coding genes and 88 RNA-only encoding genes. Genome analysis revealed genes predicting factors such as secretion systems, siderophores, detoxifying compounds or volatile components. Further analysis of the genome sequence of PICF7 will help in gaining insights into biocontrol and endophytism.

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

    OpenAIRE

    Aline S Romão-Dumaresq; Welington Luiz Araújo; Nicholas J Talbot; 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 t...

  8. In Vitro Evaluation Of Selected Plant Extracts As Biocontrol Agents Against Black Mold Aspergillus Niger Van Tieghem Of Onion Bulbs Allium Cepa L.

    OpenAIRE

    SAIFELDIN A. F. EL-NAGERABI; Awad H. M. Ahmed; ABDULKADIR E. ELSHAFIE

    2015-01-01

    Black mold disease caused by Aspergillus niger V. Tiegh. is the most devastating infection occurs in onions Allium cepa L. under field and store conditions. The use of biocontrol agents is ecofriendly approach for controlling seedborne and soilborne diseases compared to the use of toxic synthetic fungicides. This study has been designed to assess the contamination levels of onion seeds with A. niger and its effect on seed germination and to evaluate the in vitro antifungal activity of Prunus ...

  9. 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.

  10. Conservation of bio-control agents in cotton, gossypium hirsutum l. field by food supplements for insect pests management

    International Nuclear Information System (INIS)

    The study reports the use of artificial food sprays to conserve the parasitoids and predators for the management of insect pests in cotton field. Cotton crop was treated with bio-control agents, Chrysoperla carnea and Trichogramma chilonis alongwith different food attractants such as Protein hydrolysate and sugar alone and in combination in a randomized complete block design. Each treatment was applied on one-acre field with three replications. Results showed that the chemicals tested helped in increasing the populations of beneficial insects including; C. carnea, T. chilonis and Orius spp., in the field. The populations of C. carnea and T. chilonis were found the highest in the combined treatment of protein hydrolysate and sugar as compared to other treatments where protein hydrolysate and sugar were used separately. However, the population of Orius spp. was higher in the treatment where only sugar solution was sprayed as food supplement. Consequently, incorporation of food supplements in the trial increased the establishment of natural enemies and subsequently the predation/ parasitism percentage enhanced on the insect pests of cotton. (author)

  11. Effects of local vegetation and plantation age for the parasitoid Asecodes mento-a biocontrol agent in organic strawberry fields

    Institute of Scientific and Technical Information of China (English)

    Johan A.Stenberg

    2012-01-01

    The parasitoid Asecodes mento (Walker,1839) (Hymenoptera:Eulophidae)is the most important biocontrol agent of the strawberry leaf beetle Galerucella tenella (L.) (Coleoptera:Chrysomelidae) in northern Europe.Here,I investigated whether natural parasitism in organic strawberry plantations was affected by the presence of the alternative host plant meadowsweet (Filipendula ulmaria),and whether parasitism rates differed between plantations of different ages (6 to 79 years).I also investigated whether parasitoid brood size,body size and sex ratio differed between the two host plants in the field.Parasitism was very low (0%) in newly established plantations and increased to a plateau (~40%) in fields where strawberries had been grown for approximately 20 years or longer.Such an extended colonization process is unacceptable for commercial growers.It would thus be desirable to find a method to catalyze parasitoid population buildup in young plantations.Parasitoid brood sizes were larger in beetles collected from meadowsweet,while body size and sex ratio did not differ between parasitoids collected from the two plants.These findings suggest that meadowsweet can export parasitoids to neighboring strawberry fields.Although this is a possibility,I did not find any significant differences in parasitism rates between isolated strawberry fields and fields adjacent to meadowsweet stands,indicating that effects of local vegetation are small on parasitism rates.Releasing parasitoids in newly established strawberry plantations may be a better strategy for quickly obtaining high parasitism than intercropping with meadowsweet.

  12. Biology and host preferences of Cryptorhynchus melastomae (Coleoptera: Curculionidae), a possible biocontrol agent for Miconia calvescens (Melastomataceae) in Hawaii.

    Science.gov (United States)

    Reichert, Elisabeth; Johnson, M Tracy; Chacón, Eduardo; Anderson, Robert S; Wheeler, Terry A

    2010-12-01

    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 feeds on M. calvescens in its native Costa Rica and has been successfully reared under greenhouse conditions. Comparison of its environmental conditions in Costa Rica with those in the Miconia infested areas of Hawaii indicates the latter is a suitable habitat for C. melastomae. C. melastomae has one or two generations per year. Adults feed on new stems, petioles, leaf buds, veins, and lamina, whereas larvae mine the stem until pupation. Adults appear to prefer saplings for oviposition and feeding. Under greenhouse conditions both adults and larvae can seriously damage and kill small M. calvescens. Preliminary host testing indicates that C. melastomae may be family specific on Melastomataceae. However, because Hawaii lacks native melastomes and has many other serious melastome weeds, a family specific insect may be suitable as a biocontrol agent in this case. PMID:22182550

  13. Biocontrol agents-mediated suppression of oxalic acid induced cell death during Sclerotinia sclerotiorum-pea interaction.

    Science.gov (United States)

    Jain, Akansha; Singh, Akanksha; Singh, Surendra; Sarma, Birinchi Kumar; Singh, Harikesh Bahadur

    2015-05-01

    Oxalic acid (OA) is an important pathogenic factor during early Sclerotinia sclerotiorum-host interaction and might work by reducing hydrogen peroxide production (H2 O2 ). In the present investigation, oxalic acid-induced cell death in pea was studied. Pea plants treated with biocontrol agents (BCAs) viz., Pseudomonas aeruginosa PJHU15, Bacillus subtilis BHHU100, and Trichoderma harzianum TNHU27 either singly and/or in consortium acted on S. sclerotiorum indirectly by enabling plants to inhibit the OA-mediated suppression of oxidative burst via induction of H2 O2 . Our results showed that BCA treated plants upon treatment with culture filtrate of the pathogen, conferred the resistance via. significantly decreasing relative cell death of pea against S. sclerotiorum compared to control plants without BCA treatment but treated with the culture filtrate of the pathogen. The results obtained from the present study indicate that the microbes especially in consortia play significant role in protection against S. sclerotiorum by modulating oxidative burst and partially enhancing tolerance by increasing the H2 O2 generation, which is otherwise suppressed by OA produced by the pathogen.

  14. Evaluation of antifungal activity of carbonate and bicarbonate salts alone or in combination with biocontrol agents in control of citrus green mold.

    Science.gov (United States)

    Zamani, M; Sharifi Tehrani, A; Ali Abadi, A Alizadeh

    2007-01-01

    The aim of this research was to determine if the attacks of green mold on orange could be reduced by edible salts alone or in combination with biocontrol agent. For this purpose toxicity to Pantoea digitatum and practical use of sodium carbonate (SC), sodium bicarbonate (SBC) and potassium carbonate, and potassium bicarbonate alone or in combination with antagonistic bacteria (Pseudomonas fluorescens isolate PN, Bacillus subtilis isolate VHN, Pantoea agglomerans isolate CA) to control green mold were determined. All were fungistatic. SC and SBC were equal and superior to the other salts for control of green mold on oranges inoculated 6h before treatment and were chosen for subsequent trails under cold storage conditions. The biocontrol agents were found completely tolerant to 3% sodium bicarbonate and sodium carbonate at room temperature; although their culturability was reduced by > 1000-fold after 60 min in 1% other salt solutions. Satisfactory results were also obtained with the combined treatment for control of green mold. A significant increase in biocontrol activity of all isolate was observed when combined with sodium carbonate and sodium bicarbonate. The treatments comprising CA combined with SB was as effective as fungicide treatment. Thus, use of sodium bicarbonate treatment at 3% followed by the antagonist P. agglomerans CA could be an alternative to chemical fungicides for control of green mold on oranges. PMID:18396809

  15. Survival of the biocontrol agents Brevibacillus brevis ZJY-1 and Bacillus subtilis ZJY-116 on the spikes of barley in the field

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin; ZHANG Bing-xin; ZHANG Zhen; SHEN Wei-feng; YANG Ching-hong; YU Jing-quan; ZHAO Yu-hua

    2005-01-01

    Fusarium head blight (FHB) caused by Fusarium graminearum is a devastating disease that results in extensive yield losses to wheat and barley. A green fluorescent protein (GFP) expressing plasmid pRP22-GFP was constructed for monitoring the colonization of two biocontrol agents, Brevibacillus brevis ZJY-1 and Bacillus subtilis ZJY-116, on the spikes of barley and their effect on suppression of FHB. Survival and colonization of the Brevibacillus brevis ZJY- 1 and Bacillus subtilis ZJY- 116 strains on spikes of barley were observed by tracking the bacterial transformants with GFP expression. Our field study revealed that plasmid pRP22-GFP was stably maintained in the bacterial strains without selective pressure. The retrieved GFP-tagged strains showed that the bacterial population fluctuation accorded with that of the rain events. Furthermore, both biocontrol strains gave significant protection against FHB on spikes of barley in fields. The greater suppression of barley FHB disease was resulted from the treatment of barley spikes with biocontrol agents before inoculation with F. graminearum.

  16. Trichoderma harzianum as a biocontrol agent against Alternaria alternata on tobacco

    Directory of Open Access Journals (Sweden)

    Jugoslav Ziberoski

    2012-06-01

    Full Text Available Trichoderma fungi are the most popular agents used in a biological control. Therefore, our aim was to determine an impact of Trichoderma harzianum on the fungus Alternaria alternata - a causing agent of the brown spot disease on tobacco. In vitro analyses were made in several variants of double culture, in order to study the effect of difusible and volatile metabolites. There was strong reducing effect on the development of A.alternata with various mechanisms of antagonistic influence. The volatile metabolites have also shown reducing effect. Some abnormalities were observed in the pathogen's morphology both in difusible and volatile metabolites. The strong reducing effect of T.harzianum towards A. alternata can be applied in biological control of this pathogen.

  17. 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.

  18. 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

  19. Peptaibol, secondary-metabolite, and hydrophobin pattern of commercial biocontrol agents formulated with species of the Trichoderma harzianum complex.

    Science.gov (United States)

    Degenkolb, Thomas; Fog Nielsen, Kristian; Dieckmann, Ralf; Branco-Rocha, Fabiano; Chaverri, Priscila; Samuels, Gary J; Thrane, Ulf; von Döhren, Hans; Vilcinskas, Andreas; Brückner, Hans

    2015-04-01

    The production of bioactive polypeptides (peptaibiotics) in vivo is a sophisticated adaptation strategy of both mycoparasitic and saprotrophic Trichoderma species for colonizing and defending their natural habitats. This feature is of major practical importance, as the detection of peptaibiotics 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(®) , Vitalin(®) , Promot(®) WP, and TrichoMax(®) , formulated with recently described species of the Trichoderma harzianum complex, viz. T. afroharzianum, T. simmonsii, and T. guizhouense. By using the well-established, HPLC/MS-based peptaibiomics approach, it could unequivocally be demonstrated that all of these formulations contained new and recurrent peptaibols, i.e., peptaibiotics carrying an acetylated N-terminus, the C-terminus of which is reduced to a 1,2-amino alcohol. Their chain lengths, including the amino alcohol, were 11, 14, and 18 residues, respectively. Peptaibols were also to be the dominating secondary metabolites in plate cultures of the four strains obtained from four of the Trichoderma- based BCAs, contributing 95% of the UHPLC-UV/VIS peak areas and 99% of the total ion count MS peak area from solid media. Furthermore, species-specific hydrophobins, as well as non-peptaibiotic secondary 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.

  20. Peptaibol, secondary-metabolite, and hydrophobin pattern of commercial biocontrol agents formulated with species of the Trichoderma harzianum complex.

    Science.gov (United States)

    Degenkolb, Thomas; Fog Nielsen, Kristian; Dieckmann, Ralf; Branco-Rocha, Fabiano; Chaverri, Priscila; Samuels, Gary J; Thrane, Ulf; von Döhren, Hans; Vilcinskas, Andreas; Brückner, Hans

    2015-04-01

    The production of bioactive polypeptides (peptaibiotics) in vivo is a sophisticated adaptation strategy of both mycoparasitic and saprotrophic Trichoderma species for colonizing and defending their natural habitats. This feature is of major practical importance, as the detection of peptaibiotics 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(®) , Vitalin(®) , Promot(®) WP, and TrichoMax(®) , formulated with recently described species of the Trichoderma harzianum complex, viz. T. afroharzianum, T. simmonsii, and T. guizhouense. By using the well-established, HPLC/MS-based peptaibiomics approach, it could unequivocally be demonstrated that all of these formulations contained new and recurrent peptaibols, i.e., peptaibiotics carrying an acetylated N-terminus, the C-terminus of which is reduced to a 1,2-amino alcohol. Their chain lengths, including the amino alcohol, were 11, 14, and 18 residues, respectively. Peptaibols were also to be the dominating secondary metabolites in plate cultures of the four strains obtained from four of the Trichoderma- based BCAs, contributing 95% of the UHPLC-UV/VIS peak areas and 99% of the total ion count MS peak area from solid media. Furthermore, species-specific hydrophobins, as well as non-peptaibiotic secondary 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. PMID:25879509

  1. Osmotically induced trehalose and glycine betaine accumulation improves tolerance to desiccation, survival and efficacy of the postharvest biocontrol agent Pantoea agglomerans EPS125.

    Science.gov (United States)

    Bonaterra, Anna; Camps, Jaume; Montesinos, Emilio

    2005-09-01

    The application of the biocontrol agent Pantoea agglomerans EPS125 to unwounded fruits was practically ineffective for control of postharvest blue mould caused by Penicillium expansum when the treatment and subsequent wounding and pathogen inoculation were separated by periods of unfavourable conditions. This was due to a rapid decrease in viability of the alocthonous introduced biocontrol agent in the intact peel surface. A system for osmoadaptation of the biocontrol agent was developed by combining saline osmotic stress and osmolyte amendment to the growth medium. Osmoadapted cells accumulated trehalose and glycine betaine (GB) intracellularly and showed a higher tolerance to desiccation than non-osmoadapted cells. Osmoadaptation in NaCl plus GB during inoculum preparation increased considerably survival on the peel surface of apple fruits. This effect was significant under low relative humidity (RH) and fluctuating RH conditions, but was not significant at high RH. Osmoadaptation significantly improved blue mould control under conditions where the standard biological control treatments were ineffective. The rot diameter was significantly reduced in apple fruits which were treated with EPS125 and incubated for several days under low, high or fluctuating RH, followed by wounding and inoculation of P. expansum. Growth of EPS125 with NaCl, either with or without the addition of GB, was an effective osmoadaptation treatment for improving blue mould rot control. However, the addition of GB to the NaCl amended growth medium increased 4-5-fold growth rate and OD of the cultures. This is an advantage for mass production of P. agglomerans EPS125 in a NaCl amended growth medium.

  2. Caracterización de películas biodegradables con la incorporación de un agente de biocontrol

    OpenAIRE

    TORREGROSA MORENO, BELÉN

    2016-01-01

    [ES] El control biológico es una de las alternativas más eficientes y prácticas a los fungicidas químicos para el control de enfermedades producidas por hongos en agricultura. Su aplicación práctica no ha tenido lugar en gran medida por la sensibilidad de los agentes de biocontrol (ABCs) a condiciones ambientales adversas, que dan lugar a variabilidad y poca reproducibilidad en los resultados. Se ha trabajado con el ABC Candida sake, una levadura efectiva en el control de enfer...

  3. Biocontrol of Rhizoctonia solani, the causal agent of bean damping-off by fluorescent pseudomonads.

    Science.gov (United States)

    Afsharmanesh, H; Ahmadzadeh, M; Sharifi-Tehrani, A

    2006-01-01

    Rhizosphere bacteria belonging to the fluorescent pseudomonads are receiving increasing attention for the protection of plants against soil-borne fungal pathogens. Among these pathogens, Rhizoctonia solani, the causal agent of bean damping- off is very important in bean fields of Iran. In this study, the antagonistic activity of 46 isolates of fluorescent pseudomonads (isolated from different area of Iran) and Pseudomonas fluorescens strain CHA0 investigated against one isolate of R. solani. About 64% of isolates revealed antagonistic activity against R. solani. Production of antifungal metabolites such as HCN, siderophore and protease was evaluated. The results showed that 97.8%, 17% and 78% of isolates produced siderophore, HCN and protease respectively. There was no significant correlation between antagonistic activity and production of these metabolites. Isolates P-5, P-10 and P-32 with strain CHA0 were selected in order to investigate involvement of siderophore, volatile metabolites (HCN), and non-volatile metabolites in reducing mycelial growth of R. olani. Isolate P-5 showed much more inhibitory effect by production of volatile metabolites and siderophore. Non-volatile metabolites in isolates P-32 and P-5 completely inhibited mycelial growth of the fungus. After the primary labrotory tests, isolates P-14, P-35, P-30, P-5 and strain CHA0 were selected for in vivo experiments. These selected isolates with benomyl fungicide were used as seed coating and soil drenching in sterile soil under greenhouse condition. The result indicated that in seed treatment method, isolates P-30 by 66% had the most effect in disease reduction while in soil treatment method, strain CHAO by 60% had the most effect, such that this two isolates showed significant differences in comparison with plants inoculated with R. solani inoculums. PMID:17390854

  4. 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.

  5. The effect of locust bean gum (LBG)-based edible coatings carrying biocontrol yeasts against Penicillium digitatum and Penicillium italicum causal agents of postharvest decay of mandarin fruit.

    Science.gov (United States)

    Parafati, Lucia; Vitale, Alessandro; Restuccia, Cristina; Cirvilleri, Gabriella

    2016-09-01

    Strains belonging to Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans species were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic molds Penicillium digitatum and Penicillium italicum. Moreover, studies aimed at screening the antifungal activity of selected yeast strains in vivo conditions against P. digitatum and P. italicum, and investigated the efficacy of a polysaccharidic matrix, locust bean gum (LBG), enriched with the tested BCAs, in controlling postharvest decays in artificially inoculated mandarins. The population dynamics of BCAs on wounds and the magnitude of peroxidase (POD) and superoxide dismutase (SOD) in fruit tissues were also investigated after treatments of mandarins with antagonistic yeasts. W. anomalus BS91, M. pulcherrima MPR3 and A. pullulans PI1 provided excellent control of postharvest decays caused by P. digitatum and P. italicum on mandarins, both when the yeasts were used alone and in combination with LBG, which enhanced the yeast cell viability over time. Finally, the increased activity of POD and lower decrease in SOD activity in response to BCAs application in mandarin fruits confirmed their involvement in the biocontrol mechanism. PMID:27217363

  6. Postharvest Biocontrol: Introspection and Paradigm Shifts

    Science.gov (United States)

    The use of postharvest biocontrol agents as an alternative to the synthetic, chemical fungicides on a widespread basis has many constraints. During the last twenty years, the field of postharvest biocontrol research has significantly grown and developed and seen the creation of several products. Des...

  7. Typhlodromus pyri and Euseius finlandicus (Acari: Phytoseiidae) as potential biocontrol agents against spider mites (Acari: Tetranychidae) inhabiting willows: laboratory studies on predator development and reproduction on four diets.

    Science.gov (United States)

    Puchalska, Ewa K; Kozak, Marcin

    2016-01-01

    Typhlodromus pyri Scheuten and Euseius finlandicus (Oudemans) are important predators of phytophagous mites. The present laboratory study aimed to determine whether both species can develop and reach maturity feeding on spider mites occurring on willows, i.e., Schizotetranychus schizopus (Zacher), Schizotetranychus garmani Pritchard & Baker, and Tetranychus urticae Koch, and on Brassica napus L. pollen. The predators' development, reproduction and demographic parameters were significantly affected by diet. The data suggest that rape pollen can be useful in mass rearing of E. finlandicus but is completely unsuitable as alternative food for T. pyri. Short development time and high values of population parameters achieved by T. pyri feeding on larvae and protonymphs of S. schizopus and by E. finlandicus feeding on juvenile stages of S. garmani indicate great suitability of these preys as food for the phytoseiids, and make both predatory species promising biocontrol agents in spider mite control on willows. PMID:26530991

  8. Typhlodromus pyri and Euseius finlandicus (Acari: Phytoseiidae) as potential biocontrol agents against spider mites (Acari: Tetranychidae) inhabiting willows: laboratory studies on predator development and reproduction on four diets.

    Science.gov (United States)

    Puchalska, Ewa K; Kozak, Marcin

    2016-01-01

    Typhlodromus pyri Scheuten and Euseius finlandicus (Oudemans) are important predators of phytophagous mites. The present laboratory study aimed to determine whether both species can develop and reach maturity feeding on spider mites occurring on willows, i.e., Schizotetranychus schizopus (Zacher), Schizotetranychus garmani Pritchard & Baker, and Tetranychus urticae Koch, and on Brassica napus L. pollen. The predators' development, reproduction and demographic parameters were significantly affected by diet. The data suggest that rape pollen can be useful in mass rearing of E. finlandicus but is completely unsuitable as alternative food for T. pyri. Short development time and high values of population parameters achieved by T. pyri feeding on larvae and protonymphs of S. schizopus and by E. finlandicus feeding on juvenile stages of S. garmani indicate great suitability of these preys as food for the phytoseiids, and make both predatory species promising biocontrol agents in spider mite control on willows.

  9. In Vitro Evaluation Of Selected Plant Extracts As Biocontrol Agents Against Black Mold Aspergillus Niger Van Tieghem Of Onion Bulbs Allium Cepa L.

    Directory of Open Access Journals (Sweden)

    Saifeldin A. F. El-Nagerabi

    2015-08-01

    Full Text Available Black mold disease caused by Aspergillus niger V. Tiegh. is the most devastating infection occurs in onions Allium cepa L. under field and store conditions. The use of biocontrol agents is ecofriendly approach for controlling seedborne and soilborne diseases compared to the use of toxic synthetic fungicides. This study has been designed to assess the contamination levels of onion seeds with A. niger and its effect on seed germination and to evaluate the in vitro antifungal activity of Prunus mahaleb seeds Commiphora myrrha resin 0.5 1.0 1.5 2.0 g100 ml Syzygium aromaticum dry buds clove and Panax ginseng roots extracts 0.5 1.0 2.0 2.5 g100 ml against black mold of onion bulbs. The fungus is seedborne pathogen which significantly contaminated onion seeds 89-100 and reduced seed germination 39-83. The extracts of clove caused 43-96 inhibition in spore germination followed by mahaleb 37-96 myrrha 33-88 and ginseng 34-87. The highest concentration of these extracts 3.0 did not affect seed germination but significantly reduced seed contamination by A. niger up to 84 80 71 and 65 for Syzygium aromaticum Syzygium aromaticum Panax ginseng and Prunus mahaleb respectively. The extracts apparently inhibited the fungal growth and mold development on stored onion bulbs which indicates the antifungal property of these extracts against A. niger. Therefore they can be recommended as effective biocontrol agents to reduce seed contamination and enhance the storability of onion bulbs. Thus the use of healthy and certified seeds for onion production is a priority.

  10. Identification of Volatiles Produced by Cladosporium cladosporioides CL-1, a Fungal Biocontrol Agent That Promotes Plant Growth

    Directory of Open Access Journals (Sweden)

    Diby Paul

    2013-10-01

    Full Text Available Certain microbial Volatile Organic Compounds (VOCs have been reported to enhance the growth and development of plants. The biocontrol fungi, Cladosporium cladosporioides CL-1 significantly improved the growth of tobacco seedlings in vitro when they were co-cultivated without physical contact. SPME Quadrupole GC/MS/MS revealed that CL-1 emited the volatiles α-pinene, (−-trans-caryophyllene, tetrahydro-2,2,5,5-tetramethylfuran, dehydroaromadendrene, and (+-sativene. Potential roles of these volatiles in plant growth and development are discussed. Even though there were several fungal VOCs reported in the past that could influence plant growth, their exact mechanisms of action are not fully known. Fungal VOC-mediated plant growth promotion requires in-depth study in order for this technology to be used in large scale for crops, especially those grown under greenhouse conditions.

  11. Identification of volatiles produced by Cladosporium cladosporioides CL-1, a fungal biocontrol agent that promotes plant growth.

    Science.gov (United States)

    Paul, Diby; Park, Kyung Seok

    2013-10-16

    Certain microbial Volatile Organic Compounds (VOCs) have been reported to enhance the growth and development of plants. The biocontrol fungi, Cladosporium cladosporioides CL-1 significantly improved the growth of tobacco seedlings in vitro when they were co-cultivated without physical contact. SPME Quadrupole GC/MS/MS revealed that CL-1 emited the volatiles α-pinene, (-)-trans-caryophyllene, tetrahydro-2,2,5,5-tetramethylfuran, dehydroaromadendrene, and (+)-sativene. Potential roles of these volatiles in plant growth and development are discussed. Even though there were several fungal VOCs reported in the past that could influence plant growth, their exact mechanisms of action are not fully known. Fungal VOC-mediated plant growth promotion requires in-depth study in order for this technology to be used in large scale for crops, especially those grown under greenhouse conditions.

  12. Colonization and degradation of senescent flowers of zucchini squash by Trichoderma harzianum YC459, a biocontrol agent of gray mold, Botrytis cinerea

    Institute of Scientific and Technical Information of China (English)

    Geun Gon Kim; Young Ryun Chung

    2004-01-01

    @@ In commercial greenhouses, senescent flower petals or flowers of vegetables such as tomato,strawberry, hot pepper and zucchini squash were blighted to be removed from fruits within five days after spraying of Trichoderna harzianun YC459 (TORY() , JGreen Inc.), a biocontrol agent with good and consistent efficacy as chemical fungicides for the control of gray mold rot caused by B.cinerea. The mechanism for selective colonization of senescent floral tissues by T. harzianum YCA59was elucidated using fresh and senescent (4 days and 14 days after pollination, respectively) floral tissues of zucchini squash (Cucurbita moschata Duchesne) . The spores of T. harzianum YCA59were produced much more on water agar and liquid culture media supplemented with 5% dry powder of senescent floral tissues than with fresh tissues during 15 days incubation. Mycelial growth was also much better in the media with senescent tissues than with fresh tissues. Enzyme activities of carboxymethyl cellulase, amylase and polygalacturonase in the liquid media, which might be involved in the colonization and degradation of tissues by T. harzianum YCA59 were compared. The activities of three enzymes were significantly higher in the media with senescent floral tissues than with fresh floral tissues reaching to the maximum during 9 to 12 days of incubation. Especially, the activities of carboxymethyl cellulase and polygalacturonase of T. harzianum YC459 were much higher than those of other Trichoderma species, T. asperellum, T. viride and T. koningii in the liquid media with senescent floral tissues. Based on the results, the selective colonization and degradation of senescent floral tissues, an important habitat for B. cinerea, may be another mechanism for the biocontrol of gray mold rot of vegetables by T. harzianurm YC459.

  13. Biocontrol of Botrytis allii Munn the Causal Agent of Neck Rot, the Post Harvest Disease in Onion, by use of a New Iranian Isolate of Streptomyces

    Directory of Open Access Journals (Sweden)

    M. Jorjandi

    2009-01-01

    Full Text Available Problem statement: Soil actinomycetes particularly Streptomyces spp. showed antagonistic activity against wide range of plant pathogens. In the recent decades they have attracted high interests as biocontrol agents. Onion neck rot or gray mold caused by Botrytis allii have imposed economic post harvest damages to onion bulbs and decreased its storage durability and market value. Approach: To investigate for biocontrol means against the pathogen, antagonistic activity of 50 isolates of soil Actinomycetes were assayed through agar disk method and dual culture bioassays. Active isolates were exposed to chloroform for detection of antibiotic. Minimum Inhibitory Concentration (MIC value and solubility of active crude extract in organic solvents were determined for Streptomyces isolate No. 347 which showed a unique and stable property of inhibiting Botrytis allii. To investigate the antagonistic effect of Streptomyces isolate No. 347 on control of onion gray mold, 4 different treatments were tested by means of Tukey HSD test. Results: From the tested isolates, 13 showed anti gray mold activities. Exposure of active isolates to chloroform revealed that Streptomyces isolates No. 347, 263 and 350 retained their antifungal activities. The active metabolite(s of Streptomyces isolate No. 347 was polar, soluble in H2O but insoluble in chloroform and methanol. MIC of the crude was determined as 0.05 mg mL-1 against B. allii. Stability of the active crude in distilled water at room temperature (12-30°C was about 6 months. Statistical studies indicated that Streptomyces isolates No. 347 can decrease losses of neck rot with significant level (pConclusion: The future goals include investigation of the antifungal genes in active isolates as candidates for genetic engineering of onion for increased tolerance against B. allii.

  14. 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.

  15. Functional analysis of the class II hydrophobin gene HFB2-6 from the biocontrol agent Trichoderma asperellum ACCC30536.

    Science.gov (United States)

    Huang, Ying; Mijiti, Gulijimila; Wang, Zhiying; Yu, Wenjing; Fan, Haijuan; Zhang, Rongshu; Liu, Zhihua

    2015-02-01

    A class II hydrophobin gene, HFB2-6, was cloned from Trichoderma asperellum ACCC30536 and its biocontrol function was studied. According to our previous transcriptome data, six of the eight class II hydrophobin genes were obviously differential expression in four inducing conditions, especially the gene HFB2-6. Moreover, HFB2-6 proven to be differentially transcribed under eight different treatments. HFB2-6 transcripts were up-regulated under 1% Alternaria alternata cell wall and 5% A. alternata fermentation liquid treatments, and by nutritional stress conditions, suggesting that HFB2-6 plays roles in interactions with both biotic and abiotic environmental conditions. HFB2-6 expression was down-regulated under 1% poplar leaf powder culture conditions, but its expression was up-regulated under 1% poplar root powder, indicating that HFB2-6 has a function in root colonization. Furthermore, the recombinant hydrophobin rHFB2-6 was successfully expressed in Escherichia coli BL21-HFB2-6 and purified from the recombinant strain. Genes related to both the jasmonic acid and salicylic acid signal transduction pathways were up-regulated by interaction with renatured rHFB2-6. The ORCA3 (octadecanoid-derivative responsive Catharanthus AP2-domain) gene of the poplar jasmonic acid signal transduction pathway showed a peak expression of 4.48 times at 2 h, and the peak expression of PR1 (pathogenesis-related protein gene) in the salicylic acid signal transduction pathway was 4.58 times at 72 h. Two genes, MP (monopteros) and GH3.17 (auxin original response gene), in the auxin signal transduction pathway were also up-regulated after induction with rHFB2-6, indicating that rHFB2-6 can promote poplar growth and confer broad-spectrum resistance to pathogens.

  16. 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. PMID:25305653

  17. Isolation of Stem rot Disease Causing Organism of Brinjal and their in-vitro Inhibition with Fungicides and Bio-control Agents

    Directory of Open Access Journals (Sweden)

    Shaily Javeria

    2014-09-01

    Full Text Available Different strains of Sclerotinia sclerotiorum were isolated from the diseased samples collected from different hosts and locations. Among the 14 isolates, 12 isolates colonies covered the entire Petri plates within 96 hours but, two isolates from fababean and yellow mustard showed slow colony growth within 96 hours. All isolates produced sclerotia which were varied in number, but the fenugreek isolate produced maximum (43 number of sclerotia and lambs quarter isolate produced minimum number of sclerotia (12 on PDA medium. To examine inhibitory effect of fungicide on the mycelial growth of the pathogen, 9 fungicides were tested in vitro against Sclerotinia sclerotiorum, of those carbendazim, carboxin, topsin-M and carbendazim+ mancozeb (SAAF were found most effective and inhibited the mycelial growth of pathogen up to 100 per cent at 0.05%, 0.1%, and 0.2% concentration. The effect of different bioagents viz., Trichoderma harzianum, T. viride, T. koningii, T. atroviride, T. longibraciatum, Aspergillus niger, Chaetomium globosome and Penicillium notatum in inhibiting the growth of Sclerotinia sclerotiorum was studied through “Dual Culture Technique”. The data showed that among the eight biocontrol agent six were fond effective. The maximum inhibition was found by T. harzianum causing 70.82% inhibition of mycelial growth of the pathogen S. sclerotiorum.

  18. Pseudozyma aphidis fungemia after abdominal surgery: First adult case

    Directory of Open Access Journals (Sweden)

    Agathe Herb

    2015-06-01

    Full Text Available Pseudozyma aphidis is an environmental Basidiomycete yeast, and has been involved in the ten past years in rare cases of invasive infection. Pseudozyma species are naturally resistant to caspofungin and often present decreased susceptibility or resistance to fluconazole. This fungus may be difficult to recognize and misidentifications are reported with conventional phenotypical methods. We report a case of P. aphidis invasive infection in an adult with a metastatic ampulloma who had gone through digestive surgery.

  19. Pseudozyma aphidis fungemia after abdominal surgery: First adult case

    OpenAIRE

    Agathe Herb; Marcela Sabou; Jean-Baptiste Delhorme; Patrick Pessaux; Didier Mutter; Ermanno Candolfi; Valérie Letscher-Bru

    2015-01-01

    Pseudozyma aphidis is an environmental Basidiomycete yeast, and has been involved in the ten past years in rare cases of invasive infection. Pseudozyma species are naturally resistant to caspofungin and often present decreased susceptibility or resistance to fluconazole. This fungus may be difficult to recognize and misidentifications are reported with conventional phenotypical methods. We report a case of P. aphidis invasive infection in an adult with a metastatic ampulloma who had gone thro...

  20. Pseudozyma aphidis fungemia after abdominal surgery: First adult case.

    Science.gov (United States)

    Herb, Agathe; Sabou, Marcela; Delhorme, Jean-Baptiste; Pessaux, Patrick; Mutter, Didier; Candolfi, Ermanno; Letscher-Bru, Valérie

    2015-06-01

    Pseudozyma aphidis is an environmental Basidiomycete yeast, and has been involved in the ten past years in rare cases of invasive infection. Pseudozyma species are naturally resistant to caspofungin and often present decreased susceptibility or resistance to fluconazole. This fungus may be difficult to recognize and misidentifications are reported with conventional phenotypical methods. We report a case of P. aphidis invasive infection in an adult with a metastatic ampulloma who had gone through digestive surgery. PMID:25870786

  1. Effects of selected pesticides and adjuvants on germination and vegetative growth of Phomopsis amaranthicola, a biocontrol agent for Amaranthus spp.

    OpenAIRE

    Wyss, G. S.; Charudattan, R.; Rosskopf, E.; Littell, R.

    2004-01-01

    Summary: Phomopsis amaranthicola, a bioherbicide agent for Amaranthus spp., was tested in vitro for its compatibility with commercial formulations of 16 adjuvants, 24 herbicides, nine fungicides and four insecticides at 2X, 1X (highest labelled product dose rate), 0.75X, 0.5X and 0.25X concentrations. These chemicals were tested for their effects on spore germination. Selected herbicides and fungicides at 1X were also tested for their influence on colony growth and sporulation. All tested ...

  2. Screening Commercially Available Entomopathogenic Biocontrol Agents for the Control of Aethina tumida (Coleoptera: Nitidulidae) in the UK

    OpenAIRE

    Budge, Giles E.; Brown, Mike A; Stephane Pietravalle; Gay Marris; Powell, Michelle E.; Andrew G. S. Cuthbertson; Blackburn, Lisa F.; Mathers, James J.

    2012-01-01

    The Small hive beetle, Aethina tumida, is an invasive pest of honey bees. Indigenous to sub-Saharan Africa, it has now become established in North America and Australia. It represents a serious threat to European honey bees. Commercially available entomopathogenic agents were screened for their potential to control beetle larvae. Entomopathogenic fungi investigated had minimal impact. The nematodes Steinernema kraussei and

  3. The Biocontrol Agent Phlebiopsis gigantea: Efficacy and Impacts on the Stump Bacterial Biota and Conifer tree Defences

    OpenAIRE

    Sun, Hui

    2011-01-01

    Phlebiopsis gigantea has been for a long time known as a strong competitor against Heterobasidion annosum and intensively applied as a biological control agent on stump surfaces of Picea abies in Fennoscandia. However, the mechanism underlying its antagonistic activity is still unknown. A primary concern is the possible impact of P. gigantea treatment on resident non-target microbial biota of conifer stumps. Additional risk factor is the potential of P. gigantea to acquire a necrotrophic habi...

  4. Suppression of the biocontrol agent trichoderma harzianum by mycelium of the arbuscular mycorrhizal fungus glomus intraradices in root-free soil

    Science.gov (United States)

    Green; Larsen; Olsson; Jensen; Jakobsen

    1999-04-01

    Trichoderma harzianum is an effective biocontrol agent against several fungal soilborne plant pathogens. However, possible adverse effects of this fungus on arbuscular mycorrhizal fungi might be a drawback in its use in plant protection. The objective of the present work was to examine the interaction between Glomus intraradices and T. harzianum in soil. The use of a compartmented growth system with root-free soil compartments enabled us to study fungal interactions without the interfering effects of roots. Growth of the fungi was monitored by measuring hyphal length and population densities, while specific fatty acid signatures were used as indicators of living fungal biomass. Hyphal 33P transport and beta-glucuronidase (GUS) activity were used to monitor activity of G. intraradices and a GUS-transformed strain of T. harzianum, respectively. As growth and metabolism of T. harzianum are requirements for antagonism, the impact of wheat bran, added as an organic nutrient source for T. harzianum, was investigated. The presence of T. harzianum in root-free soil reduced root colonization by G. intraradices. The external hyphal length density of G. intraradices was reduced by the presence of T. harzianum in combination with wheat bran, but the living hyphal biomass, measured as the content of a membrane fatty acid, was not reduced. Hyphal 33P transport by G. intraradices also was not affected by T. harzianum. This suggests that T. harzianum exploited the dead mycelium but not the living biomass of G. intraradices. The presence of external mycelium of G. intraradices suppressed T. harzianum population development and GUS activity. Stimulation of the hyphal biomass of G. intraradices by organic amendment suggests that nutrient competition is a likely means of interaction. In conclusion, it seemed that growth of and phosphorus uptake by the external mycelium of G. intraradices were not affected by the antagonistic fungus T. harzianum; in contrast, T. harzianum was adversely

  5. 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...

  6. 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. PMID:27565489

  7. IN-VITRO EVALUATION OF FUNGICIDES, BIOCONTROL AGENTS AND PLANT EXTRACTS AGAINST RICE SHEATH BLIGHT PATHOGEN RHIZOCTONIA SOLANI

    Directory of Open Access Journals (Sweden)

    P. Srinivas

    2014-02-01

    Full Text Available Of the fourteen fungicides of different groups evaluated in-vitro against Rhizoctonia solani , Metalaxyl (0.1%, Mancozeb (0.1%, Tricyclazole (0.1%, Thiophenate methyl (0.1%, Carbendizm+ Mancozeb (0.1% were proved to be most effective in inhibiting the growth of the fungus. Among the bio-agents screened, Trichoderma viride was most effective in restricting the growth of Rhizoctonia solani followed by Penicillium notatum where as Aspergillus niger was proved least effective. Among the thirteen plant extracts evaluated garlic extract (10% was most effective in inhibiting the growth of fungus followed by calotropis (10%. Datura leaf extract (10% was found to be least effective in inhibiting the growth of Rhizoctonia solani.

  8. Screening Commercially Available Entomopathogenic Biocontrol Agents for the Control of Aethina tumida (Coleoptera: Nitidulidae) in the UK.

    Science.gov (United States)

    Cuthbertson, Andrew G S; Mathers, James J; Blackburn, Lisa F; Powell, Michelle E; Marris, Gay; Pietravalle, Stephane; Brown, Mike A; Budge, Giles E

    2012-08-09

    The Small hive beetle, Aethina tumida, is an invasive pest of honey bees. Indigenous to sub-Saharan Africa, it has now become established in North America and Australia. It represents a serious threat to European honey bees. Commercially available entomopathogenic agents were screened for their potential to control beetle larvae. Entomopathogenic fungi investigated had minimal impact. The nematodes Steinernema kraussei and S. carpocapsae provided excellent control with 100% mortality of larvae being obtained. Sequential applications of the nematodes following larvae entering sand to pupate also provided excellent control for up to 3 weeks. The information gained supports the development of contingency plans to deal with A. tumida should it occur in the UK, and is relevant to the management of Small hive beetle where it is already present.

  9. Screening Commercially Available Entomopathogenic Biocontrol Agents for the Control of Aethina tumida (Coleoptera: Nitidulidae) in the UK.

    Science.gov (United States)

    Cuthbertson, Andrew G S; Mathers, James J; Blackburn, Lisa F; Powell, Michelle E; Marris, Gay; Pietravalle, Stephane; Brown, Mike A; Budge, Giles E

    2012-01-01

    The Small hive beetle, Aethina tumida, is an invasive pest of honey bees. Indigenous to sub-Saharan Africa, it has now become established in North America and Australia. It represents a serious threat to European honey bees. Commercially available entomopathogenic agents were screened for their potential to control beetle larvae. Entomopathogenic fungi investigated had minimal impact. The nematodes Steinernema kraussei and S. carpocapsae provided excellent control with 100% mortality of larvae being obtained. Sequential applications of the nematodes following larvae entering sand to pupate also provided excellent control for up to 3 weeks. The information gained supports the development of contingency plans to deal with A. tumida should it occur in the UK, and is relevant to the management of Small hive beetle where it is already present. PMID:26466625

  10. Complete Genome Sequence of Biocontrol Strain Pseudomonas fluorescens LBUM 223

    OpenAIRE

    Roquigny, Roxane; Arseneault, Tanya; Gadkar, Vijay J.; Novinscak, Amy; Joly, David L.; Filion, Martin

    2015-01-01

    Pseudomonas fluorescens LBUM 223 is a plant growth-promoting rhizobacterium (PGPR) with biocontrol activity against various plant pathogens. It produces the antimicrobial metabolite phenazine-1-carboxylic acid, which is involved in the biocontrol of Streptomyces scabies, the causal agent of common scab of potato. Here, we report the complete genome sequence of P. fluorescens LBUM 223.

  11. Q69 (an E. faecalis-Infecting Bacteriophage) As a Biocontrol Agent for Reducing Tyramine in Dairy Products.

    Science.gov (United States)

    Ladero, Victor; Gómez-Sordo, Carolina; Sánchez-Llana, Esther; Del Rio, Beatriz; Redruello, Begoña; Fernández, María; Martín, M Cruz; Alvarez, Miguel A

    2016-01-01

    Biogenic amines (BAs) are low molecular weight nitrogenous compounds with biological activity, formed from amino acids by decarboxylation. BAs are naturally present in all living organisms playing essential roles. However, their accumulation in food through the metabolic activity of certain microorganisms constitutes a toxicological hazard. Among foods, cheeses accumulate some of the highest concentrations of BAs since they provide an ideal environment for their accumulation. Most of the methods proposed for reducing BAs in cheese, such as milk pasteurization, have not only failed to completely solve the problem, they also affect non-BA producing lactic acid bacteria, i.e., the bacteria that participate in the development of the organoleptic characteristics of cheese. Novel technologies specifically targeted against BA producers are therefore needed to control BA accumulation. Bacteriophages have been proposed as agents for specifically controlling the presence of foodborne pathogens in food. Due to its specificity, they could be used as a biotechnological tool targeted to reduce the population of BA-producing bacteria. The present work reports the isolation, from cheese, and the characterization of bacteriophage Q69, which infects specifically Enterococcus faecalis, the species mainly responsible of the accumulation of the BA tyramine in foods. Furthermore, its capacity to reduce the accumulation of tyramine in different conditions -including a model cheese- was proven. The obtained results open up the possibility of use bacteriophages to prevent BA accumulation in fermented foods. PMID:27092117

  12. Q69, an E. faecalis-infecting bacteriophage, as a biocontrol agent for reducing tyramine in dairy products

    Directory of Open Access Journals (Sweden)

    Victor eLadero

    2016-04-01

    Full Text Available Biogenic amines (BAs are low molecular weight nitrogenous compounds with biological activity, formed from amino acids by decarboxylation. BAs are naturally present in all living organisms playing essential roles. However, their accumulation in food through the metabolic activity of certain microorganisms constitutes a toxicological hazard. Among foods, cheeses accumulate some of the highest concentrations of BAs since they provide an ideal environment for their accumulation. Most of the methods proposed for reducing BAs in cheese, such as milk pasteurisation, have not only failed to completely solve the problem, they also affect non-BA producing lactic acid bacteria (LAB, i.e., the bacteria that participate in the development of the organoleptic characteristics of cheese. Novel technologies specifically targeted against BA producers are therefore needed to control BA accumulation. Bacteriophages have been proposed as agents for specifically controlling the presence of foodborne pathogens in food. Due to its specificity, they could be used as a biotechnological tool targeted to reduce the population of BA-producing bacteria. The present work reports the isolation, from cheese, and the characterisation of bacteriophage Q69, which infects specifically Enterococcus faecalis, the species mainly responsible of the accumulation of the BA tyramine in foods. Furthermore, its capacity to reduce the accumulation of tyramine in different conditions –including a model cheese- was proven. The obtained results open up the possibility of use bacteriophages to prevent BA accumulation in fermented foods.

  13. Bacteriophage biocontrol of foodborne pathogens.

    Science.gov (United States)

    Kazi, Mustafa; Annapure, Uday S

    2016-03-01

    Bacteriophages are viruses that only infect bacterial cells. Phages are categorized based on the type of their life cycle, the lytic cycle cause lysis of the bacterium with the release of multiple phage particles where as in lysogenic phase the phage DNA is incorporated into the bacterial genome. Lysogeny does not result in lysis of the host. Lytic phages have several potential applications in the food industry as biocontrol agents, biopreservatives and as tools for detecting pathogens. They have also been proposed as alternatives to antibiotics in animal health. Two unique features of phage relevant for food safety are that they are harmless to mammalian cells and high host specificity, keeping the natural microbiota undisturbed. However, the recent approval of bacteriophages as food additives has opened the discussion about 'edible viruses'. This article reviews in detail the application of phages for the control of foodborne pathogens in a process known as "biocontrol". PMID:27570260

  14. Draft Genome Sequences of Pseudomonas fluorescens Strains SF39a and SF4c, Potential Plant Growth Promotion and Biocontrol Agents.

    Science.gov (United States)

    Ly, Lindsey K; Underwood, Grace E; McCully, Lucy M; Bitzer, Adam S; Godino, Agustina; Bucci, Vanni; Brigham, Christopher J; Príncipe, Analía; Fischer, Sonia E; Silby, Mark W

    2015-03-26

    Pseudomonas fluorescens SF4c and SF39a, strains isolated from wheat rhizosphere, have potential applications in plant growth promotion and biocontrol of fungal diseases of crop plants. We report the draft genome sequences of SF4c and SF39a with estimated sizes of 6.5 Mb and 5.9 Mb, respectively.

  15. 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.

  16. Accumulation of cellobiose lipids under nitrogen-limiting conditions by two ustilaginomycetous yeasts, Pseudozyma aphidis and Pseudozyma hubeiensis.

    Science.gov (United States)

    Morita, Tomotake; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2013-02-01

    Some basidiomycetous yeast strains extracellularly produce cellobiose lipids (CLs), glycolipid biosurfactants which have strong fungicidal activity. The representative CL producer Ustilago maydis produces CLs together with the other glycolipids, mannosylerythritol lipids (MELs); the preference of the two glycolipids is affected considerably by the nitrogen source. To develop new CL producers, 12 MEL producers were cultured under the nitrogen-limited conditions. Pseudozyma aphidis and Pseudozyma. hubeiensis were characterized as new CL producers. CL production was induced on three strains, P. aphidis, Pseudozyma graminicola, and P. hubeiensis under these conditions. The putative homologous genes of U. maydis cyp1, which encodes a P450 monooxygenase, essential for CL biosynthesis, were partially amplified from their genomic DNA. The nucleotide sequences of the gene fragments from P. hubeiensis and P. aphidis shared identities with U. maydis cyp1 of 99% and 78%, respectively. Furthermore, all of the deduced translation products are tightly clustered in the phylogenic tree of the monooxygenase. These results suggest that the genes involved with CL biosynthesis must be widely distributed in the basidiomycetous fungi as well as the MEL biosynthesis genes, and thus, the genus Pseudozyma has great potential as a biosurfactant producer. PMID:22985214

  17. Characterization of PhlG, a Hydrolase That Specifically Degrades the Antifungal Compound 2,4-Diacetylphloroglucinol in the Biocontrol Agent Pseudomonas fluorescens CHA0

    OpenAIRE

    Bottiglieri, Mélanie; Keel, Christoph

    2006-01-01

    The potent antimicrobial compound 2,4-diacetylphloroglucinol (DAPG) is a major determinant of biocontrol activity of plant-beneficial Pseudomonas fluorescens CHA0 against root diseases caused by fungal pathogens. The DAPG biosynthetic locus harbors the phlG gene, the function of which has not been elucidated thus far. The phlG gene is located upstream of the phlACBD biosynthetic operon, between the phlF and phlH genes which encode pathway-specific regulators. In this study, we assigned a func...

  18. Biocontrol Ability and Action Mechanism of Starmerella bacillaris (Synonym Candida zemplinina) Isolated from Wine Musts against Gray Mold Disease Agent Botrytis cinerea on Grape and Their Effects on Alcoholic Fermentation.

    Science.gov (United States)

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

    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 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 5 days, a concentration of 10(6) 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 glicerol 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. This work

  19. Biocontrol Ability and Action Mechanism of Starmerella bacillaris (Synonym Candida zemplinina) Isolated from Wine Musts against Gray Mold Disease Agent Botrytis cinerea on Grape and Their Effects on Alcoholic Fermentation

    Science.gov (United States)

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

    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 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 5 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 glicerol 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. This work introduces

  20. The relationship of biofilm production to biocontrol activity of Burkholderia pyrrocinia FP62

    Science.gov (United States)

    Foliar biocontrol agent (BCA) efficacy is often inconsistent due to poor colonization and survival on plant surfaces. Burkholderia pyrrocinia FP62, a superior leaf colonist and BCA of Botrytis cinerea, forms unsaturated biofilms on plant surfaces. To determine the relationship between biocontrol act...

  1. Advances in biocontrol mechanism and application of Trichoderma spp. for plant diseases

    Institute of Scientific and Technical Information of China (English)

    HUANG Caihong; YANG Qian

    2007-01-01

    Trichoderma spp. is a filamentous soil fungus known as an effective biocontrol agent of a range of important airborne and soilborne pathogens, it has universal distribution and economic importance. This article reviewed the researches on biocontrol mechanism for plant diseases and application of Trichoderma spp., especially Trichoderma harzianum in recent years.

  2. Yeast microflora of nectarines and their potential for biocontrol of brown rot

    Science.gov (United States)

    Resident fruit microflora has been the source of biocontrol agents for the control of postharvest decays of fruits and the active ingredient in commercialized biocontrol products. With the exception of grapes and apples, information on the resident microflora of other fruits is only fragmentary; ho...

  3. 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. PMID:20542109

  4. 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

  5. Potential analysis of grass endophytes Neotyphodium as biocontrol agents%禾草内生真菌作为生防因子的潜力分析

    Institute of Scientific and Technical Information of China (English)

    李秀璋; 姚祥; 李春杰; 南志标

    2015-01-01

    Many grasses in the subfamily Pooideae develop symbioses with Neotyphodium fungal endophytes, which exist widely in nature. The stably symbiotic relationship not only ensures accessible nutrients required by Neotypho-dium fungal endophytes, but also significantly increases the resistance of host grasses to biological stresses through the production of secondary metabolites. Previous studies show that infected grasses with endophytic fungi have prominently enhanced resistance to pests, plant diseases, companion plants and other biological stresses. Grass endophytic fungi show remarkable resistant to at least 79 species of pests from three classes;arachnida, nematode and insecta, and to at least 22 species of pathogenic fungi. Although the biotechnological application of endophytic fungi in grass breeding for variety selection and quality improvement has progressed well, opportunities remain for further exploring the use of fungal endophytes among different host grasses coupled with the examination of genetic stability of Neotyphodium in novel host grasses. In the future application of endophytic fungi as a bio-control method, researchers should not only consider specificities of host grasses, but also need to have comprehensive analysis and knowledge about the mutual relationships among grasses, endo-phytic fungi and ecological environments, which will help use endophytic fungi to better serve humanity.%早熟禾亚科多种禾草可与Neotyphodium内生真菌形成禾草-内生真菌共生体,这种植物-微生物共生体性状较为稳定,且在自然界中广泛存在。禾草-内生真菌共生体稳定的互利共生关系不但保证了内生真菌所需的全部营养物质,而且共生体产生的次生代谢物又可显著提高宿主禾草对生物胁迫的抗逆性。众多研究表明,内生真菌的侵染可显著提高宿主禾草对虫害、病害及伴生植物等多种生物胁迫的抗性。据不完全统计,禾草内生真菌对蛛

  6. Interregional comparison of the size-structure of populations of Melaleuca quinquenervia in its native and exotic range, with and without biocontrol agents

    Science.gov (United States)

    We compare size structure and rates of recruitment and mortality in populations of Melaleuca quinquenervia in its native and exotic ranges. In the exotic range study sites were chosen to include contrasts in presence and abundance of two biological control agents. We tagged and measured (DBH) all ...

  7. Polysaccharide benefits dry storage survival of the biocontrol agent Pseudomonas fluorescens S11:P:12 effective against several maladies of stored potatoes

    Science.gov (United States)

    Pseudomonas fluorescens S11:P:12 (NRRL B-21133) is a biological control agent able to suppress several storage maladies of potatoes including sprouting, Fusarium dry rot incited by Gibberella pulicaris, pink rot incited by Phytophthora erythroseptica, and late blight incited by Phytophthora infestan...

  8. Physiological differences in the formation of the glycolipid biosurfactants, mannosylerythritol lipids, between Pseudozyma antarctica and Pseudozyma aphidis.

    Science.gov (United States)

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2007-02-01

    Vegetable oil is the usual carbon source for the production of biosurfactants (BS), mannosylerythritol lipids (MEL). To simplify the procedures of BS production and recovery, we investigated the extracellular production of MEL from water-soluble carbon sources instead of vegetable oils by using two representative yeast strains. The formation of extracellular MEL from glucose was confirmed by thin layer chromatography (TLC) and HPLC analysis. On glucose cultivation, pure MEL were easily prepared by only solvent extraction of the culture medium, different from the case of soybean oil cultivation. The fatty acid profile of the major MEL produced from glucose was similar to that produced from soybean oil based on GC-MS analysis. The resting cells of Pseudozyma antarctica T-34 produced MEL by feeding of glucose only and gave a yield of 12 g l(-1). In contrast, Pseudozyma aphidis ATCC 32657 gave no MEL from glucose. Moreover, the extracellular lipase activities were detected at high levels during the cultivation regardless of the carbon sources. These results indicate that all the biosynthesis pathways for MEL in P. antarctica T-34 should constitutively function. In conclusion, P. antarctica T-34 thus has potential for BS production from glucose. PMID:17103161

  9. 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.

  10. Screening Commercially Available Entomopathogenic Biocontrol Agents for the Control of Aethina tumida (Coleoptera: Nitidulidae in the UK

    Directory of Open Access Journals (Sweden)

    Giles E. Budge

    2012-08-01

    Full Text Available The Small hive beetle, Aethina tumida, is an invasive pest of honey bees. Indigenous to sub-Saharan Africa, it has now become established in North America and Australia. It represents a serious threat to European honey bees. Commercially available entomopathogenic agents were screened for their potential to control beetle larvae. Entomopathogenic fungi investigated had minimal impact. The nematodes Steinernema kraussei and S. carpocapsae provided excellent control with 100% mortality of larvae being obtained. Sequential applications of the nematodes following larvae entering sand to pupate also provided excellent control for up to 3 weeks. The information gained supports the development of contingency plans to deal with A. tumida should it occur in the UK, and is relevant to the management of Small hive beetle where it is already present.

  11. 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

  12. 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

  13. 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; Choi, In-Geol; Kim, Ki Deok

    2016-01-01

    Strain KJ1R5 of the rhizobacterium ITALIC! Chryseobacterium kwangjuenseis an effective biocontrol agent against Phytophthora blight of pepper caused by a destructive soilborne oomycete, ITALIC! 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

  14. Laboratory evaluation ofLimnatis nilotica leech (Annelida:Hirudinea) as a biocontrol agent for the schistosome-vector snail,Bulinus truncatus

    Institute of Scientific and Technical Information of China (English)

    Yassir Sulieman; Abdel-Aziz A Ahmed; Azzam Afifi; Theerakamol Pengsakul

    2015-01-01

    Objective:To investigate the predation efficacy of the freshwater leech,Limnatis nilotica(L. nilotica) as a potential biological control agent against different stages of theBulinus truncatus (B. truncatus), the intermediate host of humanSchistosoma haematobium, under laboratory conditions. Methods:The leechL. nilotica and the snailB. truncatus were collected from El Kiryab Agriculture Scheme, Sudan. Thereafter, the predatory activity of the leech was evaluated against eggs, neonates and adults of the snail in a series of different experiments under laboratory conditions. Results:The findings showed that theL. nilotica leech was a voracious predator towards the eggs and neonates ofB. truncatus snails with a shell length of up to 3 mm, as well as of adult snails with an shell length greater than 3 mm. Conclusions: The results showed thatL. nilotica had a significant impact onB. truncatus populations. However, long term studies under natural field conditions are needed to support these results.

  15. 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. PMID:27664721

  16. 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

  17. 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

  18. Pseudozyma spp catheter-associated blood stream infection, an emerging pathogen and brief literature review.

    Science.gov (United States)

    Siddiqui, Wajid; Ahmed, Yasir; Albrecht, Helmut; Weissman, Sharon

    2014-01-01

    Pseudozyma spp are amorphic yeasts. They are commonly plant pathogens, but rarely cause invasive fungal disease in humans. Only three cases of central venous catheter (CVC)-associated blood stream infections due to this organism have been reported in the literature. Main underlying risk factors for Pseudozyma spp infection are bowel surgery, CVC and total parenteral nutrition. We present a rare case of Pseudozyma spp catheter-associated blood stream infection that was successfully treated with antifungal therapy and removal of CVC. It is important to recognise and differentiate this species from other yeasts as it may require the use of amphotericin B or voriconazole instead of fluconazole, to which the organism is variably resistant. PMID:25498807

  19. Biocontrol: Bacillus penetrans and Related Parasites of Nematodes

    OpenAIRE

    Sayre, R. M.

    1980-01-01

    Bacillus penetrans Mankau, 1975, previously described as Duboscqia penetrans Thorne 1940, is a candidate agent for biocontrol of nematodes. This review considers the life stages of this bacterium: vegetative growth phase, colony fragmentation, sporogenesis, soil phase, spore attachment, and penetration into larvae of root-knot nematodes. The morphology of the microthallus colonies and the unusual external features of the spore are discussed. Taxonomic affinities with the actinomycetes, partic...

  20. Antifungal Activity of Flocculosin, a Novel Glycolipid Isolated from Pseudozyma flocculosa

    OpenAIRE

    Mimee, Benjamin; Labbé, Caroline; Pelletier, René; Bélanger, Richard R.

    2005-01-01

    Flocculosin, a glycolipid isolated from the yeast-like fungus Pseudozyma flocculosa, was investigated for in vitro antifungal activity. The compound displayed antifungal properties against several pathogenic yeasts. Synergistic activity was observed between flocculosin and amphotericin B, and no significant cytotoxicity was demonstrated when tested against human cell lines.

  1. Yeast extract stimulates production of glycolipid biosurfactants, mannosylerythritol lipids, by Pseudozyma hubeiensis SY62.

    Science.gov (United States)

    Konishi, Masaaki; Nagahama, Takahiko; Fukuoka, Tokuma; Morita, Tomotake; Imura, Tomohiro; Kitamoto, Dai; Hatada, Yuji

    2011-06-01

    We improved the culture conditions for a biosurfactant producing yeast, Pseudozyma hubeiensis SY62. We found that yeast extract greatly stimulates MEL production. Furthermore, we demonstrated a highly efficient production of MELs in the improved medium by fed-batch cultivation. The final concentration of MELs reached 129 ± 8.2g/l for one week. PMID:21393057

  2. 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

    The influence of the organic compounds tryptic soy broth, cellulose, glucose and chitosan on cucumber damping-off caused by Pythium aphanidermatum and biocontrol efficacy of the biocontrol agents (BCAs) Paenibacillus macerans and P. polymyxa were examined in a seedling emergence bioassay. Results...... 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...... effects against Pythium damping-off compared with the corresponding treatments with P. aphanidermatum alone, but the biocontrol efficacy depended on the type of organic compounds added. Both BCAs counteracted damping-off in treatments with TSB and chitosan. However, P. polymyxa counteracted damping...

  3. [Improvement of Trichoderma strains for biocontrol].

    Science.gov (United States)

    Benítez, T; Rey, M; Delgado-Jarana, J; Rincón, A M; Limón, M C

    2000-03-01

    The use of the fungal genus Trichoderma to control fungal plant diseases is a promising alternative to the use of chemical compounds. The aim of this work has been to obtain Trichoderma strains with improved capacity as biological control agents. To do so, the hydrolytic capacity on fungal cell walls of strains of the fungus Trichoderma harzianum has been increased. On one hand, transformation experiments with genes which coded for chitinases and glucanases have been carried out in T. harzianumstra ins. On the other hand, the medium composition has also been modified in order to eliminate proteolytic degradation of some of the overproduced enzymes. Finally, hybrid chitinolytic enzymes with substrate-binding domains have been produced as an alternative to obtain improved biocontrol strains. The transformant strains, when compared with the wild type, showed improved antifungal capacity against the phytopathogenic fungus Rhizoctonia solani, in in vitro experiments. PMID:15762779

  4. 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

  5. What magnitude are observed non-target impacts from weed biocontrol?

    Science.gov (United States)

    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 ...

  6. 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.

  7. 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.

  8. Augmentative Biocontrol in Natural Marine Habitats: Persistence, Spread and Non-Target Effects of the Sea Urchin Evechinus chloroticus

    OpenAIRE

    Javier Atalah; Hopkins, Grant A.; Forrest, Barrie M.

    2013-01-01

    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 Fiord...

  9. Direct xylan conversion into glycolipid biosurfactants, mannosylerythritol lipids, by Pseudozyma antarctica PYCC 5048(T).

    Science.gov (United States)

    Faria, Nuno Torres; Marques, Susana; Fonseca, César; Ferreira, Frederico Castelo

    2015-04-01

    Mannosylerythritol lipids (MEL) are glycolipid biosurfactants, produced by Pseudozyma spp., with increasing commercial interest. While MEL can be produced from d-glucose and d-xylose, the direct conversion of the respective lignocellulosic polysaccharides, cellulose and xylan, was not reported yet. The ability of Pseudozyma antarctica PYCC 5048(T) and Pseudozyma aphidis PYCC 5535(T) to use cellulose (Avicel(®)) and xylan (beechwood) as carbon and energy source has been assessed along with their capacity of producing cellulolytic and hemicellulolytic enzymes, toward a consolidated bioprocess (CBP) for MEL production. The yeasts assessed were neither able to grow in medium containing Avicel(®) nor produce cellulolytic enzymes under the conditions tested. On contrary, both yeasts were able to efficiently grow in xylan, but MEL production was only detected in P. antarctica PYCC 5048(T) cultures. MEL titers reached 1.3g/l after 10 days in batch cultures with 40g/l xylan, and 2.0g/l in fed-batch cultures with xylan feeding (additional 40g/l) at day 4. High levels of xylanase activities were detected in xylan cultures, reaching 47-62U/ml (31-32U/mg) at 50°C, and still exhibiting more than 10U/ml under physiological temperature (28°C). Total β-xylosidase activities, displayed mainly as wall-bounded and extracellular activity, accounted for 0.154 and 0.176U/ml in P. antarctica PYCC 5048(T) and P. aphidis PYCC 5535(T) cultures, respectively. The present results demonstrate the potential of Pseudozyma spp. for using directly a fraction of lignocellulosic biomass, xylan, and combining in the same bioprocess the production of xylanolytic enzymes with MEL production. PMID:25765311

  10. Draft Genome Sequence of Pseudozyma brasiliensis sp. nov. Strain GHG001, a High Producer of Endo-1,4-Xylanase Isolated from an Insect Pest of Sugarcane.

    Science.gov (United States)

    Oliveira, Juliana Velasco de Castro; Dos Santos, Renato Augusto Corrêa; Borges, Thuanny A; Riaño-Pachón, Diego Mauricio; Goldman, Gustavo Henrique

    2013-01-01

    Here, we present the nuclear and mitochondrial genome sequences of Pseudozyma brasiliensis sp. nov. strain GHG001. P. brasiliensis sp. nov. is the closest relative of Pseudozyma vetiver. P. brasiliensis sp. nov. is capable of growing on xylose or xylan as a sole carbon source and has great biotechnological potential. PMID:24356824

  11. 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.

  12. Characterization of the genus Pseudozyma by the formation of glycolipid biosurfactants, mannosylerythritol lipids.

    Science.gov (United States)

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Hiroko K; Kitamoto, Dai

    2007-03-01

    Pseudozyma antarctica is one of the best producers of the glycolipid biosurfactants known as mannosylerythritol lipids (MELs), which show not only excellent surface-active properties but also versatile biochemical actions. In order to obtain a variety of producers, all the species of the genus were examined for their production of MELs from soybean oil. Pseudozyma fusiformata, P. parantarctica and P. tsukubaensis were newly identified to be MEL producers. Of the strains tested, P. parantarctica gave the best yield of MELs (30 g L(-1)). The obtained yield corresponded to those of P. antarctica, P. aphidis and P. rugulosa, which are known high-level MEL producers. Interestingly, P. parantarctica and P. fusiformata produced mainly 4-O-[(4',6'-di-O-acetyl-2',3'-di-O-alkanoyl)-beta-d-mannopyranosyl]-meso-erythritol (MEL-A), whereas P. tsukubaensis produced mainly 4-O-[(6'-mono-O-acetyl-2',3'-di-O-alkanoyl)-beta-d-mannopyranosyl]-meso-erythritol (MEL-B). Consequently, six of the nine species clearly produced MELs. Based on the MEL production pattern, the nine species seemed to fall into four groups: the first group produces large amounts of MELs; the second produces both MELs and other biosurfactants; the third mainly produces MEL-B; and the fourth is non-MEL-producing. Thus, MEL production may be an important taxonomic index for the Pseudozyma yeasts. PMID:17328742

  13. What Magnitude Are Observed Non-Target Impacts from Weed Biocontrol?

    OpenAIRE

    David Maxwell Suckling; René François Henri Sforza

    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 (>9...

  14. Assessment of biocontrol strains for reduction of mycotoxins (aflatoxin and CPA) in maize

    Science.gov (United States)

    Aspergillus flavus strains K49, NRRL 21882 (from Afla-Guard®) and AF36 are being developed as biocontrol agents for the control of aflatoxin in maize. In this study, the three non-aflatoxigenic strains were compared to evaluate which is most effective in reducing aflatoxin. Also, we tested these st...

  15. 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. PMID:27688836

  16. Production and identification of mannosylerythritol lipid-A homologs from the ustilaginomycetous yeast Pseudozyma aphidis ZJUDM34.

    Science.gov (United States)

    Fan, Lin-Lin; Dong, Ya-Chen; Fan, Yi-Fei; Zhang, Jun; Chen, Qi-He

    2014-06-17

    Mannosylerythritol lipids (MELs) are mainly produced by strains of the genus Pseudozyma and by Ustilago maydis. These glycolipid biosurfactants exhibit not only excellent surface-active properties but also versatile bioactivities. Mannosylerythritol lipid-A (MEL-A) is worth investigating due to its self-assembling property. In this work, crude MELs were produced by resting Pseudozyma aphidis ZJUDM34 cells using different culture media. MEL-A fractions were isolated and identified using high-performance liquid chromatography combined with mass spectrometry (HPLC-MS) and gas chromatography combined with mass spectrometry (GC-MS). The results showed that MEL-A homologs had long unsaturated fatty acid chains, and the chain lengths range from C8 to C20. Nuclear magnetic resonance (NMR) was employed to confirm the chemical structures of the MEL-A homologs. Fermentation medium without NaNO3 and medium with manganese ions enhanced MEL-A production by Pseudozyma aphidis ZJUDM34. PMID:24814655

  17. Pseudozyma aphidis fungaemia with invasive fungal pneumonia in a patient with acute myeloid leukaemia: case report and literature review.

    Science.gov (United States)

    Joo, Hyonsoo; Choi, Yeon-Geun; Cho, Sung-Yeon; Choi, Jae-Ki; Lee, Dong-Gun; Kim, Hee-Je; Jo, Irene; Park, Yeon-Joon; Lee, Kyo-Young

    2016-01-01

    Pseudozyma species rarely cause invasive diseases in humans, which are usually isolated from plants. There have been anecdotal reports regarding Pseudozyma species infections in patients with underlying diseases or in neonates. However, clinical data and the pathogenicity in humans are still insufficient. We experienced a case of Pseudozyma aphidis fungaemia with invasive fungal pneumonia that developed during reinduction chemotherapy in a 51-year-old male with acute myeloid leukaemia (AML). P. aphidis was suspected based on the morphology of the yeast isolated from the blood and was confirmed via rDNA gene sequencing analysis. The patient successfully underwent stem cell transplantation with continuing antifungal treatment and finally completely recovered from both the AML and infectious complications. Here, we report a case of P. aphidis infection that developed during neutropenia in an AML patient and review the global literature. PMID:26608844

  18. Production of different types of mannosylerythritol lipids as biosurfactants by the newly isolated yeast strains belonging to the genus Pseudozyma.

    Science.gov (United States)

    Konishi, Masaaki; Morita, Tomotake; Fukuoka, Tokuma; Imura, Tomohiro; Kakugawa, Koji; Kitamoto, Dai

    2007-06-01

    Mannosylerythritol lipids (MEL), which are abundantly secreted by yeasts, are one of the most promising biosurfactants known. To obtain various types of MEL and to attain a broad range of applications for them, screening of novel producers was undertaken. Thirteen strains of yeasts were successfully isolated as potential MEL producers; they showed high production yields of MEL of around 20 g l(-1) from 40 g l(-1) of soybean oil. Based on the taxonomical study, all the strains were classified to be the genus Pseudozyma. It is interesting to note that they were categorized into three groups according to their production patterns of MEL. The first group, which included 11 strains taxonomically closely related to high-level MEL producers such as Pseudozyma antarctica and Pseudozyma aphidis, mainly produced 4-O-[(4',6'-di-O-acetyl-2',3'-di-O-alkanoyl)-beta-D-mannopyranosyl]-meso-erythritol (MEL-A) together with 4-O-[(6'-mono-O-acetyl-2',3'-di-O-alkanoyl)-beta-D-mannopyranosyl]-meso-erythritol (MEL-B) and 4-O-[(4'-mono-O-acetyl-2',3'-di-O-alkanoyl)-beta-D-mannopyranosyl]-meso-erythritol (MEL-C) as the minor components. The second group of one strain, which was related to Pseudozyma tsukubaensis, predominantly produced MEL-B. The third group of one strain, which was closely related to Pseudozyma hubeiensis, mainly produced MEL-C; this is the first observation of the efficient production of MEL-C from soybean oil. Moreover, the major fatty acids of the obtained MEL-C were C(6), C(12), and C(16) acids, and were considerably different from those of the other MEL hitherto reported. The biosynthetic manner for MEL is thus likely to significantly vary among the Pseudozyma strains; the newly isolated strains would enable us to attain a large-scale production of MEL and to obtain various types of MEL with different hydrophobic structures. PMID:17505770

  19. 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.

  20. 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. PMID:27147933

  1. Production of a novel glycolipid biosurfactant, mannosylmannitol lipid, by Pseudozyma parantarctica and its interfacial properties.

    Science.gov (United States)

    Morita, Tomotake; Fukuoka, Tokuma; Konishi, Masaaki; Imura, Tomohiro; Yamamoto, Shuhei; Kitagawa, Masaru; Sogabe, Atsushi; Kitamoto, Dai

    2009-07-01

    The development of a novel glycolipid biosurfactant was undertaken using the high-level producers of mannosylerythritol lipids (MELs) such as Pseudozyma parantarctica, Pseudozyma antarctica, and Pseudozyma rugulosa. Besides the conventional MELs (MEL-A, MEL-B, and MEL-C), these yeasts produced an unknown glycolipid when they were cultivated in a medium containing 4% (w/v) olive oil and 4% (w/w) mannitol as the carbon source. The unknown glycolipid extracted from the culture medium of P. parantarctica JCM 11752(T) displayed the spot with lower mobility than that of known MELs on TLC and provided mainly two peaks identical to mannose and mannitol on high-performance liquid chromatography after acid hydrolysis. Based on structural analysis by (1)H and (13)C nuclear magnetic resonance, the novel glycolipid was composed of mannose and mannitol as the hydrophilic sugar moiety and was identified as mannosylmannitol lipid (MML). Of the strains tested, P. parantarctica JCM 11752(T) gave the best yield of MML (18.2 g/L), which comprised approximately 35% of all glycolipids produced. We further investigated the interfacial properties of the MML, considering the unique hydrophilic structure. The observed critical micelle concentration (CMC) and the surface tension at CMC of the MML were 2.6 x 10(-6) M and 24.2 mN/m, respectively. In addition, on a water-penetration scan, the MML efficiently formed not only the lamella phase (Lalpha) but also the myelins at a wide range of concentrations, indicating its excellent self-assembling properties and high hydrophilicity. The present glycolipid should thus facilitate the application of biosurfactants as new functional materials. PMID:19296097

  2. Microbial conversion of glycerol into glycolipid biosurfactants, mannosylerythritol lipids, by a basidiomycete yeast, Pseudozyma antarctica JCM 10317(T).

    Science.gov (United States)

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2007-07-01

    Microbial conversion of glycerol into functional bio-based materials was investigated, aiming to facilitate the utilization of waste glycerol. A basidiomycete yeast, Pseudozyma antarctica JCM 10317, efficiently produced mannosylerythritol lipids (MELs) as glycolipid biosurfactants from glycerol. The amount of MEL yield reached 16.3 g l(-1) by intermittent feeding of glycerol. PMID:17697987

  3. Draft Genome Sequence of the Yeast Pseudozyma antarctica Type Strain JCM10317, a Producer of the Glycolipid Biosurfactants, Mannosylerythritol Lipids.

    Science.gov (United States)

    Saika, Azusa; Koike, Hideaki; Hori, Tomoyuki; Fukuoka, Tokuma; Sato, Shun; Habe, Hiroshi; Kitamoto, Dai; Morita, Tomotake

    2014-01-01

    The basidiomycetous yeast Pseudozyma antarctica is known as a producer of industrial enzymes and the extracellular glycolipids, mannosylerythritol lipids. Here, we report the draft genome sequence of the type strain JCM10317. The draft genome assembly has a size of 18.1 Mb and a G+C content of 60.9%, and it consists of 197 scaffolds. PMID:25291760

  4. Genome Sequence of the Basidiomycetous Fungus Pseudozyma aphidis DSM70725, an Efficient Producer of Biosurfactant Mannosylerythritol Lipids

    OpenAIRE

    Lorenz, Stefan; Guenther, Michael; Grumaz, Christian; Rupp, Steffen; Zibek, Susanne; Sohn, Kai

    2014-01-01

    Pseudozyma aphidis is an efficient producer of mannosylerythritol lipids exceeding concentrations of >100 g/liter from renewable feed stocks. Additionally, a biosurfactant cellobiose lipid is also secreted during nitrogen limitation. Here, we describe the sequencing of P. aphidis to unravel the genomic basis of biosurfactant metabolism in P. aphidis.

  5. Genome Sequence of the Basidiomycetous Fungus Pseudozyma aphidis DSM70725, an Efficient Producer of Biosurfactant Mannosylerythritol Lipids.

    Science.gov (United States)

    Lorenz, Stefan; Guenther, Michael; Grumaz, Christian; Rupp, Steffen; Zibek, Susanne; Sohn, Kai

    2014-01-01

    Pseudozyma aphidis is an efficient producer of mannosylerythritol lipids exceeding concentrations of >100 g/liter from renewable feed stocks. Additionally, a biosurfactant cellobiose lipid is also secreted during nitrogen limitation. Here, we describe the sequencing of P. aphidis to unravel the genomic basis of biosurfactant metabolism in P. aphidis. PMID:24526638

  6. 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.

  7. A basidiomycetous yeast, Pseudozyma crassa, produces novel diastereomers of conventional mannosylerythritol lipids as glycolipid biosurfactants.

    Science.gov (United States)

    Fukuoka, Tokuma; Kawamura, Mayo; Morita, Tomotake; Imura, Tomohiro; Sakai, Hideki; Abe, Masahiko; Kitamoto, Dai

    2008-11-24

    Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by the yeast strains of the genus Pseudozyma. These compounds show not only excellent surface-active properties, but also versatile biochemical actions. During a survey of new MEL producers, we found that a basidiomycetous yeast, Pseudozyma crassa, extracellularly produces three glycolipids. When glucose and oleic acid were used as the carbon source, the total amount of glycolipids reached approximately 4.6g/L in the culture medium. The structures of these glycolipids were similar to those of well-known MEL-A, -B, and -C, respectively. Very interestingly, in all the present glycolipids, the configuration of the erythritol moiety was entirely opposite to that of conventional MELs. The present glycolipids were identified to have the carbohydrate structure of 4-O-beta-D-mannopyranosyl-(2R,3S)-erythritol, stereochemically different from 4-O-beta-D-mannopyranosyl-(2S,3R)-erythritol of conventional MELs. Furthermore, these new glycolipids possessed both short-chain acids (C(2) or C(4)) and long-chain acids (C(14), C(16), or C(18)) on the mannose moiety. The major component of the present glycolipids clearly showed different interfacial and biological properties, compared to conventional MELs comprising two medium-chain acids on the mannose moiety. Accordingly, the novel MEL diastereomers produced by P. crassa should provide us with different glycolipid functions, and facilitate a broad range of applications of MELs. PMID:18805521

  8. Production of glycolipid biosurfactants, mannosylerythritol lipids, by Pseudozyma siamensis CBS 9960 and their interfacial properties.

    Science.gov (United States)

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2008-05-01

    The search for a novel producer of glycolipid biosurfactants, mannosylerythritol lipids (MELs), was undertaken on the basis of the analysis of ribosomal DNA sequences of yeast strains of the genus Pseudozyma. In the course of the investigation, Pseudozyma siamensis CBS 9960, which is closely related to Pseudozyma shanxiensis, a known MEL-C producer but with a different morphology, was found to accumulate a large amount of glycolipids. On thin layer chromatography, the extracellular glycolipids showed nearly the same spots as those of the MELs produced by P. shanxiensis. However, the result of high-performance liquid chromatography analysis revealed that the present strain has a much higher glycolipid production yield than P. shanxiensis. From the structural characterization by (1)H and (13)C NMR, the major glycolipid (more than 84% of the total) was identified as a mixture of 4-O-[(2',4'-di-O-acetyl-3'-O-alka(e)noyl)-beta-D-mannopyranosyl]-D-erythritol and 4-O-[(4'-O-acetyl-3'-O-alka(e)noyl-2'-O-butanoyl)-beta-D-mannopyranosyl]-D-erythritol, both of which are types of MEL-C. The present MEL-C possessed a short-chain acid (C(2) or C(4)) at the C-2' position and a long-chain acid (C(16)) at the C-3' position of the mannose moiety, and thus, the hydrophobic part was considerably different from that of conventional MELs, which mainly possess two medium-chain acids (C(10)) at the C-2' and C-3' positions. Under optimal growth conditions with safflower oil in a shake culture, the total amount of MELs reached approximately 19 g/l after 9 d at 25 degrees C. We further investigated the interfacial properties of the present MEL-C, considering its unique hydrophobic structure. The observed critical micelle concentration (CMC) and the surface tension at the CMC of the MEL were 4.5 x 10(-6) M and 30.7 mN/m, respectively. In addition, on a water penetration scan, the MEL efficiently formed the liquid crystal phases such as hexagonal (H) and lamella (L(a)) at a wide range of

  9. Biocontrol of Escherichia coli O157:H7 on fresh-cut lettuce and cantaloupe by treatment with bacteriophage

    Science.gov (United States)

    Introduction: Outbreaks of foodborne illness have been associated with the consumption of cantaloupes and fresh-cut lettuce. Bacteriophage mixtures may be effective biocontrol agents to reduce E. coli O157:H7 on produce. Purpose: The effectiveness of a mixture of bacteriophages (ECP-100) in reducin...

  10. 生物防治白僵菌与家蚕病原白僵菌的生物学特性初步比较%A Preliminary Comparison on Biological Characteristics of Biocontrol Agent Beauveria bassiana and Silkworm Pathogen Beauveria bassiana

    Institute of Scientific and Technical Information of China (English)

    刘吉平; 吕思行; 米红霞

    2011-01-01

    In order to provide experimental data for the source-tracking and control of white muscardine disease and for safety assessment of applying Beauveria bassiana insecticide in silkworm rearing areas, PDA medium and scanning electron microscopy were used for isolation, identification and observation of 2 biocontrol agents, namely B. bassiana strain Bb2 used for forest protection in Guangzhou City and B. bassiana strain Bb7 preserved in the South China Agricultural University, and of 3 B. bassiana isolates collected in Guangdong provincial silkworm rearing areas at Huazhou Silkworm Eggs Production Farm, Daqiao Village of Huazhou City, and Xiao Village of Wengyuan County, respectively. A prelimina ry comparison was conducted on the biological characteristics between the above5 strains. The results showed that there existed differences on the colonial morphology, vegetative growth, spore quantity and other biological characteristics of the 5 strains. Among them, strain Bb2 grew the fastest, and strains Bb8 and Bb13 had the highest spore quantities. The conidiospores from muscardine pupae infected by strains Bb8 and Bb14 were spherical or near-spherical under scanning electron microscope. Both of them belonged to [ Beauveria bassiana (Bals.) Vuill. ] The results also showed that there existed certain similarities in biological characteristics between the pathogens of silkworm white muscardine from some silkworm rearing areas and from biocontrol agent B. bassiana. Meanwhile, some diversity also existed in B. bassiana strains from the same silkworm rearing area. Therefore, it is implied that the source of white muscardine is rather complex, and further investigation is thus needed to ascertain whether the two biocontrol agents Bb2 and Bb7 belong to B. bassiana.%对广州市森林保护用生防白僵菌Bb2、华南农业大学保存生防用白僵菌Bb7以及收集自广东省化州蚕种场、化州市笪桥村、翁源县硝村等蚕区的3株家蚕白僵菌分离株(Bb8

  11. Ecophysiological approaches to production and formulation of the biocontrol yeast Pichia anomala

    OpenAIRE

    Mokiou, Stella

    2004-01-01

    To produce commercial biocontrol agents (BCAs) successfully, it is important that cheap and economic substrates are used which support high numbers of good quality inoculum. Production of formulations conserving ecological competence and shelf-life should also be ensured. With this in mind, studies focusing on yeast ecophysiology were conducted to produce and formulate ecologically competent P. anomala cells for controlling spoilage of moist cereal grain. The liquid culture systems used were ...

  12. Enhancement of biocontrol efficacy against Botrytis cinerea through the manipulation of nitrogen fertilization of tomato plants

    OpenAIRE

    Abro, Manzoor Ali; Lecompte, François; Bardin, Marc; Duffaud, Magali

    2013-01-01

    Although nitrogen fertilization is known to affect plant susceptibility to certain pathogens, little is known on its possible effect on the efficacy of biological control. In the present study we examined the effect of five levels of NO3- nutrition on the efficacy of two biocontrol agents (Trichoderma harzianum and Microdochium dimerum) to protect pruning wounds of tomato against Botrytis cinerea. Plants were grown for two months in a greenhouse with a soil-less drip-irrigationsystem. Differe...

  13. Characterization of new glycolipid biosurfactants, tri-acylated mannosylerythritol lipids, produced by Pseudozyma yeasts.

    Science.gov (United States)

    Fukuoka, Tokuma; Morita, Tomotake; Konishi, Masaaki; Imura, Tomohiro; Kitamoto, Dai

    2007-07-01

    Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by Pseudozyma yeasts. They show not only the excellent interfacial properties but also versatile biochemical actions. In the course of MEL production from soybean oil by P. antarctica and P. rugulosa, some new extracellular glycolipids (more hydrophobic than the previously reported di-acylated MELs) were found in the culture medium. The most hydrophobic one was identified as 1-O-alka(e)noyl-4-O-[(4',6'-di-O-acetyl-2',3'-di-O-alka(e)noyl)-beta-D-mannopyranosyl]-D-erythritol, namely tri-acylated MEL. Others were tri-acylated MELs bearing only one acetyl group. The tri-acylated MEL could be prepared by the lipase-catalyzed esterification of a di-acylated MEL with oleic acid implying that the new glycolipids are synthesized from di-acylated MELs in the culture medium containing the residual fatty acids. PMID:17417694

  14. Selective production of two diastereomers of disaccharide sugar alcohol, mannosylerythritol by Pseudozyma yeasts.

    Science.gov (United States)

    Yoshikawa, Jun; Morita, Tomotake; Fukuoka, Tokuma; Konishi, Masaaki; Imura, Tomohiro; Kakugawa, Koji; Kitamoto, Dai

    2014-01-01

    Mannosylerythritol (ME) is the hydrophilic backbone of mannosylerythritol lipids as the most promising biosurfactants produced by different Pseudozyma yeasts, and has been receiving attention as a new sugar alcohol. Different Pseudozyma yeasts were examined for the sugar alcohol production using glucose as the sole carbon source. P. hubeiensis KM-59 highly produced a conventional type of ME, i.e., 4-O-β-D-mannopyranosyl-D-erythritol (4-ME). Interestingly, P. tsukubaensis KM-160 produced a diastereomer of 4-ME, i.e., 1-O-β-D-mannopyranosyl-D-erythritol (1-ME). In shake flask culture with 200 g/l of glucose, strain KM-59 produced 4-ME at a yield of 33.2 g/l (2.2 g/l/day of the productivity), while strain KM-160 produced 1-ME at 30.0 g/l (2.0 g/l/day). Moreover, the two strains were found to produce ME from glycerol; the maximum yields of 4-ME and 1-ME from 200 g/l of glycerol were 16.1 g/l (1.1 g/l/day) and 15.8 g/l (1.1 g/l/day), respectively. The production of 1-ME as the new diastereomer was further investigated in fed batch culture using a 5-l jar-fermenter. Compared to the flask culture, strain KM-160 gave three times higher productivity of 1-ME at 38.0 g/l (6.3 g/l/day) from glucose and at 31.1 g/l (3.5 g/l/day) from glycerol, respectively. This is the first report on the selective production of two diastereomers of ME, and should thus facilitate the functional development and application of the disaccharide sugar alcohol in the food and relative industries. PMID:24272368

  15. Efficient production of mannosylerythritol lipids with high hydrophilicity by Pseudozyma hubeiensis KM-59.

    Science.gov (United States)

    Konishi, Masaaki; Morita, Tomotake; Fukuoka, Tokuma; Imura, Tomohiro; Kakugawa, Koji; Kitamoto, Dai

    2008-02-01

    Mannosylerythritol lipids (MELs) are one of the most promising biosurfactants known because of their multifunctionality and biocompatibility. A previously isolated yeast strain, Pseudozyma sp. KM-59, mainly produced a hydrophilic MEL, namely MEL-C (4-O-[4'-O-acetyl-2',3'-di-O-alka(e)noyl-beta-D: -mannopyranosyl]-D: -erythritol). In this study, we taxonomically characterize the strain in detail and investigate the culture conditions. The genetic, morphological, and physiological characteristics of the strain coincided well with those of Pseudozyma hubeiensis. On batch culture for 4 days under optimal conditions, the yield of all MELs was 21.8 g/l; MEL-C comprised approximately 65% of the all MELs. Consequently, on fed-batch culture for 16 days, the yield reached 76.3 g/l; the volumetric productivity was approximately 4.8 g l(-1) day(-1). We further examined the surface-active and self-assembling properties of the hydrophilic MELs produced by the yeast strain. They showed higher emulsifying activities against soybean oil and a mixture of hydrocarbons (2-methylnaphtarene and hexadecane, 1:1) than the synthetic surfactants tested. On water penetration scans, they efficiently formed lyotropic liquid crystalline phases such as myelines and lamella (L alpha) in a broad range of their concentrations, indicating higher hydrophilicity than conventional MELs. More interestingly, there was little difference in the liquid crystal formation between the crude product and purified MEL-C. The present glycolipids with high hydrophilicity are thus very likely to have practical potential without further purification and to expand the application of MELs especially their use in washing detergents and oil-in-water-type emulsifiers. PMID:18071643

  16. Commercialization of postharvest biocontrol: barriers and opportunities

    Science.gov (United States)

    The past twenty years has seen the field of postharvest biocontrol evolve from an unknown entity with one or two novel reports in the literature to a sophisticated science with strong research programs worldwide, hundreds of publications, patented technologies, and now several commercial products. ...

  17. Genetic Modification of a Biocontrol Agent Pseudomonas fluorescens 2P24 by a Harpin Coding Gene%利用编码harpin蛋白的基因遗传改良生防荧光假单胞菌2P24

    Institute of Scientific and Technical Information of China (English)

    赵倩; 邹丽芳; 邹华松; 李玉蓉; 陈功友

    2012-01-01

    Biocontrol agent Pseudomonas fluorescens 2P24,one of plant growth-promoting rhizobacteria(PGPR),possesses a type-Ⅲ secretion system(T3SS) for association with plants.To enable 2P24 to express a harpin protein which triggers hypersensitive response(HR) in plants and to have the ability to induce resistance to plant pathogen infection,we constructed a fusion of a hap1 gene,which encodes a harpin of Xanthomonas oryzae pv.oryzicola,with a promoter of avrPto1 of Pseudomonas syringae pv.tomato DC3000 which was induced in 2P24.This recombination led 2P24 to express the harpin protein Hpa1.The protein,secreted via the T3SS of 2P24,triggered HR in tobacco via the activation of HR marker genes,HIN1 and HRS203J,and pathogenesis-related protein gene PR1a.The genetic modified 2P24 with the harpin coding gene,as the recipient strain 2P24,had antimicrobial ability against wheat scab Fusarium graminearum and cotton wilt F.oxysporum f.sp.vasinfectum.Using HR-elicitors from plant-pathogen interactions to genetically modify biocontrol antimicrobes provides a fundamental basis for plant disease control.%荧光假单胞菌Pseudomonas fluorescens 2P24是根围促生细菌(PGPR),具有Ⅲ型分泌系统(T3SS)。为了在2P24中表达植物过敏反应激发子harpin,赋予生防菌诱导抗病性能力,本文选择可在2P24中表达的来自Pseudomonas syringae pv.tomato DC3000的avrPto1基因启动子与水稻细菌性条斑病菌Xanthomonasoryzae pv.oryzicola harpin蛋白编码基因hpa1进行融合,实现了harpin蛋白在2P24的表达。重组菌株通过T3SS分泌harpin蛋白,可激发烟草产生过敏反应(HR),激活HR途径的HIN1基因和HRS203J基因以及病程相关蛋白PR1a基因的转录表达。harpin重组菌株与2P24一样,对小麦赤霉病菌Fusarium graminearum和棉花枯萎病菌F.oxysporum f.sp.vasinfectum具有抑制作用。这为利用植物-病原物互作中激发植物产生抗病性的激发子来遗传改良生防微生物奠定了理论和实践基础。

  18. 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.

  19. 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. PMID:26774866

  20. Genome Sequence of the Basidiomycetous Yeast Pseudozyma antarctica T-34, a Producer of the Glycolipid Biosurfactants Mannosylerythritol Lipids.

    Science.gov (United States)

    Morita, Tomotake; Koike, Hideaki; Koyama, Yoshinori; Hagiwara, Hiroko; Ito, Emi; Fukuoka, Tokuma; Imura, Tomohiro; Machida, Masayuki; Kitamoto, Dai

    2013-01-01

    The basidiomycetous yeast Pseudozyma antarctica T-34 is an excellent producer of mannosylerythritol lipids (MELs), members of the multifunctional extracellular glycolipids, from various feedstocks. Here, the genome sequence of P. antarctica T-34 was determined and annotated. Analysis of the sequence might provide insights into the properties of this yeast that make it superior for use in the production of functional glycolipids, leading to the further development of P. antarctica for industrial applications. PMID:23558529

  1. Pseudozyma brasiliensis sp. nov., a xylanolytic, ustilaginomycetous yeast species isolated from an insect pest of sugarcane roots.

    Science.gov (United States)

    Oliveira, Juliana Velasco de Castro; Borges, Thuanny A; Corrêa dos Santos, Renato Augusto; Freitas, Larissa F D; Rosa, Carlos Augusto; Goldman, Gustavo Henrique; Riaño-Pachón, Diego Mauricio

    2014-06-01

    A novel ustilaginomycetous yeast isolated from the intestinal tract of an insect pest of sugarcane roots in Ribeirão Preto, São Paulo State, Brazil, represents a novel species of the genus Pseudozyma based on molecular analyses of the D1/D2 rDNA large subunit and the internal transcribed spacer (ITS1+ITS2) regions. The name Pseudozyma brasiliensis sp. nov. is proposed for this species, with GHG001(T) ( = CBS 13268(T) = UFMG-CM-Y307(T)) as the type strain. P. brasiliensis sp. nov. is a sister species of Pseudozyma vetiver, originally isolated from leaves of vetiver grass and sugarcane in Thailand. P. brasiliensis sp. nov. is able to grow well with xylan as the sole carbon source and produces high levels of an endo-1,4-xylanase that has a higher specific activity in comparison with other eukaryotic xylanases. This enzyme has a variety of industrial applications, indicating the great biotechnological potential of P. brasiliensis. PMID:24682702

  2. Isolation of Pseudozyma churashimaensis sp. nov., a novel ustilaginomycetous yeast species as a producer of glycolipid biosurfactants, mannosylerythritol lipids.

    Science.gov (United States)

    Morita, Tomotake; Ogura, Yuki; Takashima, Masako; Hirose, Naoto; Fukuoka, Tokuma; Imura, Tomohiro; Kondo, Yukishige; Kitamoto, Dai

    2011-08-01

    An ustilaginomycetous anamorphic yeast species isolated from the leaves of Saccharum officinarum (sugarcane) in Okinawa, Japan, was identified as a novel Pseudozyma species based on morphological and physiological aspects and molecular taxonomic analysis using the D1/D2 domains of the large subunit (26S) rRNA gene and the internal transcribed spacer 1 (ITS1)-5.8S-ITS2 regions. The name Pseudozyma churashimaensis sp. nov. was proposed for the novel species, with JCM 16988(T) as the type strain. Interestingly, P. churashimaensis was found to produce glycolipid biosurfactants, a mixture of mannosylerythritol lipids (MELs), including a novel tri-acetylated derivative (MEL-A2), from glucose. The observed critical micelle concentration (CMC) and the surface tension at CMC of MEL-A2 were 1.7 × 10⁻⁶ M and 29.2 mN/m, respectively. Moreover, on a water-penetration scan, MEL-A2 efficiently formed different lyotropic liquid crystalline phases, including the lamella phase at a wide range of concentrations, indicating its excellent surface-active and self-assembling properties. The novel strain of the genus Pseudozyma should thus facilitate the application of glycolipid biosurfactants in combination with other MEL producers. PMID:21606002

  3. Ecological impacts of Phlebiopsis gigantea biocontrol treatment against Heterobasidion spp. as revealed by fungal community profiling and population analyses

    OpenAIRE

    Vainio, Eeva Johanna

    2008-01-01

    Wood decay fungi belonging to the species complex Heterobasidion annosum sensu lato are among the most common and economically important species causing root rot and stem decay in conifers of the northern temperate regions. New infections by these pathogens can be suppressed by tree stump treatments using chemical or biological control agents. In Finland, the corticiaceous fungus Phlebiopsis gigantea has been formulated into a commercial biocontrol agent called Rotstop (Verdera Ltd.). Th...

  4. High-level recombinant protein production by the basidiomycetous yeast Pseudozyma antarctica under a xylose-inducible xylanase promoter.

    Science.gov (United States)

    Watanabe, Takashi; Morita, Tomotake; Koike, Hideaki; Yarimizu, Tohru; Shinozaki, Yukiko; Sameshima-Yamashita, Yuka; Yoshida, Shigenobu; Koitabashi, Motoo; Kitamoto, Hiroko

    2016-04-01

    Yeast host-vector systems are useful tools for the production of recombinant proteins. Here, we report the construction of a new high-level expression plasmid pPAX1-neo for the basidiomycetous yeast, Pseudozyma antarctica. pPAX1-neo harbours a xylose-inducible expression cassette under control of the xylanase promoter and terminator of P. antarctica T-34, a selection cassette of neomycin/G418 with an Escherichia coli neomycin resistance gene under control of the homocitrate synthase promoter of strain T-34, and an autonomously replicating sequence fragment of Ustilago maydis (UARS). Biodegradable plastic (BP)-degrading enzymes of P. antarctica JCM10317 (PaE) and Paraphoma-related fungal strain B47-9 (PCLE) were used as reporter proteins and inserted into pPAX1-neo, resulting in pPAX1-neo::PaCLE1 and pPAX1-neo::PCLE, respectively. Homologous and heterologous BP-degrading enzyme production of transformants of P. antarctica T-34 were detected on agar plates containing xylose and emulsified BP. Recombinant PaE were also produced by transformants of other Pseudozyma strains including Pseudozyma aphidis, Pseudozyma rugulosa, and Pseudozyma tsukubaensis. To improve the stability of transformed genes in cells, the UARS fragment was removed from linearized pPAX1-neo::PaCLE1 and integrated into the chromosome of the P. antarctica strain, GB-4(0), which was selected as a PaE producer in xylose media. Two transformants, GB-4(0)-X14 and X49, had an 11-fold higher activity compared with the wild type strain in xylose-containing liquid media. By xylose fed-batch cultivation using a 3-L jar fermentor, GB-4(0)-X14 produced 73.5 U mL(-1) of PaE, which is 13.4-fold higher than that of the wild type strain GB-4(0), which produced 5.5 U mL(-1) of PaE. PMID:26695155

  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. 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.

  7. Identification of Pseudozyma graminicola CBS 10092 as a producer of glycolipid biosurfactants, mannosylerythritol lipids.

    Science.gov (United States)

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Yamamoto, Shuhei; Kitagawa, Masaru; Sogabe, Atsushi; Kitamoto, Dai

    2008-01-01

    A basidiomycetous yeast, Pseudozyma graminicola CBS 10092, was found to accumulate a large amount of glycolipids in the cultured medium when grown on soybean oil as the sole carbon source. Based on thin layer chromatography, the extracellular glycolipids gave spots corresponding to those of mannosylerythritol lipids (MELs), which are highly functional and promising biosurfactants. From the structural characterization by 1H and 13C NMR, the main product was identified as 4-O-[(4'-mono-O-acetyl-2', 3'-di-O-alka(e)noyl)-beta-D-mannopyranosyl]-D-erythritol, which is a highly hydrophilic derivative of MELs known as MEL-C. According to high-performance liquid chromatography analysis, the main product, MEL-C, comprised approximately 85% of all the MELs, and the total amount reached approximately 10 g/L for 7 days. The fatty acids of the present MEL-C consisted of mainly C6, C8 and C14 acids, considerably different from those of MEL-C produced by other Pseudozyma strains such as P. antarctica and P. shanxiensis. The observed critical micelle concentration (CMC) and the surface-tension at CMC of the MEL-C were 4.0 x 10(-6) M and 24.2 mN/m, respectively, while those of MEL-A, the most intensively studied MEL, were 2.7 x 10(-6) M and 28.4 mN/m, respectively. This implied that the MEL-C has higher hydrophilicity than conventional MELs hitherto reported. In addition, on a water-penetration scan, the MEL-C efficiently formed the lamella phase (Lalpha) at a wide range of concentrations, indicating its excellent self-assembling properties. From these results, the newly identified MELs produced by P. graminicola are likely to have great potential for use in oil-in-water type emulsifiers and/or washing detergents, and would thus facilitate a broad range of applications for the promising yeast biosurfactants. PMID:18198469

  8. Draft Genome Sequence of Biocontrol Agent Bacillus cereus UW85.

    Science.gov (United States)

    Lozano, Gabriel L; Holt, Jonathan; Ravel, Jacques; Rasko, David A; Thomas, Michael G; Handelsman, Jo

    2016-01-01

    Bacillus cereus UW85 was isolated from a root of a field-grown alfalfa plant from Arlington, WI, and identified for its ability to suppress damping off, a disease caused by Phytophthora megasperma f. sp. medicaginis on alfalfa. Here, we report the draft genome sequence of B. cereus UW85, obtained by a combination of Sanger and Illumina sequencing. PMID:27587823

  9. Characterization and Inducing Melanoma Cell Apoptosis Activity of Mannosylerythritol Lipids-A Produced from Pseudozyma aphidis.

    Science.gov (United States)

    Fan, Linlin; Li, Hongji; Niu, Yongwu; Chen, Qihe

    2016-01-01

    Mannosylerythritol lipids (MELs) are natural glycolipid biosurfactants which have potential applications in the fields of food, cosmetic and medicine. In this study, MELs were produced from vegetable oil by Pseudozyma aphidis. Their structural data through LC/MS, GC/MS and NMR analysis revealed that MEL-A with two acetyls was the major compound and the identified homologs of MEL-A contained a length of C8 to C14 fatty acid chains. This glycolipid exhibited a surface tension of 27.69 mN/m at a critical micelle concentration (CMC), self-assembling into particles in the water solution. It was observed to induce cell growth-inhibition and apoptosis of B16 melanoma cells in a dose-dependent manner, as well as cause cell cycle arrest at the S phase. Further quantitative RT-PCR analysis and western blotting revealed an increasing tendency of both mRNA and protein expressions of Caspase-12, CHOP, GRP78 and Caspase-3, and a down-regulation of protein Bcl-2. Combined with the up regulation of signaling IRE1 and ATF6, it can be speculated that MEL-A-induced B16 melanoma cell apoptosis was associated with the endoplasmic reticulum stress (ERS). PMID:26828792

  10. Characterization and Inducing Melanoma Cell Apoptosis Activity of Mannosylerythritol Lipids-A Produced from Pseudozyma aphidis.

    Directory of Open Access Journals (Sweden)

    Linlin Fan

    Full Text Available Mannosylerythritol lipids (MELs are natural glycolipid biosurfactants which have potential applications in the fields of food, cosmetic and medicine. In this study, MELs were produced from vegetable oil by Pseudozyma aphidis. Their structural data through LC/MS, GC/MS and NMR analysis revealed that MEL-A with two acetyls was the major compound and the identified homologs of MEL-A contained a length of C8 to C14 fatty acid chains. This glycolipid exhibited a surface tension of 27.69 mN/m at a critical micelle concentration (CMC, self-assembling into particles in the water solution. It was observed to induce cell growth-inhibition and apoptosis of B16 melanoma cells in a dose-dependent manner, as well as cause cell cycle arrest at the S phase. Further quantitative RT-PCR analysis and western blotting revealed an increasing tendency of both mRNA and protein expressions of Caspase-12, CHOP, GRP78 and Caspase-3, and a down-regulation of protein Bcl-2. Combined with the up regulation of signaling IRE1 and ATF6, it can be speculated that MEL-A-induced B16 melanoma cell apoptosis was associated with the endoplasmic reticulum stress (ERS.

  11. Insights into the plant polysaccharide degradation potential of the xylanolytic yeast Pseudozyma brasiliensis.

    Science.gov (United States)

    Kaupert Neto, Antonio Adalberto; Borin, Gustavo Pagotto; Goldman, Gustavo Henrique; Damásio, André Ricardo de Lima; Oliveira, Juliana Velasco de Castro

    2016-03-01

    In second-generation (2G) bioethanol production, plant cell-wall polysaccharides are broken down to release fermentable sugars. The enzymes of this process are classified as carbohydrate-active enzymes (CAZymes) and contribute substantially to the cost of biofuel production. A novel basidiomycete yeast species, Pseudozyma brasiliensis, was recently discovered. It produces an endo-β-1,4-xylanase with a higher specific activity than other xylanases. This enzyme is essential for the hydrolysis of biomass-derived xylan and has an important role in 2G bioethanol production. In spite of the P. brasiliensis biotechnological potential, there is no information about how it breaks down polysaccharides. For the first time, we characterized the secretome of P. brasiliensis grown on different carbon sources (xylose, xylan, cellobiose and glucose) and also under starvation conditions. The growth and consumption of each carbohydrate and the activity of the CAZymes of culture supernatants were analyzed. The CAZymes found in its secretomes, validated by enzymatic assays, have the potential to hydrolyze xylan, mannan, cellobiose and other polysaccharides. The data show that this yeast is a potential source of hydrolases, which can be used for biomass saccharification. PMID:26712719

  12. Esterase Active in Polar Organic Solvents from the Yeast Pseudozyma sp. NII 08165

    Directory of Open Access Journals (Sweden)

    Deepthy Alex

    2014-01-01

    Full Text Available Esterases/lipases active in water miscible solvents are highly desired in biocatalysis where substrate solubility is limited and also when the solvent is desired as an acyl acceptor in transesterification reactions, as with the case of biodiesel production. We have isolated an esterase from the glycolipid producing yeast-Pseudozyma sp. NII 08165 which in its crude form was alkali active, thermo stable, halo tolerant and also capable of acting in presence of high methanol concentration. The crude enzyme which maintained 90% of its original activity after being treated at 70°C was purified and the properties were characterized. The partially purified esterase preparation had temperature and pH optima of 60°C and 8.0 respectively. The enzyme retained almost complete activity in presence of 25% methanol and 80% activity in the same strength of ethanol. Conditions of enzyme production were optimized, which lead to 9 fold increase in the esterase yield. One of the isoforms of the enzyme LIP1 was purified to homogeneity and characterized. Purified LIP1 had a Km and Vmax of 0.01 and 1.12, respectively. The purified esterase lost its thermo and halo tolerance but interestingly, retained 97% activity in methanol.

  13. Statistical media optimization for the biomass production of postharvest biocontrol yeast Rhodosporidium paludigenum.

    Science.gov (United States)

    Wang, Peng; Liu, Xia; Wang, Yifei; Ruan, Hui; Zheng, XiaoDong

    2011-01-01

    A cane molasses-based medium for the biomass production of biocontrol agent Rhodosporidium paludigenum was statistically optimized. Molasses concentration (after pretreatment), yeast extract, and initial pH were identified by the Plackett-Burman design to show significant influence on the biomass production. The three factors were further optimized by central composite design and response-surface methodology. The statistical analysis indicated the optimum values of the variables were 89.98 g/L for cane molasses, 2.35 g/L for yeast extract and an initial pH of 8.48. The biomass yield at the optimal culture achieved 15.89 g/L in flask fermentation, which was 2.1 times higher than that at the initial NYDB medium. In a 10-L fermenter, 18.97 g/L of biomass was obtained after 36 hr of cultivation. Moreover, the biocontrol efficacy of the yeast was investigated after culture optimization. The results showed the yeast harvested in the optimal medium maintained its initial biocontrol properties by reducing the percentage of decayed apples to below 20%.

  14. Statistical media optimization for the biomass production of postharvest biocontrol yeast Rhodosporidium paludigenum.

    Science.gov (United States)

    Wang, Peng; Liu, Xia; Wang, Yifei; Ruan, Hui; Zheng, XiaoDong

    2011-01-01

    A cane molasses-based medium for the biomass production of biocontrol agent Rhodosporidium paludigenum was statistically optimized. Molasses concentration (after pretreatment), yeast extract, and initial pH were identified by the Plackett-Burman design to show significant influence on the biomass production. The three factors were further optimized by central composite design and response-surface methodology. The statistical analysis indicated the optimum values of the variables were 89.98 g/L for cane molasses, 2.35 g/L for yeast extract and an initial pH of 8.48. The biomass yield at the optimal culture achieved 15.89 g/L in flask fermentation, which was 2.1 times higher than that at the initial NYDB medium. In a 10-L fermenter, 18.97 g/L of biomass was obtained after 36 hr of cultivation. Moreover, the biocontrol efficacy of the yeast was investigated after culture optimization. The results showed the yeast harvested in the optimal medium maintained its initial biocontrol properties by reducing the percentage of decayed apples to below 20%. PMID:21967338

  15. IDENTIFICATION OF PSEUDOZYMA HUBEIENSIS Y10BS025 AS A POTENT PRODUCER OF GLYCOLIPID BIOSURFACTANT MANNOSYLERYTHRITOL LIPIDS

    Directory of Open Access Journals (Sweden)

    Martha Sari

    2013-01-01

    Full Text Available Mannosylerythritol Lipids (MEL’s are glycolipid biosurfactants that contain 4-O-β-D-mannopyranosyl-meso-erythritol as a hydrophilic moiety and fatty acids as a hydrophobic moiety. MEL’s are abundantly produced by several kinds of microorganism and are one of the most promising biosurfactants currently known. The search for a novel endogenous producer of MEL’s was undertaken based on the available collection of the yeast strains from the genus Pseudozyma. Using thin layer chromatography and based on morphological and molecular taxonomic analysis using the D1/D2 domains of the large subunit 26S rRNA gene, Pseudozyma hubeiensis Y10BS025 was found to be a potential producer of MEL’s from soybean oil. The structure of the major glycolipid produced by the strain was analyzed by 1H and 13C nuclear magnetic resonance and was found to be similar to those of well known MEL-A, -B and -C respectively. Under improved shaking culture conditions, using yeast extract as nitrogen source and soybean oil as substrate, a maximum yield of 115±3.2 g.L-1 of MEL’s for 8 days of fermentation was achieved. The major fatty acids of MEL’s produced by P. hubeiensis Y10BS025 were C-18 acids, considerably different from those of MEL-C produced by other Pseudozyma strains such as P. antarctica and P. shanxiensis. The main product, MEL-C produced by P. hubeiensis Y10BS025 exhibited surface-tension-lowering activity. The results demonstrated that the newly isolated P. hubeiensis Y10BS025 provided high efficiency in MEL’s production and would thus be highly advantageous in commercial production of promising biosurfactants.

  16. Transformation of Cyclaneusma minus with Green Fluorescent Protein (GFP to Enable Screening of Fungi for Biocontrol Activity

    Directory of Open Access Journals (Sweden)

    Alison Stewart

    2012-02-01

    Full Text Available Cyclaneusma needle-cast has a major impact on the New Zealand forest industry. The causal agent, Cyclaneusma minus, causes most severe damage to 11–20 year-old trees and currently there are no economically viable procedures for control of the disease in New Zealand. Here we present a method for genetic transformation of C. minus using protoplasts generated by incubation with Glucanex™ enzyme. C. minus was transformed with a gene encoding green fluorescent protein (GFP and expression was stable after successive sub-culturing of the strain in the absence of selective pressure. Expression of the gfp gene allowed us to utilize an in vitro GFP-based screening method to identify strains of Trichoderma with potential for biocontrol of this disease. The strain that showed the most promise as a potential biocontrol candidate exhibited a low level of inhibition by uncharacterized metabolite(s that C. minus secretes into the medium, and consistently caused a loss of GFP expression from the GFP-labeled C. minus strain. The interaction between C. minus and the biocontrol strain, in the interaction zone where GFP expression was lost, was determined to be fungicidal. The utility of such biocontrol strains is discussed. This study represents the first genetic manipulation of C. minus and will pave the way for further studies of the life cycle and infection biology of this organism.

  17. Superoxide anion and hydrogen peroxide in the yeast antagonist-fruit interaction: a new role for reactive oxygen species in postharvest biocontrol?

    Science.gov (United States)

    The importance of reactive oxygen species (ROS) in plant defense responses against certain pathogens is well documented. There is some evidence that microbial biocontrol agents also induce a transient production of ROS in a host plant which triggers local and systemic defense responses to pathogens....

  18. Draft Genome Sequence of the Basidiomycetous Yeast-Like Fungus Pseudozyma hubeiensis SY62, Which Produces an Abundant Amount of the Biosurfactant Mannosylerythritol Lipids.

    Science.gov (United States)

    Konishi, Masaaki; Hatada, Yuji; Horiuchi, Jun-Ichi

    2013-01-01

    The basidiomycetous yeast-like fungus Pseudozyma hubeiensis strain SY62 is capable of producing an abundant amount of the glycolipid biosurfactant mannosylerythritol lipids (MELs), which are a major component of monoacetylated MEL (MEL-C). To reveal the synthetic pathway of the MELs of strain SY62, we present the 18.44-Mb draft genome sequence. PMID:23814110

  19. 生防菌哈茨木霉T4对黄瓜根围土壤细菌群落的影响%Effects of the Introduction of Biocontrol Agent Trichoderma harzianum T4 on the Bacterial Community in Cucumber Rhizosphere

    Institute of Scientific and Technical Information of China (English)

    尹丹韩; 高观朋; 夏飞; 王伟

    2012-01-01

    [目的]评价生防菌哈茨木霉(Trichoderma harzianum)T4对根围土壤细菌群落的影响,为生防菌田间应用的生态安全提供依据.[方法]结合DGGE技术与T-RFLP方法,综合考察引入生防菌哈茨木霉T4后黄瓜根围土壤细菌群落变化,[结果]在引入生防菌的14-56 d内(黄瓜整个生育期),木霉对根围土壤细菌群落可产生显著影响,并持续一段的时间,随后逐渐减弱.表现为对蓝细菌、β-变形细菌、葡萄球菌、伯克霍尔德菌、沙雷氏菌、酸杆菌和一些不可培养细菌的有效抑制作用,对芽孢杆菌、土壤杆菌、芽单胞菌的明显促进作用.但到70d时,即收获后2周,检测不到木霉对细菌群落影响.[结论]DGGE和T-RFLP序列分析技术相结合研究生防菌对土壤细菌群落的影响,既能全面描述土壤细菌群落结构变化,还可以初步定性描述变化细菌的种类信息.生防菌哈茨木霉T4的引入对土壤细菌群落产生短期影响,不会长期对土壤细菌群落稳定构成威胁.%[ Objective ] The objective of this study is to analysis the impact of T. Harzianum T4 introduction on the indigenous bacterial community of rhizosphere soil, and to provide objective biosafety evaluations for the field application of biocontrol agents.[ Method 1 Comprised molecular tools DGGE and T-RFLP were used in this study to assess the modifications of the bacterial community in cucumber rhizosphere after inoculation with T. Harzianum T4. [Result] Introduction of T. Harzianum T4 in the soil resulted in significant variations of the bacterial community structures from 14 to 56 days post-inoculation. During this period the impact of T4 was sustainable and weakened gradually. T. Harzianum T4 could restrain effectively Cyanobacterium, Beta-proteobacterium, Staphylococcus, Burkholderia, Serratia, Acidobacterium and some kinds of soil uncultured bacterium, while it improved the growth of Bacillus, Agrobacterium and Gemmatimonadetes observably

  20. Genome and transcriptome analysis of the basidiomycetous yeast Pseudozyma antarctica producing extracellular glycolipids, mannosylerythritol lipids.

    Directory of Open Access Journals (Sweden)

    Tomotake Morita

    Full Text Available Pseudozyma antarctica is a non-pathogenic phyllosphere yeast known as an excellent producer of mannosylerythritol lipids (MELs, multi-functional extracellular glycolipids, from vegetable oils. To clarify the genetic characteristics of P. antarctica, we analyzed the 18 Mb genome of P. antarctica T-34. On the basis of KOG analysis, the number of genes (219 genes categorized into lipid transport and metabolism classification in P. antarctica was one and a half times larger than that of yeast Saccharomyces cerevisiae (140 genes. The gene encoding an ATP/citrate lyase (ACL related to acetyl-CoA synthesis conserved in oleaginous strains was found in P. antarctica genome: the single ACL gene possesses the four domains identical to that of the human gene, whereas the other oleaginous ascomycetous species have the two genes covering the four domains. P. antarctica genome exhibited a remarkable degree of synteny to U. maydis genome, however, the comparison of the gene expression profiles under the culture on the two carbon sources, glucose and soybean oil, by the DNA microarray method revealed that transcriptomes between the two species were significantly different. In P. antarctica, expression of the gene sets relating fatty acid metabolism were markedly up-regulated under the oily conditions compared with glucose. Additionally, MEL biosynthesis cluster of P. antarctica was highly expressed regardless of the carbon source as compared to U. maydis. These results strongly indicate that P. antarctica has an oleaginous nature which is relevant to its non-pathogenic and MEL-overproducing characteristics. The analysis and dataset contribute to stimulate the development of improved strains with customized properties for high yield production of functional bio-based materials.

  1. Selective formation of mannosyl-L-arabitol lipid by Pseudozyma tsukubaensis JCM16987.

    Science.gov (United States)

    Morita, Tomotake; Fukuoka, Tokuma; Kosaka, Ayana; Imura, Tomohiro; Sakai, Hideki; Abe, Masahiko; Kitamoto, Dai

    2015-07-01

    To develop a structural homolog of mannosylerythritol lipids (MELs), Pseudozyma tsukubaensis JCM16987 (known to be a specific producer of the diastereomer type of mono-acetylated MEL (MEL-B)) was cultivated in medium containing 4 % (w/v) olive oil as the primary carbon source and 4 % L-arabitol as the supplemental sugar alcohol. Based on thin-layer chromatography (TLC), the glycolipid extract showed two major spots corresponding to MEL-B and an unknown glycolipid (GL1). Based on high-performance liquid chromatography after acid hydrolysis, GL1 from the L-arabitol culture showed two primary peaks identical to mannose and arabitol using the sugar analysis column, and one peak identical to L-arabitol was detected using the chiral resolution column. Based on NMR analysis, GL1 was identified as mono-acetylated mannosyl-L-arabitol lipid (MLAL-B) consisting of mannose, with L-arabitol as the sugar moiety. The observed critical micelle concentration (CMC) and surface tension at the CMC (γCMC) of MLAL-B were 1.2 × 10(-5) M and 32.8 mN/m, which were significantly higher than MEL-B (CMC = 3.1 × 10(-6) M and γcmc = 26.1 mN/m). Furthermore, based on a water-penetration scan, MLAL-B efficiently formed lamellar phase (Lα) and myelins at a broad concentration range. Thus, the present glycolipid showed higher hydrophilicity and/or water solubility and increased our understanding of environmentally advanced biosurfactants. PMID:25957491

  2. Genome and transcriptome analysis of the basidiomycetous yeast Pseudozyma antarctica producing extracellular glycolipids, mannosylerythritol lipids.

    Science.gov (United States)

    Morita, Tomotake; Koike, Hideaki; Hagiwara, Hiroko; Ito, Emi; Machida, Masayuki; Sato, Shun; Habe, Hiroshi; Kitamoto, Dai

    2014-01-01

    Pseudozyma antarctica is a non-pathogenic phyllosphere yeast known as an excellent producer of mannosylerythritol lipids (MELs), multi-functional extracellular glycolipids, from vegetable oils. To clarify the genetic characteristics of P. antarctica, we analyzed the 18 Mb genome of P. antarctica T-34. On the basis of KOG analysis, the number of genes (219 genes) categorized into lipid transport and metabolism classification in P. antarctica was one and a half times larger than that of yeast Saccharomyces cerevisiae (140 genes). The gene encoding an ATP/citrate lyase (ACL) related to acetyl-CoA synthesis conserved in oleaginous strains was found in P. antarctica genome: the single ACL gene possesses the four domains identical to that of the human gene, whereas the other oleaginous ascomycetous species have the two genes covering the four domains. P. antarctica genome exhibited a remarkable degree of synteny to U. maydis genome, however, the comparison of the gene expression profiles under the culture on the two carbon sources, glucose and soybean oil, by the DNA microarray method revealed that transcriptomes between the two species were significantly different. In P. antarctica, expression of the gene sets relating fatty acid metabolism were markedly up-regulated under the oily conditions compared with glucose. Additionally, MEL biosynthesis cluster of P. antarctica was highly expressed regardless of the carbon source as compared to U. maydis. These results strongly indicate that P. antarctica has an oleaginous nature which is relevant to its non-pathogenic and MEL-overproducing characteristics. The analysis and dataset contribute to stimulate the development of improved strains with customized properties for high yield production of functional bio-based materials. PMID:24586250

  3. Characterization of mannosylerythritol lipids containing hexadecatetraenoic acid produced from cuttlefish oil by Pseudozyma churashimaensis OK96.

    Science.gov (United States)

    Morita, Tomotake; Kawamura, Daisuke; Morita, Naoki; Fukuoka, Tokuma; Imura, Tomohiro; Sakai, Hideki; Abe, Masahiko; Kitamoto, Dai

    2013-01-01

    Biosurfactants are surface-active compounds produced by microorganisms. Mannosylerythritol lipids (MEL) are promising biosurfactants produced by Ustilaginomycetes, and their physicochemical and biochemical properties differ depending on the chemical structure of their hydrophilic and/or hydrophobic moieties. To further develop MEL derivatives and expand their potential applications, we focused our attention on the use of cuttlefish oil, which contains polyunsaturated fatty acids (e.g., docosahexaenoic acid, C₂₂:₆, and eicosapentaenoic acid, C₂₀:₅, as the sole carbon source. Among the microorganisms capable of producing MEL, only nine strains were able to produce them from cuttlefish oil. On gas chromatography-mass spectrometry (GC/MS) analysis, we observed that Pseudozyma churashimaensis OK96 was particularly suitable for the production of MEL-A, a MEL containing hexadecatetraenoic acid (C₁₆:₄) (23.6% of the total unsaturated fatty acids and 7.7% of the total fatty acids). The observed critical micelle concentration (CMC) and surface tension at CMC of the new MEL-A were 5.7×10⁻⁶ M and 29.5 mN/m, respectively, while those of MEL-A produced from soybean oil were 2.7×10⁻⁶ M and 27.7 mN/m, respectively. With polarized optical and confocal laser scanning microscopies, the self-assembling properties of MEL-A were found to be different from those of conventional MEL. Furthermore, based on the DPPH radical-scavenging assay, the anti-oxidative activity of MEL-A was found to be 2.1-fold higher than that of MEL-A produced from soybean oil. Thus, the newly identified MEL-A is attractive as a new functional material with excellent surface-active and antioxidative properties. PMID:23648407

  4. The transcriptomic profile of Pseudozyma aphidis during production of mannosylerythritol lipids.

    Science.gov (United States)

    Günther, Michael; Grumaz, Christian; Lorenz, Stefan; Stevens, Philip; Lindemann, Elena; Hirth, Thomas; Sohn, Kai; Zibek, Susanne; Rupp, Steffen

    2015-02-01

    The basidiomycetous fungus Pseudozyma aphidis is able to convert vegetable oils to abundant amounts of the biosurfactant mannosylerythritol lipid (MEL) with a unique product pattern of MEL-A, MEL-B, MEL-C, and MEL-D. To investigate the metabolism of MEL production, we analyzed the transcriptome of P. aphidis DSM 70725 under MEL-inducing and non-inducing conditions using deep sequencing. Following manual curation of the previously described in silico gene models based on RNA-Seq data, we were able to generate an experimentally verified gene annotation containing 6347 genes. Using this database, our expression analysis revealed that only four of the five cluster genes required for MEL synthesis were clearly induced by the presence of soybean oil. The acetyltransferase encoding gene PaGMAT1 was expressed on a much lower level, which may explain the secretion of MEL with different degrees of acetylation in P. aphidis. In parallel to MEL synthesis, microscopic observations showed morphological changes accompanied by expression of genes responsible for cell development, indicative of a coregulation between MEL synthesis and cell morphology. In addition a set of transcription factors was identified which may be responsible for regulation of MEL synthesis and cell development. The upregulation of genes required for nitrogen metabolism and other assimilation processes indicate additional metabolic pathways required under the MEL-inducing conditions used. We also searched for a conserved gene cluster for cellobiose lipids (CL) but only found seven genes with limited homology distributed over the genome. However, we detected characteristic TLC spots in fermentations using P. aphidis DSM 70725, indicative of CL secretion. PMID:25586580

  5. Analysis of expressed sequence tags from the anamorphic basidiomycetous yeast, Pseudozyma antarctica, which produces glycolipid biosurfactants, mannosylerythritol lipids.

    Science.gov (United States)

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2006-07-15

    Pseudozyma antarctica T-34 secretes a large amount of biosurfactants (BS), mannosylerythritol lipids (MEL), from different carbon sources such as hydrocarbons and vegetable oils. The detailed biosynthetic pathway of MEL remained unknown due to lack of genetic information on the anamorphic basidiomycetous yeasts, including the genus Pseudozyma. Here, in order to obtain genetic information on P. antarctica T-34, we constructed a cDNA library from yeast cells producing MEL from soybean oil and identified the genes expressed through the creation of an expressed sequence tags (EST) library. We generated 398 ESTs, assembled into 146 contiguous sequences. Based upon a BLAST search similarity cut-off of E

  6. 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

  7. 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

  8. 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

  9. Biocontrol of Soil Fungi in Tomato with Microencapsulates Containing Bacillus subtilis

    Directory of Open Access Journals (Sweden)

    Marcela H. Suarez

    2011-01-01

    Full Text Available Problem statement: An option to reduce pollution by synthetic agro-chemical in root plant disease management is the use of antagonist rhizobacteria belonging to Bacillus genus, because their inhibitory properties, stimulation of plant growth and crop yield increase. Approach: This study was carried out in order to evaluate if Bacillus subtilis strains could play an antagonists role of plant pathogens and if they can be microencapsulated inside a biopolymer matrix. It was adapted an equipment and evaluated a technique for microcapsules elaboration, in order to incorporate B. subtilis strains and to analyze their potential as biocontrol agents by determining their antagonistic effect against pathogenic soil fungi; in addition, it was analyzed their effect on tomato plant growth promotion under greenhouse conditions. B. subtilis strains identified as B1, J1, M2 and their mixture were used; microcapsules containing bacterial strains were inoculated to tomato seeds cv. Floradade. When seedlings emerged, a second application of microcapsules containing B. subtilis was performed on the pots, which previously were inoculated with the fungi Rhizoctonia solani and Fusarium oxysporum. Response variables were: Incidence and disease severity, plant growth, aerial and root dry weight, leaf area and fruit yield. Results: The outcome showed that the equipment designed and adapted for microcapsules elaboration was useful to obtain microcapsules containing the bacterial strains. B. subtilis strains exerted apparent biocontrol, since incidence and disease severity was reduced and for that reason inhibited the infective activity of the inoculated plant pathogens, also microcapsules containing Bacillus strains stimulated tomato growth and fruit yield. Conclusion: Microcapsules containing B. subtilis strains could be effective biocontrol agents against soil fungi plant pathogens and could have a potential biofertilizer effect, since they stimulated growth and yield

  10. IMPROVMENT BIOCONTROL OF DAMPING-OFF AND ROOT ROT/WILT OF FABA BEAN BY SALICYLIC ACID AND HYDROGEN PEROXIDE

    Directory of Open Access Journals (Sweden)

    Montaser F. Abdel-Monaim

    2013-04-01

    Full Text Available Rhizoctonia solani, Fusarium solani, F. oxysporum and Macrophomina phaseolina were found to be associated with root rot and wilt symptoms of faba bean plants collected from different fields in New Valley governorate, Egypt. All the obtained isolates were able to attack faba bean plants (cv. Giza 40 causing damping-off and root rot/wilt diseases. R. solani isolates 2 and 5, F. solani isolate 8, F. oxysporum isolate 12 and M. phaseolina isolate 14 were the more virulent ones in the pathogenicity tests. Biocontrol agents (Trichoderma viride, Bacillus megaterium and chemical inducers (salicylic acid and hydrogen peroxide individually or in combination were examined for biological control of damping-off and root rot/wilt and growth promotion of faba bean plants in vitro and in vivo. Both antagonistic biocontrol agents and chemical inducers either individually or in combination inhibited growth of the tested pathogenic fungi.Biocontrol agents combined with chemical inducers recorded the highest inhibited growth especially in case SA + T. viride and SA+ B. megaterium. Under green house and field conditions, all treatments significantly reduced damping-off and root rot/ wilt severity and increased survival of plants. Also, these treatments increased fresh and dry weights of the survived plants in pots compared with control.  The combination of biocontrol agents and chemical inducers were more effective than using them individually and SA+ T. viride was the best treatment in this respect. Under field conditions, all these treatments significantly increased growth parameters (plant height and No. of branches plant-1 and yield components (No. of pods and seedsplant-1, weight of 100 seeds and total yield feddan-1 and protein content in both seasons (2010-2011 and 2011-2012. Faba bean seeds soaked in SA+ T. viride and SA+ B. megaterium were recorded the highest growth parameters and yield components. Generally, the combination of biocontrol agents and

  11. 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.

  12. Biocontrol of Rhizoctonia solani with Trichoderma Spp.

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ From over 800 fungal strains of Trichoderma Spp. , 6 strains were found to greatly inhibit the growing of Rhizocotonia solani, the pathogen of rice sheath blight in dual culture. Among them, strain T3 was the best antagonist,which reduced the growing of the pathogen by 52.54% (Table 1). In field, both the pesticide Jinggangmycin and the mixture of T1 T6 could reduce the severity of rice sheath blight(Table 2), which resulted in the increases of seed setting rate and 1000 grain weight. Because the effect of the antagonists on the control of the pathogen could be partially realized in the watery environment, studies on the biocontrol mechanism of the fungi should be strengthened to help the establishment of a best way of antagonist utilization.

  13. Biocontrol activity of Paenibacillus polymyxa AC-1 against Pseudomonas syringae and its interaction with Arabidopsis thaliana.

    Science.gov (United States)

    Hong, Chi Eun; Kwon, Suk Yoon; Park, Jeong Mee

    2016-04-01

    Paenibacillus polymyxa AC-1 (AC-1) is a plant growth-promoting rhizobacterium (PGPR) that has been used as a soil inoculant for biocontrol of plant pathogenic fungi and to promote plant growth. In this study, we examine the effects of AC-1 on the bacterial phytopathogen Pseudomonas syringae and internal colonization of AC-1 by counting bacterial populations that colonize plants. AC-1 inhibited the growth of both P. syringae pv. tomato DC3000 (Pst) and P. syringae pv. tabaci (Pta) in a concentration-dependent manner in in vitro assays. Upon treatment of AC-1 dropping at root tip of axenically grown Arabidopsis, we found that most of the AC-1 was detected in interior of leaves of Arabidiopsis plants rather than roots after 5 days post infection, indicating systemic spreading of AC-1 occur. We examined further AC-1 colonization patterns in Arabidopsis mutants deficient in phytohormone signaling pathways. These results indicated that abscisic acid (ABA) and jasmonic acid (JA) signaling pathways positively and negatively contributed, respectively, to AC-1 colonization of leaves, whereas epiphytic accumulation of AC-1 around root tissues was not affected. This study shows that AC-1 is an effective biocontrol agent to suppress P. syringae growth, possibly owing to its colonization patterns as a leaf-inhabiting endophyte. The results showed in this work will help to expand our understanding of the mode of action of AC-1 as a biological control agent and consequently, its application in agriculture.

  14. Biocontrol activity of Paenibacillus polymyxa AC-1 against Pseudomonas syringae and its interaction with Arabidopsis thaliana.

    Science.gov (United States)

    Hong, Chi Eun; Kwon, Suk Yoon; Park, Jeong Mee

    2016-04-01

    Paenibacillus polymyxa AC-1 (AC-1) is a plant growth-promoting rhizobacterium (PGPR) that has been used as a soil inoculant for biocontrol of plant pathogenic fungi and to promote plant growth. In this study, we examine the effects of AC-1 on the bacterial phytopathogen Pseudomonas syringae and internal colonization of AC-1 by counting bacterial populations that colonize plants. AC-1 inhibited the growth of both P. syringae pv. tomato DC3000 (Pst) and P. syringae pv. tabaci (Pta) in a concentration-dependent manner in in vitro assays. Upon treatment of AC-1 dropping at root tip of axenically grown Arabidopsis, we found that most of the AC-1 was detected in interior of leaves of Arabidiopsis plants rather than roots after 5 days post infection, indicating systemic spreading of AC-1 occur. We examined further AC-1 colonization patterns in Arabidopsis mutants deficient in phytohormone signaling pathways. These results indicated that abscisic acid (ABA) and jasmonic acid (JA) signaling pathways positively and negatively contributed, respectively, to AC-1 colonization of leaves, whereas epiphytic accumulation of AC-1 around root tissues was not affected. This study shows that AC-1 is an effective biocontrol agent to suppress P. syringae growth, possibly owing to its colonization patterns as a leaf-inhabiting endophyte. The results showed in this work will help to expand our understanding of the mode of action of AC-1 as a biological control agent and consequently, its application in agriculture. PMID:26946374

  15. Purification and characterization of an extracellular β-xylosidase from Pseudozyma hubeiensis NCIM 3574 (PhXyl), an unexplored yeast.

    Science.gov (United States)

    Mhetras, Nutan; Liddell, Susan; Gokhale, Digambar

    2016-12-01

    This paper reports on the production of β-xylosidase from an unexplored yeast, Pseudozyma hubeinsis. The expression of this enzyme could be induced by beech wood xylan when the yeast was grown at 27 °C. The enzyme was purified to homogeneity as a glycoprotein with 23 % glycosylation. The purification protocol involved ammonium sulphate precipitation, QAE-Sephadex A50 ion exchange chromatography and sephacryl-200 column chromatography which resulted in 8.3-fold purification with 53.12 % final recovery. The purified enzyme showed prominent single band on SDS-PAGE. It is a monomeric protein of 110 kDa molecular weight confirmed by SDS-PAGE followed by MALDI-TOF mass spectrometry (112.3 kDa). The enzyme was optimally active at 60 °C and pH 4.5 and stable at pH range (4-9) and at 50 °C for 4 h. Chemical modification studies revealed that active site of the purified enzyme comprised of carboxyl, tyrosine and tryptophan residues. The carboxyl residue is involved in catalysis and tryptophan residue is solely involved in substrate binding. The best match from the search of the NCBInr database was with gi|808364558 glycoside hydrolase of Pseudozyma hubeiensis SY62 with 26 % sequence coverage confirming that it is a glycoside hydrolase/beta-glucosidase. From the search of customized SWISSPROT database, it was revealed that SWISSPROT does not contain any entries that are similar to the purified enzyme. PMID:27637943

  16. 西藏发酵制品中拮抗酵母对水晶梨青霉病的防治效果研究%Evaluation of yeasts from Tibetan fermented products as agents for biocontrol of blue mold of Nashi pear fruits

    Institute of Scientific and Technical Information of China (English)

    Hao HU; Yang XU; Huang-ping LU; Rui XIAO; Xiao-dong ZHENG‡; Ting YU

    2015-01-01

      结论:从西藏发酵制品中筛选得到一株拮抗酵母 R. mucilaginosa,其对水晶梨采后青霉病具有较好的生物防治效果。研究结果发现其主要作用机理为在果实伤口处与病原菌的营养与空间竞争。通过进一步研究,可开发为梨果实采后病害防治的新型生物保鲜剂。%A total of 20 strains of yeast isolated from Tibetan fermented products were screened for antagonism against blue mold of pear caused by Penicil ium expansum. Six isolates that inhibited incidence of postharvest decay by 35%or more were selected for further screening. Among them, the most effective was Rhodotorula mucilaginosa. The results showed that washed cel suspensions of R. mucilaginosa yielded better antagonistic efficacy than un-washed cel-culture mixtures, cel-free culture filtrates, and autoclaved cell cultures. Biocontrol activity improved with increasing concentrations of incubated cel s. The best concentration was 1×108 cel s/ml, at which the incidence of decay was only 16.7% after 6 d of incubation. The germination of conidia of P. expansum in vitro was significantly inhibited by both washed cell-suspensions and unwashed cel-culture mixtures. Rapid colonization by yeast at different concentrations showed a relationship between yeast-cel concentration and biocontrol activity. Although the titratable acidity of pear fruits increased after treatment, R. mucilaginosa did not affect the total soluble solids or ascorbic acid content. This is the first study to report that the yeast R. mucilaginosa from Tibet Autonomous Region of China may have potential as an antagonist to control the postharvest decay of pear fruits.

  17. Bio-Control of Salmonella Enteritidis in Foods Using Bacteriophages

    Directory of Open Access Journals (Sweden)

    Hongduo Bao

    2015-08-01

    Full Text Available Two lytic phages, vB_SenM-PA13076 (PA13076 and vB_SenM-PC2184 (PC2184, were isolated from chicken sewage and characterized with host strains Salmonella Enteritidis (SE ATCC13076 and CVCC2184, respectively. Transmission electron microscopy revealed that they belonged to the family Myoviridae. The lytic abilities of these two phages in liquid culture showed 104 multiplicity of infection (MOI was the best in inhibiting bacteria, with PC2184 exhibiting more activity than PA13076. The two phages exhibited broad host range within the genus Salmonella. Phage PA13076 and PC2184 had a lytic effect on 222 (71.4% and 298 (95.8% of the 311 epidemic Salmonella isolates, respectively. We tested the effectiveness of phage PA13076 and PC2184 as well as a cocktail combination of both in three different foods (chicken breast, pasteurized whole milk and Chinese cabbage contaminated with SE. Samples were spiked with 1 × 104 CFU individual SE or a mixture of strains (ATCC13076 and CVCC2184, then treated with 1 × 108 PFU individual phage or a two phage cocktail, and incubated at 4 °C or 25 °C for 5 h. In general, the inhibitory effect of phage and phage cocktail was better at 4 °C than that at 25 °C, whereas the opposite result was observed in Chinese cabbage, and phage cocktail was better than either single phage. A significant reduction in bacterial numbers (1.5–4 log CFU/sample, p < 0.05 was observed in all tested foods. The two phages on the three food samples were relatively stable, especially at 4 ºC, with the phages exhibiting the greatest stability in milk. Our research shows that our phages have potential effectiveness as a bio-control agent of Salmonella in foods.

  18. Bio-Control of Salmonella Enteritidis in Foods Using Bacteriophages

    Science.gov (United States)

    Bao, Hongduo; Zhang, Pengyu; Zhang, Hui; Zhou, Yan; Zhang, Lili; Wang, Ran

    2015-01-01

    Two lytic phages, vB_SenM-PA13076 (PA13076) and vB_SenM-PC2184 (PC2184), were isolated from chicken sewage and characterized with host strains Salmonella Enteritidis (SE) ATCC13076 and CVCC2184, respectively. Transmission electron microscopy revealed that they belonged to the family Myoviridae. The lytic abilities of these two phages in liquid culture showed 104 multiplicity of infection (MOI) was the best in inhibiting bacteria, with PC2184 exhibiting more activity than PA13076. The two phages exhibited broad host range within the genus Salmonella. Phage PA13076 and PC2184 had a lytic effect on 222 (71.4%) and 298 (95.8%) of the 311 epidemic Salmonella isolates, respectively. We tested the effectiveness of phage PA13076 and PC2184 as well as a cocktail combination of both in three different foods (chicken breast, pasteurized whole milk and Chinese cabbage) contaminated with SE. Samples were spiked with 1 × 104 CFU individual SE or a mixture of strains (ATCC13076 and CVCC2184), then treated with 1 × 108 PFU individual phage or a two phage cocktail, and incubated at 4 °C or 25 °C for 5 h. In general, the inhibitory effect of phage and phage cocktail was better at 4 °C than that at 25 °C, whereas the opposite result was observed in Chinese cabbage, and phage cocktail was better than either single phage. A significant reduction in bacterial numbers (1.5–4 log CFU/sample, p < 0.05) was observed in all tested foods. The two phages on the three food samples were relatively stable, especially at 4 °C, with the phages exhibiting the greatest stability in milk. Our research shows that our phages have potential effectiveness as a bio-control agent of Salmonella in foods. PMID:26305252

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

    Science.gov (United States)

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

    2013-01-01

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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. PMID:27121573

  4. 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 endoglucan......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...

  5. Zoospore Homing and Infection Events: Effects of the Biocontrol Bacterium Burkholderia cepacia AMMDR1 on Two Oomycete Pathogens of Pea (Pisum sativum L.)

    OpenAIRE

    Heungens, K; Parke, J. L.

    2000-01-01

    Burkholderia cepacia AMMDR1 is a biocontrol agent that protects pea and sweet corn seeds from Pythium damping-off in field experiments. The goal of this work was to understand the effect of B. cepacia AMMDR1 on Pythium aphanidermatum and Aphanomyces euteiches zoospore homing events and on infection of pea seeds or roots. In vitro, B. cepacia AMMDR1 caused zoospore lysis, prevented cyst germination, and inhibited germ tube growth of both oomycetes. B. cepacia AMMDR1 also reduced the attractive...

  6. Morphology of the female reproductive system and physiological age-grading of Megamelus scutellaris (Hemiptera: Delphacidae), a biological control agent of water hyacinth

    Science.gov (United States)

    The morphology of the female reproductive system in Megamelus scutellaris Berg (Hemiptera:Delphacidae), a biocontrol agent of Eichhornia crassipes (Mart.) Solms, was examined using standard light microscopy techniques. Ovaries extracted from individuals dissected in phosphate buffered saline were ex...

  7. Challenges and opportunities for the commercialization of postharvest biocontrol

    Science.gov (United States)

    The past twenty years has seen the field of postharvest biocontrol evolve into a sophisticated science with global research programs worldwide, numerous yearly publications, patented technologies, and the development of new commercial products. The use of these products, however, still remains limi...

  8. 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

  9. 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.

  10. 放线菌剂与腐植酸钾对魔芋抗病促生效果研究%Study of Combined Application of Actinomycetes Biocontrol Agents and Potassium Humate on Disease Resistance and Growth-promoting Effect of Amorphophallus Konjac

    Institute of Scientific and Technical Information of China (English)

    张忠良; 刘列平; 何斐

    2014-01-01

    分别以不施菌剂、不施腐植酸钾为对照,采用小区试验,探讨生防放线菌剂与腐植酸钾配施条件下二者对魔芋的防病促生作用。试验结果表明:(1)​当腐植酸钾与3号放线菌配施时,具有较强的防病促生作用。30克/株、60克/株、90克/株腐植酸钾分别配施3号菌剂时,与不施腐植酸钾对照相比,魔芋病害相对防效、增产率及增长系数分别提高了9.8%~41.6%、17.1%~76.3%和20.1%~64.2%。其中,60克/株腐植酸钾配施3号菌剂时效果最明显。(2)​当放线菌剂与腐植酸钾配施时,具有较强的防病促生作用。1、2、3号放线菌剂与60克/株腐植酸钾配施,与不施菌剂对照相比,魔芋病害相对防效、增产率及增长系数分别提高了11.7%~89.7%、33.3%~150.9%和38.5%~175.0%。其中2、3号放线菌剂与60克/株腐植酸钾配施处理效果较好。研究表明,腐植酸钾与放线菌剂配施能促进魔芋生长,提高魔芋产量,降低发病率。%With no actinomycetes and potassium humate treatments as control(CK), the effect of actinomycetes and potassium humate on disease resistance and growth-promoting of Amorphophallus konjac in the plot trials were evalu-ated. Results showed that:(1) Combined application of potassium humate and actinomycetes No.3 had strong disease resistance and growth-promoting effect. Under 30, 60, 90 gram per plant of potassium humate combined with actinomy-cetes No.3 treatment, biocontrol effect increased by 9.8%~41.6%, yield increased by 17.1%~76.3%and growth factor increased by 20.1%~64.2% compared with the group without potassium humate. Among which, the combined ap-plication of 60 gram per plant of potassium humate and actinomycetes No.3 had the most obvious effect. (2) Combined application of actinomycetes and potassium humate had signiifcant anti-disease and growth-promoting effect. Three kind of actinomycetes combined with 60 gram per plant of potassium

  11. 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

  12. Study of Combined Application of Actinomycetes Biocontrol Agents and Potassium Humate on Disease Resistance and Growth-promoting Effect of Amorphophallus Konjac%放线菌剂与腐植酸钾对魔芋抗病促生效果研究

    Institute of Scientific and Technical Information of China (English)

    张忠良; 刘列平; 何斐

    2014-01-01

    With no actinomycetes and potassium humate treatments as control(CK), the effect of actinomycetes and potassium humate on disease resistance and growth-promoting of Amorphophallus konjac in the plot trials were evalu-ated. Results showed that:(1) Combined application of potassium humate and actinomycetes No.3 had strong disease resistance and growth-promoting effect. Under 30, 60, 90 gram per plant of potassium humate combined with actinomy-cetes No.3 treatment, biocontrol effect increased by 9.8%~41.6%, yield increased by 17.1%~76.3%and growth factor increased by 20.1%~64.2% compared with the group without potassium humate. Among which, the combined ap-plication of 60 gram per plant of potassium humate and actinomycetes No.3 had the most obvious effect. (2) Combined application of actinomycetes and potassium humate had signiifcant anti-disease and growth-promoting effect. Three kind of actinomycetes combined with 60 gram per plant of potassium humate treatment, biocontrol effect increased by 11.7%~89.7%, yield increased by 33.3%~150.9% and growth factor increased by 38.5%~175.0% compared with the group without actinomycetes. In particular, No. 2 and No. 3 actinomycetes had obvious effect. These results sug-gested that the combined application of actinomycetes and potassium humate not only promoted A. konjac growth and yield, but also reduced the incidence of disease.%分别以不施菌剂、不施腐植酸钾为对照,采用小区试验,探讨生防放线菌剂与腐植酸钾配施条件下二者对魔芋的防病促生作用。试验结果表明:(1)​当腐植酸钾与3号放线菌配施时,具有较强的防病促生作用。30克/株、60克/株、90克/株腐植酸钾分别配施3号菌剂时,与不施腐植酸钾对照相比,魔芋病害相对防效、增产率及增长系数分别提高了9.8%~41.6%、17.1%~76.3%和20.1%~64.2%。其中,60克/株腐植酸钾配施3号菌剂时效果最明显。(2)​当放线菌剂与腐植酸钾配施

  13. Isolation of a novel high erythritol-producing Pseudozyma tsukubaensis and scale-up of erythritol fermentation to industrial level.

    Science.gov (United States)

    Jeya, Marimuthu; Lee, Kyoung-Mi; Tiwari, Manish Kumar; Kim, Jung-Soo; Gunasekaran, Paramasamy; Kim, Sang-Yong; Kim, In-Won; Lee, Jung-Kul

    2009-05-01

    This study isolated a novel erythritol-producing yeast strain, which is capable of growth at high osmolarity. Characteristics of the strain include asexual reproduction by multilateral budding, absence of extracellular starch-like compounds, and a negative Diazonium blue B color reaction. Phylogenetic analysis based on the 26S rDNA sequence and physiological analysis indicated that the strain belongs to the species Pseudozyma tsukubaensis and has been named P. tsukubaensis KN75. When P. tsukubaensis KN75 was cultured aerobically in a fed-batch culture with glucose as a carbon source, it produced 245 g/L of erythritol, corresponding to 2.86 g/L/h productivity and 61% yield, the highest erythritol yield ever reported by an erythritol-producing microorganism. Erythritol production was scaled up from a laboratory scale (7 L fermenter) to pilot (300 L) and plant (50,000 L) scales using the dissolved oxygen as a scale-up parameter. Erythritol production at the pilot and plant scales was similar to that at the laboratory scale, indicating that the production of erythritol by P. tsukubaensis KN75 holds commercial potential.

  14. Isolation of basidiomycetous yeast Pseudozyma tsukubaensis and production of glycolipid biosurfactant, a diastereomer type of mannosylerythritol lipid-B.

    Science.gov (United States)

    Morita, Tomotake; Takashima, Masako; Fukuoka, Tokuma; Konishi, Masaaki; Imura, Tomohiro; Kitamoto, Dai

    2010-10-01

    The producers of glycolipid biosurfactant, mannosylerythritol lipid-B (MEL-B), were isolated from leaves of Perilla frutescens on Ibaraki in Japan. Four isolates, 1D9, 1D10, 1D11, and 1E5, were identified as basidiomycetous yeast Pseudozyma tsukubaensis by rDNA sequence and biochemical properties. The structure of MEL-B produced by these strains was analyzed by (1)H nuclear magnetic resonance and gas chromatography-mass spectrometry methods, and was determined to be the same as the diastereomer MEL-B produced by P. tsukubaensis NBRC 1940. Of these isolates, P. tsukubaensis 1E5 (JCM 16987) is capable of producing the largest amount of the diastereomer MEL-B from vegetable oils. In order to progress the diastereomer MEL-B production by strain 1E5, factors affecting the production, such as carbon and organic nutrient sources, were further examined. Olive oil and yeast extract were the best carbon and nutrient sources, respectively. Under the optimal conditions, a maximum yield, productivity, and yield coefficient of 73.1 g/L, 10.4 g L(-1) day(-1), and 43.5 g/g were achieved by feeding of olive oil in a 5-L jar-fermenter culture using strain 1E5. PMID:20652239

  15. Characterization of new types of mannosylerythritol lipids as biosurfactants produced from soybean oil by a basidiomycetous yeast, Pseudozyma shanxiensis.

    Science.gov (United States)

    Fukuoka, Tokuma; Morita, Tomotake; Konishi, Masaaki; Imura, Tomohiro; Kitamoto, Dai

    2007-01-01

    Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by the yeast strains of the genus Pseudozyma. These show not only the excellent surface-active properties but also versatile biochemical actions. In course of MEL production from soybean oil by P. shanxiensis, new extracellular glycolipids (more hydrophilic than the previously reported MELs) were found in the culture medium. As a result of the structural characterization, the glycolipids were identified as a mixture of 4-O-[(2', 4'-di-O-acetyl-3'-O-alka(e)noyl)-beta-D-mannopyranosyl]-D-erythritol and 4-O-[(4'-O-acetyl-3'-O-alka(e)noyl-2'-O-butanoyl)-beta-D-mannopyranosyl]-D-erythritol. Interestingly, the new MELs possessed a much shorter chain (C(2) or C(4)) at the C-2' position of the mannose moiety compared to the MELs hitherto reported, which mainly possess a medium-chain acid (C(10)) at the position. They would thus show higher hydrophilicity and/or water-solubility, and expand the development of the environmentally advanced yeast biosurfactants. PMID:17898510

  16. Production of a novel mannosylerythritol lipid containing a hydroxy fatty acid from castor oil by Pseudozyma tsukubaensis.

    Science.gov (United States)

    Yamamoto, Shuhei; Fukuoka, Tokuma; Imura, Tomohiro; Morita, Tomotake; Yanagidani, Shusaku; Kitamoto, Dai; Kitagawa, Masaru

    2013-01-01

    Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by various yeasts belonging to the genus Pseudozyma, which exhibit excellent surface activities as well as versatile biochemical activities. A study on P. tsukubaensis NBRC1940 as a mono-acetylated MEL (MEL-B) producer revealed that the yeast accumulated a novel glycolipid from castor oil at a yield of 22 g/L. Its main chemical structure was identified as 1-O-β-(2'-O-alka(e)noyl-3'-O-hydroxyalka(e)noyl-6'-O-acetyl-D-mannopyranosyl)-D-erythritol designated as "new MEL-B." The new MEL-B, comprising a hydroxy fatty acid had a reduced surface tension of 28.5 mN/m at a critical micelle concentration (CMC) of 2.2×10⁻⁵ M in water. The observed CMC was 5-fold higher than that of conventional MEL-B. When conventional MEL-B was dispersed in water, it self-assembled to form the lamellar (L(α)) phase at a wide range of concentrations. In contrast, new MEL-B formed spherical oily droplets similar to the sponge (L₃) phase, which is observed in aqueous solutions of di-acetylated MEL (MEL-A). The data suggest that the newly identified MEL-B is likely to have a different structure and interfacial properties compared to the conventional MELs, and could facilitate an increase in the application of glycolipid biosurfactants. PMID:23728329

  17. Identification of the gene PaEMT1 for biosynthesis of mannosylerythritol lipids in the basidiomycetous yeast Pseudozyma antarctica.

    Science.gov (United States)

    Morita, Tomotake; Ito, Emi; Kitamoto, Hiroko K; Takegawa, Kaoru; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2010-11-01

    The yeast Pseudozyma antarctica produces a large amount of glycolipid biosurfactants known as mannosylerythritol lipids (MELs), which show not only excellent surface-active properties but also versatile biochemical actions. To investigate the biosynthesis of MELs in the yeast, we recently reported expressed sequence tag (EST) analysis and estimated genes expressing under MEL production conditions. Among the genes, a contiguous sequence of 938 bp, PA_004, showed high sequence identity to the gene emt1, encoding an erythritol/mannose transferase of Ustilago maydis, which is essential for MEL biosynthesis. The predicted translation product of the extended PA_004 containing the two introns and a stop codon was aligned with Emt1 of U. maydis. The predicted amino acid sequence shared high identity (72%) with Emt1 of U. maydis, although the amino-terminal was incomplete. To identify the gene as PaEMT1 encoding an erythritol/mannose transferase of P. antarctica, the gene-disrupted strain was developed by the method for targeted gene disruption, using hygromycin B resistance as the selection marker. The obtained ΔPaEMT1 strain failed to produce MELs, while its growth was the same as that of the parental strain. The additional mannosylerythritol into culture allowed ΔPaEMT1 strain to form MELs regardless of the carbon source supplied, indicating a defect of the erythritol/mannose transferase activity. Furthermore, we found that MEL formation is associated with the morphology and low-temperature tolerance of the yeast. PMID:20564650

  18. Production of a novel mannosylerythritol lipid containing a hydroxy fatty acid from castor oil by Pseudozyma tsukubaensis.

    Science.gov (United States)

    Yamamoto, Shuhei; Fukuoka, Tokuma; Imura, Tomohiro; Morita, Tomotake; Yanagidani, Shusaku; Kitamoto, Dai; Kitagawa, Masaru

    2013-01-01

    Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by various yeasts belonging to the genus Pseudozyma, which exhibit excellent surface activities as well as versatile biochemical activities. A study on P. tsukubaensis NBRC1940 as a mono-acetylated MEL (MEL-B) producer revealed that the yeast accumulated a novel glycolipid from castor oil at a yield of 22 g/L. Its main chemical structure was identified as 1-O-β-(2'-O-alka(e)noyl-3'-O-hydroxyalka(e)noyl-6'-O-acetyl-D-mannopyranosyl)-D-erythritol designated as "new MEL-B." The new MEL-B, comprising a hydroxy fatty acid had a reduced surface tension of 28.5 mN/m at a critical micelle concentration (CMC) of 2.2×10⁻⁵ M in water. The observed CMC was 5-fold higher than that of conventional MEL-B. When conventional MEL-B was dispersed in water, it self-assembled to form the lamellar (L(α)) phase at a wide range of concentrations. In contrast, new MEL-B formed spherical oily droplets similar to the sponge (L₃) phase, which is observed in aqueous solutions of di-acetylated MEL (MEL-A). The data suggest that the newly identified MEL-B is likely to have a different structure and interfacial properties compared to the conventional MELs, and could facilitate an increase in the application of glycolipid biosurfactants.

  19. Lipid production through simultaneous utilization of glucose, xylose, and L-arabinose by Pseudozyma hubeiensis: a comparative screening study.

    Science.gov (United States)

    Tanimura, Ayumi; Takashima, Masako; Sugita, Takashi; Endoh, Rikiya; Ohkuma, Moriya; Kishino, Shigenobu; Ogawa, Jun; Shima, Jun

    2016-12-01

    Co-fermentation of glucose, xylose and L-arabinose from lignocellulosic biomass by an oleaginous yeast is anticipated as a method for biodiesel production. However, most yeasts ferment glucose first before consuming pentoses, due to glucose repression. This preferential utilization results in delayed fermentation time and lower productivity. Therefore, co-fermentation of lignocellulosic sugars could achieve cost-effective conversion of lignocellulosic biomass to microbial lipid. Comprehensive screening of oleaginous yeasts capable of simultaneously utilizing glucose, xylose, and L-arabinose was performed by measuring the concentration of sugars remaining in the medium and of lipids accumulated in the cells. We found that of 1189 strains tested, 12 had the ability to co-ferment the sugars. The basidiomycete yeast Pseudozyma hubeiensis IPM1-10, which had the highest sugars consumption rate of 94.1 %, was selected by culturing in a batch culture with the mixed-sugar medium. The strain showed (1) simultaneous utilization of all three sugars, and (2) high lipid-accumulating ability. This study suggests that P. hubeiensis IPM1-10 is a promising candidate for second-generation biodiesel production from hydrolysate of lignocellulosic biomass. PMID:27566647

  20. Isolation and Selection of Epiphytic Yeast for Biocontrol of Botrytis cinerea Pers. on Table Grapes Aislación y Selección de Levaduras Epífitas para el Biocontrol de Botrytis cinerea Pers. en Uva de Mesa

    Directory of Open Access Journals (Sweden)

    Marisol Vargas

    2012-09-01

    Full Text Available Botrytis cinerea Pers., the causal agent of gray mold, infects more than 200 plant species. This pathogen has traditionally been controlled by fungicides. However, with the increasing demand for pesticide-free foods new control strategies are needed. The objective of this study was to isolate and select grapevine (Vitis vinifera L. epiphytic yeasts for the biocontrol of B. cinerea in table grapes. Of the total isolated yeasts (n = 256, 32 exhibited mycelial growth inhibition in dual cultures with a halo > 4 mm, and eight of these isolates inhibited > 90% of conidial germination. When evaluating increasing concentrations on conidial germination inhibition, a dose-dependent response was observed with EC90 values from 0.45 x 10(5 to 0.22 x 10(8 cells mL-1. The antagonistic activity of six yeasts against B. cinerea in table grape berries 'Flame Seedless' increased as the yeast colonization time increased from 1 to 24 h on the berries, resulting in a higher biocontrol activity on B. cinerea. These results show the effectiveness of grapevine epiphytic yeasts as biocontrol agents of B. cinerea on table grapes.Botrytis cinerea Pers., agente causal de la pudrición gris, infecta a más de 200 especies vegetales. Tradicionalmente, este patógeno ha sido controlado con fungicidas; sin embargo, la creciente demanda de alimentos libres de pesticidas hace necesario el uso de nuevas estrategias de control. El objetivo de este estudio fue aislar y seleccionar levaduras epífitas de vid (Vitis vinifera L. para el biocontrol de B. cinerea en uva de mesa. Del total de levaduras aisladas (n = 256, 32 presentaron inhibición del crecimiento micelial, en cultivos duales, con un halo > 4 mm y ocho de estos aislamientos inhibieron la germinación de conidias > 90%. Al evaluar concentraciones crecientes de levaduras sobre la inhibición de la germinación de conidias, se observó una respuesta dosis-dependiente, con valores de CE90 de 0,45 x 10(5 a 0,22 x 10(8 c

  1. Discovery of Pseudozyma rugulosa NBRC 10877 as a novel producer of the glycolipid biosurfactants, mannosylerythritol lipids, based on rDNA sequence.

    Science.gov (United States)

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2006-11-01

    The search for a novel producer of glycolipid biosurfactants, mannosylerythritol lipids (MEL) was undertaken based on the analysis of ribosomal DNA sequences on the yeast strains of the genus Pseudozyma. Pseudozyma rugulosa NBRC 10877 was found to produce a large amount of glycolipids from soybean oil. Fluorescence microscopic observation also demonstrated that the strain significantly accumulates polar lipids in the cells. The structure of the glycolipids produced by the strain was analyzed by (1)H and (13)C nuclear magnetic resonance and gas chromatography-mass spectrometry methods, and was determined to be the same as MEL produced by Pseudozyma antarctica, a well-known MEL producer. The major fatty acids of the present MEL consisted of C8 and C10 acids. Based on high performance liquid chromatography, the composition of the produced MEL was as follows: MEL-A (68%), MEL-B (12%), and MEL-C (20%). To enhance the production of MEL by the novel strain, factors affecting the production, such as carbon and nitrogen sources, were further examined. Soybean oil and sodium nitrate were the best carbon and nitrogen sources, respectively. The supplementation of a MEL precursor, such as erythritol, drastically enhanced the production yield from soybean oil at a rate of 70 to 90%. Under the optimal conditions in a shake culture, a maximum yield, productivity, and yield coefficient (on a weight basis to soybean oil supplied) of 142 g l(-1), 5.0 g l(-1) day(-1), and 0.5 g g(-1) were achieved by intermittent feeding of soybean oil and erythritol using the yeast. PMID:16733733

  2. Improvement of Biocontrol of Damping-off and Root Rot/Wilt of Faba Bean by Salicylic Acid and Hydrogen Peroxide.

    Science.gov (United States)

    Abdel-Monaim, Montaser Fawzy

    2013-03-01

    Rhizoctonia solani, Fusarium solani, F. oxysporum, and Macrophomina phaseolina were found to be associated with root rott and wilt symptoms of faba bean plants collected from different fieldes in New Valley governorate, Egypt. All the obtained isolates were able to attack faba bean plants (cv. Giza 40) causing damping-off and root rot/wilt diseases. R. solani isolates 2 and 5, F. solani isolate 8, F. oxysporum isolate 12 and M. phaseolina isolate 14 were the more virulent ones in the pathogenicity tests. Biocontrol agents (Trichoderma viride and Bacillus megaterium) and chemical inducers (salicylic acid [SA] and hydrogen peroxide) individually or in combination were examined for biological control of damping-off and root rot/wilt and growth promoting of faba bean plants in vitro and in vivo. Both antagonistic biocontrol agents and chemical inducers either individually or in combination inhibited growth of the tested pathogenic fungi. Biocontrol agents combined with chemical inducers recorded the highest inhibited growth especially in case SA + T. viride and SA + B. megaterium. Under green house and field conditions, all treatments significantly reduced damping-off and root rot/wilt severity and increased of survival plants. Also, these treatments increased fresh and weights of the survival plants in pots compared with control. The combination between biocontrol agents and chemical inducers were more effective than used of them individually and SA + T. viride was the best treatment in this respect. Also, under field conditions, all these treatments significantly increased growth parameters (plant height and number of branches per plant) and yield components (number of pods per plant and number of seeds per plant, weight of 100 seeds and total yield per feddan) and protein content in both seasons (2010~2011 and 2011~2012). Faba bean seeds soaked in SA + T. viride and SA + B. megaterium were recorded the highest growth parameters and yield components. Generally, the

  3. Production of lipase from Pseudozyma aphidis and determination of the activity and stability of the crude lipase preparation in polar organic solvents

    OpenAIRE

    RATKO JANKOV; FILIP BIHELOVIĆ; DEJAN BEZBRADICA; DUŠAN VELIČKOVIĆ; ALEKSANDRA DIMITRIJEVIĆ; NENAD MILOSAVIĆ

    2011-01-01

    The production of lipase from Pseudozyma aphidis (DSM 70725) was determined in six different media. The highest lipase production was ob­served in a medium with glucose as the sole carbon source, and yeast extract and sodium nitrate as the nitrogen sources. The time course studies of growth and lipase production in the optimal medium revealed that the highest lipase production was achieved at the end of the log phase of growth, reaching the va­lue of 35.0 U cm-3 in the fifth day of cultivatio...

  4. Effect assessment of Puccinia xanthii f sp ambrosiae-trifidae as a biocontrol agent to control giant ragweed%苍耳柄锈菌三裂叶豚草专化型对三裂叶豚草控制效果评价

    Institute of Scientific and Technical Information of China (English)

    丁建云; 姚丹丹; 陈继东; 崔建臣; 胡冬雪; 张小利

    2014-01-01

    Based on data from systematic investigation of giant ragweed inoculated with Puccinia xanthii f. sp. ambrosiae-trifidae in field in Huairou area in 2011-2013, the occurrence regularity and biocontrol effect of giant ragweed rust were evaluated. The results indicated that giant ragweed rust was natural epidemic in Baoshan Temple area in Huairou. Giant ragweed rust occurred in early June. All the giant ragweed plants were almost infected in the middle of July and some infected plants were died. P.xanthii f. sp. ambrosiae-trifidae exhibits good control effect on growth, seed amount and seed weight of giant ragweed. The death rate of the infected giant ragweed plants was nearly 30% in the end of September and the death plants had no seed.%2011~2013年在北京怀柔宝山寺地区通过野外接菌后定点定株系统调查,探索三裂叶豚草锈病的流行规律,评价苍耳柄锈菌三裂叶豚草专化型对三裂叶豚草的控制效果。结果表明:苍耳柄锈菌三裂叶豚草专化型在北京怀柔宝山寺地区能完成周年侵染循环:6月初三裂叶豚草开始有感染锈病症状,7月中、下旬几乎全部三裂叶豚草植株感病,且开始有整株死亡。苍耳柄锈菌三裂叶豚草专化型对三裂叶豚草有较好的控制效果:该菌抑制三裂叶豚草植株生长,减少种子数量,减轻种子重量,9月末30%左右的感病三裂叶豚草植株死亡,死亡植株不能产生种子。

  5. Intracellular trehalose and sorbitol synergistically promoting cell viability of a biocontrol yeast, Pichia anomala, for aflatoxin reduction.

    Science.gov (United States)

    Hua, Sui Sheng T; Hernlem, Bradley J; Yokoyama, Wallace; Sarreal, Siov Bouy L

    2015-05-01

    Pichia anomala (Wickerhamomyces anomalus) WRL-076 was discovered by a visual screening bioassay for its antagonism against Aspergillus flavus. The yeast was shown to significantly inhibit aflatoxin production and the growth of A. flavus. P. anomala is a potential biocontrol agent for reduction of aflatoxin in the food chain. Maintaining the viability of biocontrol agents in formulated products is a great challenge for commercial applications. Four media, NYG, NYGS, NYGT and NYGST are described which support good growth of yeast cells and were tested as storage formulations. Post growth supplement of 5 % trehalose to NYGST resulted in 83 % viable yeast cells after 12 months in cold storage. Intracellular sorbitol and trehalose concentrations were determined by HPLC analysis at the beginning of the storage and at the end of 12 month. Correlation of cell viability to both trehalose and sorbitol suggested a synergistic effect. Bonferroni (Dunn) t Test, Tukey's Studentized Range (HSD) Test and Duncan's Multiple Range Test, all showed that yeast cell viability in samples with both intracellular trehalose and sorbitol were significantly higher than those with either or none, at a 95 % confidence level. DiBAC4(5) and CFDA-AM were used as the membrane integrity fluorescent stains to create a two-color vital staining scheme with red and green fluorescence, respectively. Yeast cells stored in formulations NYG and NYGS with no detectable trehalose, displayed mostly red fluorescence. Yeast cells in NYGST+5T showed mostly green fluorescence.

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

    Science.gov (United States)

    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. PMID:27583463

  7. 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. PMID:27583463

  8. 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

  9. Genome Sequence of the Biocontrol Strain Pseudomonas fluorescens F113

    OpenAIRE

    Redondo-Nieto, M.; M. Barret; Morrisey, J; Germaine, K.; Martínez-Granero, F.; Barahona, E.; Navazo, A.; Sánchez-Contreras, M.; Moynihan, J.; Giddens, S.; Coppoolse, E.; Muriel, C.; Stiekema, W.; Rainey, P; Dowling, D

    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.

  10. Mannosylerythritol lipids secreted by phyllosphere yeast Pseudozyma antarctica is associated with its filamentous growth and propagation on plant surfaces.

    Science.gov (United States)

    Yoshida, Shigenobu; Morita, Tomotake; Shinozaki, Yukiko; Watanabe, Takashi; Sameshima-Yamashita, Yuka; Koitabashi, Motoo; Kitamoto, Dai; Kitamoto, Hiroko

    2014-01-01

    The biological function of mannosylerythritol lipids (MELs) towards their producer, Pseudozyma antarctica, on plant surfaces was investigated. MEL-producing wild-type strain and its MEL production-defective mutant strain (ΔPaEMT1) were compared in terms of their phenotypic traits on the surface of plastic plates, onion peels, and fresh leaves of rice and wheat. While wild-type cells adhering on plastic surfaces and onion peels changed morphologically from single cells to elongated ones for a short period of about 4 h and 1 day, respectively, ΔPaEMT1 cells did not. Microscopic observation of both strains grown on plant leaf surfaces verified that the wild type colonized a significantly bigger area than that of ΔPaEMT1. However, when MELs were exogenously added to the mutant cells on plant surfaces, their colonized area became enlarged. High-performance liquid chromatography analysis revealed a secretion of higher amount of MELs in the cell suspension incubated with wheat leaf cuttings compared to that in the suspension without cuttings. Transcriptional analysis by real-time reverse transcriptase PCR verified that the expression of erythritol/mannose transferase gene and MELs transporter gene of P. antarctica increased in the cells inoculated onto wheat leaves at 4, 6, and 8 days of incubation, indicating a potential of P. antarctica to produce MELs on the leaves. These findings demonstrate that MELs produced by P. antarctica on plant surfaces could be expected to play a significant role in fungal morphological development and propagation on plant surfaces.

  11. Formation of the two novel glycolipid biosurfactants, mannosylribitol lipid and mannosylarabitol lipid, by Pseudozyma parantarctica JCM 11752T.

    Science.gov (United States)

    Morita, Tomotake; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2012-11-01

    In order to develop novel glycolipid biosurfactants, Pseudozyma parantarctica JCM 11752(T), which is known as a producer of mannosylerythritol lipids (MEL), was cultivated using different sugar alcohols with the presence of vegetable oil. When cultivated in a medium containing 4 % (w/v) olive oil and 4 % D-ribitol or D-arabitol, the yeast strain provided different glycolipids, compared to the case of no sugar alcohol. On TLC, both of the extracted glycolipid fractions gave two major spots corresponding to MEL-A (di-acetylated MEL) and MEL-B (mono-acetylated MEL). Based on (1)H NMR analysis, one glycolipid was identified as MEL-A, but the other was not MEL-B. On high-performance liquid chromatography after acid hydrolysis, the unknown glycolipid from the D-ribitol culture provided mainly two peaks identical to D-mannose and D-ribitol, and the other unknown glycolipid from the D-arabitol culture did two peaks identical to D-mannose and D-arabitol. Accordingly, the two unknown glycolipids were identified as mannosylribitol lipid (MRL) and mannosylarabitol lipid (MAL), respectively. The observed critical micelle concentration (CMC) and surface tension at CMC of MRL were 1.6 × 10(-6) M and 23.7 mN/m, and those of MAL were 1.5 × 10(-6) M and 24.2 mN/m, respectively. These surface-tension-lowering activities were significantly higher compared to conventional MEL. Furthermore, on a water-penetration scan, MRL and MAL efficiently formed not only the lamella phase (L(α)) but also the myelins at a wide range of concentrations, indicating their excellent self-assembling properties and high hydrophilicity. The present two glycolipids should thus facilitate the application of biosurfactants as new functional materials. PMID:22722912

  12. Control of enzymatic degradation of biodegradable polymers by treatment with biosurfactants, mannosylerythritol lipids, derived from Pseudozyma spp. yeast strains.

    Science.gov (United States)

    Fukuoka, Tokuma; Shinozaki, Yukiko; Tsuchiya, Wataru; Suzuki, Ken; Watanabe, Takashi; Yamazaki, Toshimasa; Kitamoto, Dai; Kitamoto, Hiroko

    2016-02-01

    Cutinase-like esterase from the yeasts Pseudozyma antarctica (PaE) shows strong degradation activity in an agricultural biodegradable plastic (BP) model of mulch films composed of poly(butylene succinate-co-adipate) (PBSA). P. antarctica is known to abundantly produce a glycolipid biosurfactant, mannosylerythritol lipid (MEL). Here, the effects of MEL on PaE-catalyzed degradation of BPs were investigated. Based on PBSA dispersion solution, the degradation of PBSA particles by PaE was inhibited in the presence of MEL. MEL behavior on BP substrates was monitored by surface plasmon resonance (SPR) using a sensor chip coated with polymer films. The positive SPR signal shift indicated that MEL readily adsorbed and spread onto the surface of a BP film. The amount of BP degradation by PaE was monitored based on the negative SPR signal shift and was decreased 1.7-fold by MEL pretreatment. Furthermore, the shape of PBSA mulch films in PaE-containing solution was maintained with MEL pretreatment, whereas untreated films were almost completely degraded and dissolved. These results suggest that MEL covering the surface of BP film inhibits adsorption of PaE and PaE-catalyzed degradation of BPs. We applied the above results to control the microbial degradation of BP mulch films. MEL pretreatment significantly inhibited BP mulch film degradation by both PaE solution and BP-degradable microorganism. Moreover, the degradation of these films was recovered after removal of the coated MEL by ethanol treatment. These results demonstrate that the biodegradation of BP films can be readily and reversibly controlled by a physical approach using MEL. PMID:26512003

  13. Mannosylerythritol lipids secreted by phyllosphere yeast Pseudozyma antarctica is associated with its filamentous growth and propagation on plant surfaces.

    Science.gov (United States)

    Yoshida, Shigenobu; Morita, Tomotake; Shinozaki, Yukiko; Watanabe, Takashi; Sameshima-Yamashita, Yuka; Koitabashi, Motoo; Kitamoto, Dai; Kitamoto, Hiroko

    2014-01-01

    The biological function of mannosylerythritol lipids (MELs) towards their producer, Pseudozyma antarctica, on plant surfaces was investigated. MEL-producing wild-type strain and its MEL production-defective mutant strain (ΔPaEMT1) were compared in terms of their phenotypic traits on the surface of plastic plates, onion peels, and fresh leaves of rice and wheat. While wild-type cells adhering on plastic surfaces and onion peels changed morphologically from single cells to elongated ones for a short period of about 4 h and 1 day, respectively, ΔPaEMT1 cells did not. Microscopic observation of both strains grown on plant leaf surfaces verified that the wild type colonized a significantly bigger area than that of ΔPaEMT1. However, when MELs were exogenously added to the mutant cells on plant surfaces, their colonized area became enlarged. High-performance liquid chromatography analysis revealed a secretion of higher amount of MELs in the cell suspension incubated with wheat leaf cuttings compared to that in the suspension without cuttings. Transcriptional analysis by real-time reverse transcriptase PCR verified that the expression of erythritol/mannose transferase gene and MELs transporter gene of P. antarctica increased in the cells inoculated onto wheat leaves at 4, 6, and 8 days of incubation, indicating a potential of P. antarctica to produce MELs on the leaves. These findings demonstrate that MELs produced by P. antarctica on plant surfaces could be expected to play a significant role in fungal morphological development and propagation on plant surfaces. PMID:24706213

  14. Efficient production of di- and tri-acylated mannosylerythritol lipids as glycolipid biosurfactants by Pseudozyma parantarctica JCM 11752(T).

    Science.gov (United States)

    Morita, Tomotake; Konishi, Masaaki; Fukuoka, Tokuma; Imura, Tomohiro; Sakai, Hideki; Kitamoto, Dai

    2008-01-01

    Mannosylerythritol lipids (MELs) are one of the most promising biosurfactants known, because of their multifunctionality and biocompatibility. In order to attain an efficient production of MELs, Pseudozyma parantarctica JCM 11752(T), which is a newly identified strain of the genus, was examined for the productivity of MELs at different culture conditions. The yeast strain showed significant cell growth and production of di-acylated MELs even at 36 degrees C. In contrast, on conventional high-level MEL producers including P. rugulosa, the MEL yield considerably decreased with an increase of the cultivation temperature at over 30 degrees C. On P. parantarctica, soybean oil and sodium nitrate were the best carbon and nitrogen sources, respectively. Under the optimal conditions on a shake-flask culture at 34 degrees C, the amount of di-acylated MELs reached over 100 g/L by intermittent feeding of only soybean oil. Interestingly, the yeast strain produced tri-acylated MELs as well as di-acylated ones when grown on the medium containing higher soybean oil concentrations than 8% (vol/vol). The production of tri-acylated MELs was significantly accelerated at between 34 and 36 degrees C. With 20 % (vol/vol) of soybean oil at 34 degrees C, the yield of tri-acylated MELs reached 22.7 g/L. The extracellular lipase activity considerably depended on the culture temperature, and became the maximum at 34 degrees C; this would bring the accelerated production of tri-acylated MELs. Accordingly, the present strain of P. parantarctica provided high efficiency in MEL production at elevated temperatures compared to conventional MEL producers, and would thus be highly advantageous for the commercial production of the promising biosurfactants. PMID:18781056

  15. A basidiomycetous yeast, Pseudozyma tsukubaensis, efficiently produces a novel glycolipid biosurfactant. The identification of a new diastereomer of mannosylerythritol lipid-B.

    Science.gov (United States)

    Fukuoka, Tokuma; Morita, Tomotake; Konishi, Masaaki; Imura, Tomohiro; Kitamoto, Dai

    2008-02-25

    Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by the yeast strains of the genus Pseudozyma. These compounds show not only excellent surface-active properties but also versatile biochemical activities. In the course of MEL production by Pseudozyma tsukubaensis, we found an unusual MEL that had a different carbohydrate structure from that of conventional MELs. The carbohydrate structure was identified as 1-O-beta-D-mannopyranosyl-D-erythritol, and the MEL was confirmed to be 1-O-beta-(2',3'-di-O-alka(e)noyl-6'-O-acetyl-D-mannopyranosyl)-D-erythritol. Interestingly, the configuration of the erythritol moiety in the present MEL was opposite to that of the known MEL-B, 4-O-beta-(2',3'-di-O-alka(e)noyl-6'-O-acetyl-D-mannopyranosyl)-D-erythritol, and to that of all MELs hitherto reported. The present MEL should thus provide different interfacial and biochemical properties compared to conventional MELs. PMID:18083152

  16. Selection and characterization of Argentine isolates of Trichoderma harzianum for effective biocontrol of Septoria leaf blotch of wheat.

    Science.gov (United States)

    Stocco, Marina C; Mónaco, Cecilia I; Abramoff, Cecilia; Lampugnani, Gladys; Salerno, Graciela; Kripelz, Natalia; Cordo, Cristina A; Consolo, Verónica F

    2016-03-01

    Species of the genus Trichoderma are economically important as biocontrol agents, serving as a potential alternative to chemical control. The applicability of Trichoderma isolates to different ecozones will depend on the behavior of the strains selected from each zone. The present study was undertaken to isolate biocontrol populations of Trichoderma spp. from the Argentine wheat regions and to select and characterize the best strains of Trichoderma harzianum by means of molecular techniques. A total of 84 out of the 240 strains of Trichoderma were able to reduce the disease severity of the leaf blotch of wheat. Thirty-seven strains were selected for the reduction equal to or greater than 50% of the severity, compared with the control. The percentage values of reduction of the pycnidial coverage ranged between 45 and 80%. The same last strains were confirmed as T. harzianum by polymerase chain reaction amplification of internal transcribed spacers, followed by sequencing. Inter-simple sequence repeat was used to examine the genetic variability among isolates. This resulted in a total of 132 bands. Further numerical analysis revealed 19 haplotypes, grouped in three clusters (I, II, III). Shared strains, with different geographical origins and isolated in different years, were observed within each cluster. The origin of the isolates and the genetic group were partially related. All isolates from Paraná were in cluster I, all isolates from Lobería were in cluster II, and all isolates from Pergamino and Santa Fe were in cluster III. Our results suggest that the 37 native strains of T. harzianum are important in biocontrol programs and could be advantageous for the preparation of biopesticides adapted to the agroecological conditions of wheat culture.

  17. Selection and characterization of Argentine isolates of Trichoderma harzianum for effective biocontrol of Septoria leaf blotch of wheat.

    Science.gov (United States)

    Stocco, Marina C; Mónaco, Cecilia I; Abramoff, Cecilia; Lampugnani, Gladys; Salerno, Graciela; Kripelz, Natalia; Cordo, Cristina A; Consolo, Verónica F

    2016-03-01

    Species of the genus Trichoderma are economically important as biocontrol agents, serving as a potential alternative to chemical control. The applicability of Trichoderma isolates to different ecozones will depend on the behavior of the strains selected from each zone. The present study was undertaken to isolate biocontrol populations of Trichoderma spp. from the Argentine wheat regions and to select and characterize the best strains of Trichoderma harzianum by means of molecular techniques. A total of 84 out of the 240 strains of Trichoderma were able to reduce the disease severity of the leaf blotch of wheat. Thirty-seven strains were selected for the reduction equal to or greater than 50% of the severity, compared with the control. The percentage values of reduction of the pycnidial coverage ranged between 45 and 80%. The same last strains were confirmed as T. harzianum by polymerase chain reaction amplification of internal transcribed spacers, followed by sequencing. Inter-simple sequence repeat was used to examine the genetic variability among isolates. This resulted in a total of 132 bands. Further numerical analysis revealed 19 haplotypes, grouped in three clusters (I, II, III). Shared strains, with different geographical origins and isolated in different years, were observed within each cluster. The origin of the isolates and the genetic group were partially related. All isolates from Paraná were in cluster I, all isolates from Lobería were in cluster II, and all isolates from Pergamino and Santa Fe were in cluster III. Our results suggest that the 37 native strains of T. harzianum are important in biocontrol programs and could be advantageous for the preparation of biopesticides adapted to the agroecological conditions of wheat culture. PMID:26873560

  18. Antagonistic and Biocontrol Potential of Trichoderma asperellum ZJSX5003 Against the Maize Stalk Rot Pathogen Fusarium graminearum.

    Science.gov (United States)

    Li, Yaqian; Sun, Ruiyan; Yu, Jia; Saravanakumar, Kandasamy; Chen, Jie

    2016-09-01

    The efficacy of seven strains of Trichoderma asperellum collected from the fields in Southern China was assessed against Fusarium graminearum (FG) the causal agent of corn stalk rot of maize were in vitro for their antagonistic properties followed by statistical model of principal compound analysis to identify the beneficial antagonist T. asperellum strain. The key factors of antagonist activity were attributed to a total of 13 factors including cell wall degrading enzymes (chitnase, protease and β-glucanases), secondary metabolites and peptaibols and these were analyzed from eight strains of Trichoderma. A linear regression model demonstrated that interaction of enzymes and secondary metabolites of T. asperellum strain ZJSX5003 enhanced the antagonist activity against FG. Further, this strain displayed a disease reduction of 71 % in maize plants inoculated with FG compared to negative control. Pointing out that the T. asperellum strain ZJSX5003 is a potential source for the development of a biocontrol agent against corn stalk rot.

  19. Antagonistic and Biocontrol Potential of Trichoderma asperellum ZJSX5003 Against the Maize Stalk Rot Pathogen Fusarium graminearum.

    Science.gov (United States)

    Li, Yaqian; Sun, Ruiyan; Yu, Jia; Saravanakumar, Kandasamy; Chen, Jie

    2016-09-01

    The efficacy of seven strains of Trichoderma asperellum collected from the fields in Southern China was assessed against Fusarium graminearum (FG) the causal agent of corn stalk rot of maize were in vitro for their antagonistic properties followed by statistical model of principal compound analysis to identify the beneficial antagonist T. asperellum strain. The key factors of antagonist activity were attributed to a total of 13 factors including cell wall degrading enzymes (chitnase, protease and β-glucanases), secondary metabolites and peptaibols and these were analyzed from eight strains of Trichoderma. A linear regression model demonstrated that interaction of enzymes and secondary metabolites of T. asperellum strain ZJSX5003 enhanced the antagonist activity against FG. Further, this strain displayed a disease reduction of 71 % in maize plants inoculated with FG compared to negative control. Pointing out that the T. asperellum strain ZJSX5003 is a potential source for the development of a biocontrol agent against corn stalk rot. PMID:27407296

  20. Efficacy of Pseudomonas fluorescens for biocontrol of Escherichia coli 0157:H7 on spinach

    Science.gov (United States)

    Control of foodborne pathogens on leafy green vegetables is crucial for consumer food safety. Biocontrol microbes may inhibit or suppress foodborne pathogen growth and enhance existing post-harvest intervention controls. The efficacy of Pseudomonas fluorescens for biocontrol of Escherichia coli O157...

  1. In Planta Biocontrol of Pectobacterium atrosepticum by Rhodococcus erythropolis Involves Silencing of Pathogen Communication by the Rhodococcal Gamma-Lactone Catabolic Pathway.

    Directory of Open Access Journals (Sweden)

    Corinne Barbey

    Full Text Available The virulence of numerous Gram-negative bacteria is under the control of a quorum sensing process based on synthesis and perception of N-acyl homoserine lactones. Rhodococcus erythropolis, a Gram-positive bacterium, has recently been proposed as a biocontrol agent for plant protection against soft-rot bacteria, including Pectobacterium. Here, we show that the γ-lactone catabolic pathway of R. erythropolis disrupts Pectobacterium communication and prevents plant soft-rot. We report the first characterization and demonstration of N-acyl homoserine lactone quenching in planta. In particular, we describe the transcription of the R. erythropolis lactonase gene, encoding the key enzyme of this pathway, and the subsequent lactone breakdown. The role of this catabolic pathway in biocontrol activity was confirmed by deletion of the lactonase gene from R. erythropolis and also its heterologous expression in Escherichia coli. The γ-lactone catabolic pathway is induced by pathogen communication rather than by pathogen invasion. This is thus a novel and unusual biocontrol pathway, differing from those previously described as protecting plants from phytopathogens. These findings also suggest the existence of an additional pathway contributing to plant protection.

  2. Biocontrol ability and action mechanism of food-isolated yeast strains against Botrytis cinerea causing post-harvest bunch rot of table grape.

    Science.gov (United States)

    Parafati, Lucia; Vitale, Alessandro; Restuccia, Cristina; Cirvilleri, Gabriella

    2015-05-01

    Strains belonging to the species Saccharomyces cerevisiae, Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans, isolated from different food sources, were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic mold Botrytis cinerea. All yeast strains demonstrated antifungal activity at different levels depending on species and medium. Killer strains of W. anomalus and S. cerevisiae showed the highest biocontrol in vitro activity, as demonstrated by largest inhibition halos. The competition for iron and the ability to form biofilm and to colonize fruit wounds were hypothesized as the main action mechanisms for M. pulcherrima. The production of hydrolytic enzymes and the ability to colonize the wounds were the most important mechanisms for biocontrol activity in A. pullulans and W. anomalus, which also showed high ability to form biofilm. The production of volatile organic compounds (VOCs) with in vitro and in vivo inhibitory effect on pathogen growth was observed for the species W. anomalus, S. cerevisiae and M. pulcherrima. Our study clearly indicates that multiple modes of action may explain as M. pulcherrima provide excellent control of postharvest botrytis bunch rot of grape. PMID:25583341

  3. 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.

  4. Transaldolase gene Tal67 enhances the biocontrol activity of Clonostachys rosea 67-1 against Sclerotinia sclerotiorum.

    Science.gov (United States)

    Liu, Jing-Yu; Li, Shi-Dong; Sun, Man-Hong

    2016-06-01

    Clonostachys rosea is a promising biocontrol agent that parasitizes various fungal plant pathogens. In this paper, transaldolase gene Tal67 was found to be greatly upregulated in C. rosea isolate 67-1 during mycoparasitism of Sclerotinia sclerotiorum sclerotia. Quantitative real-time PCR revealed a significant increase in expression at 0-48 h after induction by sclerotia, and the level peaked at 13.9-fold higher than the control at 24 h. Gene disruption led to a decrease in the growth rate of the Tal67-deficient strain ΔTal67 to 5.3 mm/day, which was much lower than the wild type and the complemented strain ΔTal67+ (P Sclerotinia stem rot was evaluated in the greenhouse, and the control efficiency of isolate 67-1 reached 65.3%, while the efficiency of the ΔTal67 strain decreased sharply to 17.8%, and the complemented strain ΔTal67+ recovered to 64.8%. These results suggest that Tal67 plays an important role in the growth and biocontrol activity of C. rosea. PMID:27130824

  5. Screening of bacterial biocontrols against sapstain fungus (Lasiodiplodia theobromae Pat.) of rubberwood (Hevea brasiliensis Muell.Arg.).

    Science.gov (United States)

    Sajitha, K L; Maria Florence, E J; Dev, Suma Arun

    2014-09-01

    Diverse bacterial biocontrol agents from various sources of aerobic composts against the sapstain fungus Lasiodiplodia theobromae in rubberwood (Hevea brasiliensis) were isolated, screened and identified by various morphological, biochemical and molecular techniques. The inhibitory effect of seventeen bacterial isolates was examined and seven exhibited inhibition towards the sapstain fungus. Among the seven antagonists, six were conclusively identified as Bacillus subtilis and one as Paenibacillus polymyxa using 16S rRNA-encoding gene sequencing. This is the first report on the occurrence of P. polymyxa, a potent biofertilizer and antagonist in vermicompost. HiCrome Bacillus agar was identified as an effective medium for differentiation of B. subtilis from other Bacillus species. The present work demonstrates the efficacy of the antagonistic property of B. subtilis strains against rubberwood sapstain fungus. Culture-based antagonistic inhibition displayed by B. subtilis can be extended to cater to the biocontrol requirements of wood-based industries against the stain fungus. The study showed the utility of an integrated approach, employing morphological, biochemical and molecular tools for conclusive identification of several bacterial isolates present in aerobic composts from diverse sources. PMID:25049165

  6. The ABC transporter ABCG29 is involved in H2O2 tolerance and biocontrol traits in the fungus Clonostachys rosea.

    Science.gov (United States)

    Dubey, Mukesh; Jensen, Dan Funck; Karlsson, Magnus

    2016-04-01

    For successful biocontrol interactions, biological control organisms must tolerate toxic metabolites produced by themselves or plant pathogens during mycoparasitic/antagonistic interactions, by host plant during colonization of the plant, and xenobiotics present in the environment. ATP-binding cassette (ABC) transporters can play a significant role in tolerance of toxic compounds by mediating active transport across the cellular membrane. This paper reports on functional characterization of an ABC transporter ABCG29 in the biocontrol fungus Clonostachys rosea strain IK726. Gene expression analysis showed induced expression of abcG29 during exposure to the Fusarium spp. mycotoxin zearalenone (ZEA) and the fungicides Cantus, Chipco Green and Apron. Expression of abcG29 in C. rosea was significantly higher during C. rosea-C. rosea (Cr-Cr) interaction or in exposure to C. rosea culture filtrate for 2 h, compared to interaction with Fusarium graminearum or 2 h exposure to F. graminearum culture filtrate. In contrast with gene expression data, ΔabcG29 strains did not display reduced tolerance towards ZEA, fungicides or chemical agents known for inducing oxidative, cell wall or osmotic stress, compared to C. rosea WT. The exception was a significant reduction in tolerance to H2O2 (10 mM) in ΔabcG29 strains when conidia were used as an inoculum. The antagonistic ability of ΔabcG29 strains towards F. graminearum, Fusarium oxysporum or Botrytis cinerea in dual plate assays were not different compared with WT. However, in biocontrol assays ΔabcG29 strains displayed reduced ability to protect Arabidopsis thaliana leaves from B. cinerea, and barley seedling from F. graminearum as measured by an A. thaliana detached leaf assay and a barley foot rot disease assay, respectively. These data show that the ABCG29 is dispensable for ZEA and fungicides tolerance, and antagonism but not H2O2 tolerance and biocontrol effects in C. rosea. PMID:26520102

  7. Gluconic acid: an antifungal agent produced by Pseudomonas species in biological control of take-all.

    Science.gov (United States)

    Kaur, Rajvinder; Macleod, John; Foley, William; Nayudu, Murali

    2006-03-01

    Pseudomonas strain AN5 (Ps. str. AN5), a non-fluorescent Australian bacterial isolate, is an effective biological control (biocontrol) agent of the take-all disease of wheat caused by the fungus Gaeumannomyces graminis var. tritici (Ggt). Ps. str. AN5 controls Ggt by producing an antifungal compound which was purified by thin layer and column chromatography, and identified by NMR and mass spectroscopic analysis to be d-gluconic acid. Commercially bought pure gluconic acid strongly inhibited Ggt. Two different transposon mutants of Ps. str. AN5 which had lost take-all biocontrol did not produce d-gluconic acid. Gluconic acid production was restored, along with take-all biocontrol, when one of these transposon mutants was complemented with the corresponding open reading frame from wild-type genomic DNA. Gluconic acid was detected in the rhizosphere of wheat roots treated with the wild-type Ps. str. AN5, but not in untreated wheat or wheat treated with a transposon mutant strain which had lost biocontrol. The antifungal compounds phenazine-1-carboxylic acid and 2,4-diacetylphloroglucinol, produced by other Pseudomonads and previously shown to be effective in suppressing the take-all disease, were not detected in Ps. str. AN5 extracts. These results suggest that d-gluconic acid is the most significant antifungal agent produced by Ps. str. AN5 in biocontrol of take-all on wheat roots.

  8. Impact of 2,4-Diacetylphloroglucinol-Producing Biocontrol Strain Pseudomonas fluorescens F113 on Intraspecific Diversity of Resident Culturable Fluorescent Pseudomonads Associated with the Roots of Field-Grown Sugar Beet Seedlings

    OpenAIRE

    Moënne-Loccoz, Yvan; Tichy, Hans-Volker; O'Donnell, Anne; Simon, Reinhard; O'Gara, Fergal

    2001-01-01

    The impact of the 2,4-diacetylphloroglucinol-producing biocontrol agent Pseudomonas fluorescens F113Rif on the diversity of the resident community of culturable fluorescent pseudomonads associated with the roots of field-grown sugar beet seedlings was evaluated. At 19 days after sowing, the seed inoculant F113Rif had replaced some of the resident culturable fluorescent pseudomonads at the rhizoplane but had no effect on the number of these bacteria in the rhizosphere. A total of 498 isolates ...

  9. Monolayers assembled from a glycolipid biosurfactant from Pseudozyma (Candida) antarctica serve as a high-affinity ligand system for immunoglobulin G and M.

    Science.gov (United States)

    Imura, Tomohiro; Ito, Seya; Azumi, Reiko; Yanagishita, Hiroshi; Sakai, Hideki; Abe, Masahiko; Kitamoto, Dai

    2007-06-01

    A carbohydrate ligand system has been developed which is composed of self-assembled monolayers (SAMs) of mannosylerythritol lipid-A (MEL-A) from Pseudozyma antarctica, serving for human immunoglobulin G and M (HIgG and HIgM). The estimated binding constants from surface plasmon resonance (SPR) measurement were Ka = 9.4 x 10(6) M(-1) for HIgG and 5.4 x 10(6) M(-1) for HIgM, respectively. The binding site was not in the Fc region of immunoglobulin but in the Fab region. Large amounts of HIgG and HIgM bound to MEL-A SAMs were directly observed by atomic force microscopy. PMID:17342348

  10. Structural characterization and surface-active properties of a new glycolipid biosurfactant, mono-acylated mannosylerythritol lipid, produced from glucose by Pseudozyma antarctica.

    Science.gov (United States)

    Fukuoka, Tokuma; Morita, Tomotake; Konishi, Masaaki; Imura, Tomohiro; Sakai, Hideki; Kitamoto, Dai

    2007-09-01

    Mannosylerythritol lipids (MELs), which are glycolipid biosurfactants produced by Pseudozyma yeasts, show not only excellent interfacial properties but also versatile biochemical actions. In the course of MEL production from glucose as the sole carbon source, P. antarctica was found to produce unknown glycolipids more hydrophilic than conventional "di-acylated MELs," which have two fatty acyl esters on the mannose moiety. Based on a detailed characterization, the most hydrophilic one was identified as 4-O-(3'-O-alka(e)noyl-beta-D: -mannopyranosyl)-D: -erythritol namely, "mono-acylated MEL." The mono-acylated MEL reduced the surface tension of water to 33.8 mN/m at a critical micelle concentration (CMC) of 3.6 x 10(-4) M, and its hydrophilic-lipophilic balance was tentatively calculated to be 12.15. The observed CMC was 100-fold higher than that of the MELs hitherto reported. Interestingly, of the yeast strains of the genus Pseudozyma, only P. antarctica and P. parantarctica gave the mono-acylated MEL from glucose, despite a great diversity of di-acylated MEL producers in the genus. These strains produced MELs including the mono-acylated one at a rate of 20-25%. From these results, the new MEL is likely to have great potential for use in oil-in-water-type emulsifiers and washing detergents because of its higher water solubility compared to conventional MELs and will thus contribute to facilitating a broad range of applications for the environmentally advanced surfactants. PMID:17607573

  11. Enhanced biodegradation of lindane using oil-in-water bio-microemulsion stabilized by biosurfactant produced by a new yeast strain, Pseudozyma VITJzN01.

    Science.gov (United States)

    Abdul Salam, Jaseetha; Das, Nilanjana

    2013-11-28

    Organochlorine pesticide residues continue to remain as a major environmental threat worldwide. Lindane is an organochlorine pesticide widely used as an acaricide in medicine and agriculture. In the present study, a new lindane-degrading yeast strain, Pseudozyma VITJzN01, was identified as a copious producer of glycolipid biosurfactant. The glycolipid structure and type were elucidated by FTIR, NMR spectroscopy, and GC-MS analysis. The surface activity and stability of the glycolipid was analyzed. The glycolipids, characterized as mannosylerythritol lipids (MELs), exhibited excellent surface active properties and the surface tension of water was reduced to 29 mN/m. The glycolipid was stable over a wide range of pH, temperature, and salinity, showing a very low CMC of 25 mg/l. Bio-microemulsion of olive oil-in-water (O/W) was prepared using the purified biosurfactant without addition of any synthetic cosurfactants, for lindane solubilization and enhanced degradation assay in liquid and soil slurry. The O/W bio-microemulsions enhanced the solubility of lindane up to 40-folds. Degradation of lindane (700 mg/l) by VITJzN01 in liquid medium amended with bio-microemulsions was found to be enhanced by 36% in 2 days, compared with degradation in 12 days in the absence of bio-microemulsions. Lindane-spiked soil slurry incubated with bio-microemulsions also showed 20-40% enhanced degradation compared with the treatment with glycolipids or yeast alone. This is the first report on lindane degradation by Pseudozyma sp., and application of bio-microemulsions for enhanced lindane degradation. MEL-stabilized bio-microemulsions can serve as a potential tool for enhanced remediation of diverse lindanecontaminated environments. PMID:23928846

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

    Directory of Open Access Journals (Sweden)

    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.

  13. Yeasts from native Brazilian Cerrado plants: Occurrence, diversity and use in the biocontrol of citrus green mould.

    Science.gov (United States)

    Sperandio, Eugenio Miranda; do Vale, Helson Mario Martins; 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. PMID:26466874

  14. Biocontrol of Aspergillus species on peanut kernels by antifungal diketopiperazine producing Bacillus cereus associated with entomopathogenic nematode.

    Science.gov (United States)

    Kumar, Sasidharan Nishanth; Sreekala, Sreerag Ravikumar; Chandrasekaran, Dileep; Nambisan, Bala; Anto, Ruby John

    2014-01-01

    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.

  15. Bacillus amyloliquefaciens GA1 as a source of potent antibiotics and other secondary metabolites for biocontrol of plant pathogens

    Directory of Open Access Journals (Sweden)

    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

  16. The advantages of mosquito biocontrol by stocking edible fish in rice paddies.

    Science.gov (United States)

    Wu, N; Liao, G H; Li, D F; Luo, Y L; Zhong, G M

    1991-09-01

    Edible fish stocked in rice fields at a density of 600-800 fry per mu (1 mu = 1/15 hectare) for 150-170 days may act as an effective mosquito biocontrol agent. Common carp (Cyprinus carpio), grass carp Ctenopharyngodon idella) and Tilopia spp. killed late stage larvae and pupae of Anopheles sinensis and Culex tritaeniorrhyncus in laboratory and field trials. Stocking of fish in experimental rice fields decreased larval numbers significantly in comparison with control areas. Expansion of fish stocking in rice fields on a large scale over several years correlated with a marked decrease in malaria transmission. The addition of fish to the rice fields also resulted in increased yields. A ditch-ridge system of field arrangements is described for optimization of fish handling. Preliminary cost-benefit analysis indicates that this approach to mosquito control conveys considerable economic advantage and thus provides incentive to the community to participate in vector control programs. Farmers' experience in Guangxi over a number of years indicates that the use of edible fish for this purpose can be carried on a large, commercially viable scale.

  17. What magnitude are observed non-target impacts from weed biocontrol?

    Directory of Open Access Journals (Sweden)

    David Maxwell Suckling

    Full Text Available 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

  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. Biocontrol Characteristics of Bacillus Species in Suppressing Stem Rot of Grafted Cactus Caused by Bipolaris cactivora

    Directory of Open Access Journals (Sweden)

    Sooil Bae

    2013-03-01

    Full Text Available One of the most important limiting factors for the production of the grafted cactus in Korea is the qualitative and quantitative yield loss derived from stem rots especially caused by Bipolaris cactivora. This study is aimed to develop microbial control agents useful for the control of the bipolaris stem rot. Two bacteria (GA1-23 and GA4-4 selected out of 943 microbial isolates because of their strong antibiotic activity against B. cactivora were identified as Bacillus subtilis and B. amyloliquefaciens, respectively, by the cultural characteristics, Biolog program and 16S rRNA sequencing analyses. Both bacterial isolates significantly inhibited the conidial germination and mycelial growth of the pathogen with no significant difference between the two, of which the inhibitory efficacies varied depending on the cultural conditions such as temperature, nutritional compositions and concentrations. Light and electron microscopy of the pathogen treated with the bacterial isolates showed the inhibition of spore germination with initial malformation of germ tubes and later formation of circle-like vesicles with no hyphal growth and hyphal disruption sometimes accompanied by hyphal swellings and shrinkages adjacent to the bacteria, suggesting their antibiotic mode of antagonistic activity. Control efficacy of B. subtilis GA1-23 and B. amyloliquefaciens GA4-4 on the cactus stem rot were not as high as but comparable to that of fungicide difenoconazole when they were treated simultaneously at the time of pathogen inoculation. All of these results suggest the two bacterial isolates have a good potential to be developed as biocontrol agents for the bipolaris stem rot of the grafted cactus.

  20. 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

  1. 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

  2. Identification of Volatile Metabolites from Fungal Endophytes with Biocontrol Potential towards Fusarium oxysporum F. sp. cubense Race 4

    Directory of Open Access Journals (Sweden)

    A. S. Y. Ting

    2010-01-01

    Full Text Available Problem statement: Fungal endophytes are widely studied for their potential as biocontrol agents towards fungal pathogens. In vitro assessments usually reveal their antibiosis and mycoparasitism nature, but little is understood regarding their production of volatile metabolites as mechanisms of antagonism. Approach: This study explored the potential of fungal endophytes in controlling the pathogen responsible for Fusarium wilt disease. Nine fungal endophytes were tested for their ability to inhibit the growth of the pathogenic Fusarium oxysporum F. sp. cubense race 4 (FocR4 via production of volatile inhibitory metabolites. The type of volatile metabolites produced were subsequently characterized and identified using the Gas-Chromatography Mass-Spectrophotometry (GCMS. Results: Eight of the isolates (BTF05, BTF07, BTF08, BTF15, BTF21, WAA03, WAA02, MIF01 showed positive results with percentages of inhibition varying from 1.43-31.43% while one isolate (ALF01, showed negative result (0% inhibition. Volatile profiles showed that these fungal endophytes produced between 15-47 volatile metabolites per isolate. However, the more volatile metabolites produced by a single endophyte does not indicate better biocontrol potential. Isolate BTF05 produced 47 different volatile metabolites, but has only 8.57% inhibition, compared to isolate BTF21 with 15 metabolites but a percentage of 11.43% inhibition. The potency of the volatile metabolites produced may also influenced the biocontrol potential of the fungal endophytes as some isolates such as BTF08 and MIF01 have only two to three known inhibitory metabolites but have higher PIDG values at 31.43 and 11.43%, respectively. Contrary, isolates WAA02 and WAA03 which has five to six metabolites but PIDG values of less than 3%. Conclusion: Fungal endophytes have the ability to produce several types of volatile metabolites to inhibit the growth of FocR4. These volatile inhibitory metabolites can be further

  3. Colonization pattern of the biocontrol strain Pseudomonas chlororaphis MA 342 on barley seeds visualized by using green fluorescent protein.

    Science.gov (United States)

    Tombolini, R; van der Gaag, D J; Gerhardson, B; Jansson, J K

    1999-08-01

    Pseudomonas chlororaphis MA 342 is a potent biocontrol agent that can be used against several seed-borne diseases of cereal crops, including net blotch of barley caused by the fungus Drechslera teres. In this study, strain MA 342 was tagged with the gfp gene (encoding the green fluorescent protein) in order to study the fate of cells after seed inoculation. The gfp-tagged strain, MA 342G2, had the same biocontrol efficacy as the wild type when it was applied at high cell concentrations to seeds but was less effective at lower cell concentrations. By comparing cell counts determined by microscopy to the number of CFU, we found that the number of culturable cells was significantly lower than the total number of bacteria on seeds which were inoculated and dried for 20 h. Confocal microscopy and epifluorescence stereomicroscopy were used to determine the pattern of MA 342G2 colonization and cell aggregation on barley seeds. Immediately after inoculation of seeds, bacteria were found mainly under the seed glume, and there was no particular aggregation pattern. However, after the seeds were sown, irregularly distributed areas of bacterial aggregation were found, which reflected epiphytic colonization of glume cells. There was a trend towards bacterial aggregation near the embryo but never within the embryo. Bacterial aggregates were regularly found in the groove of each seed formed by the base of the coleoptile and the scutellum. Based on these results, we suggest that MA 342 colocalizes with the pathogen D. teres, which facilitates the action of the fungistatic compound(s) produced by this strain.

  4. 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.

  5. TURNING THE TIDE – USING THE STERILE INSECT TECHNIQUE TO MITIGATE AN UNWANTED WEED BIOCONTROL AGENT

    Science.gov (United States)

    The most successful program of classical biological control of weeds has been the control of invasive prickly-pear cactus (Opuntia spp.) by the Argentine cactus moth Cactoblastis cactorum. However, the moth has now become an invasive pest in the southeastern USA and its ability to dramatically contr...

  6. Greenhouse evaluation of rhizobia as biocontrol agent of root-infecting fungi in okra

    OpenAIRE

    Siddiqui, I. A.; S. Ehteshamul-Haque; Zaki, M. J.; Ghaffar, A.

    2013-01-01

    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. ...

  7. A BROAD-SPECTRUM ANTAGONISTIC ACTIVITY OF THE BIOCONTROL AGENT PSEUDOMONAS SYNXANTHA BG33R

    Science.gov (United States)

    Pseudomonas synxantha strain BG33R was previously reported to be effective in controlling the Peach Tree Short Life (PTSL) syndrome by suppressing the ring nematode (Mesocriconema xenoplax) through terminating the eggs of the second juvenile stage from further development. In this research the spec...

  8. Optimization of Media for Production of an Effective Yeast Biocontrol Agent Pichia membranefaciens

    Institute of Scientific and Technical Information of China (English)

    WAN Ya-kun; TIAN Shi-ping

    2004-01-01

    The growth of Pichia membranefaciens was studied using different nitrogen and carbonsources as substrates. Among nitrogen sources tested, soya peptone, yeast extract power,beef extract and polypeptone were relatively favorable to the growth of yeast. Thedensity of the yeast showed to be directly proportional to carbon sources supplementation.Glucose and fructose were good carbon sources for the yeast growth. However, lactoseshowed poor performance for the cell growth of the yeast. In this study, beef extractpresented a good synergic effect on the yeast growth with different carbonhydrates. Themedium for P.membranefaciens used glucose and beef extract as substrates. The higherconcentration of glucose and beef extract, the better growth of P.membranefaciens. Theaddition of chlorella growth factor (CGF) stimulated markedly the growth of P.membranefaci-ens. The increased concentration of CGF from 0.5 to 1% did not enhance the numbers ofP.membranefaciens. This result will help design a better strategy for scale-up produc-tion of P.membranefaciens.

  9. 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.

  10. 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.

  11. Species clarification of Isaria isolates used as biocontrol agents against Diaphorina citri (Hemiptera: Liviidae) in Mexico.

    Science.gov (United States)

    Gallou, Adrien; Serna-Domínguez, María G; Berlanga-Padilla, Angélica M; Ayala-Zermeño, Miguel A; Mellín-Rosas, Marco A; Montesinos-Matías, Roberto; Arredondo-Bernal, Hugo C

    2016-03-01

    Entomopathogenic fungi belonging to the genus Isaria (Hypocreales: Cordycipitaceae) are promising candidates for microbial control of insect pests. Currently, the Mexican government is developing a biological control program based on extensive application of Isaria isolates against Diaphorina citri (Hemiptera: Liviidae), a vector of citrus huanglongbing disease. Previous research identified three promising Isaria isolates (CHE-CNRCB 303, 305, and 307; tentatively identified as Isaria fumosorosea) from Mexico. The goal of this work was to obtain a complete morphological and molecular characterization of these isolates. Comparative analysis of morphology established that the isolates showed similar characteristics to Isaria javanica. Multi-gene analysis confirmed the morphological identification by including the three isolates within the I. javanica clade. Additionally, this work demonstrated the misidentifications of three other Isaria isolates (CHE-CNRCB 310 and 324: I. javanica, formerly I. fumosorosea; CHE-CNRCB 393: I. fumosorosea, formerly Isaria farinosa), underlying the need for a full and correct characterization of an isolate before developing a biological control program. Finally, the inter-simple sequence repeat (ISSR) genotyping method revealed that the CHE-CNRCB 303, 305, and 307 isolates belong to three different genotypes. This result indicates that ISSR markers could be used as a tool to monitor their presence in field conditions. PMID:26895870

  12. Novel Approaches for Risk Assessment: Feasibility Studies on Temporary Reversible Releases of Biocontrol Agents

    Science.gov (United States)

    In accordance with a 1999 Executive Order adopted by the US government, federal agencies are mandated not to promote any environmental actions, e.g. biological control, unless the agencies determine that the benefits outweigh the risks and that measures will be taken to minimize potential harm. Rec...

  13. Species clarification of Isaria isolates used as biocontrol agents against Diaphorina citri (Hemiptera: Liviidae) in Mexico.

    Science.gov (United States)

    Gallou, Adrien; Serna-Domínguez, María G; Berlanga-Padilla, Angélica M; Ayala-Zermeño, Miguel A; Mellín-Rosas, Marco A; Montesinos-Matías, Roberto; Arredondo-Bernal, Hugo C

    2016-03-01

    Entomopathogenic fungi belonging to the genus Isaria (Hypocreales: Cordycipitaceae) are promising candidates for microbial control of insect pests. Currently, the Mexican government is developing a biological control program based on extensive application of Isaria isolates against Diaphorina citri (Hemiptera: Liviidae), a vector of citrus huanglongbing disease. Previous research identified three promising Isaria isolates (CHE-CNRCB 303, 305, and 307; tentatively identified as Isaria fumosorosea) from Mexico. The goal of this work was to obtain a complete morphological and molecular characterization of these isolates. Comparative analysis of morphology established that the isolates showed similar characteristics to Isaria javanica. Multi-gene analysis confirmed the morphological identification by including the three isolates within the I. javanica clade. Additionally, this work demonstrated the misidentifications of three other Isaria isolates (CHE-CNRCB 310 and 324: I. javanica, formerly I. fumosorosea; CHE-CNRCB 393: I. fumosorosea, formerly Isaria farinosa), underlying the need for a full and correct characterization of an isolate before developing a biological control program. Finally, the inter-simple sequence repeat (ISSR) genotyping method revealed that the CHE-CNRCB 303, 305, and 307 isolates belong to three different genotypes. This result indicates that ISSR markers could be used as a tool to monitor their presence in field conditions.

  14. 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.

  15. 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. PMID:25432333

  16. Mycotoxins in food and their control by the use of non-toxigenic biocontrol agents

    Science.gov (United States)

    Mycotoxins problems have been recognized at least since medieval times, when contaminated rye caused neurological problems and death. However, about 50 years ago, mycotoxin contamination of feed caused an epidemic of "Turkey X disease", resulting in the death of thousands of turkeys. The toxin was i...

  17. 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. PMID:27052701

  18. Isolation and evaluation of biocontrol agents in controlling anthracnose disease of mango in Thailand

    Directory of Open Access Journals (Sweden)

    Rungjindamai Nattawut

    2016-07-01

    Full Text Available The agricultural based economy is a core business in Thailand and food export is one of the main sources of income for the Thai population. However, pesticides are overused and misused. As a result there is an urgent need to reduce the use of synthetic chemicals. Biological control offers an alternative to the use of pesticides. Mango (Mangifera indica L. is widely planted in Thailand and is one of the major cash crops for international export. However, mango suffers from various diseases especially anthracnose, a fungal disease caused by Colletotrichum gloeosporioides. One hundred and twelve isolates of epiphytic microbes were isolated from healthy leaves and fruits of mangoes; this included 93 and 19 isolates of epiphytic bacteria and yeasts, respectively. They were screened for bioactivity against a pathogenic strain of C. gloeosporioides isolated from diseased mangoes using a dual culture technique. Out of 112 isolates, eight isolates exhibited at least 60% inhibition. These isolates were further screened for their inhibition on mango using fruit inoculation. Two isolates reduced the lesion sizes caused by C. gloeosporioides compared to control treatment. These two isolates, based on phenotypical and biochemical tests, were identified as Bacillus sp. MB61 and Bacillus sp. LB72.

  19. Aureobasidium pullulans as a biocontrol agent of postharvest pathogens of apples in Uruguay

    Science.gov (United States)

    The yeast, Aureobasidium pullulans, was the microorganism most frequently recovered from the surface of apple fruit (cv. Red Delicious) stored in commercial cold chambers for six months. In the present work, ten isolates of Aureobasidium pullulans were assayed to determine if they could control blu...

  20. 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.

  1. 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.

  2. 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.

  3. Biocontrol of Botrytis cinerea by successful introduction of Pantoea ananatis in the grapevine phyllosphere

    Directory of Open Access Journals (Sweden)

    Gasser F

    2012-12-01

    Full Text Available Florian Gasser,1 Massimiliano Cardinale,1 Barbara Schildberger,2 Gabriele Berg11Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria; 2Höhere Bundesanstalt und Bundesamt für Wein-und Obstbau, Klosterneuburg, AustriaBackground and aims: The fungus Botrytis cinerea is a common problem in viticulture and leads to serious losses in both yield and quality. The objective was to study the potential of the antagonist Pantoea ananatis BLBT1-08 for controlling this disease.Methods: Pathogen suppression by Pantoea treatments was investigated in different field trials and in detached leaf assays. The mode of action was studied by confocal laser scanning microscopy of treated grape leaves and by in vitro assays.Results: The introduction of P. ananatis BLBT1-08 in a 3-year field trial resulted in statistically significant reduction of disease symptoms. However, B. cinerea abundance, measured by quantitative real-time polymerase chain reaction of a B. cinerea specific gene, was not reduced when compared to non-treated, symptom-free leaves. A DsRed fluorescent protein labeled BLBT1-08 strain showed a high phyllosphere competence and competition on the leaf surface, but did not colonize the inner parts of plant tissue. Germination of B. cinerea was not inhibited by BLBT1-08 on the leaf, but mycelial growth and symptoms were suppressed without direct pathogen-antagonist contact. The antimicrobial activity was amino acid and temperature dependent.Conclusion: P. ananatis BLBT1-08 is a competitive and promising biocontrol agent for the control of B. cinerea and is highly effective at reducing disease incidence.Keywords: biological control, sustainable viticulture, antagonism

  4. 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.

  5. 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

  6. Comparison of real-time PCR and microscopy to evaluate sclerotial colonisation by a biocontrol fungus.

    Science.gov (United States)

    Kim, Tae Gwan; Knudsen, Guy R

    2011-01-01

    The biocontrol agent Trichoderma harzianum colonises sclerotia of the plant pathogenic fungus Sclerotinia sclerotiorum. Plating of sclerotia typically has been used to determine the incidence of mycoparasitism, but does not quantify the extent to which individual sclerotia are colonised. We developed a specific PCR primer/probe set for the green fluorescent protein (GFP)-transformant T. harzianum ThzID1-M3, which exhibited high precision and reproducibility. Quantitative real-time PCR was evaluated along with epifluorescence microscopy and image analysis to investigate dynamics of colonisation of sclerotia in non-sterile soil. Amounts of ThzID1-M3 DNA and S. sclerotiorum DNA from entire individual sclerotia were quantified using real-time PCR. Epifluorescence micrographs were captured from sclerotial thin-section samples, and GFP fluorescence from these was quantified using computer image analysis in order to estimate colonisation on a per-sclerotium basis. As determined by either method, ThzID1-M3 colonised sclerotia in soil, and both methods quantified colonisation dynamics over time. In a separate experiment, colonisation of sclerotia on agar plates was observed using confocal laser scanning microscopy to view the GFP-fluorescing hyphae of ThzID1-M3. This method, while highly labour-intensive, provided high spatial resolution of colonisation dynamics. Thus, each method has advantages: microscopy combined with image analysis can provide useful information on the spatial and temporal dynamics of colonisation, while real-time PCR can provide a more precise assessment of the extent of sclerotial colonisation over time and can more easily be used to sample entire sclerotia. PMID:21530913

  7. The role of PaAAC1 encoding a mitochondrial ADP/ATP carrier in the biosynthesis of extracellular glycolipids, mannosylerythritol lipids, in the basidiomycetous yeast Pseudozyma antarctica.

    Science.gov (United States)

    Morita, Tomotake; Ito, Emi; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2010-07-01

    Pseudozyma antarctica produces large amounts of the glycolipid biosurfactants known as mannosylerythritol lipids (MEL), which show not only excellent surface-active properties but also versatile biochemical actions. A gene homologous with a mitochondrial ADP/ATP carrier was dominantly expressed in P. antarctica under MEL-producing conditions on the basis of previous gene expression analysis. The gene encoding the mitochondrial ADP/ATP carrier of P. antarctica (PaAAC1) contained a putative open reading frame of 954 bp and encodes a polypeptide of 317 amino acids. The deduced translation product shared high identity of 66%, 70%, 69%, 74%, 75% and 52% with the mitochondrial ADP/ATP carrier of Saccharomyces cerevisiae (AAC1), S. cerevisiae (AAC2), S. cerevisiae (AAC3), Kluyveromyces lactis (KlAAC), Neurospora crassa (NcAAC) and human (ANT1), respectively, and conserved the consensus sequences of all ADP/ATP carrier proteins. The gene expression by introducing a plasmid pUXV1-PaAAC1 into the yeast cells increased the MEL production. In addition, the expression of PaAAC1 in which the conserved arginine and leucine required for ATP transport activity were replaced with isoleucine and serine, respectively, failed to increase MEL production. Accordingly, these results suggest that PaAAC1 encoding a mitochondrial ADP/ATP carrier should be involved in MEL biosynthesis in the yeast. PMID:20146402

  8. Attachment capability of antagonistic yeast Rhodotorula glutinis to Botrytis cinerea contributes to biocontrol efficacy

    Directory of Open Access Journals (Sweden)

    Boqiang eLi

    2016-05-01

    Full Text Available Rhodotorula glutinis as an antagonism show good biocontrol performance against various postharvest 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 mould 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.

  9. 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...

  10. 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...

  11. A Gene Cluster for Biosynthesis of Mannosylerythritol Lipids Consisted of 4-O-β-D-Mannopyranosyl-(2R,3S)-Erythritol as the Sugar Moiety in a Basidiomycetous Yeast Pseudozyma tsukubaensis.

    Science.gov (United States)

    Saika, Azusa; Koike, Hideaki; Fukuoka, Tokuma; Yamamoto, Shuhei; Kishimoto, Takahide; Morita, Tomotake

    2016-01-01

    Mannosylerythritol lipids (MELs) belong to the glycolipid biosurfactants and are produced by various fungi. The basidiomycetous yeast Pseudozyma tsukubaensis produces diastereomer type of MEL-B, which contains 4-O-β-D-mannopyranosyl-(2R,3S)-erythritol (R-form) as the sugar moiety. In this respect it differs from conventional type of MELs, which contain 4-O-β-D-mannopyranosyl-(2S,3R)-erythritol (S-form) as the sugar moiety. While the biosynthetic gene cluster for conventional type of MELs has been previously identified in Ustilago maydis and Pseudozyma antarctica, the genetic basis for MEL biosynthesis in P. tsukubaensis is unknown. Here, we identified a gene cluster involved in MEL biosynthesis in P. tsukubaensis. Among these genes, PtEMT1, which encodes erythritol/mannose transferase, had greater than 69% identity with homologs from strains in the genera Ustilago, Melanopsichium, Sporisorium and Pseudozyma. However, phylogenetic analysis placed PtEMT1p in a separate clade from the other proteins. To investigate the function of PtEMT1, we introduced the gene into a P. antarctica mutant strain, ΔPaEMT1, which lacks MEL biosynthesis ability owing to the deletion of PaEMT1. Using NMR spectroscopy, we identified the biosynthetic product as MEL-A with altered sugar conformation. These results indicate that PtEMT1p catalyzes the sugar conformation of MELs. This is the first report of a gene cluster for the biosynthesis of diastereomer type of MEL. PMID:27327162

  12. A Gene Cluster for Biosynthesis of Mannosylerythritol Lipids Consisted of 4-O-β-D-Mannopyranosyl-(2R,3S)-Erythritol as the Sugar Moiety in a Basidiomycetous Yeast Pseudozyma tsukubaensis

    Science.gov (United States)

    Saika, Azusa; Koike, Hideaki; Fukuoka, Tokuma; Yamamoto, Shuhei; Kishimoto, Takahide; Morita, Tomotake

    2016-01-01

    Mannosylerythritol lipids (MELs) belong to the glycolipid biosurfactants and are produced by various fungi. The basidiomycetous yeast Pseudozyma tsukubaensis produces diastereomer type of MEL-B, which contains 4-O-β-D-mannopyranosyl-(2R,3S)-erythritol (R-form) as the sugar moiety. In this respect it differs from conventional type of MELs, which contain 4-O-β-D-mannopyranosyl-(2S,3R)-erythritol (S-form) as the sugar moiety. While the biosynthetic gene cluster for conventional type of MELs has been previously identified in Ustilago maydis and Pseudozyma antarctica, the genetic basis for MEL biosynthesis in P. tsukubaensis is unknown. Here, we identified a gene cluster involved in MEL biosynthesis in P. tsukubaensis. Among these genes, PtEMT1, which encodes erythritol/mannose transferase, had greater than 69% identity with homologs from strains in the genera Ustilago, Melanopsichium, Sporisorium and Pseudozyma. However, phylogenetic analysis placed PtEMT1p in a separate clade from the other proteins. To investigate the function of PtEMT1, we introduced the gene into a P. antarctica mutant strain, ΔPaEMT1, which lacks MEL biosynthesis ability owing to the deletion of PaEMT1. Using NMR spectroscopy, we identified the biosynthetic product as MEL-A with altered sugar conformation. These results indicate that PtEMT1p catalyzes the sugar conformation of MELs. This is the first report of a gene cluster for the biosynthesis of diastereomer type of MEL. PMID:27327162

  13. A Gene Cluster for Biosynthesis of Mannosylerythritol Lipids Consisted of 4-O-β-D-Mannopyranosyl-(2R,3S-Erythritol as the Sugar Moiety in a Basidiomycetous Yeast Pseudozyma tsukubaensis.

    Directory of Open Access Journals (Sweden)

    Azusa Saika

    Full Text Available Mannosylerythritol lipids (MELs belong to the glycolipid biosurfactants and are produced by various fungi. The basidiomycetous yeast Pseudozyma tsukubaensis produces diastereomer type of MEL-B, which contains 4-O-β-D-mannopyranosyl-(2R,3S-erythritol (R-form as the sugar moiety. In this respect it differs from conventional type of MELs, which contain 4-O-β-D-mannopyranosyl-(2S,3R-erythritol (S-form as the sugar moiety. While the biosynthetic gene cluster for conventional type of MELs has been previously identified in Ustilago maydis and Pseudozyma antarctica, the genetic basis for MEL biosynthesis in P. tsukubaensis is unknown. Here, we identified a gene cluster involved in MEL biosynthesis in P. tsukubaensis. Among these genes, PtEMT1, which encodes erythritol/mannose transferase, had greater than 69% identity with homologs from strains in the genera Ustilago, Melanopsichium, Sporisorium and Pseudozyma. However, phylogenetic analysis placed PtEMT1p in a separate clade from the other proteins. To investigate the function of PtEMT1, we introduced the gene into a P. antarctica mutant strain, ΔPaEMT1, which lacks MEL biosynthesis ability owing to the deletion of PaEMT1. Using NMR spectroscopy, we identified the biosynthetic product as MEL-A with altered sugar conformation. These results indicate that PtEMT1p catalyzes the sugar conformation of MELs. This is the first report of a gene cluster for the biosynthesis of diastereomer type of MEL.

  14. 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. PMID:27394000

  15. Biocontrol of Potato Common Scab is Associated with High Pseudomonas fluorescens LBUM223 Populations and Phenazine-1-Carboxylic Acid Biosynthetic Transcript Accumulation in the Potato Geocaulosphere.

    Science.gov (United States)

    Arseneault, Tanya; Goyer, Claudia; Filion, Martin

    2016-09-01

    Pseudomonads are often used as biocontrol agents because they display a broad range of mechanisms to control diseases. Common scab of potato, caused by Streptomyces scabies, was previously reported to be controlled by Pseudomonas fluorescens LBUM223 through phenazine-1-carboxylic acid (PCA) production. In this study, we aimed at characterizing the population dynamics of LBUM223 and the expression of phzC, a key gene involved in the biosynthesis of PCA, in the rhizosphere and geocaulosphere of potato plants grown under controlled and field conditions. Results obtained from controlled experiments showed that soil populations of LBUM223 significantly declined over a 15-week period. However, at week 15, the presence of S. scabies in the geocaulosphere was associated with significantly higher populations of LBUM223 than when the pathogen was absent. It also led to the detection of significantly higher phzC gene transcript numbers. Under field conditions, soil populations of LBUM223 followed a similar decline in time when a single inoculation was applied in spring but remained stable when reinoculated biweekly, which also led to greater phzC gene transcripts accumulation. Taken together, our findings suggest that LBUM223 must colonize the potato geocaulosphere at high levels (10(7) bacteria/g of soil) in order to achieve biocontrol of common scab through increased PCA production. PMID:27088392

  16. 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.

  17. Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis.

    Science.gov (United States)

    Großkinsky, Dominik K; Tafner, Richard; Moreno, María V; Stenglein, Sebastian A; García de Salamone, Inés E; Nelson, Louise M; Novák, Ondřej; Strnad, Miroslav; van der Graaff, Eric; Roitsch, Thomas

    2016-01-01

    Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience. PMID:26984671

  18. 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…

  19. 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.

  20. 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.

  1. Study on Attenuation Characteristics of Biocontrol Strain Anti-8098A, Bacillus cereus, against Ralstoniasolanacearum

    Institute of Scientific and Technical Information of China (English)

    BoLIU; Ying-ZhiLIN; Yu-JingZHU; Ci-BinGE; YiCAO

    2004-01-01

    The present study dealt with the attenuation characteristics of bacterial-wilt-disease biocontrol strain Anti-8098A, Bacillus cereus, againstpathogeny Ralstonia solanacearum (RS). In order to distinguish the pathogenicity of RS, the attenuation index (radius of the center red ring/radius of the whole mycelium ring, on TTC culture medium) was established (Hayward, 1976), companying with the mortality of tomato

  2. Draft genome sequences of the Pseudomonas fluorescens biocontrol strains Wayne1R and Wood1R.

    Science.gov (United States)

    Rong, Xiaoqing; Gurel, Fulya Baysal; Meulia, Tea; McSpadden Gardener, Brian B

    2012-02-01

    Pseudomonas fluorescens strains Wayne1R and Wood1R have proven capacities to improve plant health. Here we report the draft genome sequences and automatic annotations of both strains. Genome comparisons reveal similarities with P. fluorescens strain Pf-5, reveal the novelty of Wood1R, and indicate some genes that may be related to biocontrol.

  3. Biocontrol potential of endophytes harbored in Radula marginata (liverwort) from the New Zealand ecosystem.

    Science.gov (United States)

    Kusari, Parijat; Kusari, Souvik; Spiteller, Michael; Kayser, Oliver

    2014-10-01

    Radula marginata and Cannabis sativa L. are two phylogenetically unrelated plant species containing structurally similar secondary metabolites like cannabinoids. The major objective of our work was the isolation, identification, biocontrol efficacies, biofilm forming potential and anti-biofilm ability of endophytic microbial community of the liverwort R. marginata, as compared to bacterial endophytic isolates harbored in C. sativa plants. A total of 15 endophytic fungal and 4 endophytic bacterial isolates were identified, including the presence of a bacterial endosymbiont within an endophytic fungal isolate. The endosymbiont was visible only when the fungus containing it was challenged with two phytopathogens Botrytis cinerea and Trichothecium roseum, highlighting a tripartite microbe-microbe interaction and biocontrol potency of endophytes under biotic stress. We also observed sixteen types of endophytic fungal-pathogen and twelve types of endophytic bacterial-pathogen interactions coupled to varying degree of growth inhibitions of either the pathogen or endophyte or both. This showed the magnitude of biocontrol efficacies of endophytes in aiding plant fitness benefits under different media (environmental) conditions. Additionally, it was ecologically noteworthy to find the presence of similar endophytic bacterial genera in both Radula and Cannabis plants, which exhibited similar functional traits like biofilm formation and general anti-biofilm activities. Thus far, our work underlines the biocontrol potency and defensive functional traits (in terms of antagonism and biofilm formation) of endophytes harbored in liverwort R. marginata as compared to the endophytic community of phylogenetically unrelated but phytochemically similar plant C. sativa. PMID:25100187

  4. 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. PMID:26637302

  5. 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...

  6. Draft Genome Sequences of the Pseudomonas fluorescens Biocontrol Strains Wayne1R and Wood1R

    OpenAIRE

    Rong, Xiaoqing; Baysal Gurel, Fulya; Meulia, Tea; McSpadden Gardener, Brian B

    2012-01-01

    Pseudomonas fluorescens strains Wayne1R and Wood1R have proven capacities to improve plant health. Here we report the draft genome sequences and automatic annotations of both strains. Genome comparisons reveal similarities with P. fluorescens strain Pf-5, reveal the novelty of Wood1R, and indicate some genes that may be related to biocontrol.

  7. 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...

  8. 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.

  9. 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. PMID:27199931

  10. Towards understanding the ecology and mechanisms of biocontrol of Clonostachys rosea IK726

    Institute of Scientific and Technical Information of China (English)

    Mette Lübeck; Inge M B Knudsen; Birgit Jensen; Mojtaba Mamarabadi; Dan Funck Jensen

    2004-01-01

    @@ Clonostachys rosea (syn. Gliocladium roseum ) IK726 was originally selected as an effective biocontrol agent (BCA) against cereal seed borne diseases caused by Fusarium culmorum and Bipolaris sorokiniana. We have studied the efficacy of the antagonist against different pathogens in several crops and found that the antagonist also is able to control Alternaria radicina and A. dauci on carrot seeds and different cold-storage fungi in acorns. IK726 is also able to reduce severity of soil borne Pythium spp. in cabbage, carrot and sugar beet. In addition, growth-promoting effects of IK726 have been demonstrated in barley and tomato. In order to develop and improve application methods and control strategies, essential basic studies of ecology and the mechanisms of control of IK726 is needed and has led us to use various molecular tools. The UP-PCR technology is used for strain recognition and we have developed GUS and GFP-transformants that resembles the wildtype strain in ecological fitness parameters. Using either the GUS-transformant or UP-PCR we have found that IK726, when applied with seeds, reproduces and survives several months in the rhizosphere of field grown barley and carrot.The GFP-transformant is used to study the behavior and in situ interactions of the antagonist with pathogens and plants. Using the GFP marker, we have observed conidial germination, colonization and conidiogenesis in natural soil, in vermiculite and on carrot and barley seed and roots and on barley leaves. Moreover in situ interactions with Alternaria on carrot material have been studied. The modes of action of C. rosea are not well understood but enzymatic activity, mycoparasitism, substrate competition, antibiosis and induced resistance are thought to play a role. Barley treated with C. rosea IK726 has an enhanced chitinolytic and glucanolytic activity compared to the activity in non-treated barley in pot experiments with field soil. Identification of chitinases from IK726 and studies

  11. Pichia angusta is an effective biocontrol yeast against postharvest decay of apple fruit caused by Botrytis cinerea and Monilia fructicola.

    Science.gov (United States)

    Fiori, Stefano; Fadda, Angela; Giobbe, Sara; Berardi, Enrico; Migheli, Quirico

    2008-09-01

    The efficacy of eight isolates of Pichia angusta against three common postharvest pathogens of apple fruit was evaluated for the first time. All tested strains showed significant biocontrol activity against both Botrytis cinerea and Monilia fructicola, whereas efficacy against Penicillium expansum was poor. A leucine-auxotrophic mutant had no significant biocontrol activity against brown rot of apple, while the addition of 0.6-1.2 g L(-1) leucine in the fruit wound fully restored the biocontrol activity of this mutant against M. fructicola. Given the extremely well-developed classical and molecular genetics, the availability of genomic libraries, and its complete genomic sequence, this species can serve to elucidate the mechanisms related to biocontrol capacity.

  12. Biosynthesis of Antibiotic Leucinostatins in Bio-control Fungus Purpureocillium lilacinum and Their Inhibition on Phytophthora Revealed by Genome Mining

    Science.gov (United States)

    Li, Erfeng; Mao, Zhenchuan; Ling, Jian; Yang, Yuhong; Yin, Wen-Bing; Xie, Bingyan

    2016-01-01

    Purpureocillium lilacinum of Ophiocordycipitaceae is one of the most promising and commercialized agents for controlling plant parasitic nematodes, as well as other insects and plant pathogens. However, how the fungus functions at the molecular level remains unknown. Here, we sequenced two isolates (PLBJ-1 and PLFJ-1) of P. lilacinum from different places Beijing and Fujian. Genomic analysis showed high synteny of the two isolates, and the phylogenetic analysis indicated they were most related to the insect pathogen Tolypocladium inflatum. A comparison with other species revealed that this fungus was enriched in carbohydrate-active enzymes (CAZymes), proteases and pathogenesis related genes. Whole genome search revealed a rich repertoire of secondary metabolites (SMs) encoding genes. The non-ribosomal peptide synthetase LcsA, which is comprised of ten C-A-PCP modules, was identified as the core biosynthetic gene of lipopeptide leucinostatins, which was specific to P. lilacinum and T. ophioglossoides, as confirmed by phylogenetic analysis. Furthermore, gene expression level was analyzed when PLBJ-1 was grown in leucinostatin-inducing and non-inducing medium, and 20 genes involved in the biosynthesis of leucionostatins were identified. Disruption mutants allowed us to propose a putative biosynthetic pathway of leucinostatin A. Moreover, overexpression of the transcription factor lcsF increased the production (1.5-fold) of leucinostatins A and B compared to wild type. Bioassays explored a new bioactivity of leucinostatins and P. lilacinum: inhibiting the growth of Phytophthora infestans and P. capsici. These results contribute to our understanding of the biosynthetic mechanism of leucinostatins and may allow us to utilize P. lilacinum better as bio-control agent. PMID:27416025

  13. Biosynthesis of Antibiotic Leucinostatins in Bio-control Fungus Purpureocillium lilacinum and Their Inhibition on Phytophthora Revealed by Genome Mining.

    Directory of Open Access Journals (Sweden)

    Gang Wang

    2016-07-01

    Full Text Available Purpureocillium lilacinum of Ophiocordycipitaceae is one of the most promising and commercialized agents for controlling plant parasitic nematodes, as well as other insects and plant pathogens. However, how the fungus functions at the molecular level remains unknown. Here, we sequenced two isolates (PLBJ-1 and PLFJ-1 of P. lilacinum from different places Beijing and Fujian. Genomic analysis showed high synteny of the two isolates, and the phylogenetic analysis indicated they were most related to the insect pathogen Tolypocladium inflatum. A comparison with other species revealed that this fungus was enriched in carbohydrate-active enzymes (CAZymes, proteases and pathogenesis related genes. Whole genome search revealed a rich repertoire of secondary metabolites (SMs encoding genes. The non-ribosomal peptide synthetase LcsA, which is comprised of ten C-A-PCP modules, was identified as the core biosynthetic gene of lipopeptide leucinostatins, which was specific to P. lilacinum and T. ophioglossoides, as confirmed by phylogenetic analysis. Furthermore, gene expression level was analyzed when PLBJ-1 was grown in leucinostatin-inducing and non-inducing medium, and 20 genes involved in the biosynthesis of leucionostatins were identified. Disruption mutants allowed us to propose a putative biosynthetic pathway of leucinostatin A. Moreover, overexpression of the transcription factor lcsF increased the production (1.5-fold of leucinostatins A and B compared to wild type. Bioassays explored a new bioactivity of leucinostatins and P. lilacinum: inhibiting the growth of Phytophthora infestans and P. capsici. These results contribute to our understanding of the biosynthetic mechanism of leucinostatins and may allow us to utilize P. lilacinum better as bio-control agent.

  14. 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 cons

  15. The science, development, and commercialization of postharvest biocontrol

    Science.gov (United States)

    Postharvest biological control agents as a viable alternative to the use of synthetic chemicals have been the focus of considerable research for the last 30 years by many scientists and several commercial companies worldwide. Several antagonists of postharvest pathogens have been identified and tes...

  16. 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...

  17. 木霉菌生物防治作用机理与应用研究进展%Progress on Mechanism and Applications of Trichoderma as a Biocontrol Microbe

    Institute of Scientific and Technical Information of China (English)

    陈捷; 朱洁伟; 张婷; 王秉丽

    2011-01-01

    Trichoderma is widely used as a biocontrol microbe against plant diseases in the world, which is mainly applied for controlling a variety of soil bome plant diseases and some plant aboveground diseases. With the advent of MAMPs (microbe-associated molecular patterns) theory, the study on mechanism of plant disease control and improved plant resistance to stress factors with Trichoderma as a biocontrol agent has come into a new stage, especially as the development of technologies based on systems biology, it has become possible to understand the nature of interaction of plant- Trichoderma -pathogen from point of "omics" view, which therefore would intensively enrich the theory basis of Trichoderma as biocontrol agent. Meanwhile, a diversified technical system for applying Trichoderma products developed in national agricultural industry would provide great promotion to sustainable development of agriculture in the future. This review will focus on new research progress on biocontrol mechanism with Trichoderma against plant diseases at molecular level.%木霉菌Trichoderma是国际上应用非常普遍的生防真菌.随着植物免疫的MAMPs(微生物互作分子模式)理论的发展,利用木霉菌防治病害和提高作物抗逆性机理研究进入了一个新阶段,尤其是系统生物学方法的应用,使得人们在"组学"尺度上认识木霉菌与植物和病原菌互作的本质成为可能,这将极大丰富木霉菌生物防治植物病害的理论基础.在我国建立木霉菌多样化应用技术途径是发挥木霉菌在农业可持续发展中作用的重要发展方向.本文重点介绍木霉菌生物防治分子机理研究的新进展.

  18. Combining UV-C treatment with biocontrol yeast to control postharvest decay of melon.

    Science.gov (United States)

    Huang, Ke; Zou, Yong; Luo, Jie; Liu, Yiqing

    2015-09-01

    Significant losses in harvested melon can be directly attributable to decay fungi. In the present study, the use of UV-C treatment combined with biocontrol yeast, Pichia cecembensis, was evaluated for their ability to control postharvest decay of melon fruits after they were artificially inoculated with Fusarium oxysporum and Alternaria alternata. Natural infection of fruit was also assessed. As a stand-alone treatment, UV-C or P. cecembensis significantly reduced Fusarium rot and Alternaria rot, and also the level of natural infection on melon fruit, relative to the untreated control. The combination of UV-C or P. cecembensis, however, provided a superior level of decay control on artificially inoculated and naturally infected fruit, compared to either treatment alone. None of the treatments impaired fruit quality. Integrating the use of UV-C treatment with biocontrol yeast has potential as an effective method to control postharvest decay of melon.

  19. Biocontrol Efficacy of Two Antagonistic Yeasts Against Postharvest Diseases in Peach Fruits During Storage Periods

    Institute of Scientific and Technical Information of China (English)

    LIN Li; TIAN Shi-ping; QIN Guo-zheng; XU Yong

    2003-01-01

    Two antagonistic yeasts, Thichosporon pullulans and Cryptococcus laurentii, were investigated for their biocontrol potential to blue mold rot and rhizopus rot on harvested peach fruits (Prunus persica L. Batsch, cv. Okubao), alone or in combination with a Iow dose of iprodione (50 μg mi-1 ). The results indicated that T. pullulans and C. laurentii were effective at reducing disease incidence and severity of blue mold rot and rhizopus rot in peach fruits. Biocontrol efficacy of C. laurentii and T. pullulans were significantly enhanced by combination with a Iow dose of iprodione (50 μg mi-1) against blue mold and rhizopus rot in peach fruits. T. pullulans and C. laurentii combined with a low dose of iprodione (50 μg mi-1 ) resulted in better disease control than either iprodione or the yeasts used alone. Dipping fruits in suspensions of antagonist cells showed the similar control effect as the treatment with iprodione (500 μg ml-1 ).

  20. The Pochonia chlamydosporia Serine Protease Gene vcp1 Is Subject to Regulation by Carbon, Nitrogen and pH: Implications for Nematode Biocontrol

    Science.gov (United States)

    Ward, Elaine; Kerry, Brian R.; Manzanilla-López, Rosa H.; Mutua, Gerald; Devonshire, Jean; Kimenju, John; Hirsch, Penny R.

    2012-01-01

    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. PMID:22558192

  1. 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.

  2. Trichoderma spp.capable of growing at low temperatures with biocontrol potential

    Institute of Scientific and Technical Information of China (English)

    Szakacs G; Tavaszi A

    2004-01-01

    @@ Though there are successful commercial biocontrol products with Trichoderma spp. In many countries including US, Israel and Europe, their usefulness is limited in cold environments such as mid-and northern part of Europe, US and Canada, especially in the late fall, winter and early spring period.Trichoderma isolates capable of growing at low temperatures (5-10 ℃) and showing good antagonistic properties against plant pathogenic fungi may have therefore both scientific and commercial value.

  3. Enhanced biocontrol activity of Trichoderma through inactivation of a mitogen-activated protein kinase

    OpenAIRE

    Mendoza-Mendoza, Artemio; Pozo, María J.; Grzegorski, Darlene; Martínez, Pedro; García, Juan M.; Olmedo-Monfil, Vianey; Cortés, Carlos; Kenerley, Charles; Herrera-Estrella, Alfredo

    2003-01-01

    The production of lytic enzymes in Trichoderma is considered determinant in its parasitic response against fungal species. A mitogen-activated protein kinase encoding gene, tvk1, from Trichoderma virens was cloned, and its role during the mycoparasitism, conidiation, and biocontrol was examined in tvk1 null mutants. These mutants showed a clear increase in the level of the expression of mycoparasitism-related genes under simulated mycoparasitism and during direct confrontation with the plant ...

  4. Complete Genome Sequence of the Endophytic Biocontrol Strain Bacillus velezensis CC09

    Science.gov (United States)

    Cai, Xunchao; Kang, Xingxing; Xi, Huan

    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 volatile organic compound synthesis were identified in the genome. PMID:27688342

  5. 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

    2016-01-01

    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 volatile organic compound synthesis were identified in the genome. PMID:27688342

  6. 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.

  7. 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. PMID:27362639

  8. Antibiotic Agents

    Science.gov (United States)

    ... either as public health or as non-public health antimicrobial agents. What is the difference between bacteriostats, sanitizers, disinfectants ... bacteria, however, there is considerable controversy surrounding their health benefits. The ... producing agents (Table of Antibacterials) have been used for many ...

  9. 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. PMID:24310522

  10. Chitinolytic Bacteria Isolated from Chili Rhizosphere: Chitinase Characterization and Its Application as Biocontrol for Whitefly (Bemisia tabaci Genn.

    Directory of Open Access Journals (Sweden)

    Nisa R. Mubarik

    2010-01-01

    Full Text Available Problem statement: Chitin, a common constituent of insect exoskeleton, could be hydrolyzed by chitinase. The research was conducted to screen chitinolytic rhizobacteria isolated from rhizosphere of chilli pepper and to determine their chitinase activity in degrading chitin of whitefly, Bemisia tabaci Genn. (Hemiptera: Aleyrodidae. Whitefly is recognized as an important pest on many crops including chilli pepper. Approach: Screening and molecular identification based on 16S rRNA sequence of chitinolytic isolates, chitinase productions, measurement of chitinase activity, characterization of chitinase and effect of the chitinase treatment on whitefly were studied. Results: A total of 25 isolates of rhizobacteria formed a clear zone on solid chitin media. Two isolates, i.e., I.5 and I.21 isolates had the highest chitinolytic index. Based on sequence of 16S rRNA gene, the isolates of I.5 and I.21 were identified as Bacillus sp. and Bacillus cereus, respectively. The highest chitinolytic index and specific activity of I.5 isolate was 0.94 and 0.11 U mg-1 proteins, respectively. Maximum production of I.5 chitinase was occured after 36 h cultivation at 30°C and pH 7.0. The highest chitinolytic index and specific activity of I.21isolate was 0.75 and 0.114 U mg-1 proteins, respectively. Maximum production of I.21 chitinase was occured after 36 h cultivation at 55°C and pH 7.0. Cell culture and crude enzyme of the isolates were tested on chitin of B. tabaci and the effect was observed using a microscope and sterile water was used as a negative control. Hydrolytic observation showed that crude enzyme of I.21 isolate could degrade chitin of B. tabaci exoskeleton and the activity was better than that of I.5 isolate. Conclusion: Chitinase produced by Bacillus cereus I.21 strain has potential application as biocontrol agents for B. tabaci.

  11. The effect of biological and chemical control agents on the health status of the very early potato cultivar Rosara

    OpenAIRE

    Cwalina-Ambroziak Bożena; Damszel Marta Maria; Głosek-Sobieraj Małgorzata

    2015-01-01

    The external appearance and quality of table potatoes are determined, among other factors, by the health status of the plants during the growing season. Chemical control methods are often combined with biocontrol agents to effectively fight potato pathogens. Potatoes of the very early cultivar Rosara were grown in experimental plots. The plots were located in Tomaszkowo (NE Poland, 2007-2009). The experiment involved the following treatments: 1) biological control − mycorrhizal Glomus spp. in...

  12. Non-target trials with Pseudomonas fluorescens strain CL145A, a lethal control agent of dreissenid mussels (Bivalvia: Dreissenidae)

    OpenAIRE

    Molloy, Daniel P.; Denise A. Mayer; Michael J. Gaylo; Burlakova, Lyubov E.; Karatayev, Alexander Y.; Kathleen T. Presti; Paul M. Sawyko; John T. Morse; Eric A. Paul

    2013-01-01

    In an effort to develop an efficacious and environmentally safe method for managing zebra mussels (Dreissena polymorpha) and quaggamussels (Dreissena rostriformis bugensis), we initiated a research project investigating the potential use of bacteria and their naturalmetabolic products as biocontrol agents. This project resulted in the discovery of an environmental isolate lethal to dreissenid mussels,Pseudomonas fluorescens strain CL145A (Pf-CL145A). In previous published reports we have demo...

  13. Bio-protective microbial agents from rhizosphere eco-systems trigger plant defense responses provide protection against sheath blight disease in rice (Oryza sativa L.).

    Science.gov (United States)

    Singh, Udai B; Malviya, Deepti; Wasiullah; Singh, Shailendra; Pradhan, Jatindra K; Singh, Bhanu P; Roy, Manish; Imram, Mohd; Pathak, Neelam; Baisyal, B M; Rai, Jai P; Sarma, B K; Singh, Rajiv K; Sharma, P K; Kaur, Saman Deep; Manna, M C; Sharma, Sushil K; Sharma, Arun K

    2016-11-01

    Sheath blight of rice (Oryza sativa L.) caused by Rhizoctonia solani is a major disease and attempts are being made to develop microbe based technologies for biocontrol of this pathogen. However, the mechanisms of biocontrol are not fully understood and still require indepth study in the backdrop of emerging concepts in biological systems. The present investigation was aimed at deciphering the mechanisms of biocontrol of sheath blight of rice employing Pseudomonas fluorescens and Trichoderma harzianum as model agents for biocontrol. Initially 25, 5 and 5 strains of P. fluorescens, T. viride and T. harzianum, respectively, were screened for their biocontrol potential. Out of which, six strains with higher value of percent inhibition of fungal mycelium in dual plate assay were selected. The role of P. fluorescens, T. viride and T. harzianum were investigated in induction and bioaccumulation of natural antioxidants, defence-related biomolecules and other changes in plant which lead not only to growth promotion but also protection from pathogenic stress conditions in rice. The two most promising strains, P. fluorescens PF-08 and T. harzianum UBSTH-501 selected on the basis of in planta evaluation, when applied individually or in combination, significantly enhanced the accumulation of defence-related biomolecules, enzymes and exhibited biocontrol potential against R. solani. A modified/newly developed delivery system was applied for the first time in the experiments involving inoculation of plants with both bioagents, viz. P. fluorescens PF-08 and T. harzianum UBSTH-501. Results suggested that application of P. fluorescens PF-08 and T. harzianum UBSTH-501 alone or in combination, not only helps in control of the disease but also increases plant growth along with reduction in application of toxic chemical pesticides. PMID:27664749

  14. Bio-control potential of Cladosporium sp. (MCPL-461), against a noxious weed Parthenium hysterophorus L.

    Science.gov (United States)

    Kumar, Anuj; Verma, V C; Gond, S K; Kumar, V; Kharwar, R N

    2009-03-01

    The phenological survey of Parthenium hysterophorus L., in and around the campus of Banaras Hindu University (BHU) was done for about two years (2004-06). During Nov 2004, a few Parthenium plants were found diseased, and symptoms were restricted to the flowers, buds, and inflorescences. The disease causes sterility and reduces seed viability, which was observed with seed germination test from infected and healthy plants. The fungal pathogen was isolated and identified as Cladosporium sp. (MCPL-461). The severity of pathogen to the reproductive organs led to serious damages of the Parthenium plants. Thus in vitro and in vivo experiments were conducted to determine the bio-control potential of Cladosporium sp. (MCPL 461) against Parthenium weed. A combinatorial effort of Cladosporium sp. (MCPL 461) bio-control potential was evaluated with different culture media, incubation periods and spores strength. Spore suspension of 10(5) to 10(12) spores ml(-1) were used to spray on healthy Parthenium plants, and it was found that severe infection symptoms were appeared at 10(10) to 10(12) spores ml(-1) suspension. LD50 was found at 10(7) spores ml(-1). To enhance the myco-herbicide activity 3% sucrose was added to the spore suspension, which further resolute the bio-control efficacy of the isolates. Only 20-30% seeds of infected plants could germinate. However the safety of non-targeted and wild plants was also tested with Lantana camera, Chromolaena odorata and found that suspension up to 10(12) spores ml(-1) were not sufficient for disease outbreak in them. PMID:20121037

  15. Bio-control potential of Cladosporium sp. (MCPL-461), against a noxious weed Parthenium hysterophorus L.

    Science.gov (United States)

    Kumar, Anuj; Verma, V C; Gond, S K; Kumar, V; Kharwar, R N

    2009-03-01

    The phenological survey of Parthenium hysterophorus L., in and around the campus of Banaras Hindu University (BHU) was done for about two years (2004-06). During Nov 2004, a few Parthenium plants were found diseased, and symptoms were restricted to the flowers, buds, and inflorescences. The disease causes sterility and reduces seed viability, which was observed with seed germination test from infected and healthy plants. The fungal pathogen was isolated and identified as Cladosporium sp. (MCPL-461). The severity of pathogen to the reproductive organs led to serious damages of the Parthenium plants. Thus in vitro and in vivo experiments were conducted to determine the bio-control potential of Cladosporium sp. (MCPL 461) against Parthenium weed. A combinatorial effort of Cladosporium sp. (MCPL 461) bio-control potential was evaluated with different culture media, incubation periods and spores strength. Spore suspension of 10(5) to 10(12) spores ml(-1) were used to spray on healthy Parthenium plants, and it was found that severe infection symptoms were appeared at 10(10) to 10(12) spores ml(-1) suspension. LD50 was found at 10(7) spores ml(-1). To enhance the myco-herbicide activity 3% sucrose was added to the spore suspension, which further resolute the bio-control efficacy of the isolates. Only 20-30% seeds of infected plants could germinate. However the safety of non-targeted and wild plants was also tested with Lantana camera, Chromolaena odorata and found that suspension up to 10(12) spores ml(-1) were not sufficient for disease outbreak in them.

  16. Role of gluconic acid production in the regulation of biocontrol traits of Pseudomonas fluorescens CHA0.

    Science.gov (United States)

    de Werra, Patrice; Péchy-Tarr, Maria; Keel, Christoph; Maurhofer, Monika

    2009-06-01

    The rhizobacterium Pseudomonas fluorescens CHA0 promotes the growth of various crop plants and protects them against root diseases caused by pathogenic fungi. The main mechanism of disease suppression by this strain is the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG) and pyoluteorin (PLT). Direct plant growth promotion can be achieved through solubilization of inorganic phosphates by the production of organic acids, mainly gluconic acid, which is one of the principal acids produced by Pseudomonas spp. The aim of this study was to elucidate the role of gluconic acid production in CHA0. Therefore, mutants were created with deletions in the genes encoding glucose dehydrogenase (gcd) and gluconate dehydrogenase (gad), required for the conversion of glucose to gluconic acid and gluconic acid to 2-ketogluconate, respectively. These enzymes should be of predominant importance for rhizosphere-colonizing biocontrol bacteria, as major carbon sources provided by plant root exudates are made up of glucose. Our results show that the ability of strain CHA0 to acidify its environment and to solubilize mineral phosphate is strongly dependent on its ability to produce gluconic acid. Moreover, we provide evidence that the formation of gluconic acid by CHA0 completely inhibits the production of PLT and partially inhibits that of DAPG. In the Deltagcd mutant, which does not produce gluconic acid, the enhanced production of antifungal compounds was associated with improved biocontrol activity against take-all disease of wheat, caused by Gaeumannomyces graminis var. tritici. This study provides new evidence for a close association of gluconic acid metabolism with antifungal compound production and biocontrol activity in P. fluorescens CHA0.

  17. 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.

  18. Characterization of the biocontrol activity of pseudomonas fluorescens strain X reveals novel genes regulated by glucose.

    Science.gov (United States)

    Kremmydas, Gerasimos F; Tampakaki, Anastasia P; Georgakopoulos, Dimitrios G

    2013-01-01

    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. DECOLORIZATION OF REACTIVE BLACK KN-B BY PSEUDOZYMA RUGULOSA Y48%酵母菌Y48对活性黑KN-B的脱色研究

    Institute of Scientific and Technical Information of China (English)

    陈曦; 余志晟; 贺菲; 张洪勋

    2011-01-01

    从土壤中分离获得了一株对偶氮染料具有明显脱色效果的酵母菌Pseudozyma rugulosa Y48,其对初始浓度为100 mg·L-1的活性黑KN-B的最大脱色率可达99%.采用酵母菌Y48对偶氮染料脱色的优化控制条件是:接种量应不低于3%(体积分数);最适pH值在6-_9之间;氮源(NH4)2SO4的浓度不低于0.1%;碳源葡萄糖的浓度为1%.对其脱色机理的研究表明,Y48对活件黑KN-B的脱色是由吸附和降解两个过程完成的,而对活性黑KN-B分子的去除则主要依靠生物降解.此研究表明,酵母菌Y48在染料废水的处理上具有较大的应用潜能.%A yeast strain Pseudozyma rugulosa Y48, which was isolated from soil by screening experiments, could effectively decolorize azo dyes. This strain gave a maximal decolorization rate of 99% for Reactive Black KN-B of initial concentration of 100 mg·L-1. The optimal culture conditions were as follow: inoculation volume ≥3% (V/V); pH 6-9; ( NH4 ) 2SO4 concentration ≥0. 1% and glucose concentration ≥ 1%. The results on the mechanism showed that decolorization of the dye proceeded primarily by absorption and degradation. The removal of the Reactive Black KN-B molecules relied mainly on biodegradation. These results indicated that the yeast strain Y48 could have potential application in dye wastewater treatment.

  20. Agent, autonomous

    OpenAIRE

    Luciani, Annie

    2007-01-01

    The expression autonomous agents, widely used in virtual reality, computer graphics, artificial intelligence and artificial life, corresponds to the simulation of autonomous creatures, virtual (i.e. totally computed by a program), or embodied in a physical envelope, as done in autonomous robots.

  1. Biocontrol of Aspergillus flavus on peanut kernels by use of a strain of marine Bacillus megaterium.

    Science.gov (United States)

    Kong, Qing; Shan, Shihua; Liu, Qizheng; Wang, Xiudan; Yu, Fangtang

    2010-04-30

    A strain of marine Bacillus megaterium isolated from the Yellow Sea of East China was evaluated for its activity in reducing postharvest decay of peanut kernels caused by Aspergillus flavus in in vitro and in vivo tests. The results showed that the concentrations of antagonist had a significant effect on biocontrol effectiveness in vivo: when the concentration of the washed bacteria cell suspension was used at 1x10(9)CFU/ml, the percentage rate of rot of peanut kernels was 31.67%+/-2.89%, which was markedly lower than that treated with water (the control) after 7days of incubation at 28 degrees C. The results also showed that unwashed cell culture of B. megaterium was as effective as the washed cell suspension, and better biocontrol was obtained when longer incubation time of B. megaterium was applied. When the incubation time of B. megaterium was 60-h, the rate of decay declined to 41.67%+/-2.89%. Furthermore, relative to the expression of 18S rRNA, the mRNA abundances of aflR gene and aflS gene in the experiment group were 0.28+/-0.03 and 0.024+/-0.005 respectively, indicating that this strain of B. megaterium could significantly reduce the biosynthesis of aflatoxins and expression of aflR gene and aflS gene (pagainst postharvest fungal disease caused by A. flavus. PMID:20156660

  2. Systematics of the Trichoderma harzianum species complex and the re-identification of commercial biocontrol strains.

    Science.gov (United States)

    Chaverri, Priscila; Branco-Rocha, Fabiano; Jaklitsch, Walter; Gazis, Romina; Degenkolb, Thomas; Samuels, Gary J

    2015-01-01

    Trichoderma harzianum is known as a cosmopolitan, ubiquitous species associated with a wide variety of substrates. It is possibly the most commonly used name in agricultural applications involving Trichoderma, including biological control of plant diseases. While various studies have suggested that T. harzianum is a species complex, only a few cryptic species are named. In the present study the taxonomy of the T. harzianum species complex is revised to include at least 14 species. Previously named species included in the complex are T. guizhouense, T. harzianum, and T. inhamatum. Two new combinations are proposed, T. lentiforme and T. lixii. Nine species are described as new, T. afarasin, T. afroharzianum, T. atrobrunneum, T. camerunense, T. endophyticum, T. neotropicale, T. pyramidale, T. rifaii and T. simmonsii. We isolated Trichoderma cultures from four commercial biocontrol products reported to contain T. harzianum. None of the biocontrol strains were identified as T. harzianum s. str. In addition, the widely applied culture 'T. harzianum T22' was determined to be T. afroharzianum. Some species in the T. harzianum complex appear to be exclusively endophytic, while others were only isolated from soil. Sexual states are rare. Descriptions and illustrations are provided. A secondary barcode, nuc translation elongation factor 1-α (TEF1) is needed to identify species in this complex.

  3. Enhanced biocontrol activity of Trichoderma through inactivation of a mitogen-activated protein kinase.

    Science.gov (United States)

    Mendoza-Mendoza, Artemio; Pozo, María J; Grzegorski, Darlene; Martínez, Pedro; García, Juan M; Olmedo-Monfil, Vianey; Cortés, Carlos; Kenerley, Charles; Herrera-Estrella, Alfredo

    2003-12-23

    The production of lytic enzymes in Trichoderma is considered determinant in its parasitic response against fungal species. A mitogen-activated protein kinase encoding gene, tvk1, from Trichoderma virens was cloned, and its role during the mycoparasitism, conidiation, and biocontrol was examined in tvk1 null mutants. These mutants showed a clear increase in the level of the expression of mycoparasitism-related genes under simulated mycoparasitism and during direct confrontation with the plant pathogen Rhizoctonia solani. The null mutants displayed an increased protein secretion phenotype as measured by the production of lytic enzymes in culture supernatant compared to the wild type. Consistently, biocontrol assays demonstrated that the null mutants were considerably more effective in disease control than the wild-type strain or a chemical fungicide. In addition, tvk1 gene disruptant strains sporulated abundantly in submerged cultures, a condition that is not conducive to sporulation in the wild type. These data suggest that Tvk1 acts as a negative modulator during host sensing and sporulation in T. virens. PMID:14673101

  4. Implementing plant biostimulants and biocontrol strategies in the agroecological management of cultivated ecosystems. A review

    Directory of Open Access Journals (Sweden)

    Le Mire, G.

    2016-01-01

    Full Text Available Introduction. In the context of sustainable agricultural production, agroecology aims at optimizing the economic and environmental performances of beneficial ecosystem services in order to (i increase the productivity and resilience of cultivated ecosystems and (ii preserve their natural resources. The maintenance of such performances is supported by research via the development of new tools that enhance plant tolerance to numerous biotic and abiotic stresses. Literature. Biostimulants can be used as a tool to complement the use of chemical inputs, by involving non-living-based products, or living-based products containing beneficial rhizosphere microbiome, such as plant growth-promoting rhizobacteria (PGPR. Pest management research has also made major advances in the development of efficient biocontrol methods. Elicitors and semiochemicals are considered to be some of the most promising tools for inducing plant resistance to various diseases and enhancing natural predation, respectively. Several products are already on the market. This review discusses current methods for exploiting and applying biostimulant and biocontrol products in contemporary agricultural systems. Future applications of these tools for sustainable management of cultivated ecosystems are also discussed. Conclusions. These tools are still difficult to use because of their lack of reliability in the field and their uneasy integration in the cropping systems. Further studies are needed to better understand the parameters influencing the efficiency of PGPR, elicitors and semiochemicals. Special attention needs to be given to the formulation and the interactions of these products with plant physiology and the environment.

  5. Diversity, biocontrol, and plant growth promoting abilities of xylem residing bacteria from solanaceous crops.

    Science.gov (United States)

    Achari, Gauri A; Ramesh, Raman

    2014-01-01

    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. PMID:24963298

  6. Strain-level diversity of secondary metabolism in the biocontrol species Aneurinibacillus migulanus.

    Science.gov (United States)

    Alenezi, Faizah N; Rekik, Imen; Bełka, Marta; Ibrahim, Abrar F; Luptakova, Lenka; Jaspars, Marcel; Woodward, Steve; Belbahri, Lassaad

    2016-01-01

    Aneurinibacillus migulanus strains Nagano and NCTC 7096 show potential in biocontrol against fungal and fungus-like plant pathogens, including a wide range of Ascomycota, Basidiomycota, and Oomycetes. Differences in terms of the range of pathogens that each strain inhibits, however, suggested that production of a single antibiotic cyclic peptide, gramicidin S (GS), by the two strains, is not the sole mechanism of inhibition. The availability of four sequenced genomes of Aneurinibacillus prompted us to apply genome mining techniques to identify the bioactive potential of A. migulanus and to provide insights into the secondary metabolite arsenal of the genus Aneurinibacillus. Up to eleven secondary metabolite biosynthetic gene clusters were present in the three Aneurinibacillus species. Biosynthetic gene clusters specifying bacteriocins, microcins, non-ribosomal peptides, polyketides, terpenes, phosphonates, lasso peptides and linaridins were identified. Chitinolytic potential and iron metabolism regulation were also investigated. With increasing numbers of biocontrol bacterial genomes being sequenced and mined, the use of approaches similar to those described in this paper will lead to an increase in the numbers of environmentally friendly natural products available to use against plant diseases. PMID:26686620

  7. 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.

  8. Bio-control trials of Chaetomium spirale ND35 against apple canker

    Institute of Scientific and Technical Information of China (English)

    XINYa-fen; SHANGJin-jie

    2005-01-01

    A new endophytic antagonistic fungus, Chaetomium spirale ND35 from Populus tomentosa, was reported. The bio-control trials of C. spirale ND35 against the Valsa Canker of apple were preliminarily investigated. The results of dual culture on PDA plate showed that C. spirale ND35 was capable of strong antagonism against Valsa ceratosperma, and for inhibiting the mycelial growth of V. ceratosperma,.the crude extract of liquid culture of corn steep powder broth was more effective than that one of malt extract broth (MEB). The results of bio-control in greenhouse and field indicated that the disease incidence of apple tree treated with C. spirale ND35 was lower significantly than that treated by other methods. The re-isolation experiment suggested that C. spirale ND35 could colonize in stems and branches of apple trees successfully, and the ND35 colonization rate of the treatment with solid wheat bran culture was higher than that of corn steep powder broth, but the field experiment result the control effect of liquid culture of C. spirale ND35 was better than that of solid culture.

  9. 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.

  10. Assessment of endophytic yeast diversity in rice leaves by a culture-independent approach.

    Science.gov (United States)

    Tantirungkij, Manee; Nasanit, Rujikan; Limtong, Savitree

    2015-09-01

    Endophytic microorganisms inhabit internal plant tissues in the host plant without causing any symptoms or negative effects. Although the diversity of endophytes has been evaluated by both culture-dependent and culture-independent methods, less information is available on yeast communities. Therefore, in this study a culture-independent method was used to examine endophytic yeasts associated with rice leaves based on the large subunit of ribosomal DNA using a semi-nested PCR technique. Sequence analysis indicated that the colonization frequency and the relative species frequency (RF) of endophytic yeast phylotypes were 0.41 and 0.06, respectively, and the majority of the yeast phylotypes were basidiomycetous yeasts. The phylotypes were designated as five known species (Cryptococcus victoriae, Debaryomyces hansenii, Debaryomyces vindobonensis, Meyerozyma guilliermondii and Pseudozyma antarctica), together with seventeen phylotypes closest to Candida metapsilosis, Cryp. foliicola, Cryp. laurentii, Pseudozyma abaconensis, Pseudozyma aphidis and Trichosporon asahii, among which some could be novel species. The most prevalent phylotypes were those closest to Cryp. foliicola (47.5 % RF) followed by D. hansenii (22.8 % RF) and P. antarctica (16.8 % RF). The presence of the phylotypes related to species known for their potential applications as biocontrol agents and plant growth promoting hormone producers suggests that they may have valuable applications. In addition, our findings revealed the occurrence of novel phylotypes at high frequency, which should encourage extensive studies to discover novel yeast species and to understand their roles in the rice leaves. PMID:26122889

  11. Non-Target Plant Use by a Weed Biocontrol Agent in Idaho: Host Expansion or Opportunistic Behavior?

    Science.gov (United States)

    The weevil Larinus curtus Hochhuth (Coleoptera: Curculionidae) was first introduced into western United States from Greece for the biological control of yellow starthistle (YST), Centaurea solstitialis L. in 1992. Adults feed on YST pollen and flowers, laying eggs among flowers of YST capitula. Th...

  12. IN VITRO MANAGEMENT OF CURVULARIA LEAF SPOT OF MAIZE USING BOTANICALS, ESSENTIAL OILS AND BIO-CONTROL AGENTS

    OpenAIRE

    JYOTIKA PUROHIT; SRINIVASANRAGHVAN, A.; PRADEEP KUMAR; SUNAINA BISHT

    2013-01-01

    Different plant extracts, essential oils and different strains of Trichoderma harzianum were evaluated in vitroagainst Curvularia lunata. Amongst the plant extracts, Lantana was highly effective @ 15 per cent (86.76 inhibition%) and 20 per cent (89.49 inhibition %) followed by Morphankhi @ 5 per cent (83.53 %) and 10 per cent (85.88%) respectively. Among the essential oils, complete inhibition was recorded in Citronella oil at all 3 concentrations(2µL, 4µL and 8) and Peppermint oil at 4µL and...

  13. Q69, an E. faecalis-infecting bacteriophage, as a biocontrol agent for reducing tyramine in dairy products

    OpenAIRE

    Victor eLadero; Carolina eGomez-Sordo; Esther eSanchez-LLana; Beatriz edel Rio; Maria Begoña eRedruello; Maria eFernandez; Maria Cruz Martin; Alvarez, Miguel A.

    2016-01-01

    Biogenic amines (BAs) are low molecular weight nitrogenous compounds with biological activity, formed from amino acids by decarboxylation. BAs are naturally present in all living organisms playing essential roles. However, their accumulation in food through the metabolic activity of certain microorganisms constitutes a toxicological hazard. Among foods, cheeses accumulate some of the highest concentrations of BAs since they provide an ideal environment for their accumulation. Most of the met...

  14. Q69 (an E. faecalis-Infecting Bacteriophage) As a Biocontrol Agent for Reducing Tyramine in Dairy Products

    OpenAIRE

    Ladero, Victor; Gómez-Sordo, Carolina; Sánchez-Llana , Esther; del Rio, Beatriz; Redruello, Begoña; Fernández, María; Martín, M. Cruz; Alvarez, Miguel A.

    2016-01-01

    Biogenic amines (BAs) are low molecular weight nitrogenous compounds with biological activity, formed from amino acids by decarboxylation. BAs are naturally present in all living organisms playing essential roles. However, their accumulation in food through the metabolic activity of certain microorganisms constitutes a toxicological hazard. Among foods, cheeses accumulate some of the highest concentrations of BAs since they provide an ideal environment for their accumulation. Most of the meth...

  15. Genome Sequence of the Endophytic Bacterium Bacillus thuringiensis Strain KB1, a Potential Biocontrol Agent against Phytopathogens

    OpenAIRE

    Jeong, Haeyoung; Jo, Sung Hee; Hong, Chi Eun; Park, Jeong Mee

    2016-01-01

    Bacillus thuringiensis is the most widely known microbial pesticide used in agricultural applications. Herein, we report a draft genome sequence of the endophytic bacterium Bacillus thuringiensis strain KB1, which exhibits antagonism against phytopathogens.

  16. 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.

  17. 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

    Rose (Rosa hybrida L.) is the most important ornamental crop in Kenya, with huge investments in pest management. We provide the first full-scale, replicated experiment comparing cost and yield of conventional two-spotted spider mite (Tetranychus urticae Koch) control with hot-spot applications...... blanket-treated with an acaricide to decrease infestations. Roses subjected to the hot-spot treatment had significantly lower T. urticae infestations compared with conventionally treated roses. In addition, significantly fewer high spider mite infestations were recorded in roses with the hot...... 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...

  18. 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 ...

  19. A new species of Dichrorampha (Lepidoptera: Tortricidae) from Jamaica: A potential biocontrol agent against Chromolaena odorata (Asterasceae)

    Science.gov (United States)

    Dichrorampha odorata Brown and Zachariades, new species, is described and illustrated from Jamaica. It is most similar to D. sapodilla Heppner among described species, both superficially and in the male genitalia. However, the two are easily separated by the long costal fold of the male forewing of ...

  20. Biocontrol of Rhizoctonia solani AG-2, the causal agent of damping-off by Muscodor cinnamomi CMU-Cib 461.

    Science.gov (United States)

    Suwannarach, Nakarin; Kumla, Jaturong; Bussaban, Boonsom; Lumyong, Saisamorn

    2012-11-01

    Rhizoctonia solani is a damping-off pathogen that causes significant crop loss worldwide. In this study, the potential of Muscodor cinnamomi, a new species of endophytic fungus for controlling R. solani AG-2 damping-off disease of plant seedlings by biological fumigation was investigated. In vitro tests showed that M. cinnamomi volatile compounds inhibited mycelial growth of pathogens. Among nine solid media tested, rye grain was the best grain for inoculum production. An in vivo experiment of four seedlings, bird pepper, bush bean, garden pea and tomato were conducted. The results indicated that treatment with 30 g of M. cinnamomi inoculum was the minimum dose that caused complete control of damping-off symptoms of all seedlings after one month of planting. The R. solani-infested soil showed the lowest percentage of seed germination. In addition, M. cinnamomi did not cause any disease symptoms. From the results it is clear that M. cinnamomi is effective in controlling R. solani AG-2 both in vitro and in vivo. PMID:22806753

  1. Genome Sequence of the Endophytic Bacterium Bacillus thuringiensis Strain KB1, a Potential Biocontrol Agent against Phytopathogens.

    Science.gov (United States)

    Jeong, Haeyoung; Jo, Sung Hee; Hong, Chi Eun; Park, Jeong Mee

    2016-04-21

    ITALIC! Bacillus thuringiensisis the most widely known microbial pesticide used in agricultural applications. Herein, we report a draft genome sequence of the endophytic bacterium ITALIC! Bacillus thuringiensisstrain KB1, which exhibits antagonism against phytopathogens.

  2. Mycotoxigenic Fusarium and Deoxynivalenol Production Repress Chitinase Gene Expression in the Biocontrol Agent Trichoderma atroviride P1

    OpenAIRE

    Lutz, Matthias P.; Feichtinger, Georg; Défago, Geneviève; Duffy, Brion

    2003-01-01

    Mycotoxin contamination associated with head blight of wheat and other grains caused by Fusarium culmorum and F. graminearum is a chronic threat to crop, human, and animal health throughout the world. One of the most important toxins in terms of human exposure is deoxynivalenol (DON) (formerly called vomitoxin), an inhibitor of protein synthesis with a broad spectrum of toxigenicity against animals. Certain Fusarium toxins have additional antimicrobial activity, and the phytotoxin fusaric aci...

  3. Effects of plant essential oils and biocontrol agents on the growth of and mycotoxin production by Aspergillus spp. on groundnut

    OpenAIRE

    Alamene, Azawei

    2015-01-01

    Groundnut, Arachis hypogaea (L.), can be attacked by a range of pathogens, including Aspergillus species, which can cause accumulation of the mycotoxin aflatoxin. Although some success in controlling this pathogen has been achieved with application of fungicides, their use is not always feasible in developing nations like Nigeria. The aim of this study was, therefore, to evaluate naturally-occurring plant oils and BCAs with a past history of efficacy as alternatives to fungicides for reductio...

  4. Effects of nitrogen availability and spore concentration on the biocontrol activity of Ascochyta caulina in common lambsquarters (Chenopodium album)

    NARCIS (Netherlands)

    Ghorbani, R.; Scheepens, P.C.; Zweerde, van der W.; Leifert, C.; McDonald, A.J.S.; Seel, W.

    2002-01-01

    Common lambsquarters is an annual weed of many important crops. Ascochyta caulina is a plant pathogenic fungus that causes necrotic lesions on the leaves and stems of common lambsquarters. The objective of the present study was to estimate the effect of plant N supply on the biocontrol activity of A

  5. 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 ph

  6. Biocontrol potential of Steinernema thermophilum and its symbiont Xenorhabdus indica against lepidopteran pests: virulence to egg and larval stages

    Science.gov (United States)

    Under laboratory conditions, the biocontrol potential of Steinernema thermophilum was tested against eggs and larval stages of two important lepidopteran insect pests, Helicoverpa armigera and Spodoptera litura (polyphagous pests), as well as Galleria mellonella (used as a model host) . In terms of ...

  7. Complete Genome Sequence of Pseudomonas fluorescens LBUM636, a Strain with Biocontrol Capabilities against Late Blight of Potato.

    Science.gov (United States)

    Morrison, Christopher K; Novinscak, Amy; Gadkar, Vijay J; Joly, David L; Filion, Martin

    2016-01-01

    Herein provided is the full-genome sequence of Pseudomonas fluorescens LBUM636. This strain is a plant growth-promoting rhizobacterium (PGPR) which produces phenazine-1-carboxylic acid, an antibiotic involved in the biocontrol of numerous plant pathogens, including late blight of potato caused by the plant pathogen Phytophthora infestans. PMID:27231373

  8. Reliability of the entomovector technology using Prestop-Mix and Bombus terrestris L. as a fungal disease biocontrol method in open field

    Science.gov (United States)

    Karise, Reet; Dreyersdorff, Gerit; Jahani, Mona; Veromann, Eve; Runno-Paurson, Eve; Kaart, Tanel; Smagghe, Guy; Mänd, Marika

    2016-01-01

    Botrytis cinerea Pers.:Fr. is a major plant pathogen, and a new approach is needed for its control in strawberry to minimise the increasing use of synthetic fungicides. The biofungicide Prestop-Mix, which contains Gliocladium catenulatum, is effective against Botrytis infections; however, the need for frequent applications increases the costs for farmers. Here, we demonstrate that bumble bees, Bombus terrestris L., effectively disseminate the preparation onto flowers in open field conditions. Over the course of three years, we found a highly significant decrease in the rate of Botrytis infection. Pathogen control was achieved with relatively low numbers of G. catenulatum spores per flower, even using flowers that are not highly attractive to bumble bees. An even distribution of spores was detected up to 100 m from the hives, either due to primary inoculation by bumble bees or secondary distribution by other flower visitors such as honey bees and solitary bees. We showed that the application of a biocontrol agent by bumble bees is reliable for the use of environmentally friendly pest control strategies in northern climatic conditions. This low cost technology is especially relevant for organic farming. This study provides valuable information for introducing this method into practice in open strawberry fields. PMID:27530075

  9. Characterization of novel Trichoderma spp. isolates as a search for effective biocontrollers of fungal diseases of economically important crops in Argentina.

    Science.gov (United States)

    Consolo, Verónica Fabiana; Mónaco, Cecilia Inés; Cordo, Cristina Alicia; Salerno, Graciela Lidia

    2012-04-01

    Monoconidial cultures of 33 isolates of Trichoderma from Buenos Aires Province, Argentina were characterized on the basis of twenty eight morphological, physiological and biochemical features. All of them were screened for proteinase, endochitinase and β-1,3 glucanase activity. Universally primed PCR (UP-PCR) and inter-simple sequence repeat (ISSR) techniques were used to examine the genetic variability among isolates, which resulted in 127 bands for the total number of isolates. These results were subjected to numerical analysis revealing 20 haplotypes grouped in five clusters. The ability of Trichoderma isolates to antogonize soil-borne fungal plant pathogens using a dual culture assay was done against five fungal species: Alternaria sp., Bipolaris sorokiniana, Fusarium graminearum, F. solani, and Pyricularia oryzae. The highest inhibition values (85% RI) were obtained against B. sorokiniana and P. oryzae. Three isolates of T. harzianum named as FCCT2, FCCT3 and FCCT9 were capable of causing a high growth inhibition on four of the fungal species assayed, which was in agreement with their higher extracellular hydrolytic activity. Our results suggest that these isolates have the potential to be effective agents for biocontrol of cereal and tomato fungal pathogens. PMID:22805919

  10. 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.

  11. Zoospore homing and infection events: effects of the biocontrol bacterium Burkholderia cepacia AMMDR1 on two oomycete pathogens of pea (Pisum sativum L.).

    Science.gov (United States)

    Heungens, K; Parke, J L

    2000-12-01

    Burkholderia cepacia AMMDR1 is a biocontrol agent that protects pea and sweet corn seeds from Pythium damping-off in field experiments. The goal of this work was to understand the effect of B. cepacia AMMDR1 on Pythium aphanidermatum and Aphanomyces euteiches zoospore homing events and on infection of pea seeds or roots. In vitro, B. cepacia AMMDR1 caused zoospore lysis, prevented cyst germination, and inhibited germ tube growth of both oomycetes. B. cepacia AMMDR1 also reduced the attractiveness of seed exudates to Pythium zoospores to nondetectable levels. However, when present at high levels on seeds, B. cepacia AMMDR1 had little net effect on zoospore attraction, probably because it also enhanced seed exudation. Seed-applied B. cepacia AMMDR1 dramatically reduced the incidence of infection by Pythium zoospores in situ compared with an antibiosis-deficient Tn5 mutant strain. This mutant strain also decreased Pythium infection incidence to some extent, but only when the pathogen inoculum potential was low. B. cepacia AMMDR1 did not affect attraction of Aphanomyces zoospores or Aphanomyces root rot incidence. These results suggest that B. cepacia AMMDR1 controls P. aphanidermatum largely through antibiosis, but competition for zoospore-attracting compounds can contribute to the effect. Differences in suppression of Aphanomyces and Pythium are discussed in relation to differences in the ecology of the two pathogens. PMID:11097889

  12. Characterization of novel Trichoderma spp. isolates as a search for effective biocontrollers of fungal diseases of economically important crops in Argentina.

    Science.gov (United States)

    Consolo, Verónica Fabiana; Mónaco, Cecilia Inés; Cordo, Cristina Alicia; Salerno, Graciela Lidia

    2012-04-01

    Monoconidial cultures of 33 isolates of Trichoderma from Buenos Aires Province, Argentina were characterized on the basis of twenty eight morphological, physiological and biochemical features. All of them were screened for proteinase, endochitinase and β-1,3 glucanase activity. Universally primed PCR (UP-PCR) and inter-simple sequence repeat (ISSR) techniques were used to examine the genetic variability among isolates, which resulted in 127 bands for the total number of isolates. These results were subjected to numerical analysis revealing 20 haplotypes grouped in five clusters. The ability of Trichoderma isolates to antogonize soil-borne fungal plant pathogens using a dual culture assay was done against five fungal species: Alternaria sp., Bipolaris sorokiniana, Fusarium graminearum, F. solani, and Pyricularia oryzae. The highest inhibition values (85% RI) were obtained against B. sorokiniana and P. oryzae. Three isolates of T. harzianum named as FCCT2, FCCT3 and FCCT9 were capable of causing a high growth inhibition on four of the fungal species assayed, which was in agreement with their higher extracellular hydrolytic activity. Our results suggest that these isolates have the potential to be effective agents for biocontrol of cereal and tomato fungal pathogens.

  13. 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. PMID:26654914

  14. 生防细菌SF-16产芽胞条件的研究%Studies on Biocontrol Bacteria SF-16 Spore Production Condition

    Institute of Scientific and Technical Information of China (English)

    张明; 李欢; 朱莹

    2012-01-01

    生防细菌SF-16为土壤中筛选得到的1株细菌,研究表明,其对多种植物致病真菌有抑制作用。为了提高生防细菌SF-16的芽胞形成率及芽胞数量,以及为工厂化生产生物菌剂提供理论依据,采用摇瓶发酵对芽胞形成的主要影响因素进行了考察。通过单因素实验和正交实验对SF-16菌株产芽胞条件进行了分析,确定了摇瓶发酵最佳条件为:乳糖0.5%、黄豆饼粉2.0%、MnSO4·5H2O0.30%。在该优化条件下,发酵液中颉颃菌的出芽率达到98.3%,最终生物量达到2×109个/mL。%Biocontrol bacteria SF-16 was a selected bacteria strain,research showed that its inhibitory effect on multiple plants.In order to improve biocontrol bacteria SF-16 spore formation rate and quantity,provide theoretical basis for factory production of biological agent,use flask fermentation with a survey on main influencing factors of spore formation.Through single factor experiment and orthogonal experiment,the optimal shaking flask fermentation condition was determined as follow:media composed of 0.5% lactose,2.0% soybean meal,0.30% MnSO4·5H2O.Under this optimum condition,the germination rate achieves 98.3 percentages,Biomass achieves 2×109/mL.

  15. 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

  16. Lepidopterans as potential agents for the biological control of the invasive plant, Miconia calvescens.

    Science.gov (United States)

    Morais, Elisangela G F; Picanço, Marcelo C; Semeão, Altair A; Barreto, Robert W; Rosado, Jander F; Martins, Julio C

    2012-01-01

    This work investigated eight species of Lepidoptera associated with Miconia calvescens DC. (Myrtales: Melastomataceae) in Brazil, including six defoliators, Salbia lotanalis Druce (Lepidoptera: Pyralidae), Druentia inscita Schaus (Mimallonidae), Antiblemma leucocyma Hampson (Noctuidae), three Limacodidae species, a fruit borer Carposina cardinata Meyrick (Carposinidae), and a damager of flowers Pleuroprucha rudimentaria Guenée (Geometridae). Based on host specificity and the damage caused to plants, S. lotanalis and D. inscita are the most promising species for biological control of M. calvescens. Furthermore, if C. cardinata and P. rudimentaria have host specificity in future tests, these caterpillars could also be considered as appropriate biocontrol agents. PMID:22938203

  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. Synthesis of biocontrol macromolecules by derivative of chitosan with surfactin and antifungal evaluation.

    Science.gov (United States)

    Yuan, Bo; Xu, Pei-Yuan; Zhang, Yue-Ji; Wang, Pei-Pei; Yu, Hong; Jiang, Ji-Hong

    2014-05-01

    A derivative of chitosan was prepared with chitosan and β-cyclodextrins, which was synthesized by the immobilization reaction, as a carrier to adsorb surfactin produced from Bacillus amyloliquefaciens and got biological macromolecules. The antifungal activity against three sapstain fungi by a combination of macromolecules was tested. The results showed that the macromolecules inhibited the mycelium growth of sapstain fungi Lasiodiplodia rubropurpurea, L. crassispora, and L. theobromae by about 73.22%, 76.72%, and 70.22%, respectively. The macromolecules were relatively thermally stable with more than 50% of the antifungal activity even after being held at 121°C for 30 min. Meanwhile, the activity of the macromolecules remained more than 55% at a pH value ranging from 4 to 12. The macromolecules were resistant to hydrolysis by most protein-denaturing detergents and other enzymes. The results indicated the macromolecules might provide an alternative bioresource for the bio-control of sapstain. PMID:24530369

  19. Cell wall degrading isoenzyme profiles of Trichoderma biocontrol strains show correlation with rDNA species

    Institute of Scientific and Technical Information of China (English)

    Sanz L; Hermosa M R; González F J; Monte E

    2004-01-01

    @@ Species of the fungus Trichoderma, a genus of Hyphomycetes, are ubiquitous in the environment, but especially in soil. They have been used in a wide range of commercial applications including the production of hydrolases and in the biological control of plant diseases. A fundamental part of the Trichoderma antifungal system consists of a series of genes coding for a surprising variety of extracellular cell wall degrading enzymes (CWDE).Characterisation and identification of strains at the species level is the first step in utilizing the full potential of fungi in specific applications. One aim when isolating Trichoderma strains is to identify those which can be used in new agricultural and industrial applications. In the past it was not uncommon that biocontrol strains were defined as T. harzianum Rifai, due to the limited classification system of the genus Trichoderma. In recent years, several PCR-based molecular techniques have been used to detect and discriminate among microorganisms. Sequence analysis of the ITS regions of the ribosomal DNA and gene fragments as those corresponding to tef1 gene have been helpful in the neotypification, description and characterization of species in the genus Trichoderna.Another useful method for the identification of Trichoderma strains is the randomly amplified polymorphic DNA (RAPD) technique.Isozyme polymorphisms evaluation of five putative extracellular lytic enzymes loci (β-1,3-glucanase, β-1,6-glucanase, cellulase, chitinase and protease antivities) were carried out using representative strains of defined molecular groups. CWDE groupings obtained from biocontrol strains are discussed in relation to their phylogenetic location and antifungal activities.Compiling morphological, biochemical and sequence information data into a common database would provide a useful resource that could be used to accurately name new haplotypes identified in the future and correctly place them within the genus Trichoderma.

  20. Biocontrol of geosmin-producing Streptomyces spp. by two Bacillus strains from Chinese liquor.

    Science.gov (United States)

    Zhi, Yan; Wu, Qun; Du, Hai; Xu, Yan

    2016-08-16

    Streptomyces spp. producing geosmin have been regarded as the most frequent and serious microbial contamination causing earthy off-flavor in Chinese liquor. It is therefore necessary to control the Streptomyces community during liquor fermentation. Biological control, using the native microbiota present in liquor making, appears to be a better solution than chemical methods. The objective of this study was to isolate native microbiota antagonistic toward Streptomyces spp. and then to evaluate the possible action mode of the antagonists. Fourteen Bacillus strains isolated from different Daqu (the fermentation starter) showed antagonistic activity against Streptomyces sampsonii, which is one of the dominant geosmin producers. Bacillus subtilis 2-16 and Bacillus amyloliquefaciens 1-45 from Maotai Daqu significantly inhibited the growth of S. sampsonii by 57.8% and 84.3% respectively, and effectively prevented the geosmin production in the simulated fermentation experiments (inoculation ratio 1:1). To probe the biocontrol mode, the ability of strain 2-16 and 1-45 to produce antimicrobial metabolites and to reduce geosmin in the fermentation system was investigated. Antimicrobial substances were identified as lipopeptides by ultra-performance liquid chromatography tandem electrospray ionization/quadrupole-time-of-flight mass spectrometry (UPLC-ESI/Q-TOF MS) and in vitro antibiotic assay. In addition, strains 2-16 and 1-45 were able to remove 45% and 15% of the geosmin respectively in the simulated solid-state fermentation. This study highlighted the potential of biocontrol, and how the use of native Bacillus species in Daqu could provide an eco-friendly method to prevent growth of Streptomyces spp. and geosmin contamination in Chinese liquor fermentation.

  1. The importance of chorismate mutase in the biocontrol potential of Trichoderma parareesei.

    Science.gov (United States)

    Pérez, Esclaudys; Rubio, M Belén; Cardoza, Rosa E; Gutiérrez, Santiago; Bettiol, Wagner; Monte, Enrique; Hermosa, Rosa

    2015-01-01

    Species of Trichoderma exert direct biocontrol activity against soil-borne plant pathogens due to their ability to compete for nutrients and to inhibit or kill their targets through the production of antibiotics and/or hydrolytic enzymes. In addition to these abilities, Trichoderma spp. have beneficial effects for plants, including the stimulation of defenses and the promotion of growth. Here we study the role in biocontrol of the T. parareesei Tparo7 gene, encoding a chorismate mutase (CM), a shikimate pathway branch point leading to the production of aromatic amino acids, which are not only essential components of protein synthesis but also the precursors of a wide range of secondary metabolites. We isolated T. parareesei transformants with the Tparo7 gene silenced. Compared with the wild-type, decreased levels of Tparo7 expression in the silenced transformants were accompanied by reduced CM activity, lower growth rates on different culture media, and reduced mycoparasitic behavior against the phytopathogenic fungi Rhizoctonia solani, Fusarium oxysporum and Botrytis cinerea in dual cultures. By contrast, higher amounts of the aromatic metabolites tyrosol, 2-phenylethanol and salicylic acid were detected in supernatants from the silenced transformants, which were able to inhibit the growth of F. oxysporum and B. cinerea. In in vitro plant assays, Tparo7-silenced transformants also showed a reduced capacity to colonize tomato roots. The effect of Tparo7-silencing on tomato plant responses was examined in greenhouse assays. The growth of plants colonized by the silenced transformants was reduced and the plants exhibited an increased susceptibility to B. cinerea in comparison with the responses observed for control plants. In addition, the plants turned yellowish and were defective in jasmonic acid- and ethylene-regulated signaling pathways which was seen by expression analysis of lipoxygenase 1 (LOX1), ethylene-insensitive protein 2 (EIN2) and pathogenesis

  2. The importance of chorismate mutase in the biocontrol potential of Trichoderma parareesei

    Directory of Open Access Journals (Sweden)

    Esclaudys ePérez

    2015-10-01

    Full Text Available Species of Trichoderma exert direct biocontrol activity against soil-borne plant pathogens due to their ability to compete for nutrients and to inhibit or kill their targets through the production of antibiotics and/or hydrolytic enzymes. In addition to these abilities, Trichoderma spp. have beneficial effects for plants, including the stimulation of defenses and the promotion of growth. Here we study the role in biocontrol of the T. parareesei Tparo7 gene, encoding a chorismate mutase (CM, a shikimate pathway branch point leading to the production of aromatic amino acids, which are not only essential components of protein synthesis but also the precursors of a wide range of secondary metabolites. We isolated T. parareesei transformants with the Tparo7 gene silenced. Compared with the wild-type, decreased levels of Tparo7 expression in the silenced transformants were accompanied by reduced CM activity, lower growth rates on different culture media, and reduced mycoparasitic behavior against the phytopathogenic fungi Rhizoctonia solani, Fusarium oxysporum and Botrytis cinerea in dual cultures. By contrast, higher amounts of the aromatic metabolites tyrosol, 2-phenylethanol and salicylic acid were detected in supernatants from the silenced transformants, which were able to inhibit the growth of F. oxysporum and B. cinerea. In in vitro plant assays, Tparo7-silenced transformants also showed a reduced capacity to colonize tomato roots. The effect of Tparo7-silencing on tomato plant responses was examined in greenhouse assays. The growth of plants colonized by the silenced transformants was reduced and the plants exhibited an increased susceptibility to B. cinerea in comparison with the responses observed for control plants. In addition, the plants turned yellowish and were defective in jasmonic acid- and ethylene-regulated signaling pathways which was seen by expression analysis of lipoxygenase 1 (LOX1, ethylene-insensitive protein 2 (EIN2 and

  3. 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.

  4. Evaluación de microorganismos con potencial de promoción de crecimiento vegetal y biocontrol de Spongospora subterranea

    Directory of Open Access Journals (Sweden)

    Juliana Soler Arango

    2012-04-01

    Full Text Available Normal 0 21 false false false ES-CO X-NONE X-NONE MicrosoftInternetExplorer4 Título en ingles: Evaluation of microorganisms  with potential  for plant  growth  promotion and biological control of    Spongospora subterranea Resumen: La sarna polvosa de la papa es causada por el patógeno Spongospora subterranea, que disminuye la calidad y producción de tubérculos y facilita la entrada de otros patógenos. Esta enfermedad afecta las principales zonas productoras del mundo, debido a la falta de tratamientos efectivos contra el patógeno y al comercio de tubérculos-semilla infectados. Algunas investigaciones indican que los agentes biocontroladores podrían contribuir a reducir la actividad de S. subterranea a través de efectos sobre la viabilidad de sus quistosoros o mediante efectos estimulantes del crecimiento de la planta. En este estudio se emplearon bacterias aisladas del interior de raíz, rizósfera y superficie de tubérculos de un cultivo de papa (Solanum tuberosum variedad Diacol Capiro y seleccionadas por su capacidad para producir indoles totales y quitinasas. En estudios paralelos se determinó su capacidad para promover la velocidad de germinación en brotes de tubérculos o para controlar  S. subterranea en raíces y promover el crecimiento vegetal de plántulas en invernadero. La mayoria de los aislamientos evaluados incrementraron la longitud de brotes de tubérculos en el laboratorio. En el invernadero, en suelo no estéril y en presencia del patógeno, se encontró que 2 de los 10 aislamientos seleccionados por su capacidad para producir indoles totales y quitinasas, presentaron promoción de crecimiento vegetal y posible biocontrol del patógeno. Estos resultados sugieren un gran potencial para la selección de microorganismos biocontroladores y desarrollo de bioproductos a partir de recursos microbiológicos locales. Palabras clave: sarna polvosa de la papa; indoles totales; quitinasas; control biológico. Abstract

  5. Canada thistle biological control agents on two South Dakota wildlife refuges

    Science.gov (United States)

    Reed, C.C.; Larson, D.L.; Larson, J.L.

    2006-01-01

    We monitored populations of Canada thistle biocontrol agents Cassida rubiginosa, Ceutorhynchus litura, Larinus (= Hadroplantus) planus, Urophora cardui, Orellia (= Terellia) ruficauda, and Rhinocyllus conicus on Canada thistle (Cirsium arvense) at two national wildlife refuges in South Dakota from 1999 through 2003. C. litura, U. cardui, O. ruficauda, and R. conicus were present on both refuges. Agent populations were low except for C. litura, which was present in up to 90% of stems in some plots. C. litura infestation did not reduce thistle flowering, stem length, or over-winter survival. There was no change in thistle stem numbers over the study period and no difference in stem numbers in areas of high C. litura populations compared to areas of low C. litura populations. Our results suggest that insect biological control agents are inadequate for reduction of Canada thistle in southern South Dakota.

  6. An agent framework for dynamic agent retraining: Agent academy

    OpenAIRE

    Mitkas, P.; A. Symeonidis; Kechagias, D.; Athanasiadis, I.N.; Laleci, G.; KURT, G.; Kabak, Y.; Acar, A.; Dogac, A.

    2004-01-01

    Agent Academy (AA) aims to develop a multi-agent society that can train new agents for specific or general tasks, while constantly retraining existing agents in a recursive mode. The system is based on collecting information both from the environment and the behaviors of the acting agents and their related successes/failures to generate a body of data, stored in the Agent Use Repository, which is mined by the Data Miner module, in order to generate useful knowledge about the application domai...

  7. Isolation and selection of local isolates of chitinolitic bacteria that potent to biocontrol of larva stadia of Aedes aegypti L.

    Directory of Open Access Journals (Sweden)

    SRI PUJIYANTO

    2008-01-01

    Full Text Available The dengue fever was the most dangerously epidemic in Indonesia, so it is important to prevent the population of Aedes aegypti L. The larva stages of Ae. aegypti had an exosceleton from chitin, so if its exosceleton had been degraded the larva would be died. Many bacteria had chitin degradation activities, and the bacteria had potential as a biocontrol for Ae. aegypti larva stages. This research was got many of the local chitinolitic bacteria that had been potential as a biocontrol for Ae. aegypti larva stages. The chitinolitic bacteria were isolated with selective agar medium. The sources of isolates were collected from Central Java and West Java water resources. Selected isolates was done to get the higher chitinolitic activity in mineral water medium. The isolate LMB1-5 was potential as a bioinsecticide for Ae. aegypti larva stages. This isolate decreased 86.7% of the larva population in 7 days.

  8. Arbuscular mycorrhizal fungi for the biocontrol of plant-parasitic nematodes: a review of the mechanisms involved

    OpenAIRE

    Nele eSchouteden; Dirk eDe Waele; Bart ePanis; Christine M Vos

    2015-01-01

    Arbuscular mycorrhizal fungi (AMF) are obligate root symbionts that can protect their host plant against biotic stress factors such as plant parasitic nematode (PPN) infection. PPN consist of a wide range of species with different life styles that can cause major damage in many important crops worldwide. Various mechanisms have been proposed to play a role in the biocontrol effect of AMF against PPN. This review presents an overview of the different mechanisms that have been proposed, and dis...

  9. Arbuscular mycorrhizal fungi for the biocontrol of plant-parasitic nematodes: a review of the mechanisms involved

    OpenAIRE

    Schouteden, Nele; de Waele, Dirk; Panis, Bart; Christine M Vos

    2015-01-01

    Arbuscular mycorrhizal fungi (AMF) are obligate root symbionts that can protect their host plant against biotic stress factors such as plant-parasitic nematode (PPN) infection. PPN consist of a wide range of species with different life styles that can cause major damage in many important crops worldwide. Various mechanisms have been proposed to play a role in the biocontrol effect of AMF against PPN. This review presents an overview of the different mechanisms that have been proposed, and dis...

  10. In Vitro Screening for Abiotic Stress Tolerance in Potent Biocontrol and Plant Growth Promoting Strains of Pseudomonas and Bacillus spp.

    OpenAIRE

    G. Praveen Kumar; Mir Hassan Ahmed, S. K.; Suseelendra Desai; Leo Daniel Amalraj, E.; Abdul Rasul

    2014-01-01

    Plant growth promoting rhizobacteria (PGPR) has been identified as a group of microbes that are used for plant growth enhancement and biocontrol for management of plant diseases. The inconsistency in performance of these bacteria from laboratory to field conditions is compounded due to the prevailing abiotic stresses in the field. Therefore, selection of bacterial strains with tolerance to abiotic stresses would benefit the end-user by successful establishment of the strain for showing desire...

  11. Elucidation of a key position for acyltransfer activity in Candida parapsilosis lipase/acyltransferase (CpLIP2) and in Pseudozyma antarctica lipase A (CAL-A) by rational design.

    Science.gov (United States)

    Jan, Anne-Hélène; Subileau, Maeva; Deyrieux, Charlotte; Perrier, Véronique; Dubreucq, Éric

    2016-02-01

    Performing transesterifications in aqueous media is becoming a priority challenge in lipid biotechnology in order to develop more eco-friendly and efficient biocatalytic processes in systems containing both polar and apolar substrates. In this context, our group has explored for several years the high potential of the lipase/acyltransferase CpLIP2 from Candida parapsilosis and of several of its homologs, that catalyze efficiently acyltransfer reactions in lipid/water media with high water activity (aw>0.9). The discovery of a new member of this group, CduLAc from Candida dubliniensis, with a higher acyltransferase activity than CpLIP2, has provided a new insight on structure-function relationships in this group. Indeed, the comparison of sequences and 3D models, especially of CpLIP2 and CduLAc, with those of the phylogenetically related lipase A from Pseudozyma antarctica (CAL-A), allowed elucidating a key structural determinant of the acyltransferase activity: serine S369 in CpLIP2 and its equivalents E370 in CAL-A and A366 in CduLAc. Mutants obtained by rational design at this key position showed significant changes in acyltransfer activity. Whereas mutation S369E resulted in an increase in the hydrolytic activity of CpLIP2, S369A increased alcoholysis. More strikingly, the single E370A mutation in CAL-A drastically increased the acyltransferase activity of this enzyme, giving it the character of a lipase/acyltransferase. Indeed, this single mutation lowered the methanol concentration for which the initial rates of alcoholysis and hydrolysis are equal from 2M in CAL-A down to 0.3M in its mutant, while the exceptional stability of the parental enzyme toward alcohol and temperature was conserved.

  12. Arbuscular Mycorrhizal Fungi for the Biocontrol of Plant-Parasitic Nematodes: A Review of the Mechanisms Involved.

    Science.gov (United States)

    Schouteden, Nele; De Waele, Dirk; Panis, Bart; Vos, Christine M

    2015-01-01

    Arbuscular mycorrhizal fungi (AMF) are obligate root symbionts that can protect their host plant against biotic stress factors such as plant-parasitic nematode (PPN) infection. PPN consist of a wide range of species with different life styles that can cause major damage in many important crops worldwide. Various mechanisms have been proposed to play a role in the biocontrol effect of AMF against PPN. This review presents an overview of the different mechanisms that have been proposed, and discusses into more detail the plausibility of their involvement in the biocontrol against PPN specifically. The proposed mechanisms include enhanced plant tolerance, direct competition for nutrients and space, induced systemic resistance (ISR) and altered rhizosphere interactions. Recent studies have emphasized the importance of ISR in biocontrol and are increasingly placing rhizosphere effects on the foreground as well, both of which will be the focal point of this review. Though AMF are not yet widely used in conventional agriculture, recent data help to develop a better insight into the modes of action, which will eventually lead toward future field applications of AMF against PPN. The scientific community has entered an exciting era that provides the tools to actually unravel the underlying molecular mechanisms, making this a timely opportunity for a review of our current knowledge and the challenges ahead. PMID:26635750

  13. Arbuscular mycorrhizal fungi for the biocontrol of plant-parasitic nematodes: a review of the mechanisms involved

    Directory of Open Access Journals (Sweden)

    Nele eSchouteden

    2015-11-01

    Full Text Available Arbuscular mycorrhizal fungi (AMF are obligate root symbionts that can protect their host plant against biotic stress factors such as plant parasitic nematode (PPN infection. PPN consist of a wide range of species with different life styles that can cause major damage in many important crops worldwide. Various mechanisms have been proposed to play a role in the biocontrol effect of AMF against PPN. This review presents an overview of the different mechanisms that have been proposed, and discusses into more detail the plausibility of their involvement in the biocontrol against PPN specifically. The proposed mechanisms include enhanced plant tolerance, direct competition for nutrients and space, induced systemic resistance (ISR and altered rhizosphere interactions. Recent studies have emphasized the importance of ISR in biocontrol and are increasingly placing rhizosphere effects on the foreground as well, both of which will be the focal point of this review. Though AMF are not yet widely used in conventional agriculture, recent data help to develop a better insight into the modes of action, which will eventually lead towards future field applications of AMF against PPN. The scientific community has entered an exciting era that provide the tools to actually unravel the underlying molecular mechanisms, making this a timely opportunity for a review of our current knowledge and the challenges ahead.

  14. ppGpp controlled by the Gac/Rsm regulatory pathway sustains biocontrol activity in Pseudomonas fluorescens CHA0.

    Science.gov (United States)

    Takeuchi, Kasumi; Yamada, Kosumi; Haas, Dieter

    2012-11-01

    In Pseudomonas fluorescens CHA0 and other fluorescent pseudomonads, the Gac/Rsm signal transduction pathway is instrumental for secondary metabolism and biocontrol of root pathogens via the expression of regulatory small RNAs (sRNAs). Furthermore, in strain CHA0, an imbalance in the Krebs cycle can affect the strain's ability to produce extracellular secondary metabolites, including biocontrol factors. Here, we report the metabolome of wild-type CHA0, a gacA-negative mutant, which has lost Gac/Rsm activities, and a retS-negative mutant, which shows strongly enhanced Gac/Rsm-dependent activities. Capillary electrophoresis-based metabolomic profiling revealed that the gacA and retS mutations had opposite effects on the intracellular levels of a number of central metabolites, suggesting that the Gac/Rsm pathway regulates not only secondary metabolism but also primary metabolism in strain CHA0. Among the regulated metabolites identified, the alarmone guanosine tetraphosphate (ppGpp) was characterized in detail by the construction of relA (for ppGpp synthase) and spoT (for ppGpp synthase/hydrolase) deletion mutants. In a relA spoT double mutant, ppGpp synthesis was completely abolished, the expression of Rsm sRNAs was attenuated, and physiological functions such as antibiotic production, root colonization, and plant protection were markedly diminished. Thus, ppGpp appears to be essential for sustaining epiphytic fitness and biocontrol activity of strain CHA0.

  15. The Potential Use of Wolbachia-Based Mosquito Biocontrol Strategies for Japanese Encephalitis.

    Directory of Open Access Journals (Sweden)

    Claire L Jeffries

    Full Text Available Japanese encephalitis virus (JEV is a zoonotic pathogen transmitted by the infectious bite of Culex mosquitoes. The virus causes the development of the disease Japanese encephalitis (JE in a small proportion of those infected, predominantly affecting children in eastern and southern Asia. Annual JE incidence estimates range from 50,000-175,000, with 25%-30% of cases resulting in mortality. It is estimated that 3 billion people live in countries in which JEV is endemic. The virus exists in an enzootic transmission cycle, with mosquitoes transmitting JEV between birds as reservoir hosts and pigs as amplifying hosts. Zoonotic infection occurs as a result of spillover events from the main transmission cycle. The reservoir avian hosts include cattle egrets, pond herons, and other species of water birds belonging to the family Ardeidae. Irrigated rice fields provide an ideal breeding ground for mosquitoes and attract migratory birds, maintaining the transmission of JEV. Although multiple vaccines have been developed for JEV, they are expensive and require multiple doses to maintain efficacy and immunity. As humans are a "dead-end" host for the virus, vaccination of the human population is unlikely to result in eradication. Therefore, vector control of the principal mosquito vector, Culex tritaeniorhynchus, represents a more promising strategy for reducing transmission. Current vector control strategies include intermittent irrigation of rice fields and space spraying of insecticides during outbreaks. However, Cx. Tritaeniorhynchus is subject to heavy exposure to pesticides in rice fields, and as a result, insecticide resistance has developed. In recent years, significant advancements have been made in the potential use of the bacterial endosymbiont Wolbachia for mosquito biocontrol. The successful transinfection of Wolbachia strains from Drosophila flies to Aedes (Stegomyia mosquitoes has resulted in the generation of "dengue-refractory" mosquito

  16. Mutation of rpiA in Enterobacter cloacae decreases seed and root colonization and biocontrol of damping-off caused by Pythium ultimum on cucumber.

    Science.gov (United States)

    Lohrke, Scott M; Dery, Pierre D; Li, Wei; Reedy, Ralph; Kobayashi, Donald Y; Roberts, Daniel R

    2002-08-01

    Strains of Enterobacter cloacae show promise as biocontrol agents for Pythium ultimum-induced damping-off on cucumber and other crops. E. cloacae A145 is a mini-Tn5 Km transposon mutant of strain 501R3 that was significantly reduced in suppression of damping-off on cucumber caused by P. ultimum. Strain A145 was deficient in colonization of cucumber, sunflower, and wheat seeds and significantly reduced in colonization of corn and cowpea seeds relative to strain 501R3. Populations of strain A145 were also significantly lower than those of strain 501R3 at all sampling times in cucumber, wheat, and sunflower rhizosphere. Populations of strain A145 were not detectable in any rhizosphere after 42 days, while populations of strain 501R3 remained at substantial levels throughout all experiments. Molecular characterization of strain A145 indicated mini-Tn5 Km was inserted in a region of the E. cloacae genome with a high degree of DNA and amino acid sequence similarity to rpiA, which encodes ribose-5-phosphate isomerase. In Escherichia coli, RpiA catalyzes the interconversion of ribose-5-phosphate and ribulose-5-phosphate and is a key enzyme in the pentose phosphate pathway. Ribose-5-phosphate isomerase activity in cell lysates from strain A145 was approximately 3.5% of that from strain 501R3. In addition, strain A145 was a ribose auxotroph, as expected for an rpiA mutant. Introduction of a 1.0-kb DNA fragment containing only the rpiA homologue into strain A145 restored ribose phosphate isomerase activity, prototrophy, seedling colonization, and disease suppression to levels similar to those associated with strain 501R3. Experiments reported here indicate a key role for rpiA and possibly the pentose phosphate pathway in suppression of damping-off and colonization of subterranean portions of plants by E. cloacae. PMID:12182339

  17. DNA-based methodologies for the quantification of live and dead cells in formulated biocontrol products based on Pantoea agglomerans CPA-2.

    Science.gov (United States)

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

    2015-10-01

    Pantoea agglomerans strain CPA-2 is an effective biocontrol agent (BCA) against the major postharvest pathogens present on pome and citrus fruits. Dehydration, such as freeze-drying, spray-drying and fluidized bed drying is one of the best ways to formulate BCAs. In this work, the survival of CPA-2 cells after formulation was determined by dilution plating and molecular methods as qPCR alone and combined with a sample pretreatment with a propidium monoazide dye (PMA-qPCR) and they were used to calculate treatment concentrations in efficacy trials on postharvest oranges. Furthermore, no significant differences in CPA-2 survival were observed as determined by dilution plating and PMA-qPCR after both the freeze drying and fluidized bed drying processes; however, an interesting significant difference was observed in the spray dried product comparing all quantitative methods. A difference of 0.48 and 2.17 log10 CFU or cells g/dw was observed among PMA-qPCR with qPCR and dilution plating, respectively. According to our study, dilution plating was shown to be an unreliable tool for monitoring the survival of CPA-2 after spray drying. In contrast, the combination of PMA and qPCR enabled a quick and unequivocal methodology to enumerate viable and VBNC CPA-2 cells under stress-dried conditions. Efficacy trials showed that, after 3 days, spray drying formulation rehydrated with 10% non-fat skimmed milk (NFSM) was as effective as fresh cells to control Penicillium digitatum in oranges. PMID:26114590

  18. Distribución Diferencial de Bacterias con Potencial Biocontrolador de Spongospora subterranea en Plantas de Papa (Solanum tuberosum cv. Diacol Capiro Differential Distrubution of Candidadate Biocontrol Bacteria against Spongospora subterranea in Potato Plants (Solanum tuberosum cv. Diacol Capiro

    Directory of Open Access Journals (Sweden)

    Juliana Soler Arango

    2012-06-01

    farmers field, in this research we obtained bacteria from inside roots, rhizosphere, tubers peel or bulk soil, and determined in them the production of indol and chitinases. In general, bacteria isolated form inside the roots showed the highest production of total indols and chitinases. Simultaneous high production of both compounds was not detected in these isolates, and the frecuency of bacteria producing both, indol and chitinases was higher in roots and rhizosphere, compared to tubers peel and bulk soil samples. These results suggest that in soil, the distribution of microorganisms and functions linked to biocontrol are not randomly distributed. These findings might be usefull to guide the search for biocontrol agents, optimize resource use and speed up the development of new bioproducts.

  19. Agent Chameleons: Virtual Agents Real Intelligence

    OpenAIRE

    O'Hare, Gregory; Duffy, Brian; Schoen-Phelan, Bianca; Martin, Alan; Bradley, John

    2003-01-01

    Agent Chameleons provides virtual agents powered by real intelligence, delivering next generation autonomic entities that can seamlessly migrate, mutate and evolve on their journey between and within physical and digital information spaces.

  20. The toolbox of Trichoderma spp. in the biocontrol of Botrytis cinerea disease.

    Science.gov (United States)

    Vos, Christine M F; De Cremer, Kaat; Cammue, Bruno P A; De Coninck, Barbara

    2015-05-01

    Botrytis cinerea is a necrotrophic fungal pathogen causing disease in many plant species, leading to economically important crop losses. So far, fungicides have been widely used to control this pathogen. However, in addition to their detrimental effects on the environment and potential risks for human health, increasing fungicide resistance has been observed in the B. cinerea population. Biological control, that is the application of microbial organisms to reduce disease, has gained importance as an alternative or complementary approach to fungicides. In this respect, the genus Trichoderma constitutes a promising pool of organisms with potential for B. cinerea control. In the first part of this article, we review the specific mechanisms involved in the direct interaction between the two fungi, including mycoparasitism, the production of antimicrobial compounds and enzymes (collectively called antagonism), and competition for nutrients and space. In addition, biocontrol has also been observed when Trichoderma is physically separated from the pathogen, thus implying an indirect systemic plant defence response. Therefore, in the second part, we describe the consecutive steps leading to induced systemic resistance (ISR), starting with the initial Trichoderma-plant interaction and followed by the activation of downstream signal transduction pathways and, ultimately, the defence response resulting in ISR (ISR-prime phase). Finally, we discuss the ISR-boost phase, representing the effect of ISR priming by Trichoderma spp. on plant responses after additional challenge with B. cinerea.

  1. Chitin enhances biocontrol of Rhodotorula mucilaginosa to postharvest decay of peaches.

    Science.gov (United States)

    Zhang, Hongyin; Yang, Qiya; Ge, Lingling; Zhang, Guochao; Zhang, Xiaoli; Zhang, Xiaoyun

    2016-07-01

    Biological control using microbial antagonists is a promising alternative approach to synthetic fungicides. However, effective biological control requires enhancing the consistency and efficacy of the antagonists used to control postharvest diseases. This study investigated the effect of chitin on the biocontrol efficacy of Rhodotorula mucilaginosa against blue mold and Rhizopus decay of peaches and on the protein expression profiles of R. mucilaginosa. The antagonistic activity of R. mucilaginosa harvested from the nutrient yeast dextrose broth (NYDB) with 0.5% chitin added was significantly improved compared with culture in NYDB without chitin. The R. mucilaginosa population cultured in chitin-supplement NYDB and nutrient yeast chitin borth (NYCB) harvested from peach wounds was more than that of R. mucilaginosa cultured in NYDB without chitin throughout the storage period except at 1 d. The protein expression profiles findings revealed that there were several differentially expressed proteins of R. mucilaginosa in the 0.5% chitin-supplemented NYDB and NYCB compared with that of R. mucilaginosa in NYDB. Most of these were cellular proteomes relating to the primary metabolic reactions such as glycoside hydrolases, phosphoribosyl pyrophosphate, and NADH dehydrogenases. Some proteins were also related to signal transmission and stress response. PMID:27064085

  2. Biocontrol mechanisms of Trichoderma harzianum against soybean charcoal rot caused by Macrophomina phaseolina

    Directory of Open Access Journals (Sweden)

    Khaledi Nima

    2016-01-01

    Full Text Available Throughout the world, charcoal rot, caused by Macrophomina phaseolina, is one of the most destructive and widespread diseases of crop plants such as soybean. In this study, the biological control capability of 11 Trichoderma spp. isolates against M. phaseolina was investigated using screening tests. Among all the tested Trichoderma spp. isolates, inhibition varied from 20.22 to 58.67% in dual culture tests. Dual culture, volatile and non-volatile tests revealed that two isolates of Trichoderma harzianum (including the isolates T7 and T14 best inhibited the growth of M. phaseolina in vitro. Therefore, these isolates were selected for biocontrol of M. phaseolina in vivo. The results of greenhouse experiments revealed that disease severity in the seed treatment with T. harzianum isolates was significantly lower than that of the soil treatment. In most of the cases, though, soil treatment with T. harzianum resulted in higher plant growth parameters, such as root and shoot weight. The effects of T. harzianum isolates on the activity of peroxidase enzyme and phenolic contents of the soybean root in the presence and absence of M. phaseolina were determined in greenhouse conditions. Our results suggested that a part of the inhibitory effect of T. harzianum isolates on soybean charcoal rot might be related to the indirect influence on M. phaseolina. Plant defense responses were activated as an elicitor in addition to the direct effect on the pathogen growth.

  3. Molecular characterization of alkaline protease of Bacillus amyloliquefaciens SP1 involved in biocontrol of Fusarium oxysporum.

    Science.gov (United States)

    Guleria, Shiwani; Walia, Abhishek; Chauhan, Anjali; Shirkot, C K

    2016-09-01

    An alkaline protease gene was amplified from genomic DNA of Bacillus amyloliquefaciens SP1 which was involved in effective biocontrol of Fusarium oxysporum. We investigated the antagonistic capacity of protease of B. amyloliquifaciens SP1, under in vitro conditions. The 5.62 fold purified enzyme with specific activity of 607.69U/mg reported 24.14% growth inhibition of F. oxysporum. However, no antagonistic activity was found after addition of protease inhibitor i.e. PMSF (15mM) to purified enzyme. An 1149bp nucleotide sequence of protease gene encoded 382 amino acids of 43kDa and calculated isoelectric point of 9.29. Analysis of deduced amino acid sequence revealed high homology (86%) with subtilisin E of Bacillus subtilis. The B. amyloliquefaciens SP1 protease gene was expressed in Escherichiax coli BL21. The expressed protease was secreted into culture medium by E. coli and exhibited optimum activity at pH8.0 and 60°C. The most reliable three dimensional structure of alkaline protease was determined using Phyre 2 server which was validated on the basis of Ramachandran plot and ERRAT value. The expression and structure prediction of the enzyme offers potential value for commercial application in agriculture and industry. PMID:27294522

  4. Improved delivery of biocontrol Pseudomonas and their antifungal metabolites using alginate polymers.

    Science.gov (United States)

    Russo, A; Moënne-Loccoz, Y; Fedi, S; Higgins, P; Fenton, A; Dowling, D N; O'Regan, M; O'Gara, F

    1996-02-01

    Alginate polymer was evaluated as a carrier for seed inoculation with a genetically modified strain Pseudomonas fluorescens F113LacZY, which protects sugar-beet against Pythium-mediated damping-off. F113LacZY survived in alginate beads at 5 log10 CFU/bead or higher counts for 8 weeks of storage, regardless of the conditions of incubation. In plant inoculation experiments, colonisation of the growing area of the root by F113LacZY, derived from alginate beads placed in the soil next to the seed or from an alginate coating around the seeds, was improved compared with application of just free cells of the strain. F113LacZY trapped in alginate beads was an effective producer of antifungal phloroglucinols as indicated by direct HPLC quantification of phloroglucinols and in vitro inhibition of both the indicator bacterium Bacillus subtilis A1 and the pathogenic fungus Pythium ultimum. Alginate polymer represents a promising carrier for the delivery of biocontrol inoculants for root colonisation and production of antifungal metabolites. PMID:8867631

  5. The toolbox of Trichoderma spp. in the biocontrol of Botrytis cinerea disease.

    Science.gov (United States)

    Vos, Christine M F; De Cremer, Kaat; Cammue, Bruno P A; De Coninck, Barbara

    2015-05-01

    Botrytis cinerea is a necrotrophic fungal pathogen causing disease in many plant species, leading to economically important crop losses. So far, fungicides have been widely used to control this pathogen. However, in addition to their detrimental effects on the environment and potential risks for human health, increasing fungicide resistance has been observed in the B. cinerea population. Biological control, that is the application of microbial organisms to reduce disease, has gained importance as an alternative or complementary approach to fungicides. In this respect, the genus Trichoderma constitutes a promising pool of organisms with potential for B. cinerea control. In the first part of this article, we review the specific mechanisms involved in the direct interaction between the two fungi, including mycoparasitism, the production of antimicrobial compounds and enzymes (collectively called antagonism), and competition for nutrients and space. In addition, biocontrol has also been observed when Trichoderma is physically separated from the pathogen, thus implying an indirect systemic plant defence response. Therefore, in the second part, we describe the consecutive steps leading to induced systemic resistance (ISR), starting with the initial Trichoderma-plant interaction and followed by the activation of downstream signal transduction pathways and, ultimately, the defence response resulting in ISR (ISR-prime phase). Finally, we discuss the ISR-boost phase, representing the effect of ISR priming by Trichoderma spp. on plant responses after additional challenge with B. cinerea. PMID:25171761

  6. Biocontrol of seed pathogens and growth promotion of common bean seedlings by Trichoderma harzianum

    Directory of Open Access Journals (Sweden)

    Daniel Diego Costa Carvalho

    2011-08-01

    Full Text Available The objective of this work was to evaluate isolates of Trichoderma harzianum regarding biocontrol of common bean seed-borne pathogens, plant growth promotion, and rhizosphere competence. Five isolates of T. harzianum were evaluated and compared with commercial isolate (Ecotrich, Carboxin+Thiram, and an absolute control. Bean seeds of the cultivar Jalo Precoce, contaminated with Aspergillus, Cladosporium, and Sclerotinia sclerotiorum, were microbiolized with antagonists, and seed health tests were carried out. Isolates were evaluated on autoclaved substrate and in field conditions. Ten days after sowing (DAS, plant length was measured. To test rhizosphere competence, isolates were applied in boxes containing autoclaved washed sand, and root colonization was evaluated at 10 DAS, using five plants per box. The most effective isolates in the seed health tests were: CEN287 and CEN289 to control Aspergillus; the commercial isolate to control Cladosporium; and CEN287 and CEN316 to control S. sclerotiorum. Isolates CEN289 and CEN290 promoted bean growth in greenhouse and field. Seed treatment with T. harzianum reduces the incidence of Aspergillus, Cladosporium, and S. sclerotiorum in 'Jalo Precoce' common bean seeds.

  7. Interacting agents in finance

    NARCIS (Netherlands)

    C. Hommes

    2008-01-01

    Interacting agents in finance represent a behavioural, agent-based approach in which financial markets are viewed as complex adaptive systems consisting of many boundedly rational agents interacting through simple heterogeneous investment strategies, constantly adapting their behaviour in response t

  8. Phytohormone profiles induced by trichoderma isolates correspond with their biocontrol and plant growth-promoting activity on melon plants.

    Science.gov (United States)

    Martínez-Medina, Ainhoa; Del Mar Alguacil, Maria; Pascual, Jose A; Van Wees, Saskia C M

    2014-07-01

    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 phytohormonal network of their host plant, thus leading to an improvement of plant growth and stress tolerance. In this study, we tested whether alterations in the phytohormone signature induced by different Trichoderma isolates correspond with their ability for biocontrol and growth promotion. Four Trichoderma isolates were collected from agricultural soils and were identified as the species Trichoderma harzianum (two isolates), Trichoderma ghanense, and Trichoderma hamatum. Their antagonistic activity against the plant pathogen Fusarium oxysporum f. sp. melonis was tested in vitro, and their plant growth-promoting and biocontrol activity against Fusarium wilt on melon plants was examined in vivo, and compared to that of the commercial strain T. harzianum T-22. Several growth- and defense-related phytohormones were analyzed in the shoots of plants that were root-colonized by the different Trichoderma isolates. An increase in auxin and a decrease in cytokinins and abscisic acid content were induced by the isolates that promoted the plant growth. Principal component analysis (PCA) was used to evaluate the relationship between the plant phenotypic and hormonal variables. PCA pointed to a strong association of auxin induction with plant growth stimulation by Trichoderma. Furthermore, the disease-protectant ability of the Trichoderma strains against F. oxysporum infection seems to be more related to their induced alterations in the content of the hormones abscisic acid, ethylene, and the cytokinin trans-zeatin riboside than to the in vitro antagonism activity against F. oxysporum.

  9. Characterization of antagonistic-potential of two Bacillus strains and their biocontrol activity against Rhizoctonia solani in tomato.

    Science.gov (United States)

    Solanki, Manoj Kumar; Singh, Rajesh Kumar; Srivastava, Supriya; Kumar, Sudheer; Kashyap, Prem Lal; Srivastava, Alok K

    2015-01-01

    To investigate the biocontrol mechanism of two antagonistic Bacillus strains (Bacillus subtilis MB14 and Bacillus amyloliquefaciens MB101), three in vitro antagonism assays were screened and the results were concluded that both strains inhibited Rhizoctonia solani growth in a similar manner by dual culture assay, but the maximum percent of inhibition only resulted with MB101 by volatile and diffusible metabolite assays. Moreover, cell free supernatant (CFS) of MB101 also showed significant (p > 0.05) growth inhibition as compared to MB14, when 10 and 20% CFS mix with the growth medium of R. solani. After in vitro-validation, both strains were evaluated under greenhouse and the results concluded that strain MB101 had significant biocontrol potential as compared to MB14. Strain MB101 was enhanced the plant height, biomass and chlorophyll content of tomato plant through a higher degree of root colonization. In field trials, strain MB101 showed higher lessening in root rot symptoms with significant fruit yield as compare to strain MB14 and infected control. Next to the field study, the presence of four antibiotic genes (srfAA, fenD, ituC, and bmyB) also concluded the antifungal nature of both Bacillus strains. Phylogenetic analysis of protein sequences revealed a close relatedness of three genes (srfAA, fenD, and ituC) with earlier reported sequences of B. subtilis and B. amyloliquefaciens. However, bmyB showed heterogeneity in among both strains (MB14 and MB101) and it may be concluded that higher degree of antagonism, root colonization and different antibiotic producing genes may play an important role in biocontrol mechanism of strain MB101. PMID:24277414

  10. Shallot Aphids, Myzus ascalonicus, in Strawberry: Biocontrol Potential of Three Predators and Three Parasitoids

    DEFF Research Database (Denmark)

    Enkegaard, Annie; Sigsgaard, Lene; Kristensen, Kristian

    2013-01-01

    or sweet pepper leaves. The aphid species and the plant species did not, however, have a significant influence on the number of females laying eggs, the average number of eggs laid during the first day being 6.37±1.28 per female. Adult lady beetles had a significant preference for odor from controls...... without plants over odors from uninfested strawberry or pepper plants, but they showed no preference for either of the plant species, whether infested with aphids or not. The predation capacity of A. bipunctata on shallot aphids holds promise for its use in inundative biocontrol, and the results on egg...

  11. Evaluation of the enzymatic activity of Trichoderma inhamatum (BOL-12QD as possible biocontroller

    Directory of Open Access Journals (Sweden)

    García-Espejo Cielo Noemí

    2016-02-01

    Full Text Available It is known that Trichoderma spp. acts as a natural biocontroller of pathogen fungi, is for this reason, that this research studies the potential of its hydrolytic enzyme activity. In this article, first we determined that the speed of growth of Trichoderma inhamatum cepa BOL-12QD is 9 hours. Later, we proposed a simple and sensitive method based in the use of basal media (BM with coloidal chitin as the only carbon resource and supplemented with bromocresol purple for the qualitative determination of chitinase activi-ty. On the other hand, it was determined the celullolytic and proteolytic activities of Trichoderma in-hamatum cepa BOL-12QD and it was observed that agitation, type and concentration of sustrate are determinant factors in enzymatic production. Then, we evaluated the cellulolytic activity of Trichoderma inhamatum cepa BOL-12QD in agitation and stationary using carboxymethylcellulose (CMC as sustrate, finding that using a 2% of sustrate the highest activity is registered at 8 days of incubation in agitation with a value of 99.23 IU/L. In relation to the results at stationary the optimal value is at the fourth day with a value of 92.76 IU/L. The protease activity it was determined taking in consideration variables of agitation and stationary, using different types and concentration of sustrate at 2%, 4% y 6% (w/v of meat extract, 1%, 3%, 5% (w/v of jelly and 1%, 2%, 4% (w/v of casein. The highest protease activity was obtained at the end of the sev-enth day with an enzymatic activity of 3075.45 IU/L at stationary using a concentration of 6% (w/v of meat extract, and using jelly at 3% (w/v at stationary it was found an activity of 568.36 IU/L on the tenth day and in agitation a value of 547.27 IU/L was reached on the twelveth day, while using casein at 1% (w/v at stationary an activity of 407.06 IU/L is reached in the fifth day, and in agitation at 4% (w/v of casein a value of 547.27 IU/L is obtained on the twelfth day, while using

  12. Biocontrol efficacy and plant growth promoting activity of Bacillus altitudinis isolated from Darjeeling hills, India.

    Science.gov (United States)

    Sunar, Kiran; Dey, Pannalal; Chakraborty, Usha; Chakraborty, Bishwanath

    2015-01-01

    A total of 18 bacterial isolates were obtained from the rhizosphere of Sechium edule growing in the lower foothills of Darjeeling, India. The bacterial isolates were tested for PGPR traits in vitro such as phosphate solubilization, HCN, siderophore, IAA, chitinase, protease production as well as inhibition of pthytopathogens. Of all the bacterial isolates, one bacterium designated as BRHS/S-73 was found to possess all the tested characters which was identified on the basis of 16S rRNA gene sequence analysis as Bacillus altitudinis and was selected for in vivo studies. A significant improvement in growth measured in terms of increase in root length, shoot length, and increase in root and shoot biomass was observed when seeds of Vigna radiata, Cicer arietinum, and Glycine max were bacterized prior to sowing in field condition. Besides, the bacterium could also solubilize soil phosphate. Apart form growth promotion, root rot disease of Vigna radiata caused by Thanatephorus cucumeris was also significantly reduced by 74% when the bacterium was applied to the rhizosphere prior to pathogen challenge. The biocontrol efficacy of the bacterium was found to be 66.6% even after 30 days of pathogen inoculation. Activities of key defense related enzymes such as phenylalanine ammonia lyase, peroxidase, β-1,3-glucanase, and chitinase in both roots and leaves of treated plants were also enhanced. Results clearly suggest that B. altitudinis (BRHS/S-73) is a potential PGPR which can be used as efficient microorganism for enhancement of plant growth and suppression of fungal disease. PMID:23996212

  13. Three New Pierce's Disease Pathogenicity Effectors Identified Using Xylella fastidiosa Biocontrol Strain EB92-1.

    Directory of Open Access Journals (Sweden)

    Shujian Zhang

    Full Text Available Xylella fastidiosa (X. fastidiosa infects a wide range of plant hosts and causes economically serious diseases, including Pierce's Disease (PD of grapevines. X. fastidiosa biocontrol strain EB92-1 was isolated from elderberry and is infectious and persistent in grapevines but causes only very slight symptoms under ideal conditions. The draft genome of EB92-1 revealed that it appeared to be missing genes encoding 10 potential PD pathogenicity effectors found in Temecula1. Subsequent PCR and sequencing analyses confirmed that EB92-1 was missing the following predicted effectors found in Temecula1: two type II secreted enzymes, including a lipase (LipA; PD1703 and a serine protease (PD0956; two identical genes encoding proteins similar to Zonula occludens toxins (Zot; PD0915 and PD0928, and at least one relatively short, hemagglutinin-like protein (PD0986. Leaves of tobacco and citrus inoculated with cell-free, crude protein extracts of E. coli BL21(DE3 overexpressing PD1703 exhibited a hypersensitive response (HR in less than 24 hours. When cloned into shuttle vector pBBR1MCS-5, PD1703 conferred strong secreted lipase activity to Xanthomonas citri, E. coli and X. fastidiosa EB92-1 in plate assays. EB92-1/PD1703 transformants also showed significantly increased disease symptoms on grapevines, characteristic of PD. Genes predicted to encode PD0928 (Zot and a PD0986 (hemagglutinin were also cloned into pBBR1MCS-5 and moved into EB92-1; both transformants also showed significantly increased symptoms on V. vinifera vines, characteristic of PD. Together, these results reveal that PD effectors include at least a lipase, two Zot-like toxins and a possibly redundant hemagglutinin, none of which are necessary for parasitic survival of X. fastidiosa populations in grapevines or elderberry.

  14. Three New Pierce's Disease Pathogenicity Effectors Identified Using Xylella fastidiosa Biocontrol Strain EB92-1.

    Science.gov (United States)

    Zhang, Shujian; Chakrabarty, Pranjib K; Fleites, Laura A; Rayside, Patricia A; Hopkins, Donald L; Gabriel, Dean W

    2015-01-01

    Xylella fastidiosa (X. fastidiosa) infects a wide range of plant hosts and causes economically serious diseases, including Pierce's Disease (PD) of grapevines. X. fastidiosa biocontrol strain EB92-1 was isolated from elderberry and is infectious and persistent in grapevines but causes only very slight symptoms under ideal conditions. The draft genome of EB92-1 revealed that it appeared to be missing genes encoding 10 potential PD pathogenicity effectors found in Temecula1. Subsequent PCR and sequencing analyses confirmed that EB92-1 was missing the following predicted effectors found in Temecula1: two type II secreted enzymes, including a lipase (LipA; PD1703) and a serine protease (PD0956); two identical genes encoding proteins similar to Zonula occludens toxins (Zot; PD0915 and PD0928), and at least one relatively short, hemagglutinin-like protein (PD0986). Leaves of tobacco and citrus inoculated with cell-free, crude protein extracts of E. coli BL21(DE3) overexpressing PD1703 exhibited a hypersensitive response (HR) in less than 24 hours. When cloned into shuttle vector pBBR1MCS-5, PD1703 conferred strong secreted lipase activity to Xanthomonas citri, E. coli and X. fastidiosa EB92-1 in plate assays. EB92-1/PD1703 transformants also showed significantly increased disease symptoms on grapevines, characteristic of PD. Genes predicted to encode PD0928 (Zot) and a PD0986 (hemagglutinin) were also cloned into pBBR1MCS-5 and moved into EB92-1; both transformants also showed significantly increased symptoms on V. vinifera vines, characteristic of PD. Together, these results reveal that PD effectors include at least a lipase, two Zot-like toxins and a possibly redundant hemagglutinin, none of which are necessary for parasitic survival of X. fastidiosa populations in grapevines or elderberry. PMID:26218423

  15. Phytic acid enhances biocontrol activity of Rhodotorula mucilaginosa against Penicillium expansum contamination and patulin production in apples

    Directory of Open Access Journals (Sweden)

    Qiya eYang

    2015-11-01

    Full Text Available The effect of Rhodotorula mucilaginosa in combination with phytic acid (PA on blue mold decay and patulin contamination of apples was investigated. Results from this study show that different concentrations of PA were effective in reducing the disease incidence of apples and that PA at concentration of 4 μmol/mL, decreased the incidence of blue mold decay in apples from 86.1% to 62.5%, and showed higher control efficacy compared to untreated, control fruit during storage at 20 °C. However, R. mucilaginosa combined with PA (4 μmol/mL showed better control efficacy of blue mold decay than R. mucilaginosa used as single treatment, the disease incidence was reduced to 62.5% and lesion diameter on apples was reduced to 16.59cm. In in vitro experiments, the addition of PA enhanced the biocontrol effect of R. mucilaginosa against the growth of P. expansum and reduced patulin level when compared with either R. mucilaginosa or PA used separately. R. mucilaginosa together with PA, improved the inhibition of patulin production in wounded apples, decreasing the content of patulin by 89.6% compared to the control, under experimental conditions. Both R. mucilaginosa and R. mucilaginosa in combination with PA degraded patulin in vitro. In conclusion, the appropriate combination of R. mucilaginosa and PA may provide an effective biocontrol method for reducing postharvest decay of apples.

  16. Evidence for biotrophic lifestyle and biocontrol potential of dark septate endophyte Harpophora oryzae to rice blast disease.

    Directory of Open Access Journals (Sweden)

    Zhen-Zhu Su

    Full Text Available The mutualism pattern of the dark septate endophyte (DSE Harpophora oryzae in rice roots and its biocontrol potential in rice blast disease caused by Magnaporthe oryzae were investigated. Fluorescent protein-expressing H. oryzae was used to monitor the colonization pattern. Hyphae invaded from the epidermis to the inner cortex, but not into the root stele. Fungal colonization increased with root tissue maturation, showing no colonization in the meristematic zone, slight colonization in the elongation zone, and heavy colonization in the differentiation zone. H. oryzae adopted a biotrophic lifestyle in roots accompanied by programmed cell death. Real-time PCR facilitated the accurate quantification of fungal growth and the respective plant response. The biocontrol potential of H. oryzae was visualized by inoculation with eGFP-tagged M. oryzae in rice. H. oryzae protected rice from M. oryzae root invasion by the accumulation of H2O2 and elevated antioxidative capacity. H. oryzae also induced systemic resistance against rice blast. This systemic resistance was mediated by the OsWRKY45-dependent salicylic acid (SA signaling pathway, as indicated by the strongly upregulated expression of OsWRKY45. The colonization pattern of H. oryzae was consistent with the typical characteristics of DSEs. H. oryzae enhanced local resistance by reactive oxygen species (ROS and high antioxidative level and induced OsWRKY45-dependent SA-mediated systemic resistance against rice blast.

  17. Role of 2-hexyl, 5-propyl resorcinol production by Pseudomonas chlororaphis PCL1606 in the multitrophic interactions in the avocado rhizosphere during the biocontrol process.

    Science.gov (United States)

    Calderón, Claudia E; de Vicente, Antonio; Cazorla, Francisco M

    2014-07-01

    Different bacterial traits can contribute to the biocontrol of soilborne phytopathogenic fungus. Among others, (1) antagonism, (2) competition for nutrients and niches, (3) induction of systemic resistance of the plants and (4) predation and parasitism are the most studied. Pseudomonas chlororaphis PCL1606 is an antagonistic rhizobacterium that produces the antifungal metabolite 2-hexyl, 5-propyl resorcinol (HPR). This bacterium can biologically control the avocado white root rot caused by Rosellinia necatrix. Confocal laser scanning microscopy of the avocado rhizosphere revealed that this biocontrol bacterium and the fungal pathogen compete for the same niche and presumably also for root exudate nutrients. The use of derivative mutants in the geners related to HPR biosynthesis (dar genes) revealed that the lack of HPR production by P. chlororaphis PCL1606 negatively influences the bacterial colonisation of the avocado root surface. Microscopical analysis showed that P. chlororaphis PCL1606 closely interacts and colonises the fungal hyphae, which may represent a novel biocontrol mechanism in this pseudomonad. Additionally, the presence of HPR-producing biocontrol bacteria negatively affects the ability of the fungi to infect the avocado root. HPR production negatively affects hyphal growth, leading to alterations in the R. necatrix physiology visible under microscopy, including the curling, vacuolisation and branching of hyphae, which presumably affects the colonisation and infection abilities of the fungus. This study provides the first report of multitrophic interactions in the avocado rhizosphere, advancing our understanding of the role of HPR production in those interactions.

  18. Regulation of aflatoxin biosynthesis and branched-chain amino acids metabolism in Aspergillus flavus by 2-phenylethanol reveal biocontrol mechanism of Pichia anomala

    Science.gov (United States)

    Pichia anomala WRL-076 is a biocontrol yeast which has been shown to inhibit growth and aflatoxin production of A. flavus. Using the SPME-GC/MS analysis we identified that the volatile, 2-phenylethanol (2-PE) produced by this yeast and demonstrated that the compound inhibited aflatoxin production. W...

  19. Biocontrol traits of plant growth suppressive arbuscular mycorrhizal fungi against root rot in tomato caused by Pythium aphanidermatum

    DEFF Research Database (Denmark)

    Larsen, John; Graham, James H.; Cubero, Jaime;

    2012-01-01

    Arbuscular mycorrhizal (AM) fungi known to cause plant growth depressions in tomato were examined for their biocontrol effects against root rot caused by Pythium aphanidermatum. The main hypothesis was that plant growth suppressive AM fungi would elicit a defence response in the host plant reduci...

  20. Use of Hypocrea jecorina (anamorph Trichoderma reesei) as a model system for Trichoderma biocontrol of Pythium blight identifies new targets for genetic strain improvement

    Institute of Scientific and Technical Information of China (English)

    Seidl V; Schmoll M; Scherm B; Balmas V; Seiboth B; Migheli Q; Kubicek C P

    2004-01-01

    @@ Biocontrol by Trichoderma has been studied mainly with selected isolates of T. harzianum, T.atroviride and T. asperellum, which are members of sections Pachybasium and Trichoderma. In contrast, species from section Longibrachiatum have only rarely been studied. On the other hand, one taxon from this section-Hypocrea jecorina (anamorph: Trichoderma reesei)-has been widely used for the production of cellulolytic and hemicellulolytic enzymes and recombinant proteins. As far as Trichoderma is concerned, molecular genetic methods and tools are most advanced in H. jecorina,and its genome has recently been fully sequenced, thus making this taxon a model organism for the genus. Here we will demonstrate that H. jecorina is able to antagonize plant pathogenic fungi in plate confrontation tests, and can protect tomato and cucumber plants against Pythium ultimum blight.Using this as a model case, we made use of available H. jecorina mutants to investigate (a) whether carbon catabolite repression via the Cre1-regulator protein has an impact on biocontrol, and (b)whether cellulase gene expression is necessary for biocontrol of P. ultimum. In the first case, plate confrontation tests and in planta experiments yielded opposite results, i.e. while a Cre1 mutant was more active in antagonization of fungi on plates, the survival rates of P. ultimum-inoculated cucumber plants was lower than with the H. jecorina wild-type strain. Mutants of H. jecorina,unable to form cellulases, were still able to antagonize fungi on plates and provided similar protection of tomatos against P. ultimum as the wild type, indicating that the pronounced biocontrol ability of H.jecorina against fungi with cellulose-containing cell-walls is not due to its high cellulolytic activity. A strain disrupted in the light-modulator gene envoy (Schmoll et al., ms submitted) exhibited in planta biocontrol activity strongly exceeding that of the wild-type strain, thereby providing a first link between Trichoderma

  1. AgentChess : An Agent Chess Approach

    OpenAIRE

    Fransson, Henric

    2003-01-01

    The game of chess has many times been discussed and used for test purpose by science departments of Artificial Intelligence (AI). Although the technique of agent and as well multi-agent systems is quite old, the use of these offspring of AI within chess is limited. This report describes the project performed applying the use of agents to a chess program. To measure the performance of the logic has tests between the developed program main parts been performed. Further tests against a tradition...

  2. Riot Control Agents

    Science.gov (United States)

    ... a person has been exposed to riot control agents. Long-term health effects of exposure to riot control agents Prolonged ... person is removed from exposure to riot control agents, long-term health effects are unlikely to occur. How you can ...

  3. Reasoning about emotional agents

    NARCIS (Netherlands)

    Meyer, J.-J.

    2008-01-01

    In this paper we discuss the role of emotions in artificial agent design, and the use of logic in reasoning about the emotional or affective states an agent can reside in. We do so by extending the KARO framework for reasoning about rational agents appropriately. In particular we formalize in this f

  4. Agents modeling agents in information economies

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, J.M.; Durfee, E.H. [Univ. of Michigan, Ann Arbor, MI (United States)

    1996-12-31

    Our goal is to design and build agents that act intelligently when placed in an agent-based information economy, where agents buy and sell services (e.g. thesaurus, search, task planning services, etc.). The economy we are working in is the University of Michigan Digital Library (UMDL), a large scale multidisciplinary effort to build an infrastructure for the delivery of library services. In contrast with a typical economy, an information economy deals in goods and services that are often derived from unique sources (authors, analysts, etc.), so that many goods and services are not interchangeable. Also, the cost of replicating and transporting goods is usually negligible, and the quality of goods and services is difficult to measure objectively: even two sources with essentially the same information might appeal to different audiences. Thus, each agent has its own assessment of the quality of goods and services delivered.

  5. Biological management of gray mold in pot roses by co-inoculation of thebiocontrol agent Ulocladium atrum and the mycorrhizal fungus Glomus mosseae

    DEFF Research Database (Denmark)

    Møller, Kaare; Kristensen, Kristian; Yohalem, David;

    2009-01-01

    In pursuit of a biological disease and stress management strategy for ornamentals, a three-factorial experiment was performed to examine the effects of plant darkness stress, Ulocladium atrum and Glomus mosseae on gray mold caused by Botrytis cinerea and plant vigour in potted roses. While darkness......, and increased plant top dry weight. However, G. mosseae had no effect on dry weight under stress conditions. G. mosseae root colonization increased significantly when U. atrum was applied, but only under normal light conditions. In conclusion, a biological approach combining a foliar biocontrol agent...

  6. Combinative effects of a bacterial type-III effector and a biocontrol bacterium on rice growth and disease resistance

    Indian Academy of Sciences (India)

    Haiying Ren; Ganyu Gu; Juying Long; Qian Yin; Tingquan Wu; Tao Song; Shujian Zhang; Zhiyi Chen; Hansong Dong

    2006-12-01

    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. We studied effects of Pseudomonas cepacia on the rice variety R109 and the hpaGXoo-expressing rice line HER1. Compared to R109, HER1 showed increased growth, grain yield, and defense responses toward diseases and salinity stress. Colonization of roots by P. cepacia caused 20% and 13% increase, in contrast to controls, in root growth of R109 and HER1. Growth of leaves and stems also increased in R109 but that of HER1 was inhibited. When P. cepacia colonization was subsequent to plant inoculation with Rhizoctonia solani, a pathogen that causes sheath blight, the disease was less severe than controls in both R109 and HER1; HER1, nevertheless, was more resistant, suggesting that P. cepacia and HpaGXoo cooperate in inducing disease resistance. Several genes that critically regulate growth and defense behaved differentially in HER1 and R109 while responding to P. cepacia. In R109 leaves, the OsARF1 gene, which regulates plant growth, was expressed in consistence with growth promotion by P. cepacia. Inversely, OsARF1 expression was coincident with inhibition in growth of HER1 leaves. In both plants, the expression of OsEXP1, which encodes an expansin protein involved in plant growth, was concomitant with growth promotion in leaves instead of roots, in response to P. cepacia. We also studied OsMAPK, a gene that encodes a mitogen-activated protein kinase and controls defense responses toward salinity and infection by pathogens in rice. In response to P. cepacia, an early expression of OsMAPK was coincident with R109 resistance to the disease, while HER1 expressed the gene similarly whether P. cepacia was present or not. Evidently, P. cepacia and GXoo

  7. Biocontrol of Postharvest Anthracnose of Mango Fruit with Debaryomyces Nepalensis and Effects on Storage Quality and Postharvest Physiology.

    Science.gov (United States)

    Luo, Shanshan; Wan, Bin; Feng, Shuhan; Shao, Yuanzhi

    2015-11-01

    Anthracnose is presently recognized as one of the most important postharvest disease of mango worldwide. To control the disease, chemical fungicides for a long time was widely used among fruit farmers, but recently found that pathogen had developed increasingly resistance to it. With people's growing desire of healthy and green food, finding new and environmentally friendly biological control approach was very necessary. In this paper, we provided a kind of new antagonistic yeast which enriched the strain resources and the efficacy of Debaryomyces nepalensis against postharvest anthracnose of mango fruit and the influence on quality parameters were investigated. The results showed that the decay incidence and lesion diameter of postharvest anthracnose of mango treated by D. nepalensis were significantly reduced compared with the control fruit stored at 25 °C for 30 d or at 15 °C for 40 d, and the higher concentration of D. nepalensis was, the better the efficacy of the biocontrol was. Study also found that 1 h was the best treatment duration and antagonistic yeast inoculated earlier had good biocontrol effect on anthracnose. Meanwhile, treatment by D. nepalensis could significantly reduce postharvest anthracnose of mango, delay the decrease in firmness, TSS, TA, and ascorbic acid value, and do not impair surface color during postharvest storage. Moreover, the increase in MDA (malondialdehyde) content and increase in cell membrane permeability of fruit treated by D. nepalensis was highly inhibited. The results suggested D. nepalensis treatment could not only maintain storage quality of mango fruit, but also decrease the decay incidence to anthracnose disease. All these results indicated that D. nepalensis has great potential for development of commercial formulations to control postharvest pathogens of mango fruit.

  8. Selection, Identification and Optimization of the Growth Water Probiotic Consortium of Mangrove Ecosystems as Bioremediation and Biocontrol in Shrimp Ponds

    Directory of Open Access Journals (Sweden)

    Wilis Ari Setyati

    2015-01-01

    Full Text Available Shrimp aquaculture is an activity that potentially generates organic waste. The accumulation of organic matter is becoming one of the main factors causing the emergence of disease. Problem-solving approach that is most effective is through bioremediation. The aims of this study were to select, identify and cultivate bacteria from mangrove sediments from Cilacap, Rembang and Banyuwangi which potentially as probiotic consortium of bioremediation activity and biocontrol. The results showed that total of 45 isolates (proteolytic, 35 isolates (amylolytic, 35 isolates (lipolytic, and 18 isolates (cellulolytic. There were 59 bacterial isolates had antibacterial activity of vibrio (V. harveyi, V. alginolyticus, V. vulnificus and V. anguilarum. Based on the identification of 16 S-rRNA genes, 4 isolates showed that the C2 isolate was identified as Bacillus subtilis, C11 isolate was identified as Bacillus firmus, C13 and C14 isolates were identified as B. Flexus. This study concluded that cultivation of Bacillus subtilis C2 optimum at 2% molase and yeast extract 0.5% at pH 8 and 30 0C. Bacillus firmus C11 optimum at 2% molase and yeast extract 0.5% at pH 8 and 30 0C. Bacillus flexus C13 optimum at 2% glucose and yeast extract 0.5% at pH 8 and 30 0C. Bacillus flexus C14 optimum at 4% molase and yeast extract 0.25% at pH 8 and 30 0C. The result of culture applications of 4 isolates showed an effect of increasing shrimp weight by 141, 9% compared by the control.Keywords: sediment, mangrove, bioremediation, biocontrol

  9. Chitinase production by Bacillus subtilis ATCC 11774 and its effect on biocontrol of Rhizoctonia diseases of potato.

    Science.gov (United States)

    Saber, Wesam I A; Ghoneem, Khalid M; Al-Askar, Abdulaziz A; Rashad, Younes M; Ali, Abeer A; Rashad, Ehsan M

    2015-12-01

    Stem canker and black scurf of potato, caused by Rhizoctonia solani, can be serious diseases causing an economically significant damage. Biocontrol activity of Bacillus subtilis ATCC 11774 against the Rhizoctonia diseases of potato was investigated in this study. Chitinase enzyme was optimally produced by B. subtilis under batch fermentation conditions similar to those of the potato-growing soil. The maximum chitinase was obtained at initial pH 8 and 30 °C. In vitro, the lytic action of the B. subtilis chitinase was detected releasing 355 μg GlcNAc ml⁻¹ from the cell wall extract of R. solani and suggesting the presence of various chitinase enzymes in the bacterial filtrate. In dual culture test, the antagonistic behavior of B. subtilis resulted in the inhibition of the radial growth of R. solani by 48.1% after 4 days. Moreover, the extracted B. subtilis chitinase reduced the growth of R. solani by 42.3% when incorporated with the PDA plates. Under greenhouse conditions, application of a bacterial suspension of B. subtilis at 109 cell mL⁻¹ significantly reduced the disease incidence of stem canker and black scurf to 22.3 and 30%, respectively. In addition, it significantly improved some biochemical parameters, growth and tubers yield. Our findings indicate two points; firstly, B. subtilis possesses a good biocontrol activity against Rhizoctonia diseases of potato, secondly, the harmonization and suitability of the soil conditions to the growth and activity of B. subtilis guaranteed a high controlling capacity against the target pathogen. PMID:26616375

  10. THE INTEGRATED AGENT IN MULTI-AGENT SYSTEMS

    OpenAIRE

    Maleković, Mirko; Čubrilo, Mirko

    2000-01-01

    [n this paper, we characterize the integrated agent in multi-agent systems. The following result is proved: if a multi-agent system is reflexive (symmetric, transitive, Euclidean) then the integrated agent of the multi-agent system is reflexive (symmetric, transitive, Euclidean), respectively. We also prove that the analogous result does not hold for multi-agent system's serial ness. A knowledge relationship between the integrated agent and agents in a multiagent system is presented.

  11. Biocontrol of Escherichia coli O157:H7 using a bacteriophage cocktail in laboratory media

    Science.gov (United States)

    Bacteriophages are natural enemies of bacteria, and therefore, logical candidates to evaluate as antibacterial agents for the control of foodborne pathogens. The effect of a bacteriophage treatment on the prevention of E. coli O157:H7 growth was investigated in Tryptic Soy Broth (TSB) laboratory med...

  12. Chemical crowd control agents.

    Science.gov (United States)

    Menezes, Ritesh G; Hussain, Syed Ather; Rameez, Mansoor Ali Merchant; Kharoshah, Magdy A; Madadin, Mohammed; Anwar, Naureen; Senthilkumaran, Subramanian

    2016-03-01

    Chemical crowd control agents are also referred to as riot control agents and are mainly used by civil authorities and government agencies to curtail civil disobedience gatherings or processions by large crowds. Common riot control agents used to disperse large numbers of individuals into smaller, less destructive, and more easily controllable numbers include chloroacetophenone, chlorobenzylidenemalononitrile, dibenzoxazepine, diphenylaminearsine, and oleoresin capsicum. In this paper, we discuss the emergency medical care needed by sufferers of acute chemical agent contamination and raise important issues concerning toxicology, safety and health. PMID:26658556

  13. Decontamination Data - Blister Agents

    Data.gov (United States)

    U.S. Environmental Protection Agency — Decontamination efficacy data for blister agents on various building materials using various decontamination solutions This dataset is associated with the following...

  14. Biological Control of Sclerotinia sclerotiorum, Causal Agent of Sunflower Head and Stem Rot Disease, by Use of Soil borne Actinomycetes Isolates

    Directory of Open Access Journals (Sweden)

    F. Baniasadi

    2009-01-01

    Full Text Available Problem statement: High level of biosafety and non adverse effects on the environment of biocontrol strategies of pest management, are priorities of tomorrow's world agriculture. Actinomycetes are active biocontrol agents due to their antagonistic properties against wide range of plant pathogens particularly fungi. Fungal pathogens are liable for a big part of damages in agriculture economy. Approach: In the present research antifungal bioactivity of 50 isolates of Actinomycetes collected from soils of Kerman province of Iran was investigated against Sclerotinia sclerotiorum (Lib., the causal agent of stem rot in sunflower, through agar disc method and dual culture bioassays. The Streptomyces isolate No. 363 was propagated in submerged cultures and active crude was prepared upon which several biological characterizations performed. Greenhouse studies were achieved to confirm laboratory results. Results: Among the tested Streptomyces isolates, 10 isolates revealed antagonistic properties in dual culture procedure from which isolate No. 363 showed highest bioactivity. The active metabolite of Streptomyces isolate No. 363 was polar and well soluble in H2O. Using agar-disc method, progressive growth of the pathogen was highly reduced by the antagonist through exhibiting ability to constitute fungus-free zones of inhibitions. The results indicated that isolate No. 363 was a proper candidate for field biocontrol studies. Conclusion: Results may open a horizon for production of resistant transgenic plants having antifungal properties originated from biologically active Streptomyces spp. recognition and production of effective metabolite(s of Streptomyces spp. which was responsible for antifungal activities will be our commercial goal due to rich reserves of soil borne Actinomycetes in Iran.

  15. Biocontrol potential of salinity tolerant mutants of Trichoderma harzianum against Fusarium oxysporum Potencial de biocontrole de mutantes sal-tolerantes de Trichoderma harzianum contra Fusarium oxysporum

    Directory of Open Access Journals (Sweden)

    Hassan Abdel-Latif A. Mohamed

    2006-06-01

    Full Text Available Exposing a wild-type culture of Trichoderma harzianum to gamma irradiation induced two stable salt-tolerant mutants (Th50M6 and Th50M11. Under saline conditions, both mutants greatly surpassed their wild type strain in growth rate, sporulation and biological proficiency against Fusarium oxysporum, the causal agent of tomato wilt disease. Tolerant T. harzianum mutants detained a capability to grow and convinced sporulation in growth media containing up to 69 mM NaCl. In comparison with their parent strain, characterization of both mutants confirmed that they have reinforced contents of proline and hydroxyproline, relatively higher sodium content compared to potassium, calcium or magnesium contents, higher level of total phenols. Electrophoretic analysis of total soluble proteins in the salt tolerance mutant Th50M6 showed different bands accumulated in response to 69 mM NaCl. Data also showed that mutants produce certain active metabolites, such as chitinases, cellulases, beta-galactosidases, as well as, some antibiotics i.e., trichodermin, gliotoxin and gliovirin. Trichoderma mutants significantly reduced wilt disease incidence and improved yield and mineral contents of tomato plants under both saline and non-saline soil conditions, as well as, under infested and natural conditions. T. harzianum mutants were also more efficient in dropping the F. oxysporum growth in rhizosphere compared to the wild type strain. Population density of both mutants in rhizosphere far exceeded that of T. harzianum wild type strain.A exposição de uma cepa selvagem de Trichoderma harzianum à irradiação gama induziu dois mutantes tolerantes a sal (Th50M6 e Th50M11. Em condições salinas, os dois mutantes foram muito superiores à cepa selvagem em relação à velocidade de multiplicação, esporulação e eficiência contra Fusarium oxysporum, o agente causador da doença wilt do tomate. Os mutantes tolerantes foram capazes de multiplicação e esporulação em

  16. GUS and GFP transformation of the biocontrol strain Clonostachys rosea IK726 and the use of these marker genes in ecological studies

    DEFF Research Database (Denmark)

    Lübeck, M.; Knudsen, I.M.B.; Jensen, B.;

    2002-01-01

    Marker genes were introduced in the biocontrol strain Clonostachys rosea IK726 (IBT 9371) as a tool for monitoring the strain in ecological studies. The beta-glucuronidase (GUS) reporter gene and a gene encoding the green fluorescent protein (GFP) were, in separate experiments, integrated...... into the genome of IK726 using the Hygromycin B (HygB) resistance gene as selective marker. In order to select GUS and GFP transformants that resembled the wildtype strain, growth rate, production of enzymes and of metabolites of four GUS positive and six GFP positive transformants were tested in vitro....... In addition, the biocontrol efficacy against disease caused by seed-borne Fusarium culmorum was evaluated on barley grown in sand. Compared to the wildtype, two selected GUS and GFP transformants, IK726c5 and IK726d11, did not vary in physiological properties. Both maintained the ability to colonize barley...

  17. Research Progress of Biocontrol Effect of Trichoderma harzianum%哈茨木霉生物防治研究进展

    Institute of Scientific and Technical Information of China (English)

    吕黎; 许丽媛; 罗志威; 周艳; 郭帅; 丰来

    2013-01-01

    木霉被认为是最有希望的生物防治因子,而哈茨木霉是木霉属中应用最为广泛的菌株。从哈茨木霉的生防效果、生防作用机制以及基因水平上的抗生机制等方面的研究进展进行了综述,并阐述了哈茨木霉可能的应用前景。%Trichoderma is the most promising isolated soil fungi for their ability to protect plants and contain pathogen populations under different soil conditions. While Trichoderma harzianum is the most commonly applied strain among Trichoderma. The biocontrol effect, the biocontrol mechanism, and the antibiotic mechanism at the gene level of Trichoderma harzianum were summarized, and the applying future of it was elaborated.

  18. Screening of Mutation High-Yielding Biocontrol Bacterium BJ1 by Ion Beam Irradiation and Effect of Controlling Fusarium oxysporum cucunerinum Disease

    International Nuclear Information System (INIS)

    BJ1 of Bacillus subtilis is an important biocontrol factor in control of fungus disease. In order to improve the antagonistic ability of the strain,and obtain high-efficiency strains, 12C6+ of different doses and linear energy transfer (LET) was used to irradiate the biocontrol bacterium BJ1. The optimum dose and LET of ion beam irradiation for the BJ1 are 200-400 Gy and 60 keV/μm,respectively. The antagonistic ability is increased by 2%-21%. The control effect of mutation to Fusarium oxysporum f. sp. cucunerinum is increased by 17.48% over that of BJ1, and mutation also has better plant growth-promoting effect. (authors)

  19. Radiographic scintiscanning agent

    International Nuclear Information System (INIS)

    A new technetium-based scintiscanning agent has been prepared comprising a water soluble sup(99m)Tc-methanehydroxydiphosphonate in combination with a reducing agent selected from stannous, ferrous, chromous and titanous salts. As an additional stabilizer salts and esters of gentisic or ascorbic acids have been used. (E.G.)

  20. Agent Development Toolkits

    CERN Document Server

    Singh, Aarti; Sharma, A K

    2011-01-01

    Development of agents as well as their wide usage requires good underlying infrastructure. Literature indicates scarcity of agent development tools in initial years of research which limited the exploitation of this beneficial technology. However, today a wide variety of tools are available, for developing robust infrastructure. This technical note provides a deep overview of such tools and contrasts features provided by them.

  1. CHARACTERIZATION OF SOIL TRICHODERMA ISOLATES FOR POTENTIAL BIOCONTROL OF PLANT PATHOGENS

    OpenAIRE

    S. Matei; Gabi-Mirela Matei; Petruta Cornea; Gabriela Popa

    2011-01-01

    Various fungal strains belonging to genus Trichoderma act as biological control agents for soil born plant pathogens. Two new strains of Trichoderma harzianum (T.h.) and Trichoderma viride (T.v.) were isolated from forest soils in Ilfov county and their morphological aspects, enzymatic and antagonistic activity were examined. Current chemical fungicides had constantly, in time, less influence on pathogens due to their diversity, adaptability and increasing resistance.The paper present the mor...

  2. Asimovian Adaptive Agents

    CERN Document Server

    Gordon, D F

    2011-01-01

    The goal of this research is to develop agents that are adaptive and predictable and timely. At first blush, these three requirements seem contradictory. For example, adaptation risks introducing undesirable side effects, thereby making agents' behavior less predictable. Furthermore, although formal verification can assist in ensuring behavioral predictability, it is known to be time-consuming. Our solution to the challenge of satisfying all three requirements is the following. Agents have finite-state automaton plans, which are adapted online via evolutionary learning (perturbation) operators. To ensure that critical behavioral constraints are always satisfied, agents' plans are first formally verified. They are then reverified after every adaptation. If reverification concludes that constraints are violated, the plans are repaired. The main objective of this paper is to improve the efficiency of reverification after learning, so that agents have a sufficiently rapid response time. We present two solutions: ...

  3. How do agents represent?

    Science.gov (United States)

    Ryan, Alex

    Representation is inherent to the concept of an agent, but its importance in complex systems has not yet been widely recognised. In this paper I introduce Peirce's theory of signs, which facilitates a definition of representation in general. In summary, representation means that for some agent, a model is used to stand in for another entity in a way that shapes the behaviour of the agent with respect to that entity. Representation in general is then related to the theories of representation that have developed within different disciplines. I compare theories of representation from metaphysics, military theory and systems theory. Additional complications arise in explaining the special case of mental representations, which is the focus of cognitive science. I consider the dominant theory of cognition — that the brain is a representational device — as well as the sceptical anti-representational response. Finally, I argue that representation distinguishes agents from non-representational objects: agents are objects capable of representation.

  4. Compatibilidade de Dicyma pulvinata com defensivos agrícolas e eficiência do biocontrole do mal-das-folhas da seringueira em campo Compatibility of Dicyma pulvinata with pesticides and biocontrol efficiency of South American leaf blight of rubber tree under field conditions

    Directory of Open Access Journals (Sweden)

    Débora Ferreira Melo

    2008-02-01

    Full Text Available O objetivo deste trabalho foi avaliar quatro isolados do fungo antagonista Dicyma pulvinata quanto à compatibilidade com defensivos agrícolas e adjuvantes, e a eficiência desses isolados no controle do mal-das-folhas (Microcyclus ulei da seringueira (Hevea sp. em campo. A compatibilidade dos isolados com defensivos e adjuvantes foi avaliada com base no crescimento micelial e na esporulação do fungo, em testes conduzidos in vitro. Para avaliação da eficiência do antagonista contra M. ulei, em campo, os quatros isolados do antagonista foram comparados ao controle exercido pelo tratamento com os fungicidas propiconazol + mancozeb. Os ensaios conduzidos em laboratório indicaram a incompatibilidade de D. pulvinata com os fungicidas benomyl, carbendazim, mancozeb, propiconazol e, ainda, com o inseticida acaricida endosulfan. Dois dos adjuvantes testados (Tween 20 e Tween 80 não afetaram o desenvolvimento do fungo. Foi comprovada a ação do antagonista D. pulvinata sobre M. ulei, em campo, com destaque para os isolados CEN 62 e CEN 93, que apresentaram eficiência de controle semelhante ao tratamento fungicida padrão.The objective of this work was to evaluate four isolates of the antagonist fungus Dicyma pulvinata in terms of its compatibility with chemical pesticides and adjuvants products, and the efficiency of these isolates as biocontrol agent against South American leaf blight (Microcyclus ulei of rubber tree (Hevea sp. under field conditions. Isolates compatibility with chemical pesticides and adjuvants was evaluated on mycelial growth and fungus sporulation in vitro. To assess the efficiency of the antagonist against M. ulei under field conditions, the four isolates were compared to the control by the fungicide mixture propiconazol + mancozeb. The assays showed incompatibility of the antagonistic fungus with the fungicides benomyl, carbendazim, mancozeb, propiconazol, besides the insecticide-acaricide endosulfan. Two of the adjuvants

  5. Effect of biocontrol agent Pseudomonas fluorescens 2P24 on soil fungal community in cucumber rhizosphere using T-RFLP and DGGE.

    Directory of Open Access Journals (Sweden)

    Guanpeng Gao

    Full Text Available Fungi and fungal community play important roles in the soil ecosystem, and the diversity of fungal community could act as natural antagonists of various plant pathogens. Biological control is a promising method to protect plants as chemical pesticides may cause environment pollution. Pseudomonas fluorescens 2P24 had strong inhibitory on Rastonia solanacearum, Fusarium oxysporum and Rhizoctonia solani, etc., and was isolated from the wheat rhizosphere take-all decline soils in Shandong province, China. However, its potential effect on soil fungal community was still unknown. In this study, the gfp-labeled P. fluorescens 2P24 was inoculated into cucumber rhizosphere, and the survival of 2P24 was monitored weekly. The amount decreased from 10(8 to 10(5 CFU/g dry soils. The effect of 2P24 on soil fungal community in cucumber rhizosphere was investigated using T-RFLP and DGGE. In T-RFLP analysis, principle component analysis showed that the soil fungal community was greatly influenced at first, digested with restriction enzyme Hinf I and Taq I. However, there was little difference as digested by different enzymes. DGGE results demonstrated that the soil fungal community was greatly shocked at the beginning, but it recovered slowly with the decline of P. fluorescens 2P24. Four weeks later, there was little difference between the treatment and control. Generally speaking, the effect of P. fluorescens 2P24 on soil fungal community in cucumber rhizosphere was just transient.

  6. Integrated application of some compatible biocontrol agents along with mustard oil seed cake and furadan on Meloidogyne incognita infecting tomato plants

    Institute of Scientific and Technical Information of China (English)

    GOSWAMI Bijoy Kumar; PANDEY Rajesh Kumar; RATHOUR Kabindra Singh; BHATTACHARYA Chaitali; SINGH Lokendra

    2006-01-01

    Experiments were carried out to study the effect of two fungal bioagents along with mustard oil cake and furadan against root knot nematode Meloidogyne incognita infecting tomato under greenhouse condition. Bioagents viz., Paecilomyces lilacinus and Trichoderma viride alone or in combination with mustard cake and furadan promoted plant growth, reduced number of galls/plant, egg masses/root system and eggs/egg mass. The fungal bioagents along with mustard cake and nematicide showed least nematodes reproduction factor as compared to untreated infested soil.

  7. Effect of biocontrol agent Pseudomonas fluorescens 2P24 on soil fungal community in cucumber rhizosphere using T-RFLP and DGGE.

    Science.gov (United States)

    Gao, Guanpeng; Yin, Danhan; Chen, Shengju; Xia, Fei; Yang, Jie; Li, Qing; Wang, Wei

    2012-01-01

    Fungi and fungal community play important roles in the soil ecosystem, and the diversity of fungal community could act as natural antagonists of various plant pathogens. Biological control is a promising method to protect plants as chemical pesticides may cause environment pollution. Pseudomonas fluorescens 2P24 had strong inhibitory on Rastonia solanacearum, Fusarium oxysporum and Rhizoctonia solani, etc., and was isolated from the wheat rhizosphere take-all decline soils in Shandong province, China. However, its potential effect on soil fungal community was still unknown. In this study, the gfp-labeled P. fluorescens 2P24 was inoculated into cucumber rhizosphere, and the survival of 2P24 was monitored weekly. The amount decreased from 10(8) to 10(5) CFU/g dry soils. The effect of 2P24 on soil fungal community in cucumber rhizosphere was investigated using T-RFLP and DGGE. In T-RFLP analysis, principle component analysis showed that the soil fungal community was greatly influenced at first, digested with restriction enzyme Hinf I and Taq I. However, there was little difference as digested by different enzymes. DGGE results demonstrated that the soil fungal community was greatly shocked at the beginning, but it recovered slowly with the decline of P. fluorescens 2P24. Four weeks later, there was little difference between the treatment and control. Generally speaking, the effect of P. fluorescens 2P24 on soil fungal community in cucumber rhizosphere was just transient. PMID:22359632

  8. Molecular markers discriminate closely related Encarsia spp. (E. diaspidicola and E. berlesei): candidate biocontrol agents for white peach scale in Hawaii

    Science.gov (United States)

    The white peach scale (WPS), Pseudaulacaspis pentagona Targioni-Tozetti (Hemiptera: Diaspididae) is a serious economic pest of papaya in Hawaii. In 2006, Encarsia diaspidicola Silvestri (Hymenoptera: Aphelinidae) was imported from Samoa to perform host-range studies. Another potential future candi...

  9. Characterization of a novel plant growth-promoting bacteria strain Delftia tsuruhatensis HR4 both as a diazotroph and a potential biocontrol agent against various plant pathogens.

    Science.gov (United States)

    Han, Jigang; Sun, Lei; Dong, Xiuzhu; Cai, Zhengqiu; Sun, Xiaolu; Yang, Hailian; Wang, Yunshan; Song, Wei

    2005-01-01

    A novel, plant growth-promoting bacterium Delftia tsuruhatensis, strain HR4, was isolated from the rhizoplane of rice (Oryza sativa L., cv. Yueguang) in North China. In vitro antagonistic assay showed this strain could suppress the growth of various plant pathogens effectively, especially the three main rice pathogens (Xanthomonas oryzae pv. oryzae, Rhizoctonia solani and Pyricularia oryzae Cavara). Treated with strain HR4 culture, rice blast, rice bacterial blight and rice sheath blight for cv. Yuefu and cv. Nonghu 6 were evidently controlled in the greenhouse. Strain HR4 also showed a high nitrogen-fixing activity in N-free Döbereiner culture medium. The acetylene reduction activity and 15N2-fixing activity (N2FA) were 13.06 C2H4 nmolml(-1) h(-1) and 2.052 15Na.e.%, respectively. The nif gene was located in the chromosome of this strain. Based on phenotypic, physiological, biochemical and phylogenetic studies, strain HR4 could be classified as a member of D. tsuruhatensis. However, comparisons of characteristics with other known species of the genus Delftia suggested that strain HR4 was a novel dizotrophic PGPB strain. PMID:15709367

  10. Toxicity of pirimiphos methyl (Actellic 25EC) on Anopheles gambiae s.s., Culex quinquefasciatus (Diptera: Culicidae), and potential biocontrol agent, Poecilia reticulata (Pisces: Poeciliidae).

    Science.gov (United States)

    Anogwih, Joy A

    2014-08-01

    The toxicity of an emulsifiable formulation of pirimiphos methyl (Actellic 25EC) on Anopheles gambiae s.s. Giles, Culex quinquefasciatus Say (Diptera: Culicidae), and predator fish Poecilia reticulata Peters (Pisces: Poeciliidae) was investigated. Acute toxicity tests were carried out to determine the effect of the larvicide on mosquito larvae and fish species. To investigate the nontarget effects on P. reticulata, fish of similar size (3.5 +/- 0.2 cm) were randomly selected and exposed for 28 d, under static renewal bioassay, to sublethal concentrations of the larvicide capable of killing 30 and 70% of Cx. quinquefasciatus. The 24 h LC50 value of pirimiphos methyl on the test organisms ranged between 20.44 and 697.30 microg liter(-1). The ultrastructural changes observed in the intestinal cells of P. reticulata were characterized by degenerating cell membranes with gradual loss of gray area in pycnotic nucleus at lower concentration. Marked damage was found at higher concentration including distinct loss of gray areas in cytosol, absence of cristae, numerous ruptures, and several dead cells. Pirimiphos methyl was toxic to a predatory fish species, and for its relevance in vector control and crop protection, warrants cumulative assessment to establish its comprehensive ecological risk, and the dosage required for field larviciding.

  11. Field host range of Apanteles opuntiarum (Hymenoptera: Braconidae) in Argentina, a potential biocontrol agent of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America

    Science.gov (United States)

    Cactoblastis cactorum (Berg) (Lepidoptera, Pyralidae) was successfully used for biological control of Opuntia spp. (Cactaceae) in Australia and South Africa, where no native cacti occur. Since 1989, this South American moth has been invading the southeastern United States, threatening the unique ca...

  12. 哈茨木霉对辣椒生长的影响%Effects of Biocontrol Agents Trichoderma harzianum on Plant Growth in Capsicum

    Institute of Scientific and Technical Information of China (English)

    刘云龙; 何永宏; 张旭东

    2002-01-01

    在田间用哈茨木霉(Trichoderma harzianum)制剂处理土壤,栽培辣椒,结果表明:哈茨木霉不但对辣椒疫霉(Phytophthora capsici)和尖镰孢(Fusarium oxysporum)引起的根腐病具有一定的防病作用,而且能促进植株生长,提前开花、挂果,提高产量15%左右.

  13. Entomopathogenic fungi as potential biocontrol agents of the ecto-parasitic mite, Varroa destructor, and their effect on the immune response of honey bees (Apis mellifera L.).

    Science.gov (United States)

    Hamiduzzaman, Mollah Md; Sinia, Alice; Guzman-Novoa, Ernesto; Goodwin, Paul H

    2012-11-01

    Three isolates of each of the entomopathogenic fungi, Metarhizium anisopliae, Beauveria bassiana and Clonostachys rosea, were assessed for their pathogenicity to the honey bee parasitic mite, Varroa destructor. The fungi were applied to varroa mites by immersing them in a spore solution, and then the inoculated mites were placed on honey bee brood inside capped cells. At 7 days post inoculation (dpi), the three fungi caused significant varroa mortality compared to non-inoculated mites. In brood treated only with varroa mites, expression of the honey bee genes, hymenoptaecin and poly U binding factor 68 Kd (pUf68), decreased over time, while expression of blue cheese (BlCh) and single minded (SiMd) was not affected. In brood inoculated directly only with M. anisopliae or B. bassiana, the emerged adults showed reduced weight indicating infection by the fungi, which was confirmed by observation of hyphae in the brood. Fungal infection of the brood resulted in increased expression of hymenoptaecin, pUf68 and BlCh, but not SiMd. In brood treated with varroa mites that had been inoculated with the fungi, expression of hymenoptaecin, pUf68 and BlCh, but not SiMd, was even more up-regulated. While varroa mites can suppress gene expression in honey bee brood, varroa mites infected with entomopathogenic fungi induced their expression. This may be due to a low level of fungal infection of the bee, which negated the immunosuppression by the mites. Therefore, entomopathogenic fungi could reduce varroa mite damage to honey bee brood by both infecting the parasite and preventing varroa-associated suppression of honey bee immunity.

  14. Effects of photoperiod and temperature on reproductive diapause in Ophraella communa (Coleoptera:Chrysomelidae), a potential biocontrol agent against Ambrosia artemisiifolia

    Institute of Scientific and Technical Information of China (English)

    Dao-Hong Zhu; Jing Zhu; Zhao-Pu Peng; Fang-Hao Wan

    2012-01-01

    To investigate the seasonal adaptation strategies of Ophraella communa to new habitats,the effects and regulation mechanisms of photoperiod and temperature on the reproductive diapause in a population collected from Changsha,Hunan were examined.Adults showed obvious reproductive diapause,which was regulated by photoperiod and temperature.At 30℃,there was no adult diapause occurring under either long-day or short-day conditions; at 25℃ the pre-oviposition period was short and fecundity was high in adult females under L:D 16:8 h,whereas under L:D 12:12 h,a few females entered reproductive diapause; at 20℃ under short-day conditions,all female adults entered diapause.The pre-oviposition period was significantly prolonged when the pupae and adults were transferred from long-days to short-days,but the day length influence was not obvious when they were transferred only in the adult stage.However,the fecundity dropped greatly no matter whether the photoperiod shifted to short-days only in the adult stage or whether the shift occurred in both the pupal and adult stage.The fecundity was extremely low when photoperiod shifted from long-days to short-days in both pupal and adult stages.This was an indication that the pupal and adult stages were the photoperiod-sensitive stage for adult reproductive diapause.This was especially true for the photoperiod in the pupal stage,which has a distinctly significant regulative effect on reproductive diapause.Additionally,this article also addresses the reason for different photoperiodic response patterns in reproductive diapause induction between the Changsha strain and the Tsukuba strain (Japan) of O.communa.

  15. Spinosad and neem seed kernel extract as bio-controlling agents for malarial vector,Anopheles stephensi and non-biting midge,Chironomus circumdatus

    Institute of Scientific and Technical Information of China (English)

    Kumar AN; Murugan K; Madhiyazhagan P; Prabhu K

    2011-01-01

    Objective:Midge egg masses are reported to support non-pathogenic strains of the cholera pathogen,Vibrio cholera (V. cholera). Mosquito born diseases have been reported to cause millions of death worldwide. The present research reveals the toxicity effect of spinosad and neem seed kernel extract (NSKE)against different larval stages ofAnopheles stephensi (An. stephensi) andChironomus circumdatus (Ch. circumdatus).Methods: The neem seeds were collected from Marudamalai hills, Bharathiar University, Coimbatore, India. Neem seed kernels were powdered, extracted and diluted for different concentrations (2 ppm to10 ppm). Spinosad was purchased from Kalpatharu pesticide Limited, Coimbatore, Tamil Nadu, India and thoroughly mixed with distilled water to prepare various concentrations (0.01 to0.08 ppm) and used for bioassay.Results: The results depict that spinosad is more toxic in lower concentrations when compared toNSKE and mosquitoes are more susceptible than chironomids. Lethal concentrations were evaluated using the observed mortality. The lowest LC50 value obtained from spinosad againstAn. stephensi and Ch. circumdatus were0.002 05 ppm and0.008 91 ppm. This study investigated on effect of Spinosad andNSKE on the biology of mosquito. The immature stages of both species were susceptible to Spinosad andNSKE. Spinosad andNSKE in individual as well as combined treatment provided additional days in development for mosquitoes.Conclusions:The results conclude that Spinosad andNSKE are potential larvicides against An. stephensi andCh. circumdatus.

  16. Disruption of the Eng18B ENGase gene in the fungal biocontrol agent Trichoderma atroviride affects growth, conidiation and antagonistic ability.

    Directory of Open Access Journals (Sweden)

    Mukesh K Dubey

    Full Text Available The recently identified phylogenetic subgroup B5 of fungal glycoside hydrolase family 18 genes encodes enzymes with mannosyl glycoprotein endo-N-acetyl-β-D-glucosaminidase (ENGase-type activity. Intracellular ENGase activity is associated with the endoplasmic reticulum associated protein degradation pathway (ERAD of misfolded glycoproteins, although the biological relevance in filamentous fungi is not known. Trichoderma atroviride is a mycoparasitic fungus that is used for biological control of plant pathogenic fungi. The present work is a functional study of the T. atroviride B5-group gene Eng18B, with emphasis on its role in fungal growth and antagonism. A homology model of T. atroviride Eng18B structure predicts a typical glycoside hydrolase family 18 (αβ(8 barrel architecture. Gene expression analysis shows that Eng18B is induced in dual cultures with the fungal plant pathogens Botrytis cinerea and Rhizoctonia solani, although a basal expression is observed in all growth conditions tested. Eng18B disruption strains had significantly reduced growth rates but higher conidiation rates compared to the wild-type strain. However, growth rates on abiotic stress media were significantly higher in Eng18B disruption strains compared to the wild-type strain. No difference in spore germination, germ-tube morphology or in hyphal branching was detected. Disruption strains produced less biomass in liquid cultures than the wild-type strain when grown with chitin as the sole carbon source. In addition, we determined that Eng18B is required for the antagonistic ability of T. atroviride against the grey mould fungus B. cinerea in dual cultures and that this reduction in antagonistic ability is partly connected to a secreted factor. The phenotypes were recovered by re-introduction of an intact Eng18B gene fragment in mutant strains. A putative role of Eng18B ENGase activity in the endoplasmic reticulum associated protein degradation pathway of endogenous glycoproteins in T. atroviride is discussed in relation to the observed phenotypes.

  17. Quantitative and specific detection of the biocontrol agent, Serratia plymuthica, in plant extracts using a real-time TaqMan® assay

    NARCIS (Netherlands)

    Czajkowski, R.L.; Wolf, van der J.M.

    2012-01-01

    A Serratia plymuthica-specific TaqMan® assay was designed based on the consensus nucleotide sequence from the 3'- end of the luxS gene present in all S. plymuthica strains tested. The specificity of the assay was demonstrated by testing 21 Serratia spp. strains and 30 isolates belonging to various s

  18. Integrated application of some compatible biocontrol agents along with mustard oil seed cake and furadan on Meloidogyne incognita infecting tomato plants

    OpenAIRE

    Goswami, Bijoy Kumar; Pandey, Rajesh Kumar; Rathour, Kabindra Singh; Bhattacharya, Chaitali; SINGH, LOKENDRA

    2006-01-01

    Experiments were carried out to study the effect of two fungal bioagents along with mustard oil cake and furadan against root knot nematode Meloidogyne incognita infecting tomato under greenhouse condition. Bioagents viz., Paecilomyces lilacinus and Trichoderma viride alone or in combination with mustard cake and furadan promoted plant growth, reduced number of galls/plant, egg masses/root system and eggs/egg mass. The fungal bioagents along with mustard cake and nematicide showed least nemat...

  19. 冰核活性细菌拮抗菌株的筛选%Screening of Biocontrol Bacteria Agents Against Ice Nucleation Active Bacteria

    Institute of Scientific and Technical Information of China (English)

    崔汝强; 姬广海; 张世珖

    2004-01-01

    从多种植物根际土壤中分离到300个细菌分离物,通过含菌平板培养筛选出F015,F023,F046等近20株对冰核细菌具有较强的拮抗力,室内测定对冰核细菌病原物抑菌圈达0.8~3.0 cm. 挑选出F015,F023,F046进一步进行室内抗菌机理、菌株鉴定和室外田间小区实验.实验结果表明,菌株初步鉴定为芽孢杆菌(Bacillus spp.)和假单胞杆菌(Pseudomonas spp.).其代谢产物蛋白质粗提物对冰核细菌的生长有明显的抑制作用.室外防霜效果在19.5%~36.9%,可有效地控制霜冻害的发生与危害,具有广阔的应用前景.

  20. Impact of Pseudomonas-based biocontrol agents and solarization on Mesocriconema xenoplax populations and tree survival in a peach tree short life site

    Science.gov (United States)

    Soil solarization, alone or in combination with other disease management practices, has been shown to be effective in reducing inoculum density of many soilborne diseases, including nematodes. Pseudomonas synxantha (BG33R), isolated from a peach orchard site suppressive to peach tree short life (PT...

  1. Life history parameters of the biocontrol agent Gratiana spadicea (Chrysomelidae), reared on the natural host plant Solanum sisymbriifolium and the non-target crop Solanum melongena (Solanaceae)

    Science.gov (United States)

    Gratiana spadicea (Klug), a leaf-feeding tortoise beetle native to South America, was released in South Africa for the biological control of Solanum sisymbriifolium Lamarck (wild tomato), despite its ability to develop on cultivated eggplant (Solanum melongena L.) during laboratory host-specificity ...

  2. Effect of Bio-Control Agents on Yield, Yield Components and Root Rot Control in two Wheat Cultivars at New Valley Region

    Directory of Open Access Journals (Sweden)

    Mohamed Yosseif MOUBARK

    2011-11-01

    Full Text Available This study evaluated the effectiveness of applying the bioagents Bacillus subtilis (isolate BSM1, B. megaterium (isolate BMM5, Trichoderma viride (isolate TVM2 and T. harzianum (isolate THM4 for the control of rot root disease caused by Fusarium graminearum, Drechslera halodes and Rhizoctonia solani on two wheat cultivars (�Sakha 93� and �Bani Suif 5� under greenhouse conditions. Moreover, their effect wheat growth and yield were also studied under field conditions. In vitro, all tested bioagents were significantly in the reduced redial growth of the pathogenic fungi. Trichoderma viride was active more than the other tested bioagents followed by T. harzianum, while B. subtilis was the least ones. Under greenhouse conditions, all tested bioagents were able to reduce significantly damping-off and root rot caused by the tested pathogens compared with control and increased fresh and dry weight of the survival plants when applied as soil or grain treatments however, there was variation among bioagent isolates effect on reduction of disease severity both application methods. Trichoderma viride and B. megaterium were recorded the highest effective in this respect compared with other tested bioagents. Under field conditions, analysis of variance and mean performance were estimated for four characters: grain yield 4.8 m-2, No. of spikes m-2, No. of kernels spike-1 and 1000-kernel weight. Significant mean squares were obtained for all studied characters between the seasons (S, methods (M, (S (M, treatments (T, (S (T, (M (T and (S (M (T for �Sakha 93� cultivar and �Bani Suif 5� cultivars except application methods and (S (M for number of kernels spike-1 and 1000-kernel weight, respectively. While the treatments T. harzianum and B. megaterium were best treatments to increase grain yield, the treatments B. subtilis and T. harzianum were best treatments to increase number of spikes and the treatments B. subtilis and B. megaterium were best treatments to increase number of kernels for soil and grain application methods, respectively.

  3. Effect of Two Biological Formulations Based on Bacillus subtilis and Pseudomonas fluorescens on Control of Didymella applanata, the Causal Agent of Red Raspberry Cane Spur Blight

    Directory of Open Access Journals (Sweden)

    Margarita Shternshis

    2016-01-01

    Full Text Available In vitro and in vivo studies were conducted to estimate the efficacy of the two microbial formulations based on Bacillus subtilis Cohn. and Pseudomonas fluorescens Mig. on the fungus Didymella applanata (Niessl. Sacc., the causal agent of red raspberry (Rubus idaeus L. spur blight. In vitro, both bacteria reduced the growth of D. applanata. In inoculation experiments with raspberry canes in two cultivars with different susceptibility to D. applanata, these antagonistic bacteria suppressed fungal development by reducing the lesions area and the number of D. applanata fruiting bodies. Field trials of two biological formulations under natural conditions showed a significant suppression of the disease. B. subtilis and P. fluorescens included in the formulations revealed antagonistic activity towards D. applanata that depended on the red raspberry cultivar and weather conditions. In all cases, B. subtilis showed better results than P. fluorescens in biocontrol of the raspberry spur blight. This study demonstrated for the first time the ability of the biocontrol agents B. subtilis and P. fluorescens to suppress red raspberry cane spur blight, a serious worldwide disease.

  4. Biological warfare agents

    Directory of Open Access Journals (Sweden)

    Duraipandian Thavaselvam

    2010-01-01

    Full Text Available The recent bioterrorist attacks using anthrax spores have emphasized the need to detect and decontaminate critical facilities in the shortest possible time. There has been a remarkable progress in the detection, protection and decontamination of biological warfare agents as many instrumentation platforms and detection methodologies are developed and commissioned. Even then the threat of biological warfare agents and their use in bioterrorist attacks still remain a leading cause of global concern. Furthermore in the past decade there have been threats due to the emerging new diseases and also the re-emergence of old diseases and development of antimicrobial resistance and spread to new geographical regions. The preparedness against these agents need complete knowledge about the disease, better research and training facilities, diagnostic facilities and improved public health system. This review on the biological warfare agents will provide information on the biological warfare agents, their mode of transmission and spread and also the detection systems available to detect them. In addition the current information on the availability of commercially available and developing technologies against biological warfare agents has also been discussed. The risk that arise due to the use of these agents in warfare or bioterrorism related scenario can be mitigated with the availability of improved detection technologies.

  5. Agent-Based Optimization

    CERN Document Server

    Jędrzejowicz, Piotr; Kacprzyk, Janusz

    2013-01-01

    This volume presents a collection of original research works by leading specialists focusing on novel and promising approaches in which the multi-agent system paradigm is used to support, enhance or replace traditional approaches to solving difficult optimization problems. The editors have invited several well-known specialists to present their solutions, tools, and models falling under the common denominator of the agent-based optimization. The book consists of eight chapters covering examples of application of the multi-agent paradigm and respective customized tools to solve  difficult optimization problems arising in different areas such as machine learning, scheduling, transportation and, more generally, distributed and cooperative problem solving.

  6. Users, Bystanders and Agents

    DEFF Research Database (Denmark)

    Krummheuer, Antonia Lina

    2015-01-01

    Human-agent interaction (HAI), especially in the field of embodied conversational agents (ECA), is mainly construed as dyadic communication between a human user and a virtual agent. This is despite the fact that many application scenarios for future ECAs involve the presence of others. This paper...... the construction of the agent’s identity, and (3) how HAI, as a mediated interaction, is framed by an asymmetric participation framework. The paper concludes by suggesting various participation roles, which may inform development of ECAs....

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

    DEFF Research Database (Denmark)

    Kosawang, Chatchai

    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...... identified expansion of ABC transporter families in C. rosea as in Trichoderma virens and T. harzianum, but not in T. reesei and T. atroviridae. The expansion was profoundly observed in the subfamily G of C. rosea ABC transporters and the subfamily C of Trichoderma spp, repectively. The subfamilies C and G...

  8. Biocontrol de botrytis cinerea a partir de extractos fenólicos de fresa

    OpenAIRE

    Álvarez Gómez, Tania Belén

    2013-01-01

    Michoacán es el primer productor de fresa a nivel nacional, ocupando aproximadamente 4,300 hectáreas en el último año. El cultivo de fresa, es susceptible a microorganismos patógenos que causan enfermedades, tal como Botrytis cinerea agente causal de la podredumbre gris una de las principales enfermedades de este cultivo. Esta enfermedad, provoca pérdidas económicas importantes. Su control se hace generalmente con agroquímicos resultando en graves consecuencias ecológicas, por lo que se requi...

  9. Effect of carbon and nitrogen sources on growth and biological efficacy of Pseudomonas fluorescens and Bacillus subtilis against Rhizoctonia solani, the causal agent of bean damping-off.

    Science.gov (United States)

    Peighamy-Ashnaei, S; Sharifi-Tehrani, A; Ahmadzadeh, M; Behboudi, K

    2007-01-01

    One of the most important environmental factors that regulate the growth and antagonistic efficacy of biocontrol agents is the medium. The aim of this paper was to find the nitrogen and carbon sources that provide maximum biomass production of strains P-5 and P-6 (Pseudomonas fluorescens), B-3 and B-16 (Bacillus subtilis) and minimum cost of media, whilst maintaining biocontrol efficacy. All of the strains were grown in seven liquid media (pH=6.9) including: sucrose + yeast extract, molasses of sugar beet + yeast extract in 2:1 and 1:1 w/w ratios, molasses of sugar beet + urea, nutrient broth, molasses and malt extract, at an initial inoculation of 1 x 10(5) CFU ml(-1). Cells from over night cultures used to inoculate soil at 1 x 10(9) CFU cm(-3) soil. At the same time, fungal inoculum (infected millet seed with Rhizoctonia solani) was added to soil at the rate of 2 g kg(-1) soil. Results indicated that growth of P-6, B-3 and B-16 in molasses + yeast extract (1:1 w/w) medium was significantly higher than in the other media. Molasses + yeast extract (1:1 and 2:1 w/w) media supported rapid growth and high cell yields in P-5. In greenhouse condition, results indicated that the influence of the media on the biocontrol efficacy of P-5, P-6, B-3 and B-16 was the same and Pseudomonas fluorescens P-5 in molasses and malt extract media reduced the severity of disease up to 72.8 percent. On the other hand, there were observed significant differences on bean growth after one month in greenhouse. P-5 in molasses + yeast extract (1:1 w/w) medium had the most effects on bean growth promotion. In this study molasses media showed good yield efficacy in all of the strains. The high sucrose concentration in molasses justifies the high biomass in all of the strains. Also, the low cost of molasses allows its concentration to be increased in media. On the other hand, yeast extract was the best organic nitrogen source for antagonist bacteria but it is expensive for an industrial process

  10. Agent Standards Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation of the work herein proposed is the development of standards for software autonomous agents. These standards are essential to achieve software...

  11. 三株生防酵母菌对Botrytis cinerea的抑菌作用研究%Study on antifungal activities of biocontrol yeasts against Botrytis cinerea

    Institute of Scientific and Technical Information of China (English)

    王傲雪; 关鑫; 张俊峰; 张珍珠; 王瑞虎; 陈秀玲

    2014-01-01

    In this study, the antifungal activities of biocontrol yeasts Cryptococcus albidus 63(Ca63), Cryptococcus albidus 64 (Ca64) and Candida parapsilosis yett1006 against Botrytis cinerea were investigated. The dual culture between three biocontrol yeasts and B. cinerea t08016b results showed that no obvious inhibiting zone appeared, but the pathogen growed more weakly than the control. The results of chitinase andβ-1, 3-glucanase activities assay showed that the levels of the two enzymes activities did not change significantly (P>0.05) when the three biocontrol yeasts cultured with pathogen. The inhibition rates of three biocontrol yeast strains on mycelium growth were 88.57%, 90.66% and 85.65%, respectively. High concentrations of biocontrol yeasts had a strong inhibitory effect on the spore germination of B. cinerea t08016b. Especial y, 1 × 108 cfu·mL-1 biocontrol yeasts almost stopped the spore germination of B. cinerea t08016b. Heat-inactived yeast suspension and culture supernatant had no significant inhibitory effects on B. cinerea. These results il ustrated that the antagonic effect of biocontrol yeasts was mainly due to the competition of limited space and nutrient conditions, not secreting antifungal substances.%针对三株生防酵母菌Cryptococcus albidus 63(Ca63)、Cryptococcus albidus 64(Ca64)、Candida parapsilosis yett1006对番茄灰霉病病原菌B. cinerea t08016b的抑菌作用进行研究。三株生防酵母菌与B. cinerea t08016b的对峙培养过程中,未产生明显抑菌圈,均可减弱B. cinerea t08016b生长势;几丁质酶和β-1,3-葡聚糖酶活性测定结果表明, t08016b并无诱导三株酵母菌分泌酶活显著增加(P>0.05);研究酵母菌对B. cinerea t08016b菌丝生长和孢子萌发率影响发现,C.albidus 63、C.albidus 64和C.parapsilosis yett1006对菌丝生长量的抑制率分别为88.57%、90.66%和85.65%,高浓度菌液对孢子萌发有显著抑制效果,1×108 cfu·mL-1菌体活

  12. Programming Service Oriented Agents

    OpenAIRE

    Hirsch, Benjamin; Konnerth, Thomas; Burkhardt, Michael; Albayrak, Sahin

    2010-01-01

    This paper introduces a programming language for service-oriented agents. JADL++ combines the ease of use of scripting-languages with a state-of-the-art service oriented approach which allows the seamless integration of web-services. Furthermore, the language includes OWL-based ontologies for semantic descriptions of data and services, thus allowing agents to make intelligent decisions about service calls.

  13. Viability and stability of biological control agents on cotton and snap bean seeds.

    Science.gov (United States)

    Elliott, M L; Des Jardin, E A; Batson, W E; Caceres, J; Brannen, P M; Howell, C R; Benson, D M; Conway, K E; Rothrock, C S; Schneider, R W; Ownley, B H; Canaday, C H; Keinath, A P; Huber, D M; Sumner, D R; Motsenbocker, C E; Thaxton, P M; Cubeta, M A; Adams, P D; Backman, P A; Fajardo, J; Newman, M A; Pereira, R M

    2001-08-01

    Cotton and snap bean were selected for a multi-year, multi-state regional (south-eastern USA) research project to evaluate the efficacy of both commercial and experimental bacterial and fungal biological control agents for the management of damping-off diseases. The goal for this portion of the project was to determine the viability and stability of biological agents after application to seed. The biological seed treatments used included: (1) Bacillaceae bacteria, (2) non-Bacillaceae bacteria, (3) the fungus Trichoderma and (4) the fungus Beauveria bassiana. Seed assays were conducted to evaluate the following application factors: short-term (seed treatment; quality (i.e. isolate purity); compatibility with chemical pesticides and other biocontrol agents; application uniformity between years and plant species. For the bacterial treatments, the Bacillaceae genera (Bacillus and Paenibacillus) maintained the greatest population of bacteria per seed, the best viability over time and the best application uniformity across years and seed type. The non-Bacillaceae genera Burkholderia and Pseudomonas had the least viability and uniformity. Although Beauveria bassiana was only evaluated one year, the seed fungal populations were high and uniform. The seed fungal populations and uniformity for the Trichoderma isolates were more variable, except for the commercial product T-22. However, this product was contaminated with a Streptomyces isolate in both the years that it was evaluated. The study demonstrated that Bacillaceae can be mixed with Trichoderma isolates or with numerous pesticides to provide an integrated pest control/growth enhancement package. PMID:11517723

  14. Interaction of Ulocladium atrum, a Potential Biological Control Agent, with Botrytis cinerea and Grapevine Plantlets

    Directory of Open Access Journals (Sweden)

    Sébastien Ronseaux

    2013-09-01

    Full Text Available The effectiveness of biological control agent, Ulocladium atrum (isolates U13 and U16 in protecting Vitis vinifera L. cv. Chardonnay against gray mold disease caused by Botrytis cinerea, and simulation of the foliar defense responses was investigated. A degraded mycelium structure during cultural assay on potato dextrose agar revealed that U. atrum isolates U13 and U16 were both antagonistic to B. cinerea, mainly when isolates were inoculated two days before Botrytis. Under in vitro conditions, foliar application of U. atrum protected grapevine leaves against gray mold disease. An increase in chitinase activity was induced by the presence of U. atrum isolates indicating that the biological control agents triggered plant defense mechanisms. Moreover, U13 has the potential to colonize the grapevine plantlets and to improve their growth. The ability of U. atrum isolates to exhibit an antagonistic effect against B. cinerea in addition to their aptitude to induce plant resistance and to promote grapevine growth may explain a part of their biological activity. Hence, this study suggests that U. atrum provides a suitable biocontrol agent against gray mold in grapevines.

  15. Production of trichodiene by Trichoderma harzianum alters the perception of this biocontrol strain by plants and antagonized fungi.

    Science.gov (United States)

    Malmierca, Mónica G; McCormick, Susan P; Cardoza, Rosa E; Alexander, Nancy J; Monte, Enrique; Gutiérrez, Santiago

    2015-08-01

    Trichothecenes are phytotoxic sesquiterpenic mycotoxins that can act as virulence factors in plant diseases. Harzianum A (HA) is a non-phytotoxic trichothecene produced by Trichoderma arundinaceum. The first step in HA biosynthesis is the conversion of farnesyl diphosphate to trichodiene (TD), a volatile organic compound (VOC), catalysed by a sesquiterpene synthase encoded by the tri5 gene. Expression of tri5 in the biocontrol strain Trichoderma harzianum CECT 2413 resulted in production of TD in parallel with a reduction of ergosterol biosynthesis and an unexpected increase in the level of squalene. Transformants expressing tri5 displayed low chitinase activity and induced expression of Botrytis cinerea BOT genes, although their total antagonistic potential against phytopathogenic fungi was not reduced. VOCs released by the tri5-transformant induced expression of tomato defence genes related to salicylic acid (SA), and TD itself strongly induced the expression of SA-responsive genes and reduced the development of lateral roots. Together, these results suggest that TD acts as a signalling VOC in the interactions of Trichoderma with plants and other microorganisms by modulating the perception of this fungus to a given environment. Moreover, the TD ability to induce systemic defences indicates that complex trichothecene structures may not be necessary for inducing such responses.

  16. Improving biocontrol activity of Pseudomonas fluorescens through chromosomal integration of 2,4-diacetylphloro- glucinol biosynthesis genes

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hongyou; WEI Hailei; LIU Xili; WANG Ye; ZHANG Liqun; TANG Wenhua

    2005-01-01

    Antibiotic 2,4-diacetylphloroglucinol (2,4- DAPG) produced by Pseudomonas fluorescens CPF-10 and 2P24 is a principal factor enabling bacteria to suppress plant diseases caused by soilborne pathogens. In this study, a 2,4-DAPG biosynthesis locus phlACBDE cloned from strain CPF-10 was assembled into a mini-Tn5 transposon and introduced into the chromosome of P. fluorescens P32 (2,4- DAPG-), CPF-10 and 2P24 to construct the 2,4-DAPG overproducing derivatives P32-38, CPF10-9 and 2P24-48, respectively. All the transgenic strains showed an enhanced antibiosis capacity against plant microbial pathogens in vitro and two strains, P32-38 and CPF10-9, provided significantly better protection against wheat take-all disease caused by Gaeumannomyces graminis var. tritici and tomato bacterial wilt caused by Ralstonia solanacearum in greenhouse. Compared to their parental strains, the 2,4-DAPG overproducing derivatives colonized to the same extent on the wheat tips in the autoclaved soil, but developed larger populations in natural soil. These results indicated that production of antibiotics 2,4- DAPG by biological control pseudomonads can contribute not only to their disease suppression capacities but also to the ecological competence in the resident microflora. Our research also suggests that it is a realistic approach to improve biocontrol capacity of P. fluorescens through the genetic modification of its antibiotic 2,4-DAPG production.

  17. Biocontrol of postharvest gray and blue mold decay of apples with Rhodotorula mucilaginosa and possible mechanisms of action.

    Science.gov (United States)

    Li, Renping; Zhang, Hongyin; Liu, Weimin; Zheng, Xiaodong

    2011-03-30

    The efficacy of Rhodotorula mucilaginosa against postharvest gray mold, blue mold and natural decay development of apples and the possible mechanisms involved were investigated. The decay incidence and lesion diameter of gray mold and blue mold of apples treated by R. mucilaginosa were significantly reduced compared with the control fruits, and the higher concentration of R. mucilaginosa, the better the efficacy of the biocontrol. R. mucilaginosa also significantly reduced the natural decay development of apples following storage at 20°C for 35 days or at 4°C for 45 days followed by 20°C for 15 days. Germination and survival of spores of Penicillium expansum and Botrytis cinerea were markedly inhibited by R. mucilaginosa in an in vitro test. Rapid colonization of the yeast in apple wounds was observed whether stored at 20°C or 4°C. In apples, the activities of peroxidase (POD) and polyphenoloxidase (PPO) were significantly induced and lipid peroxidation (malondialdehyde (MDA) content) was highly inhibited by R. mucilaginosa treatment compared with those of the control fruits. All these results indicated that R. mucilaginosa has great potential for development of commercial formulations to control postharvest pathogens on fruits. Its modes of action were based on competition for space and nutrients with pathogens, inducement of activities of defense-related enzymes such as POD, PPO and inhibition of lipid peroxidation (MDA content) of apples, so as to enhance the resistance and delay the ripening and senescence of apples.

  18. Production of trichodiene by Trichoderma harzianum alters the perception of this biocontrol strain by plants and antagonized fungi.

    Science.gov (United States)

    Malmierca, Mónica G; McCormick, Susan P; Cardoza, Rosa E; Alexander, Nancy J; Monte, Enrique; Gutiérrez, Santiago

    2015-08-01

    Trichothecenes are phytotoxic sesquiterpenic mycotoxins that can act as virulence factors in plant diseases. Harzianum A (HA) is a non-phytotoxic trichothecene produced by Trichoderma arundinaceum. The first step in HA biosynthesis is the conversion of farnesyl diphosphate to trichodiene (TD), a volatile organic compound (VOC), catalysed by a sesquiterpene synthase encoded by the tri5 gene. Expression of tri5 in the biocontrol strain Trichoderma harzianum CECT 2413 resulted in production of TD in parallel with a reduction of ergosterol biosynthesis and an unexpected increase in the level of squalene. Transformants expressing tri5 displayed low chitinase activity and induced expression of Botrytis cinerea BOT genes, although their total antagonistic potential against phytopathogenic fungi was not reduced. VOCs released by the tri5-transformant induced expression of tomato defence genes related to salicylic acid (SA), and TD itself strongly induced the expression of SA-responsive genes and reduced the development of lateral roots. Together, these results suggest that TD acts as a signalling VOC in the interactions of Trichoderma with plants and other microorganisms by modulating the perception of this fungus to a given environment. Moreover, the TD ability to induce systemic defences indicates that complex trichothecene structures may not be necessary for inducing such responses. PMID:24813508

  19. Quantifying the associations between fungal endophytes and biocontrol-induced herbivory of invasive purple loosestrife (Lythrum salicaria L.).

    Science.gov (United States)

    David, Aaron S; Quiram, Gina L; Sirota, Jennie I; Seabloom, Eric W

    2016-01-01

    Fungal endophytes are one of several groups of heterotrophic organisms that associate with living plants. The net effects of these groups of organisms on each other and ultimately on their host plants depend in part on how they facilitate or antagonize one another. In this study we quantified the associations between endophyte communities and herbivory induced by a biological control in the invasive Lythrum salicaria at various spatial scales using a culture-based approach. We found positive associations between herbivory damage and endophyte isolation frequency and richness at the site level and weak, positive associations at the leaf level. Herbivory damage was more strongly influenced by processes at the site level than were endophyte isolation frequency and community structure, which were influenced by processes at the plant and leaf levels. Furthermore, endophytic taxa found in low herbivory sites were nested subsets of those taxa found at high herbivory sites. Our findings suggest that endophyte communities of L. salicaria are associated with, and potentially facilitated by, biocontrol-induced herbivory. Quantifying the associations between heterotrophic groups ultimately may lead to a clearer understanding of their complex interactions with plants. PMID:27091387

  20. In vitro evaluation of Pseudomonas bacterial isolates from rice phylloplane for biocontrol of Rhizoctonia solani and plant growth promoting traits.

    Science.gov (United States)

    Akter, Shamima; Kadir, Jugah; Juraimi, Abdul Shukor; Saud, Halimi Mohd

    2016-07-01

    The ability for biocontrol and plant growth promotion of three Pseudomonas bacterial isolates namely Pseudomonas fluorescens (UMB20), Pseudomonas aeruginosa (KMB25) and Pseudomonas asplenii (BMB42) obtained from rice plants was investigated. Fungal growth inhibition by the isolates ranged from 86.85 to 93.15% in volatile and 100% in diffusible metabolites test. Among the isolates, BMB42 showed fungal growth inhibition significantly in the volatile metabolite test. Isolates UMB20 and BMB42 were able to synthesis chitinase with chitinolytic indices of 13.66 and 13.50, respectively. In case of -1,3-glucanase, all the isolates showed activity to produce this enzyme at varied levels and isolate KMB25 showed significantly highest activity (53.53 ppm). Among the three isolates, KMB25 showed positive response to protease production and all of them were negative to pectinase and lipase and positive to the production of siderophore, and HCN, and were able to solubilize tricalcium phosphate. All the three bacterial isolates were capable of forming biofilm at different levels. Above results suggest that phylloplane Pseudomonas bacterial isolates have potential for antifungal activities and plant growth promotion. PMID:27498507