WorldWideScience

Sample records for microbially mediated plant

  1. Volatile-mediated suppression of plant pathogens is related to soil properties and microbial community composition

    NARCIS (Netherlands)

    Van Agtmaal, M.; Straathof, A.L.; Termorshuizen, Aad J; Lievens, Bart; Hoffland, Ellis; De Boer, W.

    2018-01-01

    There is increasing evidence that the soil microbial community produces a suite of volatile organic compounds that suppress plant pathogens. However, it remains unknown which soil properties and management practices influence volatile-mediated pathogen suppression. The aim of this study was to

  2. Volatile-mediated suppression of plant pathogens is related to soil properties and microbial community composition

    NARCIS (Netherlands)

    Agtmaal, van Maaike; Straathof, Angela L.; Termorshuizen, Aad; Lievens, Bart; Hoffland, Ellis; Boer, de Wietse

    2018-01-01

    There is increasing evidence that the soil microbial community produces a suite of volatile organic compounds that suppress plant pathogens. However, it remains unknown which soil properties and management practices influence volatile-mediated pathogen suppression. The aim of this study was to

  3. Plant stimulation of soil microbial community succession: how sequential expression mediates soil carbon stabilization and turnover

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Mary [Univ. of California, Berkeley, CA (United States)

    2015-03-31

    It is now understood that most plant C is utilized or transformed by soil microorganisms en route to stabilization. Hence the composition of microbial communities that mediate decomposition and transformation of root C is critical, as are the metabolic capabilities of these communities. The change in composition and function of the C-transforming microbial communities over time in effect defines the biological component of soil C stabilization. Our research was designed to test 2 general hypotheses; the first two hypotheses are discussed first; H1: Root-exudate interactions with soil microbial populations results in the expression of enzymatic capacities for macromolecular, complex carbon decomposition; and H2: Microbial communities surrounding roots undergo taxonomic succession linked to functional gene activities as roots grow, mature, and decompose in soil. Over the term of the project we made significant progress in 1) quantifying the temporal pattern of root interactions with the soil decomposing community and 2) characterizing the role of root exudates in mediating these interactions.

  4. Microbially mediated mineral carbonation

    Science.gov (United States)

    Power, I. M.; Wilson, S. A.; Dipple, G. M.; Southam, G.

    2010-12-01

    Mineral carbonation involves silicate dissolution and carbonate precipitation, which are both natural processes that microorganisms are able to mediate in near surface environments (Ferris et al., 1994; Eq. 1). (Ca,Mg)SiO3 + 2H2CO3 + H2O → (Ca,Mg)CO3 + H2O + H4SiO4 + O2 (1) Cyanobacteria are photoautotrophs with cell surface characteristics and metabolic processes involving inorganic carbon that can induce carbonate precipitation. This occurs partly by concentrating cations within their net-negative cell envelope and through the alkalinization of their microenvironment (Thompson & Ferris, 1990). Regions with mafic and ultramafic bedrock, such as near Atlin, British Columbia, Canada, represent the best potential sources of feedstocks for mineral carbonation. The hydromagnesite playas near Atlin are a natural biogeochemical model for the carbonation of magnesium silicate minerals (Power et al., 2009). Field-based studies at Atlin and corroborating laboratory experiments demonstrate the ability of a microbial consortium dominated by filamentous cyanobacteria to induce the precipitation of carbonate minerals. Phototrophic microbes, such as cyanobacteria, have been proposed as a means for producing biodiesel and other value added products because of their efficiency as solar collectors and low requirement for valuable, cultivable land in comparison to crops (Dismukes et al., 2008). Carbonate precipitation and biomass production could be facilitated using specifically designed ponds to collect waters rich in dissolved cations (e.g., Mg2+ and Ca2+), which would allow for evapoconcentration and provide an appropriate environment for growth of cyanobacteria. Microbially mediated carbonate precipitation does not require large quantities of energy or chemicals needed for industrial systems that have been proposed for rapid carbon capture and storage via mineral carbonation (e.g., Lackner et al., 1995). Therefore, this biogeochemical approach may represent a readily

  5. Plant Breeding Goes Microbial

    NARCIS (Netherlands)

    Wei, Zhong; Jousset, Alexandre

    Plant breeding has traditionally improved traits encoded in the plant genome. Here we propose an alternative framework reaching novel phenotypes by modifying together genomic information and plant-associated microbiota. This concept is made possible by a novel technology that enables the

  6. Functional diversity of microbial decomposers facilitates plant coexistence in a plant-microbe-soil feedback model.

    Science.gov (United States)

    Miki, Takeshi; Ushio, Masayuki; Fukui, Shin; Kondoh, Michio

    2010-08-10

    Theory and empirical evidence suggest that plant-soil feedback (PSF) determines the structure of a plant community and nutrient cycling in terrestrial ecosystems. The plant community alters the nutrient pool size in soil by affecting litter decomposition processes, which in turn shapes the plant community, forming a PSF system. However, the role of microbial decomposers in PSF function is often overlooked, and it remains unclear whether decomposers reinforce or weaken litter-mediated plant control over nutrient cycling. Here, we present a theoretical model incorporating the functional diversity of both plants and microbial decomposers. Two fundamental microbial processes are included that control nutrient mineralization from plant litter: (i) assimilation of mineralized nutrient into the microbial biomass (microbial immobilization), and (ii) release of the microbial nutrients into the inorganic nutrient pool (net mineralization). With this model, we show that microbial diversity may act as a buffer that weakens plant control over the soil nutrient pool, reversing the sign of PSF from positive to negative and facilitating plant coexistence. This is explained by the decoupling of litter decomposability and nutrient pool size arising from a flexible change in the microbial community composition and decomposition processes in response to variations in plant litter decomposability. Our results suggest that the microbial community plays a central role in PSF function and the plant community structure. Furthermore, the results strongly imply that the plant-centered view of nutrient cycling should be changed to a plant-microbe-soil feedback system, by incorporating the community ecology of microbial decomposers and their functional diversity.

  7. Soil environmental conditions and microbial build-up mediate the effect of plant diversity on soil nitrifying and denitrifying enzyme activities in temperate grasslands.

    Directory of Open Access Journals (Sweden)

    Xavier Le Roux

    Full Text Available Random reductions in plant diversity can affect ecosystem functioning, but it is still unclear which components of plant diversity (species number - namely richness, presence of particular plant functional groups, or particular combinations of these and associated biotic and abiotic drivers explain the observed relationships, particularly for soil processes. We assembled grassland communities including 1 to 16 plant species with a factorial separation of the effects of richness and functional group composition to analyze how plant diversity components influence soil nitrifying and denitrifying enzyme activities (NEA and DEA, respectively, the abundance of nitrifiers (bacterial and archaeal amoA gene number and denitrifiers (nirK, nirS and nosZ gene number, and key soil environmental conditions. Plant diversity effects were largely due to differences in functional group composition between communities of identical richness (number of sown species, though richness also had an effect per se. NEA was positively related to the percentage of legumes in terms of sown species number, the additional effect of richness at any given legume percentage being negative. DEA was higher in plots with legumes, decreased with increasing percentage of grasses, and increased with richness. No correlation was observed between DEA and denitrifier abundance. NEA increased with the abundance of ammonia oxidizing bacteria. The effect of richness on NEA was entirely due to the build-up of nitrifying organisms, while legume effect was partly linked to modified ammonium availability and nitrifier abundance. Richness effect on DEA was entirely due to changes in soil moisture, while the effects of legumes and grasses were partly due to modified nitrate availability, which influenced the specific activity of denitrifiers. These results suggest that plant diversity-induced changes in microbial specific activity are important for facultative activities such as denitrification

  8. Microbial brokers of insect-plant interactions revisited.

    Science.gov (United States)

    Douglas, Angela E

    2013-07-01

    Recent advances in sequencing methods have transformed the field of microbial ecology, making it possible to determine the composition and functional capabilities of uncultured microorganisms. These technologies have been instrumental in the recognition that resident microorganisms can have profound effects on the phenotype and fitness of their animal hosts by modulating the animal signaling networks that regulate growth, development, behavior, etc. Against this backdrop, this review assesses the impact of microorganisms on insect-plant interactions, in the context of the hypothesis that microorganisms are biochemical brokers of plant utilization by insects. There is now overwhelming evidence for a microbial role in insect utilization of certain plant diets with an extremely low or unbalanced nutrient content. Specifically, microorganisms enable insect utilization of plant sap by synthesizing essential amino acids. They also can broker insect utilization of plant products of extremely high lignocellulose content, by enzymatic breakdown of complex plant polysaccharides, nitrogen fixation, and sterol synthesis. However, the experimental evidence for microbial-mediated detoxification of plant allelochemicals is limited. The significance of microorganisms as brokers of plant utilization by insects is predicted to vary, possibly widely, as a result of potentially complex interactions between the composition of the microbiota and the diet and insect developmental age or genotype. For every insect species feeding on plant material, the role of resident microbiota as biochemical brokers of plant utilization is a testable hypothesis.

  9. Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

    NARCIS (Netherlands)

    Timmers, R.A.; Rothballer, M.; Strik, D.P.B.T.B.; Engel, M.; Schulz, M.; Hartmann, A.; Hamelers, H.V.M.; Buisman, C.J.N.

    2012-01-01

    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into

  10. Throughfall-mediated alterations to soil microbial community structure in a forest plot of homogenous soil texture, litter, and plant species composition

    Science.gov (United States)

    Van Stan, John; Rosier, Carl; Moore, Leslie; Gay, Trent; Reichard, James; Wu, Tiehang; Kan, Jinjun

    2015-04-01

    Identifying spatiotemporal influences on soil microbial community (SMC) structure is critical to our understanding of patterns in biogeochemical cycling and related ecological services (e.g., plant community structure, water quality, response to environmental change). Since forest canopy structure alters the spatiotemporal patterning of precipitation water and solute supplies to soils (via "throughfall"), is it possible that changes in SMC structure could arise from modifications in canopy elements? Our study investigates this question by monitoring throughfall water and dissolved ion supply to soils beneath a continuum of canopy structure: from large gaps (0% cover), to bare Quercus virginiana Mill. (southern live oak) canopy (~50-70%), to heavy Tillandsia usneoides L. (Spanish moss) canopy (>90% cover). Throughfall water supply diminished with increasing canopy cover, yet increased washoff/leaching of Na+, Cl-, PO43-, and SO42- from the canopy to the soils. Presence of T. usneoides diminished throughfall NO3-, but enhanced NH4+, concentrations supplied to subcanopy soils. The mineral soil horizon (0-10 cm) sampled in triplicate from locations receiving throughfall water and solutes from canopy gaps, bare canopy, and T. usneoides-laden canopy significantly differed in soil chemistry parameters (pH, Ca2+, Mg2+, CEC). Polymerase Chain Reaction-Denaturant Gradient Gel Electrophoresis (PCR-DGGE) banding patterns beneath similar canopy covers (experiencing similar throughfall dynamics) also produced high similarities per ANalyses Of SIMilarity (ANO-SIM), and clustered together when analyzed by Nonmetric Multidimensional Scaling (NMDS). These results suggest that modifications of forest canopy structures are capable of affecting mineral-soil horizon SMC structure via throughfall when canopies' biomass distribution is highly heterogeneous. As SMC structure, in many instances, relates to functional diversity, we suggest that future research seek to identify functional

  11. Microbially mediated barite dissolution in anoxic brines

    International Nuclear Information System (INIS)

    Ouyang, Bingjie; Akob, Denise M.; Dunlap, Darren; Renock, Devon

    2017-01-01

    Fluids injected into shale formations during hydraulic fracturing of black shale return with extraordinarily high total-dissolved-solids (TDS) and high concentrations of barium (Ba) and radium (Ra). Barite, BaSO_4, has been implicated as a possible source of Ba as well as a problematic mineral scale that forms on internal well surfaces, often in close association with radiobarite, (Ba,Ra)SO_4. The dissolution of barite by abiotic processes is well quantified. However, the identification of microbial communities in flowback and produced water necessitates the need to understand barite dissolution in the presence of bacteria. Therefore, we evaluated the rates and mechanisms of abiotic and microbially-mediated barite dissolution under anoxic and hypersaline conditions in the laboratory. Barite dissolution experiments were conducted with bacterial enrichment cultures established from produced water from Marcellus Shale wells located in northcentral Pennsylvania. These cultures were dominated by anaerobic halophilic bacteria from the genus Halanaerobium. Dissolved Ba was determined by ICP-OES and barite surfaces were investigated by SEM and AFM. Our results reveal that: 1) higher amounts of barium (up to ∼5 × ) are released from barite in the presence of Halanaerobium cultures compared to brine controls after 30 days of reaction, 2) etch pits that develop on the barite (001) surface in the presence of Halanaerobium exhibit a morphology that is distinct from those that form during control experiments without bacteria, 3) etch pits that develop in the presence of Halanaerobium exhibit a morphology that is similar to the morphology of etch pits formed in the presence of strong organic chelators, EDTA and DTPA, and 4) experiments using dialysis membranes to separate barite from bacteria suggest that direct contact between the two is not required in order to promote dissolution. These results suggest that Halanaerobium increase the rate of barite dissolution in anoxic

  12. Chlorine stress mediates microbial surface attachment in drinking water systems.

    Science.gov (United States)

    Liu, Li; Le, Yang; Jin, Juliang; Zhou, Yuliang; Chen, Guowei

    2015-03-01

    Microbial attachment to drinking water pipe surfaces facilitates pathogen survival and deteriorates disinfection performance, directly threatening the safety of drinking water. Notwithstanding that the formation of biofilm has been studied for decades, the underlying mechanisms for the origins of microbial surface attachment in biofilm development in drinking water pipelines remain largely elusive. We combined experimental and mathematical methods to investigate the role of environmental stress-mediated cell motility on microbial surface attachment in chlorination-stressed drinking water distribution systems. Results show that at low levels of disinfectant (0.0-1.0 mg/L), the presence of chlorine promotes initiation of microbial surface attachment, while higher amounts of disinfectant (>1.0 mg/L) inhibit microbial attachment. The proposed mathematical model further demonstrates that chlorination stress (0.0-5.0 mg/L)-mediated microbial cell motility regulates the frequency of cell-wall collision and thereby controls initial microbial surface attachment. The results reveal that transport processes and decay patterns of chlorine in drinking water pipelines regulate microbial cell motility and, thus, control initial surface cell attachment. It provides a mechanistic understanding of microbial attachment shaped by environmental disinfection stress and leads to new insights into microbial safety protocols in water distribution systems.

  13. Plant genotype, microbial recruitment and nutritional security.

    Science.gov (United States)

    Patel, Jai S; Singh, Akanksha; Singh, Harikesh B; Sarma, Birinchi K

    2015-01-01

    Agricultural food products with high nutritional value should always be preferred over food products with low nutritional value. Efforts are being made to increase nutritional value of food by incorporating dietary supplements to the food products. The same is more desirous if the nutritional value of food is increased under natural environmental conditions especially in agricultural farms. Fragmented researches have demonstrated possibilities in achieving the same. The rhizosphere is vital in this regard for not only health and nutritional status of plants but also for the microorganisms colonizing the rhizosphere. Remarkably robust composition of plant microbiome with respect to other soil environments clearly suggests the role of a plant host in discriminating its colonizers (Zancarini et al., 2012). A large number of biotic and abiotic factors are believed to manipulate the microbial communities in the rhizosphere. However, plant genotype has proven to be the key in giving the final shape of the rhizosphere microbiome (Berendsen et al., 2012; Marques et al., 2014).

  14. Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

    OpenAIRE

    Timmers, R.A.; Rothballer, M.; Strik, D.P.B.T.B.; Engel, M.; Schulz, M.; Hartmann, A.; Hamelers, H.V.M.; Buisman, C.J.N.

    2012-01-01

    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode-rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) w...

  15. Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

    OpenAIRE

    Timmers, Ruud A.; Rothballer, Michael; Strik, David P. B. T. B.; Engel, Marion; Schulz, Stephan; Schloter, Michael; Hartmann, Anton; Hamelers, Bert; Buisman, Cees

    2012-01-01

    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode–rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) w...

  16. Microbial Load of Some Medicinal Plants Sold in Some Local ...

    African Journals Online (AJOL)

    Microbial Load of Some Medicinal Plants Sold in Some Local Markets in Abeokuta, Nigeria. I MacDonald, S Omonigho, J Erhabor, H Efijuemue. Abstract. Purpose: To evaluate the microbial load on 17 randomly selected plant samples from 60 ethnobotanically collected medicinal plants from five local markets in Abeokuta, ...

  17. Microbial ecology of bacterially mediated PCB biodegradation

    International Nuclear Information System (INIS)

    Pettigrew, C.A. Jr.

    1989-01-01

    The roles of plasmid mediated and consortia mediated polychlorinated biphenyl (PCB) biodegradation by bacterial populations isolated from PCB contaminated freshwater sediments were investigated. PCB degrading bacteria were isolated by DNA:DNA colony hybridization, batch enrichments, and chemostat enrichment. Analysis of substrate removal and metabolite production were done using chlorinated biphenyl spray plates, reverse phase high pressure liquid chromatography, Cl - detection, and 14 C-labeled substrate mineralization methods. A bacterial consortium, designated LPS10, involved in a concerted metabolic attack on chlorinated biphenyls, was shown to mineralize 4-chlorobiphenyl (4CB) and 4,4'-dichlorobiphenyl (4,4' CB). The LPS10 consortium was isolated by both batch and chemostat enrichment using 4CB and biphenyl (BP) as sole carbon source and was found to have tree bacterial isolates that predominated; these included: Pseudomonas, testosteroni LPS10A which mediated the breakdown of 4CB and 4,4' CB to the putative meta-cleavage product and subsequently to 4-chlorobenzoic acid (4CBA), an isolate tentatively identified as an Arthrobacter sp. LPS10B which mediated 4CBA degradation, and Pseudomonas putida by A LPS10C whose role in the consortium has not been determined

  18. Microbial exopolysaccharide-mediated synthesis and stabilization of metal nanoparticles.

    Science.gov (United States)

    Sathiyanarayanan, Ganesan; Dineshkumar, Krishnamoorthy; Yang, Yung-Hun

    2017-11-01

    Exopolysaccharides (EPSs) are structurally and functionally valuable biopolymer secreted by different prokaryotic and eukaryotic microorganisms in response to biotic/abiotic stresses and to survive in extreme environments. Microbial EPSs are fascinating in various industrial sectors due to their excellent material properties and less toxic, highly biodegradable, and biocompatible nature. Recently, microbial EPSs have been used as a potential template for the rapid synthesis of metallic nanoparticles and EPS-mediated metal reduction processes are emerging as simple, harmless, and environmentally benign green chemistry approaches. EPS-mediated synthesis of metal nanoparticles is a distinctive metabolism-independent bio-reduction process due to the formation of interfaces between metal cations and the polyanionic functional groups (i.e. hydroxyl, carboxyl and amino groups) of the EPS. In addition, the range of physicochemical features which facilitates the EPS as an efficient stabilizing or capping agents to protect the primary structure of the metal nanoparticles with an encapsulation film in order to separate the nanoparticle core from the mixture of composites. The EPS-capping also enables the further modification of metal nanoparticles with expected material properties for multifarious applications. The present review discusses the microbial EPS-mediated green synthesis/stabilization of metal nanoparticles, possible mechanisms involved in EPS-mediated metal reduction, and application prospects of EPS-based metal nanoparticles.

  19. Microbially produced phytotoxins and plant disease management ...

    African Journals Online (AJOL)

    Nowadays, these evaluation techniques are becoming an important complement to classical breeding methods. The knowledge of the inactivation of microbial toxins has led to the use of microbial enzymes to inactivate phytotoxins thereby reducing incidence and severity of disease induced by microbial toxins. Considering ...

  20. Microbial community dynamics and transformation of vascular plant detritus in two wetland ecosystems

    International Nuclear Information System (INIS)

    Moran, M.A.

    1987-01-01

    The microbial ecology of two wetland ecosystems in southeastern Georgia, USA, was studied with respect to microbial community dynamics and microbially-mediated transformations of vascular plant detritus. In the Okefenokee Swamp, biomass of microorganisms in the water column and sediments was generally lower in winter months and higher during spring and summer. Biomass and activity (measured as 14 C-lignocellulose mineralization) differed significantly among five habitats within the Okefenokee, and also among locations within each habitat. Significant heterogeneity in the structure of Okefenokee microbial communities was found at scales from 30 cm to 150 m. In field and laboratory studies of vascular plant decomposition in the Okefenokee and a salt marsh on Sapelo Island, the mathematical model which best describes decomposition kinetics is the decaying coefficient model

  1. Incorporating the soil environment and microbial community into plant competition theory.

    Science.gov (United States)

    Ke, Po-Ju; Miki, Takeshi

    2015-01-01

    Plants affect microbial communities and abiotic properties of nearby soils, which in turn influence plant growth and interspecific interaction, forming a plant-soil feedback (PSF). PSF is a key determinant influencing plant population dynamics, community structure, and ecosystem functions. Despite accumulating evidence for the importance of PSF and development of specific PSF models, different models are not yet fully integrated. Here, we review the theoretical progress in understanding PSF. When first proposed, PSF was integrated with various mathematical frameworks to discuss its influence on plant competition. Recent theoretical models have advanced PSF research at different levels of ecological organizations by considering multiple species, applying spatially explicit simulations to examine how local-scale predictions apply to larger scales, and assessing the effect of PSF on plant temporal dynamics over the course of succession. We then review two foundational models for microbial- and litter-mediated PSF. We present a theoretical framework to illustrate that although the two models are typically presented separately, their behavior can be understood together by invasibility analysis. We conclude with suggestions for future directions in PSF theoretical studies, which include specifically addressing microbial diversity to integrate litter- and microbial-mediated PSF, and apply PSF to general coexistence theory through a trait-based approach.

  2. Incorporating the soil environment and microbial community into plant competition theory

    Science.gov (United States)

    Ke, Po-Ju; Miki, Takeshi

    2015-01-01

    Plants affect microbial communities and abiotic properties of nearby soils, which in turn influence plant growth and interspecific interaction, forming a plant-soil feedback (PSF). PSF is a key determinant influencing plant population dynamics, community structure, and ecosystem functions. Despite accumulating evidence for the importance of PSF and development of specific PSF models, different models are not yet fully integrated. Here, we review the theoretical progress in understanding PSF. When first proposed, PSF was integrated with various mathematical frameworks to discuss its influence on plant competition. Recent theoretical models have advanced PSF research at different levels of ecological organizations by considering multiple species, applying spatially explicit simulations to examine how local-scale predictions apply to larger scales, and assessing the effect of PSF on plant temporal dynamics over the course of succession. We then review two foundational models for microbial- and litter-mediated PSF. We present a theoretical framework to illustrate that although the two models are typically presented separately, their behavior can be understood together by invasibility analysis. We conclude with suggestions for future directions in PSF theoretical studies, which include specifically addressing microbial diversity to integrate litter- and microbial-mediated PSF, and apply PSF to general coexistence theory through a trait-based approach. PMID:26500621

  3. Incorporating the soil environment and microbial community into plant competition theory

    Directory of Open Access Journals (Sweden)

    Po-Ju eKe

    2015-10-01

    Full Text Available Plants affect microbial communities and abiotic properties of nearby soils, which in turn influence plant growth and interspecific interaction, forming a plant-soil feedback (PSF. PSF is a key determinant influencing plant population dynamics, community structure, and ecosystem functions. Despite accumulating evidence for the importance of PSF and development of specific PSF models, different models are not yet fully integrated. Here, we review the theoretical progress in understanding PSF. When first proposed, PSF was integrated with various mathematical frameworks to discuss its influence on plant competition. Recent theoretical models have advanced PSF research at different levels of ecological organizations by considering multiple species, applying spatially explicit simulations to examine how local-scale predictions apply to larger scales, and assessing the effect of PSF on plant temporal dynamics over the course of succession. We then review two foundational models for microbial- and litter-mediated PSF. We present a theoretical framework to illustrate that although the two models are typically presented separately, their behavior can be understood together by invasibility analysis. We conclude with suggestions for future directions in PSF theoretical studies, which include specifically addressing microbial diversity to integrate litter- and microbial-mediated PSF, and apply PSF to general coexistence theory through a trait-based approach.

  4. Humic substances-mediated microbial reductive dehalogenation of triclosan

    Science.gov (United States)

    Wang, L.; Xu, S.; Yang, Y.

    2015-12-01

    The role of natural organic matter in regulating the redox reactions as an electron shuttle has received lots of attention, because it can significantly affect the environmental degradation of contaminants and biogeochemical cycles of major elements. However, up to date, limited studies examined the role of natural organic matter in affecting the microbial dehalogenation of emergent organohalides, a critical detoxification process. In this study, we investigated the humic substance (HS)-mediated microbial dehalogenation of triclosan, a widely used antimicrobial agent. We found that the presence of HS stimulated the microbial degradation of triclosan by Shewanella putrefaciens CN-32. In the absence of HS, the triclosan was degraded gradually, achieving 8.6% residual at 8 days. With HS, the residual triclosan was below 2% after 4 days. Cl- was confirmed by ion chromatography analysis, but the dehalogenation processes and other byproducts warrant further investigations. The impact of HS on the degradation of triclosan was highly dependent on the concentration of HS. When the HS was below 15 mg/L, the degradation rate constant for triclosan increased with the organic carbon concentration. Beyond that point, the increased organic carbon concentration decreased the degradation of triclosan. Microbially pre-reduced HS abiotically reduced triclosan, testifying the electron shuttling processes. These results indicate that dissolved organic matter plays a dual role in regulating the degradation of triclosan: it mediates electron transport and inhibits the bioavailability through complexation. Such novel organic matter-mediated reactions for organohalides are important for evaluating the natural attenuation of emergent contaminants and designing cost-effective engineering treatment.

  5. Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell.

    Science.gov (United States)

    Timmers, Ruud A; Rothballer, Michael; Strik, David P B T B; Engel, Marion; Schulz, Stephan; Schloter, Michael; Hartmann, Anton; Hamelers, Bert; Buisman, Cees

    2012-04-01

    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode-rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) were located on the root surfaces, but they were more abundant colonising the graphite granular electrode. Anaerobic cellulolytic bacteria dominated the area where most of the EAB were found, indicating that the current was probably generated via the hydrolysis of cellulose. Due to the presence of oxygen and nitrate, short-chain fatty acid-utilising denitrifiers were the major competitors for the electron donor. Acetate-utilising methanogens played a minor role in the competition for electron donor, probably due to the availability of graphite granules as electron acceptors.

  6. Microbial rhodopsins on leaf surfaces of terrestrial plants

    OpenAIRE

    Atamna-Ismaeel, Nof; Finkel, Omri M.; Glaser, Fabian; Sharon, Itai; Schneider, Ron; Post, Anton F.; Spudich, John L.; von Mering, Christian; Vorholt, Julia A.; Iluz, David; Béjà, Oded; Belkin, Shimshon

    2011-01-01

    The above-ground surfaces of terrestrial plants, the phyllosphere, comprise the main interface between the terrestrial biosphere and solar radiation. It is estimated to host up to 1026 microbial cells that may intercept part of the photon flux impinging on the leaves. Based on 454-pyrosequencing-generated metagenome data, we report on the existence of diverse microbial rhodopsins in five distinct phyllospheres from tamarisk (Tamarix nilotica), soybean (Glycine max), Arabidopsis (Arabidopsis t...

  7. Microbial genome-enabled insights into plant-microorganism interactions.

    Science.gov (United States)

    Guttman, David S; McHardy, Alice C; Schulze-Lefert, Paul

    2014-12-01

    Advances in genome-based studies on plant-associated microorganisms have transformed our understanding of many plant pathogens and are beginning to greatly widen our knowledge of plant interactions with mutualistic and commensal microorganisms. Pathogenomics has revealed how pathogenic microorganisms adapt to particular hosts, subvert innate immune responses and change host range, as well as how new pathogen species emerge. Similarly, culture-independent community profiling methods, coupled with metagenomic and metatranscriptomic studies, have provided the first insights into the emerging field of research on plant-associated microbial communities. Together, these approaches have the potential to bridge the gap between plant microbial ecology and plant pathology, which have traditionally been two distinct research fields.

  8. Mediator: A key regulator of plant development.

    Science.gov (United States)

    Buendía-Monreal, Manuel; Gillmor, C Stewart

    2016-11-01

    Mediator is a multiprotein complex that regulates transcription at the level of RNA pol II assembly, as well as through regulation of chromatin architecture, RNA processing and recruitment of epigenetic marks. Though its modular structure is conserved in eukaryotes, its subunit composition has diverged during evolution and varies in response to environmental and tissue-specific inputs, suggesting different functions for each subunit and/or Mediator conformation. In animals, Mediator has been implicated in the control of differentiation and morphogenesis through modulation of numerous signaling pathways. In plants, studies have revealed roles for Mediator in regulation of cell division, cell fate and organogenesis, as well as developmental timing and hormone responses. We begin this review with an overview of biochemical mechanisms of yeast and animal Mediator that are likely to be conserved in all eukaryotes, as well as a brief discussion of the role of Mediator in animal development. We then present a comprehensive review of studies of the role of Mediator in plant development. Finally, we point to important questions for future research on the role of Mediator as a master coordinator of development. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Emerging microbial biocontrol strategies for plant pathogens.

    Science.gov (United States)

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

    2018-02-01

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

  10. Microbial contamination level of air in animal waste utilization plants.

    Science.gov (United States)

    Chmielowiec-Korzeniowska, Anna; Tymczyna, Leszek; Drabik, Agata; Krzosek, Łukasz

    2016-01-01

    The aim of this research was evaluation of microbial contamination of air within and in the vicinity of animal waste disposal plants. Air samples were analyzed to determine total bacterial and fungal counts as well as microbial species composition. Measurements of climate conditions (temperature, humidity, air motion) and total dust concentration were also performed. Total numbers of bacteria and fungi surpassed the threshold limit values for production halls. The most abundant bacteria detected were those consisting of physiological microflora of animal dermis and mucosa. Fungal species composition proved to be most differentiated in the air beyond the plant area. Aspergillus versicolor, a pathogenic and allergenic filamentous fungus, was isolated only inside the rendering plant processing hall. The measurement results showed a low sanitary-hygienic state of air in the plant processing halls and substantial air pollution in its immediate vicinity.

  11. Compost in plant microbial fuel cell for bioelectricity generation

    NARCIS (Netherlands)

    Moqsud, M.A.; Yoshitake, J.; Bushra, Q.S.; Hyodo, M.; Omine, K.; Strik, D.P.B.T.B.

    2015-01-01

    Recycling of organic waste is an important topic in developing countries as well as developed countries. Compost from organic waste has been used for soil conditioner. In this study, an experiment has been carried out to produce green energy (bioelectricity) by using paddy plant microbial fuel cells

  12. Augmenting Plant Immune Responses and Biological Control by Microbial Determinants

    Directory of Open Access Journals (Sweden)

    Sang Moo Lee

    2015-09-01

    Full Text Available Plant have developed sophisticated defence mechanisms against microbial pathogens. The recent accumulated information allow us to understand the nature of plant immune responses followed by recognition of microbial factors/determinants through cutting-edge genomics and multi-omics techniques. However, the practical approaches to sustain plant health using enhancement of plant immunity is yet to be fully appreciated. Here, we overviewed the general concept and representative examples on the plant immunity. The fungal, bacterial, and viral determinants that was previously reported as the triggers of plant immune responses are introduced and described as the potential protocol of biological control. Specifically, the role of chitin, glucan, lipopolysaccharides/extracellular polysaccharides, microbe/pathogen-associated molecular pattern, antibiotics, mimic-phytohormones, N-acyl homoserine lactone, harpin, vitamins, and volatile organic compounds are considered. We hope that this review stimulates scientific community and farmers to broaden their knowledge on the microbial determinant-based biological control and to apply the technology on the integrated pest management program.

  13. Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Timmers, Ruud A.; Strik, David P.B.T.B.; Hamelers, Bert; Buisman, Cees [Wageningen Univ. (Netherlands). Sub-dept. of Environmental Technology; Rothballer, Michael; Hartmann, Anton [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg (Germany). Dept. Microbe-Plant Interactions; Engel, Marion; Schulz, Stephan; Schloter, Michael [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg (Germany). Dept. Terrestrial Ecogenetics

    2012-04-15

    The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode-rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) were located on the root surfaces, but they were more abundant colonising the graphite granular electrode. Anaerobic cellulolytic bacteria dominated the area where most of the EAB were found, indicating that the current was probably generated via the hydrolysis of cellulose. Due to the presence of oxygen and nitrate, short-chain fatty acid-utilising denitrifiers were the major competitors for the electron donor. Acetate-utilising methanogens played a minor role in the competition for electron donor, probably due to the availability of graphite granules as electron acceptors. (orig.)

  14. Phosphate solubilization as a microbial strategy for promoting plant growth

    Directory of Open Access Journals (Sweden)

    Mayra Eleonora Beltrán Pineda

    2014-01-01

    Full Text Available Because of the constant application of chemical inputs in Agroecosystem, the cost of crop production and environmental quality of soil and water have been affected. Microorganisms carry out most biogeochemical cycles; therefore, their role is essential for agro ecosystem balance. One such functional group is the phosphate solubilizing microorganisms, which are recognized plant growth promoters. These microbial populations perform an important activity, since in many soils there are large reserves of insoluble phosphorus, as a result of fixing much of the phosphorus fertilizer applied, which cannot be assimilated by the plant. The phosphate solubilizing microorganisms use different solubilization mechanisms such as the production of organic acids, which solubilize theses insoluble phosphates in the rhizosphere region. Soluble phosphates are absorbed by the plant, which enhances their growth and productivity. By using these phosphate reserves in soils, application of chemical fertilizers is decreased, on the one hand, can again be fixed by ions Ca, Al or Fe making them insoluble and, by the other hand, increase the costs of crop production. Microbial populations have been widely studied in different types of ecosystems, both natural and Agroecosystem. Thanks to its effectiveness, in laboratory and field studies, the phosphate solubilizing phenotype is of great interest to microbial ecologists who have begun to establish the molecular basis of the traitr.

  15. The benzoquinone-mediated electrochemical microbial biosensor for water biotoxicity assay

    International Nuclear Information System (INIS)

    Li, Jiuming; Yu, Yuan; Wang, Yuning; Qian, Jun; Zhi, Jinfang

    2013-01-01

    Graphical abstract: The mediator can participate in microorganism respiration, accept the electrons from respiratory chains, and therefore be reduced by microorganism. The re-oxidization currents of mediators on electrode can reflect the microbial activity, and when respiration is suppressed by toxicants, it can be detected by the resulting change of currents. Unlike other biotoxicity tests, which record the toxic effect after a fixed time for incubation of biocomponents and toxicants, this mediated whole cell biosensor can provide a real-time monitor of the microbial activity during the measurement. -- Abstract: A simple mediated microbial biosensor providing real-time monitoring of water quality and evaluation of biotoxicity was fabricated by entrapping Escherichia coli (E. coli) cells in gelatin on glassy carbon electrode with benzoquinone as the redox mediator. The biotoxicity assay was based on the respiratory activity of E. coli cells estimated by the oxidation current of microbially reduced benzoquinone. The neutrality and lipophilicity rendered benzoquinone better efficiency than ferricyanide in mediated microbial reactions. After the optimization of preparation conditions, the prepared microbial biosensors have measured several common toxicants with different concentrations. In addition, the biotoxicity of binary mixtures of heavy metals and wastewater were investigated. The fabricated biosensor exhibited good repeatability and stability in the biotoxicity measurements

  16. Phytohormone mediation of interactions between herbivores and plant pathogens

    NARCIS (Netherlands)

    Lazebnik, J.; Frago, E.; Dicke, M.; Loon, van J.J.A.

    2014-01-01

    Induced plant defenses against either pathogens or herbivore attackers are regulated by phytohormones. These phytohormones are increasingly recognized as important mediators of interactions between organisms associated with plants. In this review, we discuss the role of plant defense hormones in

  17. Microbial transformations of radionuclides released from nuclear fuel reprocessing plants

    International Nuclear Information System (INIS)

    Francis, A.J.

    2007-01-01

    Microorganisms can affect the stability and mobility of the actinides U, Pu, Cm, Am, Np, and the fission products Tc, I, Cs, Sr, released from nuclear fuel reprocessing plants. Under appropriate conditions, microorganisms can alter the chemical speciation, solubility and sorption properties and thus could increase or decrease the concentrations of radionuclides in solution and the bioavailability. Dissolution or immobilization of radionuclides is brought about by direct enzymatic action or indirect non-enzymatic action of microorganisms. Although the physical, chemical, and geochemical processes affecting dissolution, precipitation, and mobilization of radionuclides have been investigated, we have only limited information on the effects of microbial processes. The mechanisms of microbial transformations of the major and minor actinides and the fission products under aerobic and anaerobic conditions in the presence of electron donors and acceptors are reviewed. (author)

  18. Leaf-Cutter Ant Fungus Gardens Are Biphasic Mixed Microbial Bioreactors That Convert Plant Biomass to Polyols with Biotechnological Applications

    Science.gov (United States)

    Somera, Alexandre F.; Lima, Adriel M.; dos Santos-Neto, Álvaro J.; Lanças, Fernando M.

    2015-01-01

    Leaf-cutter ants use plant matter to culture the obligate mutualistic basidiomycete Leucoagaricus gongylophorus. This fungus mediates ant nutrition on plant resources. Furthermore, other microbes living in the fungus garden might also contribute to plant digestion. The fungus garden comprises a young sector with recently incorporated leaf fragments and an old sector with partially digested plant matter. Here, we show that the young and old sectors of the grass-cutter Atta bisphaerica fungus garden operate as a biphasic solid-state mixed fermenting system. An initial plant digestion phase occurred in the young sector in the fungus garden periphery, with prevailing hemicellulose and starch degradation into arabinose, mannose, xylose, and glucose. These products support fast microbial growth but were mostly converted into four polyols. Three polyols, mannitol, arabitol, and inositol, were secreted by L. gongylophorus, and a fourth polyol, sorbitol, was likely secreted by another, unidentified, microbe. A second plant digestion phase occurred in the old sector, located in the fungus garden core, comprising stocks of microbial biomass growing slowly on monosaccharides and polyols. This biphasic operation was efficient in mediating symbiotic nutrition on plant matter: the microbes, accounting for 4% of the fungus garden biomass, converted plant matter biomass into monosaccharides and polyols, which were completely consumed by the resident ants and microbes. However, when consumption was inhibited through laboratory manipulation, most of the plant polysaccharides were degraded, products rapidly accumulated, and yields could be preferentially switched between polyols and monosaccharides. This feature might be useful in biotechnology. PMID:25911490

  19. Plant odour plumes as mediators of plant-insect interactions.

    Science.gov (United States)

    Beyaert, Ivo; Hilker, Monika

    2014-02-01

    Insect olfactory orientation along odour plumes has been studied intensively with respect to pheromonal communication, whereas little knowledge is available on how plant odour plumes (POPs) affect olfactory searching by an insect for its host plants. The primary objective of this review is to examine the role of POPs in the attraction of insects. First, we consider parameters of an odour source and the environment which determine the size, shape and structure of an odour plume, and we apply that knowledge to POPs. Second, we compare characteristics of insect pheromonal plumes and POPs. We propose a 'POP concept' for the olfactory orientation of insects to plants. We suggest that: (i) an insect recognises a POP by means of plant volatile components that are encountered in concentrations higher than a threshold detection limit and that occur in a qualitative and quantitative blend indicating a resource; (ii) perception of the fine structure of a POP enables an insect to distinguish a POP from an unspecific odorous background and other interfering plumes; and (iii) an insect can follow several POPs to their sources, and may leave the track of one POP and switch to another one if this conveys a signal with higher reliability or indicates a more suitable resource. The POP concept proposed here may be a useful tool for research in olfactory-mediated plant-insect interactions. © 2013 The Authors. Biological Reviews © 2013 Cambridge Philosophical Society.

  20. Empirical evidence that soil carbon formation from plant inputs is positively related to microbial growth

    Science.gov (United States)

    Mark A. Bradford; Ashley D. Keiser; Christian A. Davies; Calley A. Mersmann; Michael S. Strickland

    2012-01-01

    Plant-carbon inputs to soils in the form of dissolved sugars, organic acids and amino acids fuel much of heterotrophic microbial activity belowground. Initial residence times of these compounds in the soil solution are on the order of hours, with microbial uptake a primary removal mechanism. Through microbial biosynthesis, the dissolved compounds become dominant...

  1. Plant extracts affect in vitro rumen microbial fermentation.

    Science.gov (United States)

    Busquet, M; Calsamiglia, S; Ferret, A; Kamel, C

    2006-02-01

    Different doses of 12 plant extracts and 6 secondary plant metabolites were incubated for 24 h in diluted ruminal fluid with a 50:50 forage:concentrate diet. Treatments were: control (no additive), plant extracts (anise oil, cade oil, capsicum oil, cinnamon oil, clove bud oil, dill oil, fenugreek, garlic oil, ginger oil, oregano oil, tea tree oil, and yucca), and secondary plant metabolites (anethol, benzyl salicylate, carvacrol, carvone, cinnamaldehyde, and eugenol). Each treatment was supplied at 3, 30, 300, and 3,000 mg/L of culture fluid. At 3,000 mg/L, most treatments decreased total volatile fatty acid concentration, but cade oil, capsicum oil, dill oil, fenugreek, ginger oil, and yucca had no effect. Different doses of anethol, anise oil, carvone, and tea tree oil decreased the proportion of acetate and propionate, which suggests that these compounds may not be nutritionally beneficial to dairy cattle. Garlic oil (300 and 3,000 mg/L) and benzyl salicylate (300 and 3,000 mg/L) reduced acetate and increased propionate and butyrate proportions, suggesting that methane production was inhibited. At 3,000 mg/L, capsicum oil, carvacrol, carvone, cinnamaldehyde, cinnamon oil, clove bud oil, eugenol, fenugreek, and oregano oil resulted in a 30 to 50% reduction in ammonia N concentration. Careful selection and combination of these extracts may allow the manipulation of rumen microbial fermentation.

  2. Microbial contamination of the air at the wastewater treatment plant

    Directory of Open Access Journals (Sweden)

    Monika Vítězová

    2012-01-01

    Full Text Available Wastewater treatment plants (WWTPs primarily serve to protect the environment. Their task is to clean waste water from the agglomerations. On the other hand wastewater treatment plants can also negatively affect the environment in their neighbourhood. These include emissions of odour and microorganisms. This article discusses the microbial contamination of the air, called bioaerosols in selected wastewater treatment plant for 18 000 p.e. From results of the work is evident that the largest group of microorganisms in the monitored air were psychrophilic and mesophilic bacteria and microscopic fungi. The number of psychrophilic bacteria ranged from 14 to 12 000 CFU/m3 (colony forming units in 1 m3, the number of mesophilic bacteria varied in the range from 20 to 18 500 CFU/m3 and the fungi from 25 to 32 000 CFU/m3 in the air. The amount of actinomycetes ranged from 1 to 1 030 CFU/m3 and faecal coliform bacteria from 0 to 2 500 CFU/m3. Furthermore, it was confirmed that the highest air contamination was around the activation tank, area for dewatered sludge and around the building of mechanical cleaning, depending on the season. The density of studied microorganisms correlated with air temperature.

  3. Microbially influenced corrosion of stainless steels in nuclear power plants

    International Nuclear Information System (INIS)

    Sinha, U.P.; Wolfram, J.H.; Rogers, R.D.

    1990-01-01

    This paper reviews the components, causative agents, corrosion sites, and potential failure modes of stainless steel components susceptible to microbially influenced corrosion (MIC). The stainless steel components susceptible to MIC are located in the reactor coolant, emergency, and reactor auxiliary systems, and in many plants, in the feedwater train and condenser. The authors assessed the areas of most high occurrence of corrosion and found the sites most susceptible to MIC to the heat-affected zones in the weldments of sensitized stainless steel. Pitting is the predominant MIC corrosion mechanisms, caused by sulfur reducing bacteria (SRB). Also discussed is the current status of the diagnostic, preventive, and mitigation techniques, including use of improved water chemistry, alternate materials, and improved thermomechanical treatments. 37 refs., 3 figs

  4. Microbially-Mediated Precipitation of Calcium Carbonate Nanoparticles.

    Science.gov (United States)

    Kang, Ser Ku; Roh, Yul

    2016-02-01

    The objective of this study was to investigate the biomineralization of carbonate minerals using microorganisms (Wu Do-1) enriched from rhodoliths. A 16S rRNA sequence analysis showed that Wu Do-1 mainly contained Proteus mirabilis. The pH decreased from 6.5 to 5.3 over the first 4 days of incubation due to microbial oxidation of organic acids, after which it increased to 7.8 over the remaining incubation period. XRD analysis showed that the precipitates were Mg-rich cal- cite (MgxCa(1-x)CO3), whereas no precipitates were formed without the addition of Wu Do-1 in D-1 medium. SEM-EDS analyses showed that the Mg-rich calcite had a rhombohedron shape and consisted of Ca, Si and Mg with an extracelluar polymeric substance (EPS). In addition, TEM-EDS analyses revealed they were hexagon in shape, 500-700 nm in size, and composed of Ca, Mg, C, and O. These results indicated that Wu Do-1 induced precipitation of Mg-rich calcite on the cell walls and EPS via the accumulation of Ca and/or Mg ions. Therefore, microbial precipitation of carbonate nanoparticles may play an important role in metal and carbon biogeochemistry, as well as in carbon sequestration in natural environments.

  5. Immune-mediated diseases and microbial exposure in early life

    DEFF Research Database (Denmark)

    Bisgaard, H; Bønnelykke, K; Stokholm, Jacob

    2014-01-01

    The non-communicable disease pandemic includes immune-mediated diseases such as asthma and allergy, which are likely originating in early life where the immature immune system is prone to alterations caused by the exposome. The timing of exposure seems critical for the developing immune system...

  6. Microbial Herd Protection Mediated by Antagonistic Interaction in Polymicrobial Communities

    Science.gov (United States)

    Wong, Megan J. Q.; Liang, Xiaoye; Smart, Matt; Tang, Le; Moore, Richard; Ingalls, Brian

    2016-01-01

    ABSTRACT In host and natural environments, microbes often exist in complex multispecies communities. The molecular mechanisms through which such communities develop and persist, despite significant antagonistic interactions between species, are not well understood. The type VI secretion system (T6SS) is a lethal weapon commonly employed by Gram-negative bacteria to inhibit neighboring species through the delivery of toxic effectors. It is well established that intraspecies protection is conferred by immunity proteins that neutralize effector toxicities. In contrast, the mechanisms for interspecies protection are not clear. Here we use two T6SS-active antagonistic bacterial species, Aeromonas hydrophila and Vibrio cholerae, to demonstrate that interspecies protection is dependent on effectors. A. hydrophila and V. cholerae do not share conserved immunity genes but could coexist equally in a mixture. However, mutants lacking the T6SS or effectors were effectively eliminated by the competing wild-type strain. Time-lapse microscopic analyses showed that mutually lethal interactions drive the segregation of mixed species into distinct single-species clusters by eliminating interspersed single cells. Cluster formation provides herd protection by abolishing lethal interactions inside each cluster and restricting the interactions to the boundary. Using an agent-based modeling approach, we simulated the antagonistic interactions of two hypothetical species. The resulting simulations recapitulated our experimental observations. These results provide mechanistic insights regarding the general role of microbial weapons in determining the structures of complex multispecies communities. IMPORTANCE Investigating the warfare of microbes allows us to better understand the ecological relationships in complex microbial communities such as the human microbiota. Here we use the T6SS, a deadly bacterial weapon, as a model to demonstrate the importance of lethal interactions in

  7. Microbial herd protection mediated by antagonistic interaction in polymicrobial communities.

    Science.gov (United States)

    Wong, Megan; Liang, Xiaoye; Smart, Matt; Tang, Le; Moore, Richard; Ingalls, Brian; Dong, Tao G

    2016-09-16

    In the host and natural environments, microbes often exist in complex multispecies communities. The molecular mechanisms through which such communities develop and persist - despite significant antagonistic interactions between species - are not well understood. The type VI secretion system (T6SS) is a lethal weapon commonly employed by Gram-negative bacteria to inhibit neighboring species through delivery of toxic effectors. It is well established that intra-species protection is conferred by immunity proteins that neutralize effector toxicities. By contrast, the mechanisms for interspecies protection are not clear. Here we use two T6SS active antagonistic bacteria, Aeromonas hydrophila (AH) and Vibrio cholerae (VC), to demonstrate that interspecies protection is dependent on effectors. AH and VC do not share conserved immunity genes but could equally co-exist in a mixture. However, mutants lacking the T6SS or effectors were effectively eliminated by the other competing wild type. Time-lapse microscopy analyses show that mutually lethal interactions drive the segregation of mixed species into distinct single-species clusters by eliminating interspersed single cells. Cluster formation provides herd protection by abolishing lethal interaction inside each cluster and restricting it to the boundary. Using an agent-based modeling approach, we simulated the antagonistic interactions of two hypothetical species. The resulting simulations recapitulate our experimental observation. These results provide mechanistic insights for the general role of microbial weapons in determining the structures of complex multispecies communities. Investigating the warfare of microbes allows us to better understand the ecological relationships in complex microbial communities such as the human microbiota. Here we use the T6SS, a deadly bacterial weapon, as a model to demonstrate the importance of lethal interactions in determining community structures and exchange of genetic materials

  8. A marine microbial consortium apparently mediating anaerobic oxidation of methane

    DEFF Research Database (Denmark)

    Boetius, A.; Ravenschlag, K.; Schubert, CJ

    2000-01-01

    microorganisms mediating this reaction have not yet been isolated, and the pathway of anaerobic oxidation of methane is insufficiently understood. Recent data suggest that certain archaea reverse the process of methanogenesis by interaction with sulphate-reducing bacteria(5-7). Here we provide microscopic...... cells and are surrounded by sulphate-reducing bacteria. These aggregates were abundant in gas-hydrate-rich sediments with extremely high rates of methane-based sulphate reduction, and apparently mediate anaerobic oxidation of methane.......A large fraction of globally produced methane is converted to CO2 by anaerobic oxidation in marine sediments(1). Strong geochemical evidence for net methane consumption in anoxic sediments is based on methane profiles(2), radiotracer experiments(3) and stable carbon isotope data(4). But the elusive...

  9. Effects of uranium on soil microbial biomass carbon, enzymes, plant biomass and microbial diversity in yellow soils

    International Nuclear Information System (INIS)

    Yan, X.; Zhang, Y.; Luo, X.; Yu, L.

    2016-01-01

    We conducted an experiment to investigate the effects of uranium (U) on soil microbial biomass carbon (MBC), enzymes, plant biomass and microbial diversity in yellow soils under three concentrations: 0 mg kg"-"1 (T1, control), 30 mg kg"-"1 (T2) and 60 mg kg"-"1 (T3). Under each treatment, elevated U did not reduce soil MBC or plant biomass, but inhibited the activity of the soil enzymes urease (UR), dehydrogenase (DH) and phosphatase (PHO). The microbial diversity was different, with eight dominant phyla in T1 and six in T2 and T3. Furthermore, Proteobacteria and material X were both detected in each treatment site (T1, T2 and T3). Pseudomonas sp. was the dominant strain, followed by Acidiphilium sp. This initial study provided valuable data for further research toward a better understanding of U contamination in yellow soils in China. (authors)

  10. Increased resiliency and activity of microbial mediated carbon cycling enzymes in diversified bioenergy cropping systems

    Science.gov (United States)

    Upton, R.; Bach, E.; Hofmockel, K. S.

    2017-12-01

    Microbes are mediators of soil carbon (C) and are influenced in membership and activity by nitrogen (N) fertilization and inter-annual abiotic factors. Microbial communities and their extracellular enzyme activities (EEA) are important parameters that influence ecosystem C cycling properties and are often included in microbial explicit C cycling models. In an effort to generate model relevant, empirical findings, we investigated how both microbial community structure and C degrading enzyme activity are influenced by inter-annual variability and N inputs in bioenergy crops. Our study was performed at the Comparison of Biofuel Systems field-site from 2011 to 2014, in three bioenergy cropping systems, continuous corn (CC) and two restored prairies, both fertilized (FP) and unfertilized (P). We hypothesized microbial community structure would diverge during the prairie restoration, leading to changes in C cycling enzymes over time. Using a sequencing approach (16S and ITS) we determined the bacterial and fungal community structure response to the cropping system, fertilization, and inter-annual variability. Additionally, we used EEA of β-glucosidase, cellobiohydrolase, and β-xylosidase to determine inter-annual and ecosystem impacts on microbial activity. Our results show cropping system was a main effect for microbial community structure, with corn diverging from both prairies to be less diverse. Inter-annual changes showed that a drought occurring in 2012 significantly impacted microbial community structure in both the P and CC, decreasing microbial richness. However, FP increased in microbial richness, suggesting the application of N increased resiliency to drought. Similarly, the only year in which C cycling enzymes were impacted by ecosystem was 2012, with FP supporting higher potential enzymatic activity then CC and P. The highest EEA across all ecosystems occurred in 2014, suggesting the continued root biomass and litter build-up in this no till system

  11. A conserved pattern in plant-mediated interactions between herbivores

    OpenAIRE

    Lu Jing; Robert Christelle A. M.; Lou Yonggen; Erb Matthias

    2016-01-01

    Abstract Plant?mediated interactions between herbivores are important determinants of community structure and plant performance in natural and agricultural systems. Current research suggests that the outcome of the interactions is determined by herbivore and plant identity, which may result in stochastic patterns that impede adaptive evolution and agricultural exploitation. However, few studies have systemically investigated specificity versus general patterns in a given plant system by varyi...

  12. Plant Mediator complex and its critical functions in transcription regulation.

    Science.gov (United States)

    Yang, Yan; Li, Ling; Qu, Li-Jia

    2016-02-01

    The Mediator complex is an important component of the eukaryotic transcriptional machinery. As an essential link between transcription factors and RNA polymerase II, the Mediator complex transduces diverse signals to genes involved in different pathways. The plant Mediator complex was recently purified and comprises conserved and specific subunits. It functions in concert with transcription factors to modulate various responses. In this review, we summarize the recent advances in understanding the plant Mediator complex and its diverse roles in plant growth, development, defense, non-coding RNA production, response to abiotic stresses, flowering, genomic stability and metabolic homeostasis. In addition, the transcription factors interacting with the Mediator complex are also highlighted. © 2015 Institute of Botany, Chinese Academy of Sciences.

  13. Host plant quality mediates competition between arbuscular mycorrhizal fungi

    NARCIS (Netherlands)

    Knegt, B.; Jansa, J.; Franken, O.; Engelmoer, D.J.P.; Werner, G.D.A.; Bücking, H.; Kiers, E.T.

    2016-01-01

    Arbuscular mycorrhizal fungi exchange soil nutrients for carbon from plant hosts. Empirical works suggests that hosts may selectively provide resources to different fungal species, ultimately affecting fungal competition. However, fungal competition may also be mediated by colonization strategies of

  14. The function of the Mediator complex in plant immunity.

    Science.gov (United States)

    An, Chuanfu; Mou, Zhonglin

    2013-03-01

    Upon pathogen infection, plants undergo dramatic transcriptome reprogramming to shift from normal growth and development to immune response. During this rapid process, the multiprotein Mediator complex has been recognized as an important player to fine-tune gene-specific and pathway-specific transcriptional reprogramming by acting as an adaptor/coregulator between sequence-specific transcription factor and RNA polymerase II (RNAPII). Here, we review current understanding of the role of five functionally characterized Mediator subunits (MED8, MED15, MED16, MED21 and MED25) in plant immunity. All these Mediator subunits positively regulate resistance against leaf-infecting biotrophic bacteria or necrotrophic fungi. While MED21 appears to regulate defense against fungal pathogens via relaying signals from upstream regulators and chromatin modification to RNAPII, the other four Mediator subunits locate at different positions of the defense network to convey phytohormone signal(s). Fully understanding the role of Mediator in plant immunity needs to characterize more Mediator subunits in both Arabidopsis and other plant species. Identification of interacting proteins of Mediator subunits will further help to reveal their specific regulatory mechanisms in plant immunity.

  15. The microbially mediated soil organic carbon loss under degenerative succession in an alpine meadow.

    Science.gov (United States)

    Zhang, Yuguang; Liu, Xiao; Cong, Jing; Lu, Hui; Sheng, Yuyu; Wang, Xiulei; Li, Diqiang; Liu, Xueduan; Yin, Huaqun; Zhou, Jizhong; Deng, Ye

    2017-07-01

    Land-cover change has long been recognized as having marked effect on the amount of soil organic carbon (SOC). However, the microbially mediated processes and mechanisms on SOC are still unclear. In this study, the soil samples in a degenerative succession from alpine meadow to alpine steppe meadow in the Qinghai-Tibetan Plateau were analysed using high-throughput technologies, including Illumina sequencing and geochip functional gene arrays. The soil microbial community structure and diversity were significantly (p carbon degradation genes (e.g., pectin and hemicellulose) was significantly higher in alpine steppe meadow than in alpine meadow, but the relative abundance of soil recalcitrant carbon degradation genes (e.g., chitin and lignin) showed the opposite tendency. The Biolog Ecoplate experiment showed that microbially mediated soil carbon utilization was more active in alpine steppe meadow than in alpine meadow. Consequently, more soil labile carbon might be decomposed in alpine steppe meadow than in alpine meadow. Therefore, the degenerative succession of alpine meadow because of climate change or anthropogenic activities would most likely decrease SOC and nutrients medicated by changing soil microbial community structure and their functional potentials for carbon decomposition. © 2017 John Wiley & Sons Ltd.

  16. A recombinase-mediated transcriptional induction system in transgenic plants

    DEFF Research Database (Denmark)

    Hoff, T; Schnorr, K M; Mundy, J

    2001-01-01

    We constructed and tested a Cre-loxP recombination-mediated vector system termed pCrox for use in transgenic plants. In this system, treatment of Arabidopsis under inducing conditions mediates an excision event that removes an intervening piece of DNA between a promoter and the gene to be expressed......-mediated GUS activation. Induction was shown to be possible at essentially any stage of plant growth. This single vector system circumvents the need for genetic crosses required by other, dual recombinase vector systems. The pCrox system may prove particularly useful in instances where transgene over...

  17. Electricity generation by Enterobacter cloacae SU-1 in mediator less microbial fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Samrot, Antony V.; Senthilkumar, P.; Pavankumar, K.; Akilandeswari, G.C. [Department of Biotechnology, Sathyabama University, Rajiv Gandhi Salai, Chennai, Tamilnadu (India); Rajalakshmi, N.; Dhathathreyan, K.S. [Center for Fuel Cell Technology ARCI, IITM Research Park, Phase I, 2nd Floor, 6 Kanagam Road, Tharamani, Chennai 600 113, Tamilnadu (India)

    2010-08-15

    We have investigated a Enterobacter cloacae SU-1, bacteria for mediator less microbial fuel cell with different carbon sources and is found to be more effective as the microorganism is able to transfer electrons directly (exo-electrogenic organism) via the cytochromes or the ubiquinone. These carriers of electrons are in form of stable reversible redox couples, not biologically degraded and not toxic to cell. The major advantage of mediator less microbial fuel cells emphasize that additives in the anolyte is not compatible with the purpose of water purification. The anode chamber with the bacteria is maintained under anaerobic conditions so that the bacteria will undergo anaerobic biochemical pathways like Glycolysis, TCA cycle, Electron Transport Chain (ETC) where electrons and protons are released. Here protons are released in TCA cycle and whereas electrons are released from ETC. The mediator less microbial fuel cell delivered an open circuit potential (OCP) of 0.93 V and power of 3 mW/sq cm. During power generation from the microbes, there was a drop in coulombic efficiency in terms of fluctuations during drawing power, as the carbon source is being utilized for the cell growth. (author)

  18. Effect of long-term fertilization on humic redox mediators in multiple microbial redox reactions.

    Science.gov (United States)

    Guo, Peng; Zhang, Chunfang; Wang, Yi; Yu, Xinwei; Zhang, Zhichao; Zhang, Dongdong

    2018-03-01

    This study investigated the effects of different long-term fertilizations on humic substances (HSs), humic acids (HAs) and humins, functioning as redox mediators for various microbial redox biotransformations, including 2,2',4,4',5,5'- hexachlorobiphenyl (PCB 153 ) dechlorination, dissimilatory iron reduction, and nitrate reduction, and their electron-mediating natures. The redox activity of HSs for various microbial redox metabolisms was substantially enhanced by long-term application of organic fertilizer (pig manure). As a redox mediator, only humin extracted from soils with organic fertilizer amendment (OF-HM) maintained microbial PCB 153 dechlorination activity (1.03 μM PCB 153 removal), and corresponding HA (OF-HA) most effectively enhanced iron reduction and nitrate reduction by Shewanella putrefaciens. Electrochemical analysis confirmed the enhancement of their electron transfer capacity and redox properties. Fourier transform infrared analysis showed that C=C and C=O bonds, and carboxylic or phenolic groups in HSs might be the redox functional groups affected by fertilization. This research enhances our understanding of the influence of anthropogenic fertility on the biogeochemical cycling of elements and in situ remediation ability in agroecosystems through microorganisms' metabolisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Plant mediated detoxification of mercury and lead

    Directory of Open Access Journals (Sweden)

    Brajesh Kumar

    2017-05-01

    Full Text Available In recent years, the development of efficient green chemistry methods for detoxification of metal poisoning has become a major focus of researchers. They have investigated in order to find an eco-friendly and recyclable technique for the removal of heavy metal (Pb2+, Hg2+ contamination from the natural resources. One of the most considered methods is the removal of Pb2+, Hg2+ metal using green plants and their wastes. Among these plant wastes seem to be the best candidates and they are suitable for detoxification of heavy metals. Biosorption by plants involve complex mechanisms, mainly ion exchange, chelation, adsorption by physical forces and ion entrapment in inter and intra fibrillar capillaries and spaces of the structural polysaccharide cell wall network. The advantages of using green plants and their wastes for detoxification of heavy metal have interested researchers to investigate mechanisms of metal ion uptake, and to understand the possible utilization. In this review, we discuss the role of plants and their wastes for minimizing mercury and lead pollution with their toxic effect on both human beings and plants.

  20. Plants Rather than Mineral Fertilization Shape Microbial Community Structure and Functional Potential in Legacy Contaminated Soil.

    Science.gov (United States)

    Ridl, Jakub; Kolar, Michal; Strejcek, Michal; Strnad, Hynek; Stursa, Petr; Paces, Jan; Macek, Tomas; Uhlik, Ondrej

    2016-01-01

    Plant-microbe interactions are of particular importance in polluted soils. This study sought to determine how selected plants (horseradish, black nightshade and tobacco) and NPK mineral fertilization shape the structure of soil microbial communities in legacy contaminated soil and the resultant impact of treatment on the soil microbial community functional potential. To explore these objectives, we combined shotgun metagenomics and 16S rRNA gene amplicon high throughput sequencing with data analysis approaches developed for RNA-seq. We observed that the presence of any of the selected plants rather than fertilization shaped the microbial community structure, and the microbial populations of the root zone of each plant significantly differed from one another and/or from the bulk soil, whereas the effect of the fertilizer proved to be insignificant. When we compared microbial diversity in root zones versus bulk soil, we observed an increase in the relative abundance of Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria or Bacteroidetes, taxa which are commonly considered copiotrophic. Our results thus align with the theory that fast-growing, copiotrophic, microorganisms which are adapted to ephemeral carbon inputs are enriched in the vegetated soil. Microbial functional potential indicated that some genetic determinants associated with signal transduction mechanisms, defense mechanisms or amino acid transport and metabolism differed significantly among treatments. Genetic determinants of these categories tend to be overrepresented in copiotrophic organisms. The results of our study further elucidate plant-microbe relationships in a contaminated environment with possible implications for the phyto/rhizoremediation of contaminated areas.

  1. The Hidden World within Plants: Ecological and Evolutionary Considerations for Defining Functioning of Microbial Endophytes

    Science.gov (United States)

    van Overbeek, Leonard S.; Berg, Gabriele; Pirttilä, Anna Maria; Compant, Stéphane; Campisano, Andrea; Döring, Matthias; Sessitsch, Angela

    2015-01-01

    SUMMARY All plants are inhabited internally by diverse microbial communities comprising bacterial, archaeal, fungal, and protistic taxa. These microorganisms showing endophytic lifestyles play crucial roles in plant development, growth, fitness, and diversification. The increasing awareness of and information on endophytes provide insight into the complexity of the plant microbiome. The nature of plant-endophyte interactions ranges from mutualism to pathogenicity. This depends on a set of abiotic and biotic factors, including the genotypes of plants and microbes, environmental conditions, and the dynamic network of interactions within the plant biome. In this review, we address the concept of endophytism, considering the latest insights into evolution, plant ecosystem functioning, and multipartite interactions. PMID:26136581

  2. Mediated Plastid RNA Editing in Plant Immunity

    Science.gov (United States)

    García-Andrade, Javier; Ramírez, Vicente; López, Ana; Vera, Pablo

    2013-01-01

    Plant regulatory circuits coordinating nuclear and plastid gene expression have evolved in response to external stimuli. RNA editing is one of such control mechanisms. We determined the Arabidopsis nuclear-encoded homeodomain-containing protein OCP3 is incorporated into the chloroplast, and contributes to control over the extent of ndhB transcript editing. ndhB encodes the B subunit of the chloroplast NADH dehydrogenase-like complex (NDH) involved in cyclic electron flow (CEF) around photosystem I. In ocp3 mutant strains, ndhB editing efficiency decays, CEF is impaired and disease resistance to fungal pathogens substantially enhanced, a process recapitulated in plants defective in editing plastid RNAs encoding NDH complex subunits due to mutations in previously described nuclear-encoded pentatricopeptide-related proteins (i.e. CRR21, CRR2). Furthermore, we observed that following a pathogenic challenge, wild type plants respond with editing inhibition of ndhB transcript. In parallel, rapid destabilization of the plastidial NDH complex is also observed in the plant following perception of a pathogenic cue. Therefore, NDH complex activity and plant immunity appear as interlinked processes. PMID:24204264

  3. Plant Invasions Associated with Change in Root-Zone Microbial Community Structure and Diversity.

    Directory of Open Access Journals (Sweden)

    Richard R Rodrigues

    Full Text Available The importance of plant-microbe associations for the invasion of plant species have not been often tested under field conditions. The research sought to determine patterns of change in microbial communities associated with the establishment of invasive plants with different taxonomic and phenetic traits. Three independent locations in Virginia, USA were selected. One site was invaded by a grass (Microstegium vimineum, another by a shrub (Rhamnus davurica, and the third by a tree (Ailanthus altissima. The native vegetation from these sites was used as reference. 16S rRNA and ITS regions were sequenced to study root-zone bacterial and fungal communities, respectively, in invaded and non-invaded samples and analyzed using Quantitative Insights Into Microbial Ecology (QIIME. Though root-zone microbial community structure initially differed across locations, plant invasion shifted communities in similar ways. Indicator species analysis revealed that Operational Taxonomic Units (OTUs closely related to Proteobacteria, Acidobacteria, Actinobacteria, and Ascomycota increased in abundance due to plant invasions. The Hyphomonadaceae family in the Rhodobacterales order and ammonia-oxidizing Nitrospirae phylum showed greater relative abundance in the invaded root-zone soils. Hyphomicrobiaceae, another bacterial family within the phyla Proteobacteria increased as a result of plant invasion, but the effect associated most strongly with root-zones of M. vimineum and R. davurica. Functional analysis using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt showed bacteria responsible for nitrogen cycling in soil increased in relative abundance in association with plant invasion. In agreement with phylogenetic and functional analyses, greater turnover of ammonium and nitrate was associated with plant invasion. Overall, bacterial and fungal communities changed congruently across plant invaders, and support the hypothesis that

  4. Laser-mediated perforation of plant cells

    Science.gov (United States)

    Wehner, Martin; Jacobs, Philipp; Esser, Dominik; Schinkel, Helga; Schillberg, Stefan

    2007-07-01

    The functional analysis of plant cells at the cellular and subcellular levels requires novel technologies for the directed manipulation of individual cells. Lasers are increasingly exploited for the manipulation of plant cells, enabling the study of biological processes on a subcellular scale including transformation to generate genetically modified plants. In our setup either a picosecond laser operating at 1064 nm wavelength or a continuous wave laser diode emitting at 405 nm are coupled into an inverse microscope. The beams are focused to a spot size of about 1.5 μm and the tobacco cell protoplasts are irradiated. Optoporation is achieved when targeting the laser focal spot at the outermost edge of the plasma membrane. In case of the picosecond laser a single pulse with energy of about 0.4 μJ was sufficient to perforate the plasma membrane enabling the uptake of dye or DNA from the surrounding medium into the cytosol. When the ultraviolet laser diode at a power level of 17 mW is employed an irradiation time of 200 - 500 milliseconds is necessary to enable the uptake of macromolecules. In the presence of an EYFP encoding plasmid with a C-terminal peroxisomal signal sequence in the surrounding medium transient transformation of tobacco protoplasts could be achieved in up to 2% of the optoporated cells. Single cell perforation using this novel optoporation method shows that isolated plant cells can be permeabilized without direct manipulation. This is a valuable procedure for cell-specific applications, particularly where the import of specific molecules into plant cells is required for functional analysis.

  5. Soil microbial species loss affects plant biomass and survival of an introduced bacterial strain, but not inducible plant defences.

    Science.gov (United States)

    Kurm, Viola; van der Putten, Wim H; Pineda, Ana; Hol, W H Gera

    2018-02-12

    Plant growth-promoting rhizobacteria (PGPR) strains can influence plant-insect interactions. However, little is known about the effect of changes in the soil bacterial community in general and especially the loss of rare soil microbes on these interactions. Here, the influence of rare soil microbe reduction on induced systemic resistance (ISR) in a wild ecotype of Arabidopsis thaliana against the aphid Myzus persicae was investigated. To create a gradient of microbial abundances, soil was inoculated with a serial dilution of a microbial community and responses of Arabidopsis plants that originated from the same site as the soil microbes were tested. Plant biomass, transcription of genes involved in plant defences, and insect performance were measured. In addition, the effects of the PGPR strain Pseudomonas fluorescens SS101 on plant and insect performance were tested under the influence of the various soil dilution treatments. Plant biomass showed a hump-shaped relationship with soil microbial community dilution, independent of aphid or Pseudomonas treatments. Both aphid infestation and inoculation with Pseudomonas reduced plant biomass, and led to downregulation of PR1 (salicylic acid-responsive gene) and CYP79B3 (involved in synthesis of glucosinolates). Aphid performance and gene transcription were unaffected by soil dilution. Neither the loss of rare microbial species, as caused by soil dilution, nor Pseudomonas affect the resistance of A. thaliana against M. persicae. However, both Pseudomonas survival and plant biomass respond to rare species loss. Thus, loss of rare soil microbial species can have a significant impact on both above- and below-ground organisms. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Wastewater treatment plant effluent introduces recoverable shifts in microbial community composition in urban streams

    Science.gov (United States)

    Ledford, S. H.; Price, J. R.; Ryan, M. O.; Toran, L.; Sales, C. M.

    2017-12-01

    New technologies are allowing for intense scrutiny of the impact of land use on microbial communities in stream networks. We used a combination of analytical chemistry, real-time polymerase chain reaction (qPCR) and targeted amplicon sequencing for a preliminary study on the impact of wastewater treatment plant effluent discharge on urban streams. Samples were collected on two dates above and below treatment plants on the Wissahickon Creek, and its tributary, Sandy Run, in Montgomery County, PA, USA. As expected, effluent was observed to be a significant source of nutrients and human and non-specific fecal associated taxa. There was an observed increase in the alpha diversity at locations immediately below effluent outflows, which contributed many taxa involved in wastewater treatment processes and nutrient cycling to the stream's microbial community. Unexpectedly, modeling of microbial community shifts along the stream was not controlled by concentrations of measured nutrients. Furthermore, partial recovery, in the form of decreasing abundances of bacteria and nutrients associated with wastewater treatment plant processes, nutrient cycling bacteria, and taxa associated with fecal and sewage sources, was observed between effluent sources. Antecedent moisture conditions impacted overall microbial community diversity, with higher diversity occurring after rainfall. These findings hint at resilience in stream microbial communities to recover from wastewater treatment plant effluent and are vital to understanding the impacts of urbanization on microbial stream communities.

  7. Agrobacterium-mediated gene transfer in plants and biosafety considerations.

    Science.gov (United States)

    Mehrotra, Shweta; Goyal, Vinod

    2012-12-01

    Agrobacterium, the natures' genetic engineer, has been used as a vector to create transgenic plants. Agrobacterium-mediated gene transfer in plants is a highly efficient transformation process which is governed by various factors including genotype of the host plant, explant, vector, plasmid, bacterial strain, composition of culture medium, tissue damage, and temperature of co-cultivation. Agrobacterium has been successfully used to transform various economically and horticulturally important monocot and dicot species by standard tissue culture and in planta transformation techniques like floral or seedling infilteration, apical meristem transformation, and the pistil drip methods. Monocots have been comparatively difficult to transform by Agrobacterium. However, successful transformations have been reported in the last few years based on the adjustment of the parameters that govern the responses of monocots to Agrobacterium. A novel Agrobacterium transferred DNA-derived nanocomplex method has been developed which will be highly valuable for plant biology and biotechnology. Agrobacterium-mediated genetic transformation is known to be the preferred method of creating transgenic plants from a commercial and biosafety perspective. Agrobacterium-mediated gene transfer predominantly results in the integration of foreign genes at a single locus in the host plant, without associated vector backbone and is also known to produce marker free plants, which are the prerequisites for commercialization of transgenic crops. Research in Agrobacterium-mediated transformation can provide new and novel insights into the understanding of the regulatory process controlling molecular, cellular, biochemical, physiological, and developmental processes occurring during Agrobacterium-mediated transformation and also into a wide range of aspects on biological safety of transgenic crops to improve crop production to meet the demands of ever-growing world's population.

  8. Monodehydroascorbate reductase mediates TNT toxicity in plants.

    Science.gov (United States)

    Johnston, Emily J; Rylott, Elizabeth L; Beynon, Emily; Lorenz, Astrid; Chechik, Victor; Bruce, Neil C

    2015-09-04

    The explosive 2,4,6-trinitrotoluene (TNT) is a highly toxic and persistent environmental pollutant. Due to the scale of affected areas, one of the most cost-effective and environmentally friendly means of removing explosives pollution could be the use of plants. However, mechanisms of TNT phytotoxicity have been elusive. Here, we reveal that phytotoxicity is caused by reduction of TNT in the mitochondria, forming a nitro radical that reacts with atmospheric oxygen, generating reactive superoxide. The reaction is catalyzed by monodehydroascorbate reductase 6 (MDHAR6), with Arabidopsis deficient in MDHAR6 displaying enhanced TNT tolerance. This discovery will contribute toward the remediation of contaminated sites. Moreover, in an environment of increasing herbicide resistance, with a shortage in new herbicide classes, our findings reveal MDHAR6 as a valuable plant-specific target. Copyright © 2015, American Association for the Advancement of Science.

  9. Bacterial pathogenesis of plants: future challenges from a microbial perspective: Challenges in Bacterial Molecular Plant Pathology.

    Science.gov (United States)

    Pfeilmeier, Sebastian; Caly, Delphine L; Malone, Jacob G

    2016-10-01

    Plant infection is a complicated process. On encountering a plant, pathogenic microorganisms must first adapt to life on the epiphytic surface, and survive long enough to initiate an infection. Responsiveness to the environment is critical throughout infection, with intracellular and community-level signal transduction pathways integrating environmental signals and triggering appropriate responses in the bacterial population. Ultimately, phytopathogens must migrate from the epiphytic surface into the plant tissue using motility and chemotaxis pathways. This migration is coupled with overcoming the physical and chemical barriers to entry into the plant apoplast. Once inside the plant, bacteria use an array of secretion systems to release phytotoxins and protein effectors that fulfil diverse pathogenic functions (Fig. ) (Melotto and Kunkel, ; Phan Tran et al., ). As our understanding of the pathways and mechanisms underpinning plant pathogenicity increases, a number of central research challenges are emerging that will profoundly shape the direction of research in the future. We need to understand the bacterial phenotypes that promote epiphytic survival and surface adaptation in pathogenic bacteria. How do these pathways function in the context of the plant-associated microbiome, and what impact does this complex microbial community have on the onset and severity of plant infections? The huge importance of bacterial signal transduction to every stage of plant infection is becoming increasingly clear. However, there is a great deal to learn about how these signalling pathways function in phytopathogenic bacteria, and the contribution they make to various aspects of plant pathogenicity. We are increasingly able to explore the structural and functional diversity of small-molecule natural products from plant pathogens. We need to acquire a much better understanding of the production, deployment, functional redundancy and physiological roles of these molecules. Type III

  10. Above- and belowground linkages in Sphagnum peatland: climate warming affects plant-microbial interactions.

    Science.gov (United States)

    Jassey, Vincent E J; Chiapusio, Geneviève; Binet, Philippe; Buttler, Alexandre; Laggoun-Défarge, Fatima; Delarue, Frédéric; Bernard, Nadine; Mitchell, Edward A D; Toussaint, Marie-Laure; Francez, André-Jean; Gilbert, Daniel

    2013-03-01

    Peatlands contain approximately one third of all soil organic carbon (SOC). Warming can alter above- and belowground linkages that regulate soil organic carbon dynamics and C-balance in peatlands. Here we examine the multiyear impact of in situ experimental warming on the microbial food web, vegetation, and their feedbacks with soil chemistry. We provide evidence of both positive and negative impacts of warming on specific microbial functional groups, leading to destabilization of the microbial food web. We observed a strong reduction (70%) in the biomass of top-predators (testate amoebae) in warmed plots. Such a loss caused a shortening of microbial food chains, which in turn stimulated microbial activity, leading to slight increases in levels of nutrients and labile C in water. We further show that warming altered the regulatory role of Sphagnum-polyphenols on microbial community structure with a potential inhibition of top predators. In addition, warming caused a decrease in Sphagnum cover and an increase in vascular plant cover. Using structural equation modelling, we show that changes in the microbial food web affected the relationships between plants, soil water chemistry, and microbial communities. These results suggest that warming will destabilize C and nutrient recycling of peatlands via changes in above- and belowground linkages, and therefore, the microbial food web associated with mosses will feedback positively to global warming by destabilizing the carbon cycle. This study confirms that microbial food webs thus constitute a key element in the functioning of peatland ecosystems. Their study can help understand how mosses, as ecosystem engineers, tightly regulate biogeochemical cycling and climate feedback in peatlands. © 2012 Blackwell Publishing Ltd.

  11. Phyllosphere Microbiota Composition and Microbial Community Transplantation on Lettuce Plants Grown Indoors

    Science.gov (United States)

    Williams, Thomas R.

    2014-01-01

    ABSTRACT The aerial surfaces of plants, or phyllosphere, are microbial habitats important to plant and human health. In order to accurately investigate microbial interactions in the phyllosphere under laboratory conditions, the composition of the phyllosphere microbiota should be representative of the diversity of microorganisms residing on plants in nature. We found that Romaine lettuce grown in the laboratory contained 10- to 100-fold lower numbers of bacteria than age-matched, field-grown lettuce. The bacterial diversity on laboratory-grown plants was also significantly lower and contained relatively higher proportions of Betaproteobacteria as opposed to the Gammaproteobacteria-enriched communities on field lettuce. Incubation of field-grown Romaine lettuce plants in environmental growth chambers for 2 weeks resulted in bacterial cell densities and taxa similar to those on plants in the field but with less diverse bacterial populations overall. In comparison, the inoculation of laboratory-grown Romaine lettuce plants with either freshly collected or cryopreserved microorganisms recovered from field lettuce resulted in the development of a field-like microbiota on the lettuce within 2 days of application. The survival of an inoculated strain of Escherichia coli O157:H7 was unchanged by microbial community transfer; however, the inoculation of E. coli O157:H7 onto those plants resulted in significant shifts in the abundance of certain taxa. This finding was strictly dependent on the presence of a field-associated as opposed to a laboratory-associated microbiota on the plants. Phyllosphere microbiota transplantation in the laboratory will be useful for elucidating microbial interactions on plants that are important to agriculture and microbial food safety. PMID:25118240

  12. Taxonomic and Functional Responses of Soil Microbial Communities to Annual Removal of Aboveground Plant Biomass

    Science.gov (United States)

    Guo, Xue; Zhou, Xishu; Hale, Lauren; Yuan, Mengting; Feng, Jiajie; Ning, Daliang; Shi, Zhou; Qin, Yujia; Liu, Feifei; Wu, Liyou; He, Zhili; Van Nostrand, Joy D.; Liu, Xueduan; Luo, Yiqi; Tiedje, James M.; Zhou, Jizhong

    2018-01-01

    Clipping, removal of aboveground plant biomass, is an important issue in grassland ecology. However, few studies have focused on the effect of clipping on belowground microbial communities. Using integrated metagenomic technologies, we examined the taxonomic and functional responses of soil microbial communities to annual clipping (2010–2014) in a grassland ecosystem of the Great Plains of North America. Our results indicated that clipping significantly (P microbial respiration rates. Annual temporal variation within the microbial communities was much greater than the significant changes introduced by clipping, but cumulative effects of clipping were still observed in the long-term scale. The abundances of some bacterial and fungal lineages including Actinobacteria and Bacteroidetes were significantly (P microbial communities were significantly correlated with soil respiration and plant productivity. Intriguingly, clipping effects on microbial function may be highly regulated by precipitation at the interannual scale. Altogether, our results illustrated the potential of soil microbial communities for increased soil organic matter decomposition under clipping land-use practices. PMID:29904372

  13. Plastic potential: how the phenotypes and adaptations of pathogens are influenced by microbial interactions within plants.

    Science.gov (United States)

    O'Keeffe, Kayleigh R; Carbone, Ignazio; Jones, Corbin D; Mitchell, Charles E

    2017-08-01

    Predicting the effects of plant-associated microbes on emergence, spread, and evolution of plant pathogens demands an understanding of how pathogens respond to these microbes at two levels of biological organization: that of an individual pathogen and that of a pathogen population across multiple individual plants. We first examine the plastic responses of individual plant pathogens to microbes within a shared host, as seen through changes in pathogen growth and multiplication. We then explore the limited understanding of how within-plant microbial interactions affect pathogen populations and discuss the need to incorporate population-level observations with population genomic techniques. Finally, we suggest that integrating across levels will further our understanding of the ecological and evolutionary impacts of within-plant microbial interactions on pathogens. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Agrobacterium tumefaciens-mediated transformation of biofuel plant ...

    African Journals Online (AJOL)

    Establishment of an efficient transformation system is a prerequisite for genetic improvement of Jatropha curcas, a promising biodiesel feedstock plant, by transgenic approach. In this study an efficient Agrobacterium-mediated transformation protocol using cotyledon explants from J. curcas seeds was developed.

  15. Plant-mediated biosynthesis of silver nanoparticles by leaf extracts ...

    Indian Academy of Sciences (India)

    MS received 6 May 2016; accepted 24 June 2016. Abstract. ... is reported to control stomach ulcer [9,10]. Udosen et al [11] ... In the synthesis of nanoparticles via green approach, bio- ... In plant-mediated synthesis, the control of the size of.

  16. Leaf bacterial diversity mediates plant diversity and ecosystem function relationships.

    Science.gov (United States)

    Laforest-Lapointe, Isabelle; Paquette, Alain; Messier, Christian; Kembel, Steven W

    2017-06-01

    Research on biodiversity and ecosystem functioning has demonstrated links between plant diversity and ecosystem functions such as productivity. At other trophic levels, the plant microbiome has been shown to influence host plant fitness and function, and host-associated microbes have been proposed to influence ecosystem function through their role in defining the extended phenotype of host organisms However, the importance of the plant microbiome for ecosystem function has not been quantified in the context of the known importance of plant diversity and traits. Here, using a tree biodiversity-ecosystem functioning experiment, we provide strong support for the hypothesis that leaf bacterial diversity is positively linked to ecosystem productivity, even after accounting for the role of plant diversity. Our results also show that host species identity, functional identity and functional diversity are the main determinants of leaf bacterial community structure and diversity. Our study provides evidence of a positive correlation between plant-associated microbial diversity and terrestrial ecosystem productivity, and a new mechanism by which models of biodiversity-ecosystem functioning relationships can be improved.

  17. A microbially derived tyrosine-sulfated peptide mimics a plant peptide hormone.

    Science.gov (United States)

    Pruitt, Rory N; Joe, Anna; Zhang, Weiguo; Feng, Wei; Stewart, Valley; Schwessinger, Benjamin; Dinneny, José R; Ronald, Pamela C

    2017-07-01

    The biotrophic pathogen Xanthomonas oryzae pv. oryzae (Xoo) produces a sulfated peptide named RaxX, which shares similarity to peptides in the PSY (plant peptide containing sulfated tyrosine) family. We hypothesize that RaxX mimics the growth-stimulating activity of PSY peptides. Root length was measured in Arabidopsis and rice treated with synthetic RaxX peptides. We also used comparative genomic analyses and reactive oxygen species burst assays to evaluate the activity of RaxX and PSY peptides. Here we found that a synthetic sulfated RaxX derivative comprising 13 residues (RaxX13-sY), highly conserved between RaxX and PSY, induces root growth in Arabidopsis and rice in a manner similar to that triggered by PSY. We identified residues that are required for activation of immunity mediated by the rice XA21 receptor but that are not essential for root growth induced by PSY. Finally, we showed that a Xanthomonas strain lacking raxX is impaired in virulence. These findings suggest that RaxX serves as a molecular mimic of PSY peptides to facilitate Xoo infection and that XA21 has evolved the ability to recognize and respond specifically to the microbial form of the peptide. © 2017 UT-Battelle LLC. New Phytologist © 2017 New Phytologist Trust.

  18. Therapeutic Potential of Plants as Anti-Microbials for Drug Discovery

    Directory of Open Access Journals (Sweden)

    Ramar Perumal Samy

    2010-01-01

    Full Text Available The uses of traditional medicinal plants for primary health care have steadily increased worldwide in recent years. Scientists are in search of new phytochemicals that could be developed as useful anti-microbials for treatment of infectious diseases. Currently, out of 80% of pharmaceuticals derived from plants, very few are now being used as anti-microbials. Plants are rich in a wide variety of secondary metabolites that have found anti-microbial properties. This review highlights the current status of traditional medicine, its contribution to modern medicine, recent trends in the evaluation of anti-microbials with a special emphasis upon some tribal medicine, in vitro and in vivo experimental design for screening, and therapeutic efficacy in safety and human clinical trails for commercial outlet. Many of these commercially available compounds are crude preparations administered without performing human clinical trials. Recent methods are useful to standardize the extraction for scientific investigation of new phytochemicals and anti-microbials of traditionally used plants. It is concluded that once the local ethnomedical preparations of traditional sources are scientifically evaluated before dispensing they should replace existing drugs commonly used for the therapeutic treatment of infection. This method should be put into practice for future investigations in the field of ethnopharmacology, phytochemistry, ethnobotany and other biological fields for drug discovery.

  19. Strategies to Optimize Microbially-Mediated Mitigation of Greenhouse Gas Emissions from Landfill Cover Soils

    Energy Technology Data Exchange (ETDEWEB)

    Jeremy Semrau; Sung-Woo Lee; Jeongdae Im; Sukhwan Yoon; Michael Barcelona

    2010-09-30

    The overall objective of this project, 'Strategies to Optimize Microbially-Mediated Mitigation of Greenhouse Gas Emissions from Landfill Cover Soils' was to develop effective, efficient, and economic methodologies by which microbial production of nitrous oxide can be minimized while also maximizing microbial consumption of methane in landfill cover soils. A combination of laboratory and field site experiments found that the addition of nitrogen and phenylacetylene stimulated in situ methane oxidation while minimizing nitrous oxide production. Molecular analyses also indicated that methane-oxidizing bacteria may play a significant role in not only removing methane, but in nitrous oxide production as well, although the contribution of ammonia-oxidizing archaea to nitrous oxide production can not be excluded at this time. Future efforts to control both methane and nitrous oxide emissions from landfills as well as from other environments (e.g., agricultural soils) should consider these issues. Finally, a methanotrophic biofiltration system was designed and modeled for the promotion of methanotrophic activity in local methane 'hotspots' such as landfills. Model results as well as economic analyses of these biofilters indicate that the use of methanotrophic biofilters for controlling methane emissions is technically feasible, and provided either the costs of biofilter construction and operation are reduced or the value of CO{sub 2} credits is increased, can also be economically attractive.

  20. Acid-deposition research program. Volume 2. Effects of acid-forming emissions on soil microorganisms and microbially-mediated processes

    Energy Technology Data Exchange (ETDEWEB)

    Visser, S.; Danielson, R.M.; Parr, J.F.

    1987-02-01

    The interactions of soil physical, chemical, and biological processes are ultimately expressed in a soil's fertility and its capacity for plant production. Consequently, much of the research conducted to date regarding the impact of acid-forming pollutants on soil properties has been geared towards possible effects on plant productivity. This trend continues in this paper where the effects of acidic deposition on microbial communities are reviewed in relation to potential impact on plant growth. The objectives of the review are to discuss: (1) The effects of acid-forming emissions (primarily S-containing pollutants) on microbial community structure with emphasis on qualitative and quantitative aspects; (2) The effects of acidic deposition on microbially mediated processes (i.e., community functions); (3) Acidification effects of pollutants on symbiotic and disease-causing microorganisms. The symbionts discussed include ectomycorrhizal fungi, vesicular-arbuscular mycorrhizal fungi, and N/sub 2/-fixing bacteria, particularly Rhizobium, while the disease-causing microorganisms will include those responsible for foliage, stem, and root diseases.

  1. Soil fertility and plant diversity enhance microbial performance in metal-polluted soils.

    Science.gov (United States)

    Stefanowicz, Anna M; Kapusta, Paweł; Szarek-Łukaszewska, Grażyna; Grodzińska, Krystyna; Niklińska, Maria; Vogt, Rolf D

    2012-11-15

    This study examined the effects of soil physicochemical properties (including heavy metal pollution) and vegetation parameters on soil basal respiration, microbial biomass, and the activity and functional richness of culturable soil bacteria and fungi. In a zinc and lead mining area (S Poland), 49 sites were selected to represent all common plant communities and comprise the area's diverse soil types. Numerous variables describing habitat properties were reduced by PCA to 7 independent factors, mainly representing subsoil type (metal-rich mining waste vs. sand), soil fertility (exchangeable Ca, Mg and K, total C and N, organic C), plant species richness, phosphorus content, water-soluble heavy metals (Zn, Cd and Pb), clay content and plant functional diversity (based on graminoids, legumes and non-leguminous forbs). Multiple regression analysis including these factors explained much of the variation in most microbial parameters; in the case of microbial respiration and biomass, it was 86% and 71%, respectively. The activity of soil microbes was positively affected mainly by soil fertility and, apparently, by the presence of mining waste in the subsoil. The mining waste contained vast amounts of trace metals (total Zn, Cd and Pb), but it promoted microbial performance due to its inherently high content of macronutrients (total Ca, Mg, K and C). Plant species richness had a relatively strong positive effect on all microbial parameters, except for the fungal component. In contrast, plant functional diversity was practically negligible in its effect on microbes. Other explanatory variables had only a minor positive effect (clay content) or no significant influence (phosphorus content) on microbial communities. The main conclusion from this study is that high nutrient availability and plant species richness positively affected the soil microbes and that this apparently counteracted the toxic effects of metal contamination. Copyright © 2012 Elsevier B.V. All rights

  2. Disease induction by human microbial pathogens in plant-model systems: potential, problems and prospects.

    Science.gov (United States)

    van Baarlen, Peter; van Belkum, Alex; Thomma, Bart P H J

    2007-02-01

    Relatively simple eukaryotic model organisms such as the genetic model weed plant Arabidopsis thaliana possess an innate immune system that shares important similarities with its mammalian counterpart. In fact, some human pathogens infect Arabidopsis and cause overt disease with human symptomology. In such cases, decisive elements of the plant's immune system are likely to be targeted by the same microbial factors that are necessary for causing disease in humans. These similarities can be exploited to identify elementary microbial pathogenicity factors and their corresponding targets in a green host. This circumvents important cost aspects that often frustrate studies in humans or animal models and, in addition, results in facile ethical clearance.

  3. Extensive Management Promotes Plant and Microbial Nitrogen Retention in Temperate Grassland

    Science.gov (United States)

    de Vries, Franciska T.; Bloem, Jaap; Quirk, Helen; Stevens, Carly J.; Bol, Roland; Bardgett, Richard D.

    2012-01-01

    Leaching losses of nitrogen (N) from soil and atmospheric N deposition have led to widespread changes in plant community and microbial community composition, but our knowledge of the factors that determine ecosystem N retention is limited. A common feature of extensively managed, species-rich grasslands is that they have fungal-dominated microbial communities, which might reduce soil N losses and increase ecosystem N retention, which is pivotal for pollution mitigation and sustainable food production. However, the mechanisms that underpin improved N retention in extensively managed, species-rich grasslands are unclear. We combined a landscape-scale field study and glasshouse experiment to test how grassland management affects plant and soil N retention. Specifically, we hypothesised that extensively managed, species-rich grasslands of high conservation value would have lower N loss and greater N retention than intensively managed, species-poor grasslands, and that this would be due to a greater immobilisation of N by a more fungal-dominated microbial community. In the field study, we found that extensively managed, species-rich grasslands had lower N leaching losses. Soil inorganic N availability decreased with increasing abundance of fungi relative to bacteria, although the best predictor of soil N leaching was the C/N ratio of aboveground plant biomass. In the associated glasshouse experiment we found that retention of added 15N was greater in extensively than in intensively managed grasslands, which was attributed to a combination of greater root uptake and microbial immobilisation of 15N in the former, and that microbial immobilisation increased with increasing biomass and abundance of fungi. These findings show that grassland management affects mechanisms of N retention in soil through changes in root and microbial uptake of N. Moreover, they support the notion that microbial communities might be the key to improved N retention through tightening linkages

  4. Plant kin recognition enhances abundance of symbiotic microbial partner.

    Directory of Open Access Journals (Sweden)

    Amanda L File

    Full Text Available The stability of cooperative interactions among different species can be compromised by cheating. In the plant-mycorrhizal fungi symbiosis, a single mycorrhizal network may interact with many plants, providing the opportunity for individual plants to cheat by obtaining nutrients from the fungi without donating carbon. Here we determine whether kin selection may favour plant investment in the mycorrhizal network, reducing the incentive to cheat when relatives interact with a single network.We show that mycorrhizal network size and root colonization were greater when Ambrosia artemisiifolia L. was grown with siblings compared to strangers. Soil fungal abundance was positively correlated with group leaf nitrogen, and increased root colonization was associated with a reduced number of pathogen-induced root lesions, indicating greater benefit to plants grown with siblings.Plants can benefit their relatives through investment in mycorrhizal fungi, and kin selection in plants could promote the persistence of the mycorrhizal symbiosis.

  5. The role microbial sulfate reduction in the direct mediation of sedimentary authigenic carbonate precipitation

    Science.gov (United States)

    Turchyn, A. V.; Walker, K.; Sun, X.

    2016-12-01

    The majority of modern deep marine sediments are bathed in water that is undersaturated with respect to calcium carbonate. However, within marine sediments changing chemical conditions, driven largely by the microbial oxidation of organic carbon in the absence of oxygen, lead to supersaturated conditions and drive calcium carbonate precipitation. This sedimentary calcium carbonate is often called `authigenic carbonate', and is found in the form of cements and disseminated crystals within the marine sedimentary pile. As this precipitation of this calcium carbonate is microbially mediated, identifying authigenic carbonate within the geological record and understanding what information its geochemical and/or isotopic signature may hold is key for understanding its importance and what information it may contain past life. However, the modern controls on authigenic carbonate precipitation remain enigmatic because the myriad of microbially mediated reactions occurring within sediments both directly and indirectly impact the proton balance. In this submission we present data from 25 ocean sediment cores spanning the globe where we explore the deviation from the stoichiometrically predicted relationships among alkalinity, calcium and sulfate concentrations. In theory for every mol of organic carbon reduced by sulfate, two mol of alkalinity is produced, and to precipitate subsurface calcium carbonate one mol of calcium is used to consume two mol of alkalinity. We use this data with a model to explore changes in carbonate saturation state with depth below the seafloor. Alkalinity changes in the subsurface are poorly correlated with changes in calcium concentrations, however calcium concentrations are directly and tightly coupled to changes in sulfate concentrations in all studied sites. This suggests a direct role for sulfate reducing bacteria in the precipitation of subsurface carbonate cements.

  6. Plant-plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO

    NARCIS (Netherlands)

    Loon, Van Marloes P.; Rietkerk, Max; Dekker, Stefan C.; Hikosaka, Kouki; Ueda, Miki U.; Anten, Niels P.R.

    2016-01-01

    Background and Aims The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant-plant interactions could mediate the trajectory of vegetation responses to elevated

  7. Enhancement of electricity production by graphene oxide in soil microbial fuel cells and plant microbial fuel cells

    Directory of Open Access Journals (Sweden)

    Yuko eGoto

    2015-04-01

    Full Text Available The effects of graphene oxide (GO on electricity generation in soil microbial fuel cells (SMFCs and plant microbial fuel cell (PMFCs were investigated. GO at concentrations ranging from 0 to 1.9 g•kg-1 was added to soil and reduced for 10 days under anaerobic incubation. All SMFCs (GO-SMFCs utilizing the soils incubated with GO produced electricity at a greater rate and in higher quantities than the SMFCs which did not contain GO. In fed-batch operations, the overall average electricity generation in GO-SMFCs containing 1.0 g•kg-1 of GO was 40 ± 19 mW•m-2, which was significantly higher than the value of 6.6 ± 8.9 mW•m-2 generated from GO-free SMFCs (p -2 of electricity after 27 days of operation. Collectively, this study demonstrates that GO added to soil can be microbially reduced in soil, and facilitates electron transfer to the anode in both SMFCs and PMFCs.

  8. Belowground Carbon Allocation and Plant-Microbial Interactions Drive Resistance and Resilience of Mountain Grassland Communities to Drought

    Science.gov (United States)

    Karlowsky, S.; Augusti, A.; Ingrisch, J.; Hasibeder, R.; Lavorel, S.; Bahn, M.; Gleixner, G.

    2016-12-01

    Belowground carbon allocation (BCA) and plant-microbial interactions are crucial for the functioning of terrestrial ecosystems. Recent research suggests that extreme events can have severe effects on these processes but it is unknown how land use intensity potentially modifies their responses. We studied the resistance and resilience of mountain grassland communities to prolonged drought and investigated the role of plant C allocation and soil microbial communities in mediating drought resistance and immediate recovery. In a common garden experiment we exposed monoliths from an abandoned grassland and a hay meadow to an early summer drought. Two independent 13C pulse labeling experiments were conducted, the first during peak drought and the second during the recovery phase. The 13C incorporation was analyzed in above- and belowground plant parts and in phospho- and neutral lipid fatty acids of soil microorganisms. In addition, a 15N label was added at the rewetting to determine plant N uptake. We found that C uptake, BCA and C transfer to soil microorganisms were less strongly reduced by drought in the abandoned grassland than in the meadow. Moreover, drought induced an increase of arbuscular mycorrhiza fungi (AMF) marker in the abandoned grassland. Nevertheless, C uptake and related parameters were quickly recovered and N uptake increased in the meadow during recovery. Unexpectedly, AMF and their C uptake were generally reduced during recovery, while bacteria increased and quickly recovered C uptake, particularly in the meadow. Our results showed a negative relation between high resistance and fast recovery. The more resistant abandoned grassland plant communities seemed to invest more C below ground and into interactions with AMF during drought, likely to access water through their hyphal network. Conversely, meadow communities invested more C from recent photosynthesis into bacterial communities during recovery, obviously to gain more nutrients for regrowth

  9. Microbial transformation of (-)-isolongifolol by plant pathogenic fungus Glomerella cingulata.

    Science.gov (United States)

    Miyazawa, Mitsuo; Sakata, Kazuki; Ueda, Masashi

    2010-01-01

    The biotransformation of terpenoids using the plant pathogenic fungus as a biocatalyst to produce useful novel organic compounds was investigated. The biotransformation of sesquiterpen alcohol, (-)-isolongifolol (1) was investigated using plant pathogenic fungus Glomerella cingulata as a biocatalyst. Compound 1 was converted to (-)-(3R)-3-hydroxy-isolongifolol and (-)-(9R)-9-hydroxy-isolongifolol by G. cingulata.

  10. Microbial community functional structures in wastewater treatment plants as characterized by GeoChip.

    Science.gov (United States)

    Wang, Xiaohui; Xia, Yu; Wen, Xianghua; Yang, Yunfeng; Zhou, Jizhong

    2014-01-01

    Biological WWTPs must be functionally stable to continuously and steadily remove contaminants which rely upon the activity of complex microbial communities. However, knowledge is still lacking in regard to microbial community functional structures and their linkages to environmental variables. To investigate microbial community functional structures of activated sludge in wastewater treatment plants (WWTPs) and to understand the effects of environmental factors on their structure. 12 activated sludge samples were collected from four WWTPs in Beijing. A comprehensive functional gene array named GeoChip 4.2 was used to determine the microbial functional genes involved in a variety of biogeochemical processes such as carbon, nitrogen, phosphorous and sulfur cycles, metal resistance, antibiotic resistance and organic contaminant degradation. High similarities of the microbial community functional structures were found among activated sludge samples from the four WWTPs, as shown by both diversity indices and the overlapped genes. For individual gene category, such as egl, amyA, lip, nirS, nirK, nosZ, ureC, ppx, ppk, aprA, dsrA, sox and benAB, there were a number of microorganisms shared by all 12 samples. Canonical correspondence analysis (CCA) showed that the microbial functional patterns were highly correlated with water temperature, dissolved oxygen (DO), ammonia concentrations and loading rate of chemical oxygen demand (COD). Based on the variance partitioning analyses (VPA), a total of 53% of microbial community variation from GeoChip data can be explained by wastewater characteristics (25%) and operational parameters (23%), respectively. This study provided an overall picture of microbial community functional structures of activated sludge in WWTPs and discerned the linkages between microbial communities and environmental variables in WWTPs.

  11. Microbial community functional structures in wastewater treatment plants as characterized by GeoChip.

    Directory of Open Access Journals (Sweden)

    Xiaohui Wang

    Full Text Available BACKGROUND: Biological WWTPs must be functionally stable to continuously and steadily remove contaminants which rely upon the activity of complex microbial communities. However, knowledge is still lacking in regard to microbial community functional structures and their linkages to environmental variables. AIMS: To investigate microbial community functional structures of activated sludge in wastewater treatment plants (WWTPs and to understand the effects of environmental factors on their structure. METHODS: 12 activated sludge samples were collected from four WWTPs in Beijing. A comprehensive functional gene array named GeoChip 4.2 was used to determine the microbial functional genes involved in a variety of biogeochemical processes such as carbon, nitrogen, phosphorous and sulfur cycles, metal resistance, antibiotic resistance and organic contaminant degradation. RESULTS: High similarities of the microbial community functional structures were found among activated sludge samples from the four WWTPs, as shown by both diversity indices and the overlapped genes. For individual gene category, such as egl, amyA, lip, nirS, nirK, nosZ, ureC, ppx, ppk, aprA, dsrA, sox and benAB, there were a number of microorganisms shared by all 12 samples. Canonical correspondence analysis (CCA showed that the microbial functional patterns were highly correlated with water temperature, dissolved oxygen (DO, ammonia concentrations and loading rate of chemical oxygen demand (COD. Based on the variance partitioning analyses (VPA, a total of 53% of microbial community variation from GeoChip data can be explained by wastewater characteristics (25% and operational parameters (23%, respectively. CONCLUSIONS: This study provided an overall picture of microbial community functional structures of activated sludge in WWTPs and discerned the linkages between microbial communities and environmental variables in WWTPs.

  12. Characterization of three plant biomass-degrading microbial consortia by metagenomics- and metasecretomics-based approaches

    NARCIS (Netherlands)

    Jiménez, Diego Javier; Brossi, Maria Julia de Lima; Schuckel, Julia; Kracun, Stjepan Kresimir; Willats, William George Tycho; van Elsas, Jan Dirk

    2016-01-01

    The selection of microbes by enrichment on plant biomass has been proposed as an efficient way to develop new strategies for lignocellulose saccharification. Here, we report an in-depth analysis of soil-derived microbial consortia that were trained to degrade once-used wheat straw (WS1-M),

  13. Resilience of roof-top Plant-Microbial Fuel Cells during Dutch winter

    NARCIS (Netherlands)

    Helder, M.; Strik, D.P.B.T.B.; Timmers, R.A.; Reas, S.M.T.; Hamelers, H.V.M.; Buisman, C.J.N.

    2013-01-01

    The Plant-Microbial Fuel Cell (P-MFC) is in theory a technology that could produce sustainable electricity continuously. We operated two designs of the P-MFC under natural roof-top conditions in the Netherlands for 221 days, including winter, to test its resilience. Current and power densities are

  14. Plants Rather than Mineral Fertilization Shape Microbial Community Structure and Functional Potential in Legacy Contaminated Soil

    Czech Academy of Sciences Publication Activity Database

    Rídl, Jakub; Kolář, Michal; Strejček, M.; Strnad, Hynek; Štursa, P.; Pačes, Jan; Macek, T.; Uhlík, O.

    2016-01-01

    Roč. 7, JUN 24 (2016), č. článku 995. ISSN 1664-302X R&D Projects: GA ČR GA13-28283S Institutional support: RVO:68378050 Keywords : microbial community structure * plants * fertilization * contaminated soil * functional potential Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.076, year: 2016

  15. Effect of Some Plant Extracts on the Microbial Spoilage of Cajanus ...

    African Journals Online (AJOL)

    The effect of ethanolic extracts of seven plant sources on the microbial spoilage of Cajanus cajan extract was investigated. The results showed that the extracts obtained from Aloe vera, bitter leaf, Gultiferae (garcinia or bitter kola), Ocimum gratissimum (scent leaf) and Zingiber officialae (ginger) were effective against ...

  16. Microbial Communities in Danish Wastewater Treatment Plants with Nutrient Removal

    DEFF Research Database (Denmark)

    Mielczarek, Artur Tomasz

    Activated sludge treatment plants are the most used wastewater treatment systems worldwide for biological nutrient removal from wastewater. Nevertheless, the treatment systems have been for many years operated as so called “black-box”, where specific process parameters were adjusted without...... that plants with return sludge Side-Stream Hydrolysis (SSH) instead of the normal anaerobic process tank tended to have significantly fewer unwanted GAOs in contrast to many plants with traditional mainstream anaerobic tank and thus it was proposed that this system might be an effective strategy of control...

  17. The Hidden World within Plants: Ecological and Evolutionary Considerations for Defining Functioning of Microbial Endophytes.

    Science.gov (United States)

    Hardoim, Pablo R; van Overbeek, Leonard S; Berg, Gabriele; Pirttilä, Anna Maria; Compant, Stéphane; Campisano, Andrea; Döring, Matthias; Sessitsch, Angela

    2015-09-01

    All plants are inhabited internally by diverse microbial communities comprising bacterial, archaeal, fungal, and protistic taxa. These microorganisms showing endophytic lifestyles play crucial roles in plant development, growth, fitness, and diversification. The increasing awareness of and information on endophytes provide insight into the complexity of the plant microbiome. The nature of plant-endophyte interactions ranges from mutualism to pathogenicity. This depends on a set of abiotic and biotic factors, including the genotypes of plants and microbes, environmental conditions, and the dynamic network of interactions within the plant biome. In this review, we address the concept of endophytism, considering the latest insights into evolution, plant ecosystem functioning, and multipartite interactions. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. Exploring the under-investigated "microbial dark matter" of drinking water treatment plants.

    Science.gov (United States)

    Bruno, Antonia; Sandionigi, Anna; Rizzi, Ermanno; Bernasconi, Marzia; Vicario, Saverio; Galimberti, Andrea; Cocuzza, Clementina; Labra, Massimo; Casiraghi, Maurizio

    2017-03-14

    Scientists recently reported the unexpected detection of unknown or poorly studied bacterial diversity in groundwater. The ability to uncover this neglected biodiversity mainly derives from technical improvements, and the term "microbial dark matter" was used to group taxa poorly investigated and not necessarily monophyletic. We focused on such under-investigated microbial dark matter of drinking water treatment plant from groundwater, across carbon filters, to post-chlorination. We tackled this topic using an integrated approach where the efficacy of stringent water filtration (10000 MWCO) in recovering even the smallest environmental microorganisms was coupled with high-throughput DNA sequencing to depict an informative spectrum of the neglected microbial diversity. Our results revealed that the composition of bacterial communities varies across the plant system: Parcubacteria (OD1) superphylum is found mainly in treated water, while groundwater has the highest heterogeneity, encompassing non-OD1 candidate phyla (Microgenomates, Saccharibacteria, Dependentiae, OP3, OP1, BRC1, WS3). Carbon filters probably act as substrate for microorganism growth and contribute to seeding water downstream, since chlorination does not modify the incoming bacterial community. New questions arise about the role of microbial dark matter in drinking water. Indeed, our results suggest that these bacteria might play a central role in the microbial dynamics of drinking water.

  19. Linking the development and functioning of a carnivorous pitcher plant's microbial digestive community.

    Science.gov (United States)

    Armitage, David W

    2017-11-01

    Ecosystem development theory predicts that successional turnover in community composition can influence ecosystem functioning. However, tests of this theory in natural systems are made difficult by a lack of replicable and tractable model systems. Using the microbial digestive associates of a carnivorous pitcher plant, I tested hypotheses linking host age-driven microbial community development to host functioning. Monitoring the yearlong development of independent microbial digestive communities in two pitcher plant populations revealed a number of trends in community succession matching theoretical predictions. These included mid-successional peaks in bacterial diversity and metabolic substrate use, predictable and parallel successional trajectories among microbial communities, and convergence giving way to divergence in community composition and carbon substrate use. Bacterial composition, biomass, and diversity positively influenced the rate of prey decomposition, which was in turn positively associated with a host leaf's nitrogen uptake efficiency. Overall digestive performance was greatest during late summer. These results highlight links between community succession and ecosystem functioning and extend succession theory to host-associated microbial communities.

  20. Effects of a ciliate protozoa predator on microbial communities in pitcher plant (Sarracenia purpurea leaves.

    Directory of Open Access Journals (Sweden)

    Taylor K Paisie

    Full Text Available The aquatic communities found within the water filled leaves of the pitcher plant, Sarracenia purpurea, have a simple trophic structure providing an ideal system to study microscale interactions between protozoan predators and their bacterial prey. In this study, replicate communities were maintained with and without the presence of the bactivorous protozoan, Colpoda steinii, to determine the effects of grazing on microbial communities. Changes in microbial (Archaea and Bacteria community structure were assessed using iTag sequencing of 16S rRNA genes. The microbial communities were similar with and without the protozoan predator, with>1000 species. Of these species, Archaea were negligible, with Bacteria comprising 99.99% of the microbial community. The Proteobacteria and Bacteroidetes were the most dominant phyla. The addition of a protozoan predator did not have a significant effect on microbial evenness nor richness. However, the presence of the protozoan did cause a significant shift in the relative abundances of a number of bacterial species. This suggested that bactivorous protozoan may target specific bacterial species and/or that certain bacterial species have innate mechanisms by which they evade predators. These findings help to elucidate the effect that trophic structure perturbations have on predator prey interactions in microbial systems.

  1. Chitosan matrices modified with carbon nanotubes for use in mediated microbial biosensing

    International Nuclear Information System (INIS)

    Demirkol, D.O.; Timur, S.

    2011-01-01

    We describe a microbial sensor based on Pseudomonas fluorescens cells that was prepared by modifying graphite electrodes with chitosan and carbon nanotubes. Chronoamperometry was performed at +0.3 V in the presence of hexacyanoferrate as a mediator and revealed a good response to glucose which is linear in the 1.0 to 5.0 mM concentration range. Linearity was defined by the equation of y = 102.120x-13.279 (R2 = 0.998) (y shows current density as nA. cm-2 and x shows glucose concentration in mM). The effect of the CNTs on the response was compared to that of electrodes made without CNTs. (author)

  2. Formation of higher plant component microbial community in closed ecological system

    Science.gov (United States)

    Tirranen, L. S.

    2001-07-01

    Closed ecological systems (CES) place at the disposal of a researcher unique possibilities to study the role of microbial communities in individual components and of the entire system. The microbial community of the higher plant component has been found to form depending on specific conditions of the closed ecosystem: length of time the solution is reused, introduction of intrasystem waste water into the nutrient medium, effect of other component of the system, and system closure in terms of gas exchange. The higher plant component formed its own microbial complex different from that formed prior to closure. The microbial complex of vegetable polyculture is more diverse and stable than the monoculture of wheat. The composition of the components' microflora changed, species diversity decreased, individual species of bacteria and fungi whose numbers were not so great before the closure prevailed. Special attention should be paid to phytopathogenic and conditionally pathogenic species of microorganisms potentially hazardous to man or plants and the least controlled in CES. This situation can endanger creation of CES and make conjectural existence of preplanned components, man, specifically, and consequently, of CES as it is.

  3. Microbial activities in forest soils exposed to chronic depositions from a lignite power plant

    Energy Technology Data Exchange (ETDEWEB)

    Klose, S.; Wernecke, K.D.; Makeschin, F. [Technical University of Dresden, Tharandt (Germany)

    2004-12-01

    Atmospheric emissions of fly ash and SO{sub 2} from lignite-fired power plants strongly affect large forest areas in Germany. The impact of different deposition loads on the microbial biomass and enzyme activities was studied at three forest sites (Picea abies (L.) Karst.) along an emission gradient of 3, 6, and 15 km downwind of a coal-fired power plant, representing high, moderate and low emission rates. An additional site at a distance of 3 km from the power plant was chosen to study the influence of forest type on microbial parameters in coniferous forest soils under fly ash and SO{sub 2} emissions. Soil microbial biomass C and N, CO{sub 2} evolved and activities of L-asparaginase, L-glutaminase, beta-glucosidase, acid phosphatase and arylsulfatase (expressed on dry soil and organic C basis) were determined in the forest floor (L, Of and Oh horizon) and mineral top soil (0-10 cm). It is concluded that chronic fly ash depositions decrease litter decomposition by influencing specific microbial and enzymatic processes in forest soils.

  4. Effect of co-existing plant specie on soil microbial activity under heavy metal stress

    International Nuclear Information System (INIS)

    Nwuche, C. O.; Ugoji, E. O.

    2010-01-01

    The influence of plant primary compounds on the activity of soil microbial communities under heavy metal stress was studied in a pot-culture field experiment conducted in a green house. Amaranthus spinosus was cultivated in an agricultural soil previously amended in the laboratory with solutions of different trace elements in two separate treatment modes: singly and in combination. Culture-independent metabolism based indices such as the rate of carbon and nitrogen mineralization, microbial biomass carbon and soil basal respiration were monitored fortnightly over a period of six weeks. Result shows that plant detritus have significant modifying effect on soil microbe-metal interactions. Data on microbial and biochemical processes in the respective mesocosms did not vary from control; not even in mesocosms containing very high concentrations of copper, zinc and nickel. The soil microbial biomass carbon and the rate of carbon and nitrogen cycling were not impeded by the respective metal treatment while the respiration responses increased as a result of increase in metabolic activity of the soil microbes. The plant based substrates enabled the soil microflora to resist high metal contamination because of its tendency to absorb large amounts of inorganic cations.

  5. Plant and bird presence strongly influences the microbial communities in soils of Admiralty Bay, Maritime Antarctica.

    Science.gov (United States)

    Teixeira, Lia C R S; Yeargeau, Etienne; Balieiro, Fabiano C; Piccolo, Marisa C; Peixoto, Raquel S; Greer, Charles W; Rosado, Alexandre S

    2013-01-01

    Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen) and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies), Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific.

  6. Plant and bird presence strongly influences the microbial communities in soils of Admiralty Bay, Maritime Antarctica.

    Directory of Open Access Journals (Sweden)

    Lia C R S Teixeira

    Full Text Available Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies, Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific.

  7. Plant and Bird Presence Strongly Influences the Microbial Communities in Soils of Admiralty Bay, Maritime Antarctica

    Science.gov (United States)

    Teixeira, Lia C. R. S.; Yeargeau, Etienne; Balieiro, Fabiano C.; Piccolo, Marisa C.; Peixoto, Raquel S.; Greer, Charles W.; Rosado, Alexandre S.

    2013-01-01

    Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen) and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies), Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific. PMID:23840411

  8. Habitat Fragmentation can Modulate Drought Effects on the Plant-soil-microbial System in Mediterranean Holm Oak (Quercus ilex) Forests.

    Science.gov (United States)

    Flores-Rentería, Dulce; Curiel Yuste, Jorge; Rincón, Ana; Brearley, Francis Q; García-Gil, Juan Carlos; Valladares, Fernando

    2015-05-01

    Ecological transformations derived from habitat fragmentation have led to increased threats to above-ground biodiversity. However, the impacts of forest fragmentation on soils and their microbial communities are not well understood. We examined the effects of contrasting fragment sizes on the structure and functioning of soil microbial communities from holm oak forest patches in two bioclimatically different regions of Spain. We used a microcosm approach to simulate the annual summer drought cycle and first autumn rainfall (rewetting), evaluating the functional response of a plant-soil-microbial system. Forest fragment size had a significant effect on physicochemical characteristics and microbial functioning of soils, although the diversity and structure of microbial communities were not affected. The response of our plant-soil-microbial systems to drought was strongly modulated by the bioclimatic conditions and the fragment size from where the soils were obtained. Decreasing fragment size modulated the effects of drought by improving local environmental conditions with higher water and nutrient availability. However, this modulation was stronger for plant-soil-microbial systems built with soils from the northern region (colder and wetter) than for those built with soils from the southern region (warmer and drier) suggesting that the responsiveness of the soil-plant-microbial system to habitat fragmentation was strongly dependent on both the physicochemical characteristics of soils and the historical adaptation of soil microbial communities to specific bioclimatic conditions. This interaction challenges our understanding of future global change scenarios in Mediterranean ecosystems involving drier conditions and increased frequency of forest fragmentation.

  9. PLANT GROWTH-PROMOTING MICROBIAL INOCULANT FOR Schizolobium parahyba pv. parahyba

    Directory of Open Access Journals (Sweden)

    Priscila Jane Romano de Oliveira Gonçalves

    2015-08-01

    Full Text Available ABSTRACTSchizolobium parahyba pv. amazonicum (Huber ex Ducke Barneby (paricá occurs naturally in the Amazon and is significant commercial importance due to its rapid growth and excellent performance on cropping systems. The aim of this paper was to evaluate a microbial inoculants such as arbuscular mycorrhiza fungi (AMF and Rhizobium sp. that promote plant growth. The inocula was 10 g of root colonized and spores of Glomus clarum and/or 1 mL of cell suspension (107 CFU/mL of Rhizobium sp. and/or 100 g of chemical fertilizer NPK 20-05-20 per planting hole. The experimental design was complete randomized blocks with five replications and eight treatments (n = 800. Plant height, stem diameter and plant survival were measured. The results were tested for normality and homogeneity of variances and analyzed by ANOVA and Tukey test (p < 0.05. Rhizobium sp and AM fungi showed no effect on plant growth. Environmental factors probably influenced the effectiveness of symbiosis of both microorganisms and plant growth. The chemical fertilizer increased S. parahyba growth. During the first 120 days plants suffered with drought and frost, and at 180 days plants inoculated with microorganism plus chemical fertilizer showed higher survival when compared with control. The results showed that the microbial inoculants used showed an important role on plant survival after high stress conditions, but not in plant growth. Also was concluded that the planting time should be between November to December to avoid the presence of young plants during winter time that is dry and cold.

  10. Microbial Gas Generation Under Expected Waste Isolation Pilot Plant Repository Conditions: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Gillow, J.B.; Francis, A.

    2011-07-01

    Gas generation from the microbial degradation of the organic constituents of transuranic (TRU) waste under conditions expected in the Waste Isolation Pilot Plant (WIPP) was investigated. The biodegradation of mixed cellulosic materials and electron-beam irradiated plastic and rubber materials (polyethylene, polyvinylchloride, hypalon, leaded hypalon, and neoprene) was examined. We evaluated the effects of environmental variables such as initial atmosphere (air or nitrogen), water content (humid ({approx}70% relative humidity, RH) and brine inundated), and nutrient amendments (nitogen phosphate, yeast extract, and excess nitrate) on microbial gas generation. Total gas production was determined by pressure measurement and carbon dioxide (CO{sub 2}) and methane (CH{sub 4}) were analyzed by gas chromatography; cellulose degradation products in solution were analyzed by high-performance liquid chromatography. Microbial populations in the samples were determined by direct microscopy and molecular analysis. The results of this work are summarized.

  11. Microbial Gas Generation Under Expected Waste Isolation Pilot Plant Repository Conditions: Final Report

    International Nuclear Information System (INIS)

    Gillow, J.B.; Francis, A.

    2011-01-01

    Gas generation from the microbial degradation of the organic constituents of transuranic (TRU) waste under conditions expected in the Waste Isolation Pilot Plant (WIPP) was investigated. The biodegradation of mixed cellulosic materials and electron-beam irradiated plastic and rubber materials (polyethylene, polyvinylchloride, hypalon, leaded hypalon, and neoprene) was examined. We evaluated the effects of environmental variables such as initial atmosphere (air or nitrogen), water content (humid (∼70% relative humidity, RH) and brine inundated), and nutrient amendments (nitogen phosphate, yeast extract, and excess nitrate) on microbial gas generation. Total gas production was determined by pressure measurement and carbon dioxide (CO 2 ) and methane (CH 4 ) were analyzed by gas chromatography; cellulose degradation products in solution were analyzed by high-performance liquid chromatography. Microbial populations in the samples were determined by direct microscopy and molecular analysis. The results of this work are summarized.

  12. Aquatic Plant/microbial Filters for Treating Septic Tank Effluent

    Science.gov (United States)

    Wolverton, B. C.

    1988-01-01

    The use of natural biological processes for treating many types of wastewater have been developed by NASA at the John C. Stennis Space Center, NSTL, Mississippi, during the past 15 years. The simplest form of this technology involves the use of aquatic plant/marsh filters for treatment of septic tank effluent. Septic tank effluent from single home units can be treated to advanced secondary levels and beyond by using a 37.2 sq m (400 sq ft) surface area washed gravel filter. This filter is generally 0.3 m (1 ft) deep with a surface cover of approximately 0.15 m (6 in.) of gravel. The plants in this filter are usually aesthetic or ornamental such as calla lily (Zantedeschia aethiopica), canna lily (Canna flaccida), elephant ear (Colocasia esculenta), and water iris (Iris pseudacorus).

  13. Remediation aspect of microbial changes of plant rhizosphere in mercury contaminated soil.

    Science.gov (United States)

    Sas-Nowosielska, Aleksandra; Galimska-Stypa, Regina; Kucharski, Rafał; Zielonka, Urszula; Małkowski, Eugeniusz; Gray, Laymon

    2008-02-01

    Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation, may provide an efficient solution to some mercury contamination problems. This paper presents growth chamber experiments that tested the ability of plant species to stabilize mercury in soil. Several indigenous herbaceous species and Salix viminalis were grown in soil collected from a mercury-contaminated site in southern Poland. The uptake and distribution of mercury by these plants were investigated, and the growth and vitality of the plants through a part of one vegetative cycle were assessed. The highest concentrations of mercury were found at the roots, but translocation to the aerial part also occurred. Most of the plant species tested displayed good growth on mercury contaminated soil and sustained a rich microbial population in the rhizosphere. The microbial populations of root-free soil and rhizosphere soil from all species were also examined. An inverse correlation between the number of sulfur amino acid decomposing bacteria and root mercury content was observed. These results indicate the potential for using some species of plants to treat mercury contaminated soil through stabilization rather than extraction. The present investigation proposes a practical cost-effective temporary solution for phytostabilization of soil with moderate mercury contamination as well as the basis for plant selection.

  14. Metagenomic analysis of an ecological wastewater treatment plant's microbial communities and their potential to metabolize pharmaceuticals.

    Science.gov (United States)

    Balcom, Ian N; Driscoll, Heather; Vincent, James; Leduc, Meagan

    2016-01-01

    Pharmaceuticals and other micropollutants have been detected in drinking water, groundwater, surface water, and soil around the world. Even in locations where wastewater treatment is required, they can be found in drinking water wells, municipal water supplies, and agricultural soils. It is clear conventional wastewater treatment technologies are not meeting the challenge of the mounting pressures on global freshwater supplies. Cost-effective ecological wastewater treatment technologies have been developed in response. To determine whether the removal of micropollutants in ecological wastewater treatment plants (WWTPs) is promoted by the plant-microbe interactions, as has been reported for other recalcitrant xenobiotics, biofilm microbial communities growing on the surfaces of plant roots were profiled by whole metagenome sequencing and compared to the microbial communities residing in the wastewater. In this study, the concentrations of pharmaceuticals and personal care products (PPCPs) were quantified in each treatment tank of the ecological WWTP treating human wastewater at a highway rest stop and visitor center in Vermont. The concentrations of detected PPCPs were substantially greater than values reported for conventional WWTPs likely due to onsite recirculation of wastewater. The greatest reductions in PPCPs concentrations were observed in the anoxic treatment tank where Bacilli dominated the biofilm community. Benzoate degradation was the most abundant xenobiotic metabolic category identified throughout the system. Collectively, the microbial communities residing in the wastewater were taxonomically and metabolically more diverse than the immersed plant root biofilm. However, greater heterogeneity and higher relative abundances of xenobiotic metabolism genes was observed for the root biofilm.

  15. Community analysis of microbial sharing and specialization in a Costa Rican ant-plant-hemipteran symbiosis.

    Science.gov (United States)

    Pringle, Elizabeth G; Moreau, Corrie S

    2017-03-15

    Ants have long been renowned for their intimate mutualisms with trophobionts and plants and more recently appreciated for their widespread and diverse interactions with microbes. An open question in symbiosis research is the extent to which environmental influence, including the exchange of microbes between interacting macroorganisms, affects the composition and function of symbiotic microbial communities. Here we approached this question by investigating symbiosis within symbiosis. Ant-plant-hemipteran symbioses are hallmarks of tropical ecosystems that produce persistent close contact among the macroorganism partners, which then have substantial opportunity to exchange symbiotic microbes. We used metabarcoding and quantitative PCR to examine community structure of both bacteria and fungi in a Neotropical ant-plant-scale-insect symbiosis. Both phloem-feeding scale insects and honeydew-feeding ants make use of microbial symbionts to subsist on phloem-derived diets of suboptimal nutritional quality. Among the insects examined here, Cephalotes ants and pseudococcid scale insects had the most specialized bacterial symbionts, whereas Azteca ants appeared to consume or associate with more fungi than bacteria, and coccid scale insects were associated with unusually diverse bacterial communities. Despite these differences, we also identified apparent sharing of microbes among the macro-partners. How microbial exchanges affect the consumer-resource interactions that shape the evolution of ant-plant-hemipteran symbioses is an exciting question that awaits further research. © 2017 The Author(s).

  16. Annual Removal of Aboveground Plant Biomass Alters Soil Microbial Responses to Warming

    Directory of Open Access Journals (Sweden)

    Kai Xue

    2016-09-01

    Full Text Available Clipping (i.e., harvesting aboveground plant biomass is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened.

  17. Plant community mediation of ecosystem responses to global change factors

    Science.gov (United States)

    Churchill, A. C.

    2017-12-01

    Human alteration of the numerous environmental drivers affecting ecosystem processes is unprecedented in the last century, including changes in climate regimes and rapid increases in the availability of biologically active nitrogen (N). Plant communities may offer stabilizing or amplifying feedbacks mediating potential ecosystem responses to these alterations, and my research seeks to examine the conditions associated with when plant feedbacks are important for ecosystem change. My dissertation research focused on the unintended consequences of N deposition into natural landscapes, including alpine ecosystems which are particularly susceptible to adverse environmental impacts. In particular, I examined alpine plant and soil responses to N deposition 1) across multiple spatial scales throughout the Southern Rocky Mountains, 2) among diverse plant communities associated with unique environmental conditions common in the alpine of this region, and 3) among ecosystem pools of N contributing to stabilization of N inputs within those communities. I found that communities responded to inputs of N differently, often associated with traits of dominant plant species but these responses were intimately linked with the abiotic conditions of each independent community. Even so, statistical models predicting metrics of N processing in the alpine were improved by encompassing both abiotic and biotic components of the main community types.

  18. Good Manufacturing Practices and Microbial Contamination Sources in Orange Fleshed Sweet Potato Puree Processing Plant in Kenya

    OpenAIRE

    Malavi, Derick Nyabera; Muzhingi, Tawanda; Abong’, George Ooko

    2018-01-01

    Limited information exists on the status of hygiene and probable sources of microbial contamination in Orange Fleshed Sweet Potato (OFSP) puree processing. The current study is aimed at determining the level of compliance to Good Manufacturing Practices (GMPs), hygiene, and microbial quality in OFSP puree processing plant in Kenya. Intensive observation and interviews using a structured GMPs checklist, environmental sampling, and microbial analysis by standard microbiological methods were use...

  19. New method for characterizing electron mediators in microbial systems using a thin-layer twin-working electrode cell.

    Science.gov (United States)

    Hassan, Md Mahamudul; Cheng, Ka Yu; Ho, Goen; Cord-Ruwisch, Ralf

    2017-01-15

    Microbial biofilms are significant ecosystems where the existence of redox gradients drive electron transfer often via soluble electron mediators. This study describes the use of two interfacing working electrodes (WEs) to simulate redox gradients within close proximity (250µm) for the detection and quantification of electron mediators. By using a common counter and reference electrode, the potentials of the two WEs were independently controlled to maintain a suitable "voltage window", which enabled simultaneous oxidation and reduction of electron mediators as evidenced by the concurrent anodic and cathodic currents, respectively. To validate the method, the electrochemical properties of different mediators (hexacyanoferrate, HCF, riboflavin, RF) were characterized by stepwise shifting the "voltage window" (ranging between 25 and 200mV) within a range of potentials after steady equilibrium current of both WEs was established. The resulting differences in electrical currents between the two WEs were recorded across a defined potential spectrum (between -1V and +0.5V vs. Ag/AgCl). Results indicated that the technique enabled identification (by the distinct peak locations at the potential scale) and quantification (by the peak of current) of the mediators for individual species as well as in an aqueous mixture. It enabled a precise determination of mid-potentials of the externally added mediators (HCF, RF) and mediators produced by pyocyanin-producing Pseudomonas aeruginosa (WACC 91) culture. The twin working electrode described is particularly suitable for studying mediator-dependent microbial electron transfer processes or simulating redox gradients as they exist in microbial biofilms. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Microbial mineralization processes in Antarctic soils and on plant material

    International Nuclear Information System (INIS)

    Boelter, M.

    1991-01-01

    Soil samples and different plant material from the maritime and continental Antarctic were analyzed for their actual and potential respiration by different methods: total CO 2 -evolution, biological oxygen demand and use of 14C-labeled glucose which may serve as a model for dissolved organic carbohydrates. Since these methods are argued to indicate the mineralization of different fractions of the total organic material by different actual populations, a comparison between the data from these techniques is carried out with regard to their contributions of the total organic matter debris in these environments. The part of respired material calculated from 14C-studies may contribute to nearly 90% of the metabolized material. Results show that the individual fractions differ significantly with respect to the parent material. There are several aspects which have to be taken into account when looking at these data: the original content of water; the contents of dissolved and particulate carbohydrates; and, other edaphic factors. Of special interest is the overall respiration of plant material (mainly lichens) which is strongly influenced by the bacterial respiration of dissolved carbohydrates, probably by ongrowing organisms due to their efficiency in using dissolved organic matter. In terms of respiratory activity, the (bacterial) respiration of glucose may contribute to more than 50% of the total CO 2 -evolution. This influences considerably the modeling of overall respiration of plant material in those environments where close interactions between different parts of the system are very important for their life strategy. Further, the bacterial part may be an overlooked part of metabolic rates in Antarctic lichens

  1. Dynamics of microbial communities during decomposition of litter from pioneering plants in initial soil ecosystems

    Directory of Open Access Journals (Sweden)

    J. Esperschütz

    2013-07-01

    Full Text Available In initial ecosystems, concentrations of all macro- and micronutrients can be considered as extremely low. Plant litter therefore strongly influences the development of a degrader's food web and is an important source for C and N input into soil in such ecosystems. In the present study, a 13C litter decomposition field experiment was performed for 30 weeks in initial soils from a post-mining area near the city of Cottbus (Germany. Two of this region's dominant but contrasting pioneering plant species (Lotus corniculatus L. and Calamagrostis epigejos L. were chosen to investigate the effects of litter quality on the litter decomposing microbial food web in initially nutrient-poor substrates. The results clearly indicate the importance of litter quality, as indicated by its N content, its bioavailability for the degradation process and the development of microbial communities in the detritusphere and soil. The degradation of the L. corniculatus litter, which had a low C / N ratio, was fast and showed pronounced changes in the microbial community structure 1–4 weeks after litter addition. The degradation of the C. epigejos litter material was slow and microbial community changes mainly occurred between 4 and 30 weeks after litter addition to the soil. However, for both litter materials a clear indication of the importance of fungi for the degradation process was observed both in terms of fungal abundance and activity (13C incorporation activity

  2. Comparative mutagenesis of plant flavonoids in microbial systems

    Energy Technology Data Exchange (ETDEWEB)

    Hardigree, A.A.; Epler, J.L.

    1978-01-01

    The plant flavonoids quercetin (3,5,7,3',4'-pentahydroxyflavone), morin (3,5,7,2'4'-pentahydroxyflavone), kaempferol (3,5,7,4'tetrahydroxyflavone), chrysin (5,7-dihydroxyflavone), fisetin (3,7,3',4'-tetrahydroxyflavone), myricetin (3,5,7,3',4',5'-hexahydroxyflavone), myricitrin (myricetin-3-rhamnoside), hesperetin (3',5,7-trihydroxy-4'-methoxyflavanone), quercitrin (quercetin-3-L-rhamnoside), rutin (quercetin-3-rhamnosylglucoside or quercetin-3-rutinoside), and hesperidin (hesperetin-7-rutinoside) have been assayed for mutagenicity in the Salmonella/microsomal activation system. Quercetin, morin, kaempferol, fisetin, myricetin, quercitrin and rutin were mutagenic in the histidine reversion system with the frameshift strain TA98. The flavonols quercetin and myricetin are mutagenic without metabolic activation, although more effective when a rat liver microsomal preparation (S-9) is included; all others require metabolic activation. Flavonoids are common constituents of higher plants, with extensive medical uses. In addition to pure compounds, we have examined crude extracts of tobacco (snuff) and extracts from commonly available nutritional supplements containing rutin. Mutagenic activity can be detected and is correlated with the flavonoid content.

  3. Emerging functions of multi-protein complex Mediator with special emphasis on plants.

    Science.gov (United States)

    Malik, Naveen; Agarwal, Pinky; Tyagi, Akhilesh

    2017-10-01

    Mediator is a multi-subunit protein complex which is involved in transcriptional regulation in yeast and other eukaryotes. As a co-activator, it connects information from transcriptional activators/repressors to transcriptional machinery including RNA polymerase II and general transcription factors. It is not only involved in transcription initiation but also has important roles to play in transcription elongation and termination. Functional attributes of different Mediator subunits have been largely defined in yeast and mammalian systems earlier, while such studies in plants have gained momentum recently. Mediator regulates various processes related to plant development and is also involved in biotic and abiotic stress response. Thus, plant Mediator, like yeast and mammalian Mediator complex, is indispensable for plant growth and survival. Interaction of its multiple subunits with other regulatory proteins and their ectopic expression or knockdown in model plant like Arabidopsis and certain crop plants are paving the way to biochemical analysis and unravel molecular mechanisms of action of Mediator in plants.

  4. Rhizosphere effect of colonizer plant species on the development of soil microbial community during primary succession on postmining sites

    Energy Technology Data Exchange (ETDEWEB)

    Elhottova, D.; Kristufek, V.; Maly, S.; Frouz, J. [Academy of Sciences of the Czech Republic, Ceske Budejovice (Czech Republic). Inst. for Soil Biology

    2009-07-01

    The impact of pioneer plant species Tussilago farfara on structural, functional, and growth characterization of microbial community colonizing the spoil colliery substrate was studied in a laboratory microcosm experiment. Microcosms consisting of spoil substrate (0.7 dm{sup 3} of tertiary alkaline clay sediment from Sokolov brown-coal mine area) from a pioneer site (without vegetation, 5 years after heaping) were cultivated in a greenhouse with one plant of this species. Plant roots substantially increased microbial diversity and biomass after one season (7 months) of cultivation. Roots influenced the microbial community and had nearly twice the size, higher growth, and metabolic potential in comparison to the control. The development of microbial specialists improves the plant nutrient status. Bacterial nitrogen (N{sub 2}) fixators (Bradyrhizobium japonicum, Rhizobium radiobacter) and arbuscular mycorrhizal fungi were confirmed in the rhizosphere of Tussilago farfara.

  5. Plant Clonal Integration Mediates the Horizontal Redistribution of Soil Resources, Benefiting Neighboring Plants.

    Science.gov (United States)

    Ye, Xue-Hua; Zhang, Ya-Lin; Liu, Zhi-Lan; Gao, Shu-Qin; Song, Yao-Bin; Liu, Feng-Hong; Dong, Ming

    2016-01-01

    Resources such as water taken up by plants can be released into soils through hydraulic redistribution and can also be translocated by clonal integration within a plant clonal network. We hypothesized that the resources from one (donor) microsite could be translocated within a clonal network, released into different (recipient) microsites and subsequently used by neighbor plants in the recipient microsite. To test these hypotheses, we conducted two experiments in which connected and disconnected ramet pairs of Potentilla anserina were grown under both homogeneous and heterogeneous water regimes, with seedlings of Artemisia ordosica as neighbors. The isotopes [(15)N] and deuterium were used to trace the translocation of nitrogen and water, respectively, within the clonal network. The water and nitrogen taken up by P. anserina ramets in the donor microsite were translocated into the connected ramets in the recipient microsites. Most notably, portions of the translocated water and nitrogen were released into the recipient microsite and were used by the neighboring A. ordosica, which increased growth of the neighboring A. ordosica significantly. Therefore, our hypotheses were supported, and plant clonal integration mediated the horizontal hydraulic redistribution of resources, thus benefiting neighboring plants. Such a plant clonal integration-mediated resource redistribution in horizontal space may have substantial effects on the interspecific relations and composition of the community and consequently on ecosystem processes.

  6. Plant clonal integration mediates the horizontal redistribution of soil resources, benefiting neighbouring plants

    Directory of Open Access Journals (Sweden)

    Xuehua eYe

    2016-02-01

    Full Text Available Resources such as water taken up by plants can be released into soils through hydraulic redistribution and can also be translocated by clonal integration within a plant clonal network. We hypothesized that the resources from one (donor microsite could be translocated within a clonal network, released into different (recipient microsites and subsequently used by neighbour plants in the recipient microsite. To test these hypotheses, we conducted two experiments in which connected and disconnected ramet pairs of Potentilla anserina were grown under both homogeneous and heterogeneous water regimes, with seedlings of Artemisia ordosica as neighbours. The isotopes [15N] and deuterium were used to trace the translocation of nitrogen and water, respectively, within the clonal network. The water and nitrogen taken up by P. anserina ramets in the donor microsite were translocated into the connected ramets in the recipient microsites. Most notably, portions of the translocated water and nitrogen were released into the recipient microsite and were used by the neighbouring A. ordosica, which increased growth of the neighbouring A. ordosica significantly. Therefore, our hypotheses were supported, and plant clonal integration mediated the horizontal hydraulic redistribution of resources, thus benefiting neighbouring plants. Such a plant clonal integration-mediated resource redistribution in horizontal space may have substantial effects on the interspecific relations and composition of the community and consequently on ecosystem processes.

  7. Plant species and functional group effects on abiotic and microbial soil properties and plant-soil feedback responses in two grasslands

    NARCIS (Netherlands)

    Bezemer, T.M.; Lawson, C.S.; Hedlund, K.; Edwards, A.R.; Brooks, A.J.; Igual, J.M.; Mortimer, S.R.; Putten, van der W.H.

    2006-01-01

    1 Plant species differ in their capacity to influence soil organic matter, soil nutrient availability and the composition of soil microbial communities. Their influences on soil properties result in net positive or negative feedback effects, which influence plant performance and plant community

  8. In silico Characterization of Plant and Microbial Antifreeze Proteins

    Directory of Open Access Journals (Sweden)

    Abdul Mohin Sajib

    2012-12-01

    Full Text Available Antifreeze proteins (AFPs are class of proteins that protect organisms from the damage caused by freezing through their ability to inhibit ice growth and effectively lower the temperature at which water freezes. In this study, a total of 25 antifreeze proteins were selected from four different sources (plant, bacteria and fungus where they represent distinct physicochemical and structural features. Several Physico-chemical properties such as grand average hydropathy (GRAVY, aliphatic index (AI, extinction coefficient (EC, isolelectric point (pI, and instability index (II were computed. S-S bridges and secondary structures were analyzed using CYS_REC and SOPMA programs respectively. The three dimensional structure of Antifreeze proteins is predicted by using three homology modelling server Geno3D, Swiss-model and CPHmodels. These models were evaluated with PROCHECK, What If, and ProSA programs. Model visualization and analysis was done with Pymol. These structures will provide a good foundation for functional analysis of experimentally derived crystal structures.

  9. Ligand Receptor-Mediated Regulation of Growth in Plants.

    Science.gov (United States)

    Haruta, Miyoshi; Sussman, Michael R

    2017-01-01

    Growth and development of multicellular organisms are coordinately regulated by various signaling pathways involving the communication of inter- and intracellular components. To form the appropriate body patterns, cellular growth and development are modulated by either stimulating or inhibiting these pathways. Hormones and second messengers help to mediate the initiation and/or interaction of the various signaling pathways in all complex multicellular eukaryotes. In plants, hormones include small organic molecules, as well as larger peptides and small proteins, which, as in animals, act as ligands and interact with receptor proteins to trigger rapid biochemical changes and induce the intracellular transcriptional and long-term physiological responses. During the past two decades, the availability of genetic and genomic resources in the model plant species, Arabidopsis thaliana, has greatly helped in the discovery of plant hormone receptors and the components of signal transduction pathways and mechanisms used by these immobile but highly complex organisms. Recently, it has been shown that two of the most important plant hormones, auxin and abscisic acid (ABA), act through signaling pathways that have not yet been recognized in animals. For example, auxins stimulate cell elongation by bringing negatively acting transcriptional repressor proteins to the proteasome to be degraded, thus unleashing the gene expression program required for increasing cell size. The "dormancy" inducing hormone, ABA, binds to soluble receptor proteins and inhibits a specific class of protein phosphatases (PP2C), which activates phosphorylation signaling leading to transcriptional changes needed for the desiccation of the seeds prior to entering dormancy. While these two hormone receptors have no known animal counterparts, there are also many similarities between animal and plant signaling pathways. For example, in plants, the largest single gene family in the genome is the protein kinase

  10. Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji-Won; Rondinone, Adam Justin; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

    2017-09-19

    The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component comprising at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

  11. Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

    Science.gov (United States)

    Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji Won; Rondinone, Adam J.; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

    2014-06-24

    The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component containing at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

  12. Resilience of roof-top Plant-Microbial Fuel Cells during Dutch winter

    International Nuclear Information System (INIS)

    Helder, Marjolein; Strik, David P.B.T.B.; Timmers, Ruud A.; Raes, Sanne M.T.; Hamelers, Hubertus V.M.; Buisman, Cees J.N.

    2013-01-01

    The Plant-Microbial Fuel Cell (P-MFC) is in theory a technology that could produce sustainable electricity continuously. We operated two designs of the P-MFC under natural roof-top conditions in the Netherlands for 221 days, including winter, to test its resilience. Current and power densities are not stable under outdoor conditions. Highest obtained power density was 88 mW m −2 , which is lower than was achieved under lab-conditions (440 mW m −2 ). Cathode potential was in our case dependent on solar radiation, due to algae growth, making the power output dependent on a diurnal cycle. The anode potential of the P-MFC is influenced by temperature, leading to a decrease in electricity production during low temperature periods and no electricity production during frost periods. Due to freezing of the roots, plants did not survive winter and therefore did not regrow in spring. In order to make a sustainable, stable and weather independent electricity production system of the P-MFC attention should be paid to improving cathode stability and cold insulation of anode and cathode. Only when power output of the Plant-Microbial Fuel Cell can be increased under outdoor conditions and plant-vitality can be sustained over winter, it can be a promising sustainable electricity technology for the future. -- Highlights: ► Plant-Microbial Fuel Cells (P-MFCs) produce sustainable electricity under outdoor conditions. ► During frost periods no electricity is produced in P-MFCs. ► Cathodes limit performance of P-MFCs under outdoor conditions. ► Spartina anglica in P-MFCs does not survive on a roof-top during Dutch winter. ► The P-MFC needs optimization of power output to be a promising sustainable electricity technology

  13. Tracking dynamics of plant biomass composting by changes in substrate structure, microbial community, and enzyme activity

    Directory of Open Access Journals (Sweden)

    Wei Hui

    2012-04-01

    Full Text Available Abstract Background Understanding the dynamics of the microbial communities that, along with their secreted enzymes, are involved in the natural process of biomass composting may hold the key to breaking the major bottleneck in biomass-to-biofuels conversion technology, which is the still-costly deconstruction of polymeric biomass carbohydrates to fermentable sugars. However, the complexity of both the structure of plant biomass and its counterpart microbial degradation communities makes it difficult to investigate the composting process. Results In this study, a composter was set up with a mix of yellow poplar (Liriodendron tulipifera wood-chips and mown lawn grass clippings (85:15 in dry-weight and used as a model system. The microbial rDNA abundance data obtained from analyzing weekly-withdrawn composted samples suggested population-shifts from bacteria-dominated to fungus-dominated communities. Further analyses by an array of optical microscopic, transcriptional and enzyme-activity techniques yielded correlated results, suggesting that such population shifts occurred along with early removal of hemicellulose followed by attack on the consequently uncovered cellulose as the composting progressed. Conclusion The observed shifts in dominance by representative microbial groups, along with the observed different patterns in the gene expression and enzymatic activities between cellulases, hemicellulases, and ligninases during the composting process, provide new perspectives for biomass-derived biotechnology such as consolidated bioprocessing (CBP and solid-state fermentation for the production of cellulolytic enzymes and biofuels.

  14. Tracking dynamics of plant biomass composting by changes in substrate structure, microbial community, and enzyme activity

    Science.gov (United States)

    2012-01-01

    Background Understanding the dynamics of the microbial communities that, along with their secreted enzymes, are involved in the natural process of biomass composting may hold the key to breaking the major bottleneck in biomass-to-biofuels conversion technology, which is the still-costly deconstruction of polymeric biomass carbohydrates to fermentable sugars. However, the complexity of both the structure of plant biomass and its counterpart microbial degradation communities makes it difficult to investigate the composting process. Results In this study, a composter was set up with a mix of yellow poplar (Liriodendron tulipifera) wood-chips and mown lawn grass clippings (85:15 in dry-weight) and used as a model system. The microbial rDNA abundance data obtained from analyzing weekly-withdrawn composted samples suggested population-shifts from bacteria-dominated to fungus-dominated communities. Further analyses by an array of optical microscopic, transcriptional and enzyme-activity techniques yielded correlated results, suggesting that such population shifts occurred along with early removal of hemicellulose followed by attack on the consequently uncovered cellulose as the composting progressed. Conclusion The observed shifts in dominance by representative microbial groups, along with the observed different patterns in the gene expression and enzymatic activities between cellulases, hemicellulases, and ligninases during the composting process, provide new perspectives for biomass-derived biotechnology such as consolidated bioprocessing (CBP) and solid-state fermentation for the production of cellulolytic enzymes and biofuels. PMID:22490508

  15. Gold nanoparticles produced in situ mediate bioelectricity and hydrogen production in a microbial fuel cell by quantized capacitance charging.

    Science.gov (United States)

    Kalathil, Shafeer; Lee, Jintae; Cho, Moo Hwan

    2013-02-01

    Oppan quantized style: By adding a gold precursor at its cathode, a microbial fuel cell (MFC) is demonstrated to form gold nanoparticles that can be used to simultaneously produce bioelectricity and hydrogen. By exploiting the quantized capacitance charging effect, the gold nanoparticles mediate the production of hydrogen without requiring an external power supply, while the MFC produces a stable power density. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Contribution of above- and below-ground plant traits to the structure and function of grassland soil microbial communities.

    Science.gov (United States)

    Legay, N; Baxendale, C; Grigulis, K; Krainer, U; Kastl, E; Schloter, M; Bardgett, R D; Arnoldi, C; Bahn, M; Dumont, M; Poly, F; Pommier, T; Clément, J C; Lavorel, S

    2014-10-01

    Abiotic properties of soil are known to be major drivers of the microbial community within it. Our understanding of how soil microbial properties are related to the functional structure and diversity of plant communities, however, is limited and largely restricted to above-ground plant traits, with the role of below-ground traits being poorly understood. This study investigated the relative contributions of soil abiotic properties and plant traits, both above-ground and below-ground, to variations in microbial processes involved in grassland nitrogen turnover. In mountain grasslands distributed across three European sites, a correlative approach was used to examine the role of a large range of plant functional traits and soil abiotic factors on microbial variables, including gene abundance of nitrifiers and denitrifiers and their potential activities. Direct effects of soil abiotic parameters were found to have the most significant influence on the microbial groups investigated. Indirect pathways via plant functional traits contributed substantially to explaining the relative abundance of fungi and bacteria and gene abundances of the investigated microbial communities, while they explained little of the variance in microbial activities. Gene abundances of nitrifiers and denitrifiers were most strongly related to below-ground plant traits, suggesting that they were the most relevant traits for explaining variation in community structure and abundances of soil microbes involved in nitrification and denitrification. The results suggest that consideration of plant traits, and especially below-ground traits, increases our ability to describe variation in the abundances and the functional characteristics of microbial communities in grassland soils. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Soil Microbial Communities and Gas Dynamics Contribute to Arbuscular Mycorrhizal Nitrogen Uptake and Transfer to Plants

    Science.gov (United States)

    Hestrin, R.; Harrison, M. J.; Lehmann, J.

    2016-12-01

    Arbuscular mycorrhizal fungi (AMF) associate with most terrestrial plants and influence ecosystem ecology and biogeochemistry. There is evidence that AMF play a role in soil nitrogen cycling, in part by taking up nitrogen and transferring it to plants. However, many aspects of this process are poorly understood, including the factors that control fungal access to nitrogen stored in soil organic matter. In this study, we used stable isotopes and root exclusion to track nitrogen movement from organic matter into AMF and host plants. AMF significantly increased total plant biomass and nitrogen content, but both AMF and other soil microbes seemed to compete with plants for nitrogen. Surprisingly, gaseous nitrogen species also contributed significantly to plant nitrogen content under alkaline soil conditions. Our current experiments investigate whether free-living microbial communities that have evolved under a soil nitrogen gradient influence AMF access to soil organic nitrogen and subsequent nitrogen transfer to plants. This research links interactions between plants, mycorrhizal symbionts, and free-living microbes with terrestrial carbon and nitrogen dynamics.

  18. Interactions between plant and rhizosphere microbial communities in a metalliferous soil

    International Nuclear Information System (INIS)

    Epelde, Lur; Becerril, Jose M.; Barrutia, Oihana; Gonzalez-Oreja, Jose A.; Garbisu, Carlos

    2010-01-01

    In the present work, the relationships between plant consortia, consisting of 1-4 metallicolous pseudometallophytes with different metal-tolerance strategies (Thlaspi caerulescens: hyperaccumulator; Jasione montana: accumulator; Rumex acetosa: indicator; Festuca rubra: excluder), and their rhizosphere microbial communities were studied in a mine soil polluted with high levels of Cd, Pb and Zn. Physiological response and phytoremediation potential of the studied pseudometallophytes were also investigated. The studied metallicolous populations are tolerant to metal pollution and offer potential for the development of phytoextraction and phytostabilization technologies. T. caerulescens appears very tolerant to metal stress and most suitable for metal phytoextraction; the other three species enhance soil functionality. Soil microbial properties had a stronger effect on plant biomass rather than the other way around (35.2% versus 14.9%). An ecological understanding of how contaminants, ecosystem functions and biological communities interact in the long-term is needed for proper management of these fragile metalliferous ecosystems. - Rhizosphere microbial communities in highly polluted mine soils are determinant for the growth of pseudometallophytes.

  19. Microbial Removal Efficiency of UV in Tehran Shahid Mahallati Wastewater Treatment Plant

    Directory of Open Access Journals (Sweden)

    Reza Dabbagh

    2009-03-01

    Full Text Available Shahid Mahallati Wastewater Treatment Plant was selected for installing a UV disinfection unit to investigate its germicidal effect on microbial removal. Low pressure mercury lamps were used to generate germicidal ultraviolet radiation (UV-C. The UV system was operated over a period of 6 months that included both warm and cold seasons. A maximum UV disinfection efficiency of 14.4m3/h was recorded for the system on the basis of design criteria within turbidity ranges of 9 to 32 NTU. The minimum UV dose applied in the UV unit was 40000 µW.s/cm2 and the highest bacterial density in the UV unit influent was 5.6*107. Effluent total coliform or fecal coliform enumeration after exposure to UV ray showed the microbial density decreasing from four logs, or 99.99%, to as high as six logs, or 99.9999% removal efficiency, under different conditions. Effluent microbial densities in terms of total and fecal coliforms were below 1000MPN/100mL and 400MPN/100mL, respectively. These values comply with wastewater discharge or agricultural irrigation standards according to Iran Department of Environment. From our results, it is concluded that UV disinfection may be an effective technique for wastewater disinfection in Iranian wastewater treatment plants.

  20. Interactions between plant and rhizosphere microbial communities in a metalliferous soil

    Energy Technology Data Exchange (ETDEWEB)

    Epelde, Lur [NEIKER-Tecnalia, Department of Ecosystems, c/Berreaga 1, E-48160 Derio (Spain); Becerril, Jose M.; Barrutia, Oihana [Department of Plant Biology and Ecology, University of the Basque Country, UPV/EHU, P.O. Box 644, E-48080 Bilbao (Spain); Gonzalez-Oreja, Jose A. [NEIKER-Tecnalia, Department of Ecosystems, c/Berreaga 1, E-48160 Derio (Spain); Garbisu, Carlos, E-mail: cgarbisu@neiker.ne [NEIKER-Tecnalia, Department of Ecosystems, c/Berreaga 1, E-48160 Derio (Spain)

    2010-05-15

    In the present work, the relationships between plant consortia, consisting of 1-4 metallicolous pseudometallophytes with different metal-tolerance strategies (Thlaspi caerulescens: hyperaccumulator; Jasione montana: accumulator; Rumex acetosa: indicator; Festuca rubra: excluder), and their rhizosphere microbial communities were studied in a mine soil polluted with high levels of Cd, Pb and Zn. Physiological response and phytoremediation potential of the studied pseudometallophytes were also investigated. The studied metallicolous populations are tolerant to metal pollution and offer potential for the development of phytoextraction and phytostabilization technologies. T. caerulescens appears very tolerant to metal stress and most suitable for metal phytoextraction; the other three species enhance soil functionality. Soil microbial properties had a stronger effect on plant biomass rather than the other way around (35.2% versus 14.9%). An ecological understanding of how contaminants, ecosystem functions and biological communities interact in the long-term is needed for proper management of these fragile metalliferous ecosystems. - Rhizosphere microbial communities in highly polluted mine soils are determinant for the growth of pseudometallophytes.

  1. Variable effects of plant colonization on black slate uptake into microbial PLFAs

    Science.gov (United States)

    Seifert, Anne-Gret; Trumbore, Susan; Xu, Xiaomei; Zhang, Dachung; Gleixner, Gerd

    2013-04-01

    Microbial degradation of carbon derived from black shale and slate has been shown in vitro. However, in natural settings where other labile carbon sources are likely to exist, this has not been previously demonstrated. We investigated the uptake of ancient carbon derived from slate weathering and from recently photosynthesised organic matter by different groups of microorganisms. Therefore we isolated microbial biomarkers (phospholipid fatty acids, PLFAs) from black slates collected at a chronosequence of waste piles which differed in age and vegetation cover. We quantified the amount of PLFAs and performed stable isotope and radiocarbon measurements on individual or grouped PLFAs to quantify the fraction of slate derived carbon. We used black slate from a pile heaped in the 1950s with either uncovered black slate material (bare site) or material slightly colonized by small plants (greened site) and from a forested leaching pile (forested site) used for alum-mining in the 19th century. Colonization by plants influenced the amount and composition of the microbial community. Greater amounts of PLFAs (5410 ng PLFA/g dw) were extracted from slate sampled at the forested site as opposed to the bare site (960 ng PLFAs/g dw) or the greened (annual grasses and mosses) rock waste pile (1050 ng PLFAs/g dw). We found the highest proportion of PLFAs representing Gram-negative bacteria on the forested site and the highest proportion of PLFAs representing Gram-positive bacteria on the bare site. The fungal PLFA was most abundant at the greened site. Sites with less plant colonization (bare and greened site) tended to have more depleted δ13C values compared to the forested site. Radiocarbon measurements on PLFAs indicated that fungi and Gram-positive bacteria were best adapted to black slate carbon uptake. In the fungal PLFA (combined bare and greened waste pile sample) and in PLFAs of Gram-positive bacteria (greened site) we measured 39.7% and 28.9% ancient carbon uptake

  2. Can soil microbial diversity influence plant metabolites and life history traits of a rhizophagous insect? A demonstration in oilseed rape.

    Science.gov (United States)

    Lachaise, Tom; Ourry, Morgane; Lebreton, Lionel; Guillerm-Erckelboudt, Anne-Yvonne; Linglin, Juliette; Paty, Chrystelle; Chaminade, Valérie; Marnet, Nathalie; Aubert, Julie; Poinsot, Denis; Cortesero, Anne-Marie; Mougel, Christophe

    2017-12-01

    Interactions between plants and phytophagous insects play an important part in shaping the biochemical composition of plants. Reciprocally plant metabolites can influence major life history traits in these insects and largely contribute to their fitness. Plant rhizospheric microorganisms are an important biotic factor modulating plant metabolites and adaptation to stress. While plant-insects or plant-microorganisms interactions and their consequences on the plant metabolite signature are well-documented, the impact of soil microbial communities on plant defenses against phytophagous insects remains poorly known. In this study, we used oilseed rape (Brassica napus) and the cabbage root fly (Delia radicum) as biological models to tackle this question. Even though D. radicum is a belowground herbivore as a larva, its adult life history traits depend on aboveground signals. We therefore tested whether soil microbial diversity influenced emergence rate and fitness but also fly oviposition behavior, and tried to link possible effects to modifications in leaf and root metabolites. Through a removal-recolonization experiment, 3 soil microbial modalities ("high," "medium," "low") were established and assessed through amplicon sequencing of 16S and 18S ribosomal RNA genes. The "medium" modality in the rhizosphere significantly improved insect development traits. Plant-microorganism interactions were marginally associated to modulations of root metabolites profiles, which could partly explain these results. We highlighted the potential role of plant-microbial interaction in plant defenses against Delia radicum. Rhizospheric microbial communities must be taken into account when analyzing plant defenses against herbivores, being either below or aboveground. © 2017 Institute of Zoology, Chinese Academy of Sciences.

  3. Secreted pitfall-trap fluid of carnivorous Nepenthes plants is unsuitable for microbial growth.

    Science.gov (United States)

    Buch, Franziska; Rott, Matthias; Rottloff, Sandy; Paetz, Christian; Hilke, Ines; Raessler, Michael; Mithöfer, Axel

    2013-03-01

    Carnivorous plants of the genus Nepenthes possess modified leaves that form pitfall traps in order to capture prey, mainly arthropods, to make additional nutrients available for the plant. These pitchers contain a digestive fluid due to the presence of hydrolytic enzymes. In this study, the composition of the digestive fluid was further analysed with regard to mineral nutrients and low molecular-weight compounds. A potential contribution of microbes to the composition of pitcher fluid was investigated. Fluids from closed pitchers were harvested and analysed for mineral nutrients using analytical techniques based on ion-chromatography and inductively coupled plasma-optical emission spectroscopy. Secondary metabolites were identified by a combination of LC-MS and NMR. The presence of bacteria in the pitcher fluid was investigated by PCR of 16S-rRNA genes. Growth analyses of bacteria and yeast were performed in vitro with harvested pitcher fluid and in vivo within pitchers with injected microbes. The pitcher fluid from closed pitchers was found to be primarily an approx. 25-mm KCl solution, which is free of bacteria and unsuitable for microbial growth probably due to the lack of essential mineral nutrients such as phosphate and inorganic nitrogen. The fluid also contained antimicrobial naphthoquinones, plumbagin and 7-methyl-juglone, and defensive proteins such as the thaumatin-like protein. Challenging with bacteria or yeast caused bactericide as well as fungistatic properties in the fluid. Our results reveal that Nepenthes pitcher fluids represent a dynamic system that is able to react to the presence of microbes. The secreted liquid of closed and freshly opened Nepenthes pitchers is exclusively plant-derived. It is unsuitable to serve as an environment for microbial growth. Thus, Nepenthes plants can avoid and control, at least to some extent, the microbial colonization of their pitfall traps and, thereby, reduce the need to vie with microbes for the prey

  4. Microbial Community Activity And Plant Biomass Are Insensitive To Passive Warming In A Semiarid Ecosystem

    Science.gov (United States)

    Espinosa, N. J.; Fehmi, J. S.; Rasmussen, C.; Gallery, R. E.

    2017-12-01

    Soil microorganisms drive biogeochemical and nutrient cycling through the production of extracellular enzymes that facilitate organic matter decomposition and the flux of large amounts of carbon dioxide to the atmosphere. Although dryland ecosystems occupy over 40% of land cover and are projected to expand due to climate change, much of our current understanding of these processes comes from mesic temperate ecosystems. Understanding the responses of these globally predominant dryland ecosystems is therefore important yet complicated by co-occurring environmental changes. For example, the widespread and pervasive transition from grass to woody dominated landscapes is changing the hydrology, fire regimes, and carbon storage potential of semiarid ecosystems. In this study, we used a novel passive method of warming to conduct a warming experiment with added plant debris as either woodchip or biochar, to simulate different long-term carbon additions that accompany woody plant encroachment in semiarid ecosystems. The response of heterotrophic respiration, plant biomass, and microbial activity was monitored bi-annually. We hypothesized that the temperature manipulations would have direct and indirect effects on microbial activity. Warmer soils directly reduce the activity of soil extracellular enzymes through denaturation and dehydration of soil pores and indirectly through reducing microbe-available substrates and plant inputs. Overall, reduction in extracellular enzyme activity may reduce decomposition of coarse woody debris and potentially enhance soil carbon storage in semiarid ecosystems. For all seven hydrolytic enzymes examined as well as heterotrophic respiration, there was no consistent or significant response to experimental warming, regardless of seasonal climatic and soil moisture variation. The enzyme results observed here are consistent with the few other experimental results for warming in semiarid ecosystems and indicate that the controls over soil

  5. Microbial degradation of plant leachate alters lignin phenols and trihalomethane precursors

    Science.gov (United States)

    Pellerin, Brian A.; Hernes, Peter J.; Saraceno, John Franco; Spencer, Robert G.M.; Bergamaschi, Brian A.

    2010-01-01

    Although the importance of vascular plant-derived dissolved organic carbon (DOC) in freshwater systems has been studied, the role of leached DOC as precursors of disinfection byproducts (DBPs) during drinking water treatment is not well known. Here we measured the propensity of leachates from four crops and four aquatic macrophytes to form trihalomethanes (THMs)—a regulated class of DBPs—before and after 21 d of microbial degradation. We also measured lignin phenol content and specific UV absorbance (SUVA254) to test the assumption that aromatic compounds from vascular plants are resistant to microbial degradation and readily form DBPs. Leaching solubilized 9 to 26% of total plant carbon, which formed 1.93 to 6.72 mmol THM mol C-1 However, leachate DOC concentrations decreased by 85 to 92% over the 21-d incubation, with a concomitant decrease of 67 to 92% in total THM formation potential. Carbon-normalized THM yields in the residual DOC pool increased by 2.5 times on average, consistent with the preferential uptake of nonprecursor material. Lignin phenol concentrations decreased by 64 to 96% over 21 d, but a lack of correlation between lignin content and THM yields or SUVA254 suggested that lignin-derived compounds are not the source of increased THM precursor yields in the residual DOC pool. Our results indicate that microbial carbon utilization alters THM precursors in ecosystems with direct plant leaching, but more work is needed to identify the specific dissolved organic matter components with a greater propensity to form DBPs and affect watershed management, drinking water quality, and human health.

  6. Plant, microbial and ecosystem carbon use efficiencies interact to stabilize microbial growth as a fraction of gross primary production.

    Science.gov (United States)

    Sinsabaugh, Robert L; Moorhead, Daryl L; Xu, Xiaofeng; Litvak, Marcy E

    2017-06-01

    The carbon use efficiency of plants (CUE a ) and microorganisms (CUE h ) determines rates of biomass turnover and soil carbon sequestration. We evaluated the hypothesis that CUE a and CUE h counterbalance at a large scale, stabilizing microbial growth (μ) as a fraction of gross primary production (GPP). Collating data from published studies, we correlated annual CUE a , estimated from satellite imagery, with locally determined soil CUE h for 100 globally distributed sites. Ecosystem CUE e , the ratio of net ecosystem production (NEP) to GPP, was estimated for each site using published models. At the ecosystem scale, CUE a and CUE h were inversely related. At the global scale, the apparent temperature sensitivity of CUE h with respect to mean annual temperature (MAT) was similar for organic and mineral soils (0.029°C -1 ). CUE a and CUE e were inversely related to MAT, with apparent sensitivities of -0.009 and -0.032°C -1 , respectively. These trends constrain the ratio μ : GPP (= (CUE a  × CUE h )/(1 - CUE e )) with respect to MAT by counterbalancing the apparent temperature sensitivities of the component processes. At the ecosystem scale, the counterbalance is effected by modulating soil organic matter stocks. The results suggest that a μ : GPP value of c. 0.13 is a homeostatic steady state for ecosystem carbon fluxes at a large scale. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  7. Assessment of microbial contamination within working environments of different types of composting plants.

    Science.gov (United States)

    Gutarowska, Beata; Skóra, Justyna; Stępień, Łukasz; Szponar, Bogumiła; Otlewska, Anna; Pielech-Przybylska, Katarzyna

    2015-04-01

    The objective of the study was to determine the degree of microbiological contamination, type of microflora, bioaerosol particle size distribution, and concentration of endotoxins in dust in different types of composting plants. In addition, this study provides a list of indicator microorganisms that pose a biological threat in composting facilities, based on their prevalence within the workplace, source of isolation, and health hazards. We undertook microbiological analysis of the air, work surfaces, and compost, and assessed the particle size distribution of bioaerosols using a six-stage Andersen sampler. Endotoxins were determined using gas chromatography-mass spectrometry (GC-MS). Microbial identification was undertaken both microscopically and using biochemical tests. The predominant bacterial and fungal species were identified using 16S rRNA and ITS1/2 analysis, respectively. The number of mesophilic microorganisms in composting plants amounted to 6.9×10(2)-2.5×10(4) CFU/m3 in the air, 2.9×10(2)-3.3×10(3) CFU/100 cm2 on surfaces, and 2.2×10(5)-2.4×10(7) CFU/g in compost. Qualitative analysis revealed 75 microbial strains in composting plants, with filamentous fungi being the largest group of microorganisms, accounting for as many as 38 isolates. The total amount of endotoxins was 0.0062-0.0140 nmol/mg of dust. The dust fraction with aerodynamic particle diameter of 0.65-1.1 μm accounted for 28-39% of bacterial aerosols and 4-13% of fungal aerosols. We propose the following strains as indicators of harmful biological agent contamination: Bacillus cereus, Aspergillus fumigatus, Cladosporium cladosporioides, C. herbarum, Mucor hiemalis, and Rhizopus oryzae for both types of composting plants, and Bacillus pumilus, Mucor fragilis, Penicillium svalbardense, and P. crustosum for green waste composting plants. The biological hazards posed within these plants are due to the presence of potentially pathogenic microorganisms and the inhalation of respirable

  8. Variation in plant-mediated interactions between rhizobacteria and caterpillars: potential role of soil composition

    NARCIS (Netherlands)

    Pangesti, N.P.D.; Pineda Gomez, A.M.; Dicke, M.; Loon, van J.J.A.

    2015-01-01

    Selected strains of non-pathogenic rhizobacteria can trigger induced systemic resistance (ISR) in plants against aboveground insect herbivores. However, the underlying mechanisms of plant-mediated interactions between rhizobacteria and herbivorous insects are still poorly understood. Using

  9. Rhizosphere microbial community structure in relation to root location and plant iron nutritional status.

    Science.gov (United States)

    Yang, C H; Crowley, D E

    2000-01-01

    Root exudate composition and quantity vary in relation to plant nutritional status, but the impact of the differences on rhizosphere microbial communities is not known. To examine this question, we performed an experiment with barley (Hordeum vulgare) plants under iron-limiting and iron-sufficient growth conditions. Plants were grown in an iron-limiting soil in root box microcosms. One-half of the plants were treated with foliar iron every day to inhibit phytosiderophore production and to alter root exudate composition. After 30 days, the bacterial communities associated with different root zones, including the primary root tips, nonelongating secondary root tips, sites of lateral root emergence, and older roots distal from the tip, were characterized by using 16S ribosomal DNA (rDNA) fingerprints generated by PCR-denaturing gradient gel electrophoresis (DGGE). Our results showed that the microbial communities associated with the different root locations produced many common 16S rDNA bands but that the communities could be distinguished by using correspondence analysis. Approximately 40% of the variation between communities could be attributed to plant iron nutritional status. A sequence analysis of clones generated from a single 16S rDNA band obtained at all of the root locations revealed that there were taxonomically different species in the same band, suggesting that the resolving power of DGGE for characterization of community structure at the species level is limited. Our results suggest that the bacterial communities in the rhizosphere are substantially different in different root zones and that a rhizosphere community may be altered by changes in root exudate composition caused by changes in plant iron nutritional status.

  10. Cyclophilin 40 facilitates HSP90-mediated RISC assembly in plants.

    Science.gov (United States)

    Iki, Taichiro; Yoshikawa, Manabu; Meshi, Tetsuo; Ishikawa, Masayuki

    2012-01-18

    Posttranscriptional gene silencing is mediated by RNA-induced silencing complexes (RISCs) that contain AGO proteins and single-stranded small RNAs. The assembly of plant AGO1-containing RISCs depends on the molecular chaperone HSP90. Here, we demonstrate that cyclophilin 40 (CYP40), protein phosphatase 5 (PP5), and several other proteins with the tetratricopeptide repeat (TPR) domain associates with AGO1 in an HSP90-dependent manner in extracts of evacuolated tobacco protoplasts (BYL). Intriguingly, CYP40, but not the other TPR proteins, could form a complex with small RNA duplex-bound AGO1. Moreover, CYP40 that was synthesized by in-vitro translation using BYL uniquely facilitated binding of small RNA duplexes to AGO1, and as a result, increased the amount of mature RISCs that could cleave target RNAs. CYP40 was not contained in mature RISCs, indicating that the association is transient. Addition of PP5 or cyclophilin-binding drug cyclosporine A prevented the association of endogenous CYP40 with HSP90-AGO1 complex and inhibited RISC assembly. These results suggest that a complex of AGO1, HSP90, CYP40, and a small RNA duplex is a key intermediate of RISC assembly in plants.

  11. Microbial production of branched-chain dicarboxylate 2-methylsuccinic acid via enoate reductase-mediated bioreduction.

    Science.gov (United States)

    Wang, Jian; Yang, Yaping; Zhang, Ruihua; Shen, Xiaolin; Chen, Zhenya; Wang, Jia; Yuan, Qipeng; Yan, Yajun

    2018-01-01

    2-Methylsuccinic acid (2-MSA) is a C5 branched-chain dicarboxylate that serves as an attractive synthon for the synthesis of polymers with extensive applications in coatings, cosmetic solvents and bioplastics. However, the lack of natural pathways for 2-MSA biosynthesis has limited its application as a promising bio-replacement. Herein, we conceived a non-natural three-step biosynthetic route for 2-MSA, via employing the citramalate pathway in combination with enoate reductase-mediated bioreduction of the pathway intermediate citraconate. First, over-expression of codon-optimized citramalate synthase variant CimA* from Methanococcus jannaschii, endogenous isopropylmalate isomerase EcLeuCD and enoate reductase YqjM from Bacillus subtilis allowed the production of 2-MSA in Escherichia coli for the first time, with a titer of 0.35g/L in shake flask experiments. Subsequent screening of YqjM-like enoate reductases of different bacterial origins enabled identification and characterization of a new NAD(P)H-dependent enoate reductase KpnER from Klebsiella pneumoniae, which exhibited higher activity towards citraconate than YqjM. Incorporation of KpnER into the 2-MSA biosynthetic pathway led to 2-MSA production improvement to a titer of 0.96g/L in aerobic condition. Subsequent optimizations including cofactor regeneration, microaerobic cultivation and host strain engineering, boosted 2-MSA titer to 3.61g/L with a molar yield of 0.36 in shake flask experiments. This work established a promising platform for 2-MSA bioproduction, which enabled the highest titer of 2-MSA production in microbial hosts so far. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  12. PLANT-MICROBIAL INTERACTIONS IN THE RHIZOSPHERE – STRATEGIES FOR PLANT GROWTH-PROMOTION

    Directory of Open Access Journals (Sweden)

    Marius Stefan

    2012-03-01

    Full Text Available Plant growth-promoting rhizobacteria (PGPR are a group of bacteria that can actively colonize plant rootsand enhance plant growth using different mechanisms: production of plant growth regulators like indoleacetic acid,gibberellic acid, cytokinins and ethylene(Zahir et al., 2003, providing the host plant with fixed nitrogen, solubilizationof soil phosphorus, enhance Fe uptake, biocontrol, reducing the concentration of heavy metals. PGPR are perfectcandidates to be used as biofertilizers – eco-friendly alternative to common applied chemical fertilizer in today’sagriculture. The most important benefit of PGPR usage is related to the reduction of environmental pollution in conditionof increasing crop yield. This review presents the main mechanisms involved in PGPR promotion of plant growth.

  13. The Effect of Re-Planting Trees on Soil Microbial Communities in a Wildfire-Induced Subalpine Grassland

    Directory of Open Access Journals (Sweden)

    Ed-Haun Chang

    2017-10-01

    Full Text Available Wildfire often causes tremendous changes in ecosystems, particularly in subalpine and alpine areas, which are vulnerable due to severe climate conditions such as cold temperature and strong wind. This study aimed to clarify the effect of tree re-planting on ecosystem services such as the soil microbial community after several decades. We compared the re-planted forest and grassland with the mature forest as a reference in terms of soil microbial biomass C and N (Cmic and Nmic, enzyme activities, phospholipid fatty acids (PLFA composition, and denaturing gradient gel electrophoresis (DGGE. The Cmic and Nmic did not differ among the grassland, re-planted forest and mature forest soil; however, ratios of Cmic/Corg and Nmic/Ntot decreased from the grassland to re-planted forest and mature forest soil. The total PLFAs and those attributed to bacteria and Gram-positive and Gram-negative bacteria did not differ between the re-planted forest and grassland soil. Principle component analysis of the PLFA content separated the grassland from re-planted forest and mature forest soil. Similarly, DGGE analysis revealed changes in both bacterial and fungal community structures with changes in vegetation. Our results suggest that the microbial community structure changes with the re-planting of trees after a fire event in this subalpine area. Recovery of the soil microbial community to the original state in a fire-damaged site in a subalpine area may require decades, even under a re-planted forest.

  14. Plant Community Richness Mediates Inhibitory Interactions and Resource Competition between Streptomyces and Fusarium Populations in the Rhizosphere.

    Science.gov (United States)

    Essarioui, Adil; LeBlanc, Nicholas; Kistler, Harold C; Kinkel, Linda L

    2017-07-01

    critical to mediating the coevolutionary dynamics and selective trajectories for inhibitory and nutrient use phenotypes among Streptomyces and Fusarium populations in soil, with significant implications for microbial community functional characteristics.

  15. Extraction of solubles from plant biomass for use as microbial growth stimulant and methods related thereto

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Ming Woei

    2015-12-08

    A method for producing a microbial growth stimulant (MGS) from a plant biomass is described. In one embodiment, an ammonium hydroxide solution is used to extract a solution of proteins and ammonia from the biomass. Some of the proteins and ammonia are separated from the extracted solution to provide the MGS solution. The removed ammonia can be recycled and the proteins are useful as animal feeds. In one embodiment, the method comprises extracting solubles from pretreated lignocellulosic biomass with a cellulase enzyme-producing growth medium (such T. reesei) in the presence of water and an aqueous extract.

  16. Nutrient limitation and microbially mediated chemistry: studies using tuff inoculum obtained from the Exploratory Studies Facility, Yucca Mountain

    International Nuclear Information System (INIS)

    Chen, C. I.; Chuu, Y. J.; Meike, A.; Ringelberg, D.; Sawvel, A.

    1998-01-01

    Flow-through bioreactors are used to investigate the relationship between the supply (and limitation) of major nutrients required by microorganisms (C, N, P, S) and effluent chemistry to obtain data that can be useful to develop models of microbially mediated aqueous chemistry. The bioreactors were inoculated with crushed tuff from Yucca Mountain. Six of the 14 bioreactor experiments currently in operation have shown growth, which occurred in as few as 5 days and as much as a few months after initiation of the experiment. All of the bioreactors exhibiting growth contained glucose as a carbon source, but other nutritional components varied. Chemical signatures of each bioreactor were compared to each other and selected results were compared to computer simulations of the equivalent abiotic chemical reactions. At 21 C, the richest medium formulation produced a microbial community that lowered the effluent pH from 6.4 to as low as 3.9. The same medium formulation at 50 C produced no significant change in pH but caused a significant increase in Cl after a period of 200 days. Variations in concentrations of other elements, some of which appear to be periodic (Ca, Mg, etc.) also occur. Bioreactors fed with low C, N, P, S media showed growth, but had stabilized at lower cell densities. The room temperature bioreactor in this group exhibited a phospholipid fatty acid (PLFA) signature of sulfur- or iron-reducing bacteria, which produced a significant chemical signature in the effluent from that bioreactor. Growth had not been observed yet in the alkaline bioreactors, even in those containing glucose. The value of combining detailed chemical and community (e.g., ester-linked PLFA) analyses, long-duration experiments, and abiotic chemical models to distinguish chemical patterns is evident. Although all of the bioreactors contain the same initial microorganisms and mineral constituents, PLFA analysis demonstrates that both input chemistry and temperature determine the

  17. Modulation of neonatal microbial recognition: TLR-mediated innate immune responses are specifically and differentially modulated by human milk.

    Science.gov (United States)

    LeBouder, Emmanuel; Rey-Nores, Julia E; Raby, Anne-Catherine; Affolter, Michael; Vidal, Karine; Thornton, Catherine A; Labéta, Mario O

    2006-03-15

    The mechanisms controlling innate microbial recognition in the neonatal gut are still to be fully understood. We have sought specific regulatory mechanisms operating in human breast milk relating to TLR-mediated microbial recognition. In this study, we report a specific and differential modulatory effect of early samples (days 1-5) of breast milk on ligand-induced cell stimulation via TLRs. Although a negative modulation was exerted on TLR2 and TLR3-mediated responses, those via TLR4 and TLR5 were enhanced. This effect was observed in human adult and fetal intestinal epithelial cell lines, monocytes, dendritic cells, and PBMC as well as neonatal blood. In the latter case, milk compensated for the low capacity of neonatal plasma to support responses to LPS. Cell stimulation via the IL-1R or TNFR was not modulated by milk. This, together with the differential effect on TLR activation, suggested that the primary effect of milk is exerted upstream of signaling proximal to TLR ligand recognition. The analysis of TLR4-mediated gene expression, used as a model system, showed that milk modulated TLR-related genes differently, including those coding for signal intermediates and regulators. A proteinaceous milk component of > or =80 kDa was found to be responsible for the effect on TLR4. Notably, infant milk formulations did not reproduce the modulatory activity of breast milk. Together, these findings reveal an unrecognized function of human milk, namely, its capacity to influence neonatal microbial recognition by modulating TLR-mediated responses specifically and differentially. This in turn suggests the existence of novel mechanisms regulating TLR activation.

  18. Biochar increases plant growth and alters microbial communities via regulating the moisture and temperature of green roof substrates.

    Science.gov (United States)

    Chen, Haoming; Ma, Jinyi; Wei, Jiaxing; Gong, Xin; Yu, Xichen; Guo, Hui; Zhao, Yanwen

    2018-09-01

    Green roofs have increasingly been designed and applied to relieve environmental problems, such as water loss, air pollution as well as heat island effect. Substrate and vegetation are important components of green roofs providing ecosystem services and benefiting the urban development. Biochar made from sewage sludge could be potentially used as the substrate amendment for green roofs, however, the effects of biochar on substrate quality and plant performance in green roofs are still unclear. We evaluated the effects of adding sludge biochar (0, 5, 10, 15 and 20%, v/v) to natural soil planted with three types of plant species (ryegrass, Sedum lineare and cucumber) on soil properties, plant growth and microbial communities in both green roof and ground ecosystems. Our results showed that sludge biochar addition significantly increased substrate moisture, adjusted substrate temperature, altered microbial community structure and increased plant growth. The application rate of 10-15% sludge biochar on the green roof exerted the most significant effects on both microbial and plant biomass by 63.9-89.6% and 54.0-54.2% respectively. Path analysis showed that biochar addition had a strong effect on microbial biomass via changing the soil air-filled porosity, soil moisture and temperature, and promoted plant growth through the positive effects on microbial biomass. These results suggest that the applications of biochar at an appropriate rate can significantly alter plant growth and microbial community structure, and increase the ecological benefits of green roofs via exerting effects on the moisture, temperature and nutrients of roof substrates. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Medicinal plants used by Burundian traditional healers for the treatment of microbial diseases.

    Science.gov (United States)

    Ngezahayo, Jérémie; Havyarimana, François; Hari, Léonard; Stévigny, Caroline; Duez, Pierre

    2015-09-15

    Infectious diseases represent a serious and worldwide public health problem. They lead to high mortality, especially in non-developed countries. In Burundi, the most frequent infectious diseases are skin and respiratory (mainly in children) infections, diarrhea, added to malaria, HIV/AIDS and tuberculosis. Local population used mostly traditional herbal medicines, sometimes animal and mineral substances, to fight against these plagues. To survey in different markets and herbal shops in Bujumbura city, medicinal plants sold to treat microbial infections, with particular emphasis on the different practices of traditional healers (THs) regarding plant parts used, methods of preparation and administration, dosage and treatment duration. The ethnobotanical survey was conducted by interviewing, using a pre-set questionnaire, sixty representative healers, belonging to different associations of THs approved and recognised by the Ministry of Health. Each interviewed herbalist also participated in the collection of samples and the determination of the common names of plants. The plausibility of recorded uses has been verified through an extensive literature search. Our informants enabled us to collect 155 different plant species, distributed in 51 families and 139 genera. The most represented families were Asteraceae (20 genera and 25 species), Fabaceae (14 genera and 16 species), Lamiaceae (12 genera and 15 species), Rubiaceae (9 genera and 9 species), Solanaceae (6 genera and 6 species) and Euphorbiaceae (5 genera and 6 families). These plants have been cited to treat 25 different alleged symptoms of microbial diseases through 271 multi-herbal recipes (MUHRs) and 60 mono-herbal recipes (MOHRs). Platostoma rotundifolium (Briq.) A. J. Paton (Lamiaceae), the most cited species, has been reported in the composition of 41 MUHRs, followed by Virectaria major (Schum.) Verdc (Rubiaceae, 39 recipes), Kalanchoe crenata (Andrews) Haw. (Crassulaceae, 37 recipes), Stomatanthes

  20. The Root-Associated Microbial Community of the World's Highest Growing Vascular Plants.

    Science.gov (United States)

    Angel, Roey; Conrad, Ralf; Dvorsky, Miroslav; Kopecky, Martin; Kotilínek, Milan; Hiiesalu, Inga; Schweingruber, Fritz; Doležal, Jiří

    2016-08-01

    Upward migration of plants to barren subnival areas is occurring worldwide due to raising ambient temperatures and glacial recession. In summer 2012, the presence of six vascular plants, growing in a single patch, was recorded at an unprecedented elevation of 6150 m.a.s.l. close to the summit of Mount Shukule II in the Western Himalayas (Ladakh, India). Whilst showing multiple signs of stress, all plants have managed to establish stable growth and persist for several years. To learn about the role of microbes in the process of plant upward migration, we analysed the root-associated microbial community of the plants (three individuals from each) using microscopy and tagged amplicon sequencing. No mycorrhizae were found on the roots, implying they are of little importance to the establishment and early growth of the plants. However, all roots were associated with a complex bacterial community, with richness and diversity estimates similar or even higher than the surrounding bare soil. Both soil and root-associated communities were dominated by members of the orders Sphingomonadales and Sphingobacteriales, which are typical for hot desert soils, but were different from communities of temperate subnival soils and typical rhizosphere communities. Despite taxonomic similarity on the order level, the plants harboured a unique set of highly dominant operational taxonomic units which were not found in the bare soil. These bacteria have been likely transported with the dispersing seeds and became part of the root-associated community following germination. The results indicate that developing soils act not only as a source of inoculation to plant roots but also possibly as a sink for plant-associated bacteria.

  1. Plant species and soil type cooperatively shape the structure and function of microbial communities in the rhizosphere.

    Science.gov (United States)

    Berg, Gabriele; Smalla, Kornelia

    2009-04-01

    The rhizosphere is of central importance not only for plant nutrition, health and quality but also for microorganism-driven carbon sequestration, ecosystem functioning and nutrient cycling in terrestrial ecosystems. A multitude of biotic and abiotic factors are assumed to influence the structural and functional diversity of microbial communities in the rhizosphere. In this review, recent studies on the influence of the two factors, plant species and soil type, on rhizosphere-associated microbial communities are discussed. Root exudates and the response of microorganisms to the latter as well as to root morphology were shown to shape rhizosphere microbial communities. All studies revealed that soil is the main reservoir for rhizosphere microorganisms. Many secrets of microbial life in the rhizosphere were recently uncovered due to the enormous progress in molecular and microscopic tools. Physiological and molecular data on the factors that drive selection processes in the rhizosphere are presented here. Furthermore, implications for agriculture, nature conservation and biotechnology will also be discussed.

  2. Relationship of microbial processes to the fate and behavior of transuranic elements in soils, plants, and animals

    International Nuclear Information System (INIS)

    Wildung, R.E.; Garland, T.R.

    1977-10-01

    This review considers the influence of soil physicochemical and microbial processes on the long-term solubility, form, and bioavailability of plutonium and other transuranic elements important in the nuclear fuel cycle. Emphasis is placed on delineation of the relationships between soil chemical and microbial processes and the role of soil microorganisms in effecting solubilization, transformation and plant/animal uptake of elements considered largely insoluble in soils strictly on the basis of their inorganic chemical characteristics

  3. Good Manufacturing Practices and Microbial Contamination Sources in Orange Fleshed Sweet Potato Puree Processing Plant in Kenya

    Directory of Open Access Journals (Sweden)

    Derick Nyabera Malavi

    2018-01-01

    Full Text Available Limited information exists on the status of hygiene and probable sources of microbial contamination in Orange Fleshed Sweet Potato (OFSP puree processing. The current study is aimed at determining the level of compliance to Good Manufacturing Practices (GMPs, hygiene, and microbial quality in OFSP puree processing plant in Kenya. Intensive observation and interviews using a structured GMPs checklist, environmental sampling, and microbial analysis by standard microbiological methods were used in data collection. The results indicated low level of compliance to GMPs with an overall compliance score of 58%. Microbial counts on food equipment surfaces, installations, and personnel hands and in packaged OFSP puree were above the recommended microbial safety and quality legal limits. Steaming significantly (P<0.05 reduced microbial load in OFSP cooked roots but the counts significantly (P<0.05 increased in the puree due to postprocessing contamination. Total counts, yeasts and molds, Enterobacteriaceae, total coliforms, and E. coli and S. aureus counts in OFSP puree were 8.0, 4.0, 6.6, 5.8, 4.8, and 5.9 log10 cfu/g, respectively. In conclusion, equipment surfaces, personnel hands, and processing water were major sources of contamination in OFSP puree processing and handling. Plant hygiene inspection, environmental monitoring, and food safety trainings are recommended to improve hygiene, microbial quality, and safety of OFSP puree.

  4. Engineering microbial cell factories for the production of plant natural products: from design principles to industrial-scale production.

    Science.gov (United States)

    Liu, Xiaonan; Ding, Wentao; Jiang, Huifeng

    2017-07-19

    Plant natural products (PNPs) are widely used as pharmaceuticals, nutraceuticals, seasonings, pigments, etc., with a huge commercial value on the global market. However, most of these PNPs are still being extracted from plants. A resource-conserving and environment-friendly synthesis route for PNPs that utilizes microbial cell factories has attracted increasing attention since the 1940s. However, at the present only a handful of PNPs are being produced by microbial cell factories at an industrial scale, and there are still many challenges in their large-scale application. One of the challenges is that most biosynthetic pathways of PNPs are still unknown, which largely limits the number of candidate PNPs for heterologous microbial production. Another challenge is that the metabolic fluxes toward the target products in microbial hosts are often hindered by poor precursor supply, low catalytic activity of enzymes and obstructed product transport. Consequently, despite intensive studies on the metabolic engineering of microbial hosts, the fermentation costs of most heterologously produced PNPs are still too high for industrial-scale production. In this paper, we review several aspects of PNP production in microbial cell factories, including important design principles and recent progress in pathway mining and metabolic engineering. In addition, implemented cases of industrial-scale production of PNPs in microbial cell factories are also highlighted.

  5. Soil microbial community structure and function responses to successive planting of Eucalyptus.

    Science.gov (United States)

    Chen, Falin; Zheng, Hua; Zhang, Kai; Ouyang, Zhiyun; Li, Huailin; Wu, Bing; Shi, Qian

    2013-10-01

    Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid (PLFA) abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed "u" shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram+ to Gram- bacteria, formed "n"' shaped quadratic functions, and the ratio of cy17:0 to 16:1omega7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiohydrolase activity formed "u" shaped quadratic functions. Soil N:P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N:P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management.

  6. The Investigation of Decontamination Effects of Ozone Gas on Microbial Load and Essential Oil of Several Medicinal Plants

    Directory of Open Access Journals (Sweden)

    Razieh VALI ASILL

    2013-02-01

    Full Text Available Today, Ozone as a disinfectant method, without putting on the harmful effects on human and plant products, it is alternative common methods for disinfection of plant material. The research as a factorial experiment was conducted on the basis of randomized complete block design with three replications and the effects of Ozone gas on decreasing the microbial load of some important medicinal plants include: Peppermint (Mentha piperita, Summer savory (Satureja hortensis, Indian valerian(Valeriana wallichii, Meliss (Melissa officinalis and Iranian thyme (Zataria multiflora were investigated. Medicinal plants leaves were treated with Ozone gas concentration 0.3, 0.6 and 0.9 ml/L at times of 10 and 30 then total count, coliform and mold and yeast of the samples were studied. The result showed that Ozone gas decreases microbial load of medicinal plants samples. But Ozone gas and Ozone gas in medicinal plants interaction effect had no effect on essential oil content. The lowest and the highest of microbial load were detected in samples treated with concentration of 0.9 ml/L of Ozone gas and control respectively. The highest and the lowest of microbial load were observed in Iranian thyme and Indian valerian respectively. Also result showed that Ozone gas treatment for 30 min had the greatest of effect in reducing the microbial load and 0.9 ml/L Ozone gas concentration had the lowest of microbial load. Results of this survey reflect that the use of Ozone as a method of disinfection for medicinal plants is a decontamination.

  7. Suppressive composts: microbial ecology links between abiotic environments and healthy plants.

    Science.gov (United States)

    Hadar, Yitzhak; Papadopoulou, Kalliope K

    2012-01-01

    Suppressive compost provides an environment in which plant disease development is reduced, even in the presence of a pathogen and a susceptible host. Despite the numerous positive reports, its practical application is still limited. The main reason for this is the lack of reliable prediction and quality control tools for evaluation of the level and specificity of the suppression effect. Plant disease suppression is the direct result of the activity of consortia of antagonistic microorganisms that naturally recolonize the compost during the cooling phase of the process. Thus, it is imperative to increase the level of understanding of compost microbial ecology and population dynamics. This may lead to the development of an ecological theory for complex ecosystems as well as favor the establishment of hypothesis-driven studies.

  8. Microbial growth and quorum sensing antagonist activities of herbal plants extracts.

    Science.gov (United States)

    Al-Hussaini, Reema; Mahasneh, Adel M

    2009-09-03

    Antimicrobial and antiquorum sensing (AQS) activities of fourteen ethanolic extracts of different parts of eight plants were screened against four Gram-positive, five Gram-negative bacteria and four fungi. Depending on the plant part extract used and the test microorganism, variable activities were recorded at 3 mg per disc. Among the Grampositive bacteria tested, for example, activities of Laurus nobilis bark extract ranged between a 9.5 mm inhibition zone against Bacillus subtilis up to a 25 mm one against methicillin resistant Staphylococcus aureus. Staphylococcus aureus and Aspergillus fumigatus were the most susceptible among bacteria and fungi tested towards other plant parts. Of interest is the tangible antifungal activity of a Tecoma capensis flower extract, which is reported for the first time. However, minimum inhibitory concentrations (MIC's) for both bacteria and fungi were relatively high (0.5-3.0 mg). As for antiquorum sensing activity against Chromobacterium violaceum, superior activity (>17 mm QS inhibition) was associated with Sonchus oleraceus and Laurus nobilis extracts and weak to good activity (8-17 mm) was recorded for other plants. In conclusion, results indicate the potential of these plant extracts in treating microbial infections through cell growth inhibition or quorum sensing antagonism, which is reported for the first time, thus validating their medicinal use.

  9. Microbial Growth and Quorum Sensing Antagonist Activities of Herbal Plants Extracts

    Directory of Open Access Journals (Sweden)

    Reema Al-Hussaini

    2009-09-01

    Full Text Available Antimicrobial and antiquorum sensing (AQS activities of fourteen ethanolic extracts of different parts of eight plants were screened against four Gram-positive, five Gram-negative bacteria and four fungi. Depending on the plant part extract used and the test microorganism, variable activities were recorded at 3 mg per disc. Among the Grampositive bacteria tested, for example, activities of Laurus nobilis bark extract ranged between a 9.5 mm inhibition zone against Bacillus subtilis up to a 25 mm one against methicillin resistant Staphylococcus aureus. Staphylococcus aureus and Aspergillus fumigatus were the most susceptible among bacteria and fungi tested towards other plant parts. Of interest is the tangible antifungal activity of a Tecoma capensis flower extract, which is reported for the first time. However, minimum inhibitory concentrations (MIC's for both bacteria and fungi were relatively high (0.5-3.0 mg. As for antiquorum sensing activity against Chromobacterium violaceum, superior activity (>17 mm QS inhibition was associated with Sonchus oleraceus and Laurus nobilis extracts and weak to good activity (8-17 mm was recorded for other plants. In conclusion, results indicate the potential of these plant extracts in treating microbial infections through cell growth inhibition or quorum sensing antagonism, which is reported for the first time, thus validating their medicinal use.

  10. Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil

    Directory of Open Access Journals (Sweden)

    Graziella S Gattai

    2011-09-01

    Full Text Available The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco. Dilutions were prepared by adding lead contaminated soil (270 mg Kg-1 to uncontaminated soil (37 mg Pb Kg soil-1 in the proportions of 7.5%, 15%, and 30% (v:v. The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30% contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil.

  11. Vitality of aquatic plants and microbial activity of sediment in an oligotrophic lake (Lake Bohinj, Slovenia

    Directory of Open Access Journals (Sweden)

    Tatjana SIMČIČ

    2011-08-01

    Full Text Available The vitality of eight macrophyte species and the microbial activity of sediment in an oligotrophic lake (Lake Bohinj, Slovenia were studied via the terminal electron transport system (ETS activity of mitochondria. The levels of ETS activity of vascular plants were as follows: Ranunculus circinatus, Myriohpyllum spicatum, Potamogeton alpinus, P. perfoliatus, P. lucens. Fontinalis antipyretica exhibited the highest ETS activity of the non-vascular plants, followed by charales Chara delicatula and C. aspera. High values enable R. circinatus, an amphibious species with rapid growth, to survive under conditions in which the water level changes throughout the season. M. spicatum, a species with broad ecological tolerance, also exhibited high ETS activity. The ETS activity of the microbial community in sediment was affected by temperature and/or the amount and origin of the organic matter. A positive correlation between the ETS activity of the sediment and that of M. spicatum and R. circinatus was measured, while negative correlations or no correlation were observed for mosses and macroalgae. The high ETS activity in sediment indicates rapid mineralization of organic matter and, in turn, sufficient nutrients for growth of macrophytes.

  12. Microbial and Plant-Assisted Bioremediation of Heavy Metal Polluted Environments: A Review

    Directory of Open Access Journals (Sweden)

    Omena Bernard Ojuederie

    2017-12-01

    Full Text Available Environmental pollution from hazardous waste materials, organic pollutants and heavy metals, has adversely affected the natural ecosystem to the detriment of man. These pollutants arise from anthropogenic sources as well as natural disasters such as hurricanes and volcanic eruptions. Toxic metals could accumulate in agricultural soils and get into the food chain, thereby becoming a major threat to food security. Conventional and physical methods are expensive and not effective in areas with low metal toxicity. Bioremediation is therefore an eco-friendly and efficient method of reclaiming environments contaminated with heavy metals by making use of the inherent biological mechanisms of microorganisms and plants to eradicate hazardous contaminants. This review discusses the toxic effects of heavy metal pollution and the mechanisms used by microbes and plants for environmental remediation. It also emphasized the importance of modern biotechnological techniques and approaches in improving the ability of microbial enzymes to effectively degrade heavy metals at a faster rate, highlighting recent advances in microbial bioremediation and phytoremediation for the removal of heavy metals from the environment as well as future prospects and limitations. However, strict adherence to biosafety regulations must be followed in the use of biotechnological methods to ensure safety of the environment.

  13. Microbial and Plant-Assisted Bioremediation of Heavy Metal Polluted Environments: A Review

    Science.gov (United States)

    Ojuederie, Omena Bernard

    2017-01-01

    Environmental pollution from hazardous waste materials, organic pollutants and heavy metals, has adversely affected the natural ecosystem to the detriment of man. These pollutants arise from anthropogenic sources as well as natural disasters such as hurricanes and volcanic eruptions. Toxic metals could accumulate in agricultural soils and get into the food chain, thereby becoming a major threat to food security. Conventional and physical methods are expensive and not effective in areas with low metal toxicity. Bioremediation is therefore an eco-friendly and efficient method of reclaiming environments contaminated with heavy metals by making use of the inherent biological mechanisms of microorganisms and plants to eradicate hazardous contaminants. This review discusses the toxic effects of heavy metal pollution and the mechanisms used by microbes and plants for environmental remediation. It also emphasized the importance of modern biotechnological techniques and approaches in improving the ability of microbial enzymes to effectively degrade heavy metals at a faster rate, highlighting recent advances in microbial bioremediation and phytoremediation for the removal of heavy metals from the environment as well as future prospects and limitations. However, strict adherence to biosafety regulations must be followed in the use of biotechnological methods to ensure safety of the environment. PMID:29207531

  14. An integrated metagenome and -proteome analysis of the microbial community residing in a biogas production plant.

    Science.gov (United States)

    Ortseifen, Vera; Stolze, Yvonne; Maus, Irena; Sczyrba, Alexander; Bremges, Andreas; Albaum, Stefan P; Jaenicke, Sebastian; Fracowiak, Jochen; Pühler, Alfred; Schlüter, Andreas

    2016-08-10

    To study the metaproteome of a biogas-producing microbial community, fermentation samples were taken from an agricultural biogas plant for microbial cell and protein extraction and corresponding metagenome analyses. Based on metagenome sequence data, taxonomic community profiling was performed to elucidate the composition of bacterial and archaeal sub-communities. The community's cytosolic metaproteome was represented in a 2D-PAGE approach. Metaproteome databases for protein identification were compiled based on the assembled metagenome sequence dataset for the biogas plant analyzed and non-corresponding biogas metagenomes. Protein identification results revealed that the corresponding biogas protein database facilitated the highest identification rate followed by other biogas-specific databases, whereas common public databases yielded insufficient identification rates. Proteins of the biogas microbiome identified as highly abundant were assigned to the pathways involved in methanogenesis, transport and carbon metabolism. Moreover, the integrated metagenome/-proteome approach enabled the examination of genetic-context information for genes encoding identified proteins by studying neighboring genes on the corresponding contig. Exemplarily, this approach led to the identification of a Methanoculleus sp. contig encoding 16 methanogenesis-related gene products, three of which were also detected as abundant proteins within the community's metaproteome. Thus, metagenome contigs provide additional information on the genetic environment of identified abundant proteins. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Plant-microbe rhizosphere interactions mediated by Rehmannia glutinosa root exudates under consecutive monoculture

    Science.gov (United States)

    Wu, Linkun; Wang, Juanying; Huang, Weimin; Wu, Hongmiao; Chen, Jun; Yang, Yanqiu; Zhang, Zhongyi; Lin, Wenxiong

    2015-10-01

    Under consecutive monoculture, the biomass and quality of Rehmannia glutinosa declines significantly. Consecutive monoculture of R. glutinosa in a four-year field trial led to significant growth inhibition. Most phenolic acids in root exudates had cumulative effects over time under sterile conditions, but these effects were not observed in the rhizosphere under monoculture conditions. It suggested soil microbes might be involved in the degradation and conversion of phenolic acids from the monocultured plants. T-RFLP and qPCR analysis demonstrated differences in both soil bacterial and fungal communities during monoculture. Prolonged monoculture significantly increased levels of Fusarium oxysporum, but decreased levels of Pseudomonas spp. Abundance of beneficial Pseudomonas spp. with antagonistic activity against F. oxysporum was lower in extended monoculture soils. Phenolic acid mixture at a ratio similar to that found in the rhizosphere could promote mycelial growth, sporulation, and toxin (3-Acetyldeoxynivalenol, 15-O-Acetyl-4-deoxynivalenol) production of pathogenic F. oxysporum while inhibiting growth of the beneficial Pseudomonas sp. W12. This study demonstrates that extended monoculture can alter the microbial community of the rhizosphere, leading to relatively fewer beneficial microorganisms and relatively more pathogenic and toxin-producing microorganisms, which is mediated by the root exudates.

  16. Silver nanoparticles uptake by salt marsh plants - Implications for phytoremediation processes and effects in microbial community dynamics.

    Science.gov (United States)

    Fernandes, Joana P; Mucha, Ana P; Francisco, Telmo; Gomes, Carlos Rocha; Almeida, C Marisa R

    2017-06-15

    This study investigated the uptake of silver nanoparticles (AgNPs) by a salt marsh plant, Phragmites australis, as well as AgNPs effects on rhizospheric microbial community, evaluating the implications for phytoremediation processes. Experiments were carried out with elutriate solution doped with Ag, either in ionic form or in NP form. Metal uptake was evaluated in plant tissues, elutriate solutions and sediments (by AAS) and microbial community was characterized in terms of bacterial community structure (evaluated by ARISA). Results showed Ag accumulation but only in plant belowground tissues and only in the absence of rhizosediment, the presence of sediment reducing Ag availability. But in plant roots Ag accumulation was higher when Ag was in NP form. Multivariate analysis of ARISA profiles showed significant effect of the absence/presence of Ag either in ionic or NP form on microbial community structure, although without significant differences among bacterial richness and diversity. Overall, P. australis can be useful for phytoremediation of medium contaminated with Ag, including with AgNPs. However, the presence of Ag in either forms affected the microbial community structure, which may cause disturbances in ecosystems function and compromise phytoremediation processes. Such considerations need to be address regarding environmental management strategies applied to the very important estuarine areas. The form in which the metal was added affected metal uptake by Phragmites australis and rhizosediment microbial community structure, which can affect phytoremediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Effects of soil depth and plant-soil interaction on microbial community in temperate grasslands of northern China.

    Science.gov (United States)

    Yao, Xiaodong; Zhang, Naili; Zeng, Hui; Wang, Wei

    2018-07-15

    Although the patterns and drivers of soil microbial community composition are well studied, little is known about the effects of plant-soil interactions and soil depth on soil microbial distribution at a regional scale. We examined 195 soil samples from 13 sites along a climatic transect in the temperate grasslands of northern China to measure the composition of and factors influencing soil microbial communities within a 1-m soil profile. Soil microbial community composition was measured using phospholipid fatty acids (PLFA) analysis. Fungi predominated in topsoil (0-10 cm) and bacteria and actinomycetes in deep soils (40-100 cm), independent of steppe types. This variation was explained by contemporary environmental factors (including above- and below-ground plant biomass, soil physicochemical and climatic factors) >58% in the 0-40 cm of soil depth, but soils. Interestingly, when we considered the interactive effects between plant traits (above ground biomass and root biomass) and soil factors (pH, clay content, and soil total carbon, nitrogen, phosphorous), we observed a significant interaction effect occurring at depths of 10-20 cm soil layer, due to different internal and external factors of the plant-soil system along the soil profile. These results improve understanding of the drivers of soil microbial community composition at regional scales. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Genetic and functional diversity of soil microbial communities associated to grapevine plants and wine quality

    Science.gov (United States)

    Mocali, Stefano; Fabiani, Arturo; Kuramae, Eiko; de Hollander, Mattias; Kowalchuk, George A.; Vignozzi, Nadia; Valboa, Giuseppe; Costantini, Edoardo

    2013-04-01

    Despite the economic importance of vineyards in Italy, the wine sector is facing severe challenges from increased global competition and climate changes. The quality of the grape at harvest has a strong direct impact on wine final quality and the strong relationship between wine composition, aroma, taste, and soil properties has been outlined in the "Terroir concept". However, information on the impact of soil microbial communities on soil functions, grapevine plants, and wine quality is generally lacking. In the current study, soils from two close sites in Central Tuscany (BRO11 and BRO12) cultivated with the same grapevine cultivar Sangiovese, but with contrasting wine quality, were examined. Although the BRO12 site provided a better wine quality than the BRO11, the two soils showed similar physical, chemical, and hydrological properties. Also soil humidity, as determined by FDR (Frequency Domain Reflectometry) sensors, indicated a similar water availability in the first 75 cm during a three years trial (2000-2010). Interestingly, the mean three years value of the ratio between the two stable carbon isotopes 13C/12C, measured in the alcohol of the wines, was significantly higher in BRO12 than in BRO11 (-28,3‰ and -24,4‰, respectively), indicating the presence of a relatively higher water stress in the BRO11 soil. Functional GeoChip microarray analyses revealed higher presence of Actinobacteria in the BRO12 than in the BRO11 soil, where the alfa-Proteobacteria were more abundant. Furthermore, a consistent difference in genes involved in S cycling, with a significant overrepresentation of sulphur-oxidation genes in BRO11 and increased levels of sulphate reduction genes BRO12 was detected. These results are consistent with the high content of sulphates and the abundance of Firmicutes such as Sulfobacillus thermosulfidooxidans in the BRO11 soil. Therefore, the different microbiology of the two soils could be related to the different redox conditions of the two

  19. Soil microbial community structure is unaltered by plant invasion, vegetation clipping, and nitrogen fertilization in experimental semi-arid grasslands

    Directory of Open Access Journals (Sweden)

    Chelsea J Carey

    2015-05-01

    Full Text Available Global and regional environmental changes often co-occur, creating complex gradients of disturbance on the landscape. Soil microbial communities are an important component of ecosystem response to environmental change, yet little is known about how microbial structure and function respond to multiple disturbances, or whether multiple environmental changes lead to unanticipated interactive effects. Our study used experimental semi-arid grassland plots in a Mediterranean-climate to determine how soil microbial communities in a seasonally variable ecosystem respond to one, two, or three simultaneous environmental changes: exotic plant invasion, plant invasion + vegetation clipping (to simulate common management practices like mowing or livestock grazing, plant invasion + nitrogen (N fertilization, and plant invasion + clipping + N fertilization. We examined microbial community structure 5-6 years after plot establishment via sequencing of >1 million 16S rRNA genes. Abiotic soil properties (soil moisture, temperature, pH, and inorganic N and microbial functioning (nitrification and denitrification potentials were also measured and showed treatment-induced shifts, including altered NO3- availability, temperature, and nitrification potential. Despite these changes, bacterial and archaeal communities showed little variation in composition and diversity across treatments. Even communities in plots exposed to three interacting environmental changes were similar to those in restored native grassland plots. Historical exposure to large seasonal and inter-annual variations in key soil properties, in addition to prior site cultivation, may select for a functionally plastic or largely dormant microbial community, resulting in a microbial community that is structurally robust to single and multiple environmental changes.

  20. Controls upon microbial accessibility to soil organic matter following woody plant encroachment into grasslands

    Science.gov (United States)

    Creamer, C. A.; Boutton, T. W.; Filley, T. R.

    2009-12-01

    Woody plant encroachment (WPE) into savannas and grasslands is a global phenomenon that alters soil organic matter (SOM) dynamics through changes in litter quality and quantity, soil structure, microbial ecology, and soil hydrology. To elucidate the controls upon microbial accessibility to SOM, bulk soils from a chronosequence of progressive WPE into native grasslands at the Texas A&M Agricultural Experimental Station La Copita Research Area were incubated for one year. The quantity and stable carbon isotope composition of respired CO2, plant biopolymer chemistry in SOM, and microbial community structure were tracked. Respiration rates declined steadily over the course of the experiment with 15-25% of the total CO2 respired released in the first month of incubation. Between 8 and 18% of the total carbon was mineralized to CO2 throughout the incubation. After day 84 a significantly (p evidence of enhanced carbon stabilization in these respiration experiments. In fact, a greater proportion of total carbon was lost from the soil of mature woody stands than from young stands, suggesting carbon accumulation observed with WPE may be due to greater input rates or microbial dynamics not captured in the laboratory incubation. A cluster approximately 34 years in age represents a transition point in WPE where respiration dynamics become distinct between grassland and wooded elements. By day 84 of the incubation CO2 respired from all soils was depleted with respect to bulk SOM (1.5 to 5‰) and this pattern remained for the rest of the incubation. As the depletion of CO2 relative to bulk SOM was observed in grassland and cluster soils, we hypothesized the depleted signature resulted from the utilization of depleted biopolymers, specifically lignin, cutin and suberin, as hypothesized by others. Quantitative and isotopic comparisons of these monomers prior to and following the incubation will determine if selective compound utilization is a reason for this depletion. The results

  1. Integrating plant-microbe interactions to understand soil C stabilization with the MIcrobial-MIneral Carbon Stabilization model (MIMICS)

    Science.gov (United States)

    Grandy, Stuart; Wieder, Will; Kallenbach, Cynthia; Tiemann, Lisa

    2014-05-01

    If soil organic matter is predominantly microbial biomass, plant inputs that build biomass should also increase SOM. This seems obvious, but the implications fundamentally change how we think about the relationships between plants, microbes and SOM. Plant residues that build microbial biomass are typically characterized by low C/N ratios and high lignin contents. However, plants with high lignin contents and high C/N ratios are believed to increase SOM, an entrenched idea that still strongly motivates agricultural soil management practices. Here we use a combination of meta-analysis with a new microbial-explicit soil biogeochemistry model to explore the relationships between plant litter chemistry, microbial communities, and SOM stabilization in different soil types. We use the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, newly built upon the Community Land Model (CLM) platform, to enhance our understanding of biology in earth system processes. The turnover of litter and SOM in MIMICS are governed by the activity of r- and k-selected microbial groups and temperature sensitive Michaelis-Menten kinetics. Plant and microbial residues are stabilized short-term by chemical recalcitrance or long-term by physical protection. Fast-turnover litter inputs increase SOM by >10% depending on temperature in clay soils, and it's only in sandy soils devoid of physical protection mechanisms that recalcitrant inputs build SOM. These results challenge centuries of lay knowledge as well as conventional ideas of SOM formation, but are they realistic? To test this, we conducted a meta-analysis of the relationships between the chemistry of plant liter inputs and SOM concentrations. We find globally that the highest SOM concentrations are associated with plant inputs containing low C/N ratios. These results are confirmed by individual tracer studies pointing to greater stabilization of low C/N ratio inputs, particularly in clay soils. Our model and meta-analysis results suggest

  2. Biodiversity of Soil Microbial Communities Following Woody Plant Invasion of Grassland: An Assessment Using Molecular Methods

    Science.gov (United States)

    Kantola, I. B.; Gentry, T. J.; Filley, T. R.; Boutton, T. W.

    2012-12-01

    Woody plants have encroached into grasslands, savannas, and other grass-dominated ecosystems throughout the world during the last century. This dramatic vegetation change is likely driven by livestock grazing, altered fire frequencies, elevated atmospheric CO2 concentrations, and/or changes in atmospheric deposition patterns. Woody invasion often results in significant changes in ecosystem function, including alterations in above- and belowground primary productivity, soil C, N, and P storage and turnover, and the size and activity of the soil microbial biomass pool. The purpose of this study was to examine the relationships and interactions between plant communities and soil microbial communities in the Rio Grande Plains region of southern Texas where grasslands have been largely replaced by woodlands. Research was conducted along a successional chronosequence representing the stages of woody plant encroachment from open grassland to closed-canopy woodland. To characterize soil microbial community composition, soil samples (0-7.5 cm) were collected in remnant grasslands (representing time 0) and near the centers of woody plant clusters, groves, and drainage woodlands ranging in age from 10 to 130 yrs. Ages of woody plant stands were determined by dendrochronology. Community DNA was extracted from each soil sample with a MoBio PowerMax Soil DNA isolation kit. The DNA concentrations were quantified on a NanoDrop ND-1000 spectrophotometer and diluted to a standard concentration. Pyrosequencing was performed by the Research and Testing Laboratory (Lubbock, TX) according to Roche 454 Titanium chemistry protocols. Samples were amplified with primers 27F and 519R for bacteria, and primers ITS1F and ITS4 for fungi. Sequences were aligned using BioEdit and the RDP Pipeline and analyzed in MOTHUR. Non-metric multidimensional scaling of the operational taxonomic units identified by pyrosequencing revealed that both bacterial and fungal community composition were

  3. Native Michigan plants stimulate soil microbial species changes and PAH remediation at a legacy steel mill.

    Science.gov (United States)

    Thomas, John C; Cable, Edward; Dabkowski, Robert T; Gargala, Stephanie; McCall, Daniel; Pangrazzi, Garett; Pierson, Adam; Ripper, Mark; Russell, Donald K; Rugh, Clayton L

    2013-01-01

    A 1.3-acre phytoremediation site was constructed to mitigate polyaromatic hydrocarbon (PAH) contamination from a former steel mill in Michigan. Soil was amended with 10% (v/v) compost and 5% (v/v) poultry litter. The site was divided into twelve 11.89 m X 27.13 m plots, planted with approximately 35,000 native Michigan perennials, and soils sampled for three seasons. Soil microbial density generally increased in subplots of Eupatorium perfoliatum (boneset), Aster novae-angliae (New England aster), Andropogon gerardii (big bluestem), and Scirpus atrovirens (green bulrush) versus unplanted subplots. Using enumeration assays with root exudates, PAH degrading bacteria were greatest in soils beneath plants. Initially predominant, Arthrobacter were found capable of degrading a PAH cocktail in vitro, especially upon the addition of root exudate. Growth of some Arthrobacter isolates was stimulated by root exudate. The frequency of Arthrobacter declined in planted subplots with a concurrent increase in other species, including secondary PAH degraders Bacillus and Nocardioides. In subplots supporting only weeds, an increase in Pseudomonas density and little PAH removal were observed. This study supports the notion that a dynamic interplay between the soil, bacteria, and native plant root secretions likely contributes to in situ PAH phytoremediation.

  4. The Metagenome of Utricularia gibba's Traps: Into the Microbial Input to a Carnivorous Plant

    Science.gov (United States)

    Alcaraz, Luis David; Martínez-Sánchez, Shamayim; Torres, Ignacio; Ibarra-Laclette, Enrique; Herrera-Estrella, Luis

    2016-01-01

    The genome and transcriptome sequences of the aquatic, rootless, and carnivorous plant Utricularia gibba L. (Lentibulariaceae), were recently determined. Traps are necessary for U. gibba because they help the plant to survive in nutrient-deprived environments. The U. gibba's traps (Ugt) are specialized structures that have been proposed to selectively filter microbial inhabitants. To determine whether the traps indeed have a microbiome that differs, in composition or abundance, from the microbiome in the surrounding environment, we used whole-genome shotgun (WGS) metagenomics to describe both the taxonomic and functional diversity of the Ugt microbiome. We collected U. gibba plants from their natural habitat and directly sequenced the metagenome of the Ugt microbiome and its surrounding water. The total predicted number of species in the Ugt was more than 1,100. Using pan-genome fragment recruitment analysis, we were able to identify to the species level of some key Ugt players, such as Pseudomonas monteilii. Functional analysis of the Ugt metagenome suggests that the trap microbiome plays an important role in nutrient scavenging and assimilation while complementing the hydrolytic functions of the plant. PMID:26859489

  5. Plant carbohydrate binding module enhances activity of hybrid microbial cellulase enzyme

    Directory of Open Access Journals (Sweden)

    Caitlin Siobhan Byrt

    2012-11-01

    Full Text Available A synthetic, highly active cellulase enzyme suitable for in planta production may be a valuable tool for biotechnological approaches to develop transgenic biofuel crops with improved digestibility. Here, we demonstrate that the addition of a plant derived carbohydrate binding module (CBM to a synthetic glycosyl hydrolase (GH improved the activity of the hydrolase in releasing sugar from plant biomass. A CEL-HYB1-CBM enzyme was generated by fusing a hybrid microbial cellulase, CEL-HYB1, with the carbohydrate-binding module (CBM of the tomato (Solanum lycopersicum SlCel9C1 cellulase. CEL-HYB1 and CEL-HYB1-CBM enzymes were produced in vitro using Pichia pastoris and the activity of these enzymes was tested using CMC, MUC and native crystalline cellulose assays. The presence of the CBM substantially improved the endo-glucanase activity of CEL-HYB1, especially against the native crystalline cellulose encountered in Sorghum plant cell walls. These results indicate that addition of an endogenous plant derived CBM to cellulase enzymes may enhance hydrolytic activity.

  6. Geochemical patterns and microbial contribution to iron plaque formation in the rice plant rhizosphere

    Science.gov (United States)

    Maisch, Markus; Murata, Chihiro; Unger, Julia; Kappler, Andreas; Schmidt, Caroline

    2015-04-01

    Rice is the major food source for more than half of the world population and 80 percent of the worldwide rice cultivation is performed on water logged paddy soils. The establishment of reducing conditions in the soil and across the soil-water interface not only stimulates the microbial production and release of the greenhouse gas methane. These settings also create optimal conditions for microbial iron(III) reduction and therefore saturate the system with reduced ferrous iron. Through the reduction and dissolution of ferric minerals that are characterized by their high surface activity, sorbed nutrients and contaminants (e.g. arsenic) will be mobilized and are thus available for uptake by plants. Rice plants have evolved a strategy to release oxygen from their roots in order to prevent iron toxification in highly ferrous environments. The release of oxygen to the reduced paddy soil causes ferric iron plaque formation on the rice roots and finally increases the sorption capacity for toxic metals. To this date the geochemical and microbiological processes that control the formation of iron plaque are not deciphered. It has been hypothesized that iron(II)-oxidizing bacteria play a potential role in the iron(III) mineral formation along the roots. However, not much is known about the actual processes, mineral products, and geochemical gradients that establish within the rhizosphere. In the present study we have developed a growth set-up that allows the co-cultivation of rice plants and iron(II)-oxidizing bacteria, as well as the visual observation and in situ measurement of geochemical parameters. Oxygen and dissolved iron(II) gradients have been measured using microelectrodes and show geochemical hot spots that offer optimal growth conditions for microaerophilic iron(II) oxidizers. First mineral identification attempts of iron plaque have been performed using Mössbauer spectroscopy and microscopy. The obtained results on mineraology and crystallinity have been

  7. Rhizosphere Microbial Community Composition Affects Cadmium and Zinc Uptake by the Metal-Hyperaccumulating Plant Arabidopsis halleri

    Science.gov (United States)

    Muehe, E. Marie; Weigold, Pascal; Adaktylou, Irini J.; Planer-Friedrich, Britta; Kraemer, Ute; Kappler, Andreas

    2015-01-01

    The remediation of metal-contaminated soils by phytoextraction depends on plant growth and plant metal accessibility. Soil microorganisms can affect the accumulation of metals by plants either by directly or indirectly stimulating plant growth and activity or by (im)mobilizing and/or complexing metals. Understanding the intricate interplay of metal-accumulating plants with their rhizosphere microbiome is an important step toward the application and optimization of phytoremediation. We compared the effects of a “native” and a strongly disturbed (gamma-irradiated) soil microbial communities on cadmium and zinc accumulation by the plant Arabidopsis halleri in soil microcosm experiments. A. halleri accumulated 100% more cadmium and 15% more zinc when grown on the untreated than on the gamma-irradiated soil. Gamma irradiation affected neither plant growth nor the 1 M HCl-extractable metal content of the soil. However, it strongly altered the soil microbial community composition and overall cell numbers. Pyrosequencing of 16S rRNA gene amplicons of DNA extracted from rhizosphere samples of A. halleri identified microbial taxa (Lysobacter, Streptomyces, Agromyces, Nitrospira, “Candidatus Chloracidobacterium”) of higher relative sequence abundance in the rhizospheres of A. halleri plants grown on untreated than on gamma-irradiated soil, leading to hypotheses on their potential effect on plant metal uptake. However, further experimental evidence is required, and wherefore we discuss different mechanisms of interaction of A. halleri with its rhizosphere microbiome that might have directly or indirectly affected plant metal accumulation. Deciphering the complex interactions between A. halleri and individual microbial taxa will help to further develop soil metal phytoextraction as an efficient and sustainable remediation strategy. PMID:25595759

  8. Good Manufacturing Practices and Microbial Contamination Sources in Orange Fleshed Sweet Potato Puree Processing Plant in Kenya

    Science.gov (United States)

    Abong', George Ooko

    2018-01-01

    Limited information exists on the status of hygiene and probable sources of microbial contamination in Orange Fleshed Sweet Potato (OFSP) puree processing. The current study is aimed at determining the level of compliance to Good Manufacturing Practices (GMPs), hygiene, and microbial quality in OFSP puree processing plant in Kenya. Intensive observation and interviews using a structured GMPs checklist, environmental sampling, and microbial analysis by standard microbiological methods were used in data collection. The results indicated low level of compliance to GMPs with an overall compliance score of 58%. Microbial counts on food equipment surfaces, installations, and personnel hands and in packaged OFSP puree were above the recommended microbial safety and quality legal limits. Steaming significantly (P contamination. Total counts, yeasts and molds, Enterobacteriaceae, total coliforms, and E. coli and S. aureus counts in OFSP puree were 8.0, 4.0, 6.6, 5.8, 4.8, and 5.9 log10 cfu/g, respectively. In conclusion, equipment surfaces, personnel hands, and processing water were major sources of contamination in OFSP puree processing and handling. Plant hygiene inspection, environmental monitoring, and food safety trainings are recommended to improve hygiene, microbial quality, and safety of OFSP puree. PMID:29808161

  9. Good Manufacturing Practices and Microbial Contamination Sources in Orange Fleshed Sweet Potato Puree Processing Plant in Kenya.

    Science.gov (United States)

    Malavi, Derick Nyabera; Muzhingi, Tawanda; Abong', George Ooko

    2018-01-01

    Limited information exists on the status of hygiene and probable sources of microbial contamination in Orange Fleshed Sweet Potato (OFSP) puree processing. The current study is aimed at determining the level of compliance to Good Manufacturing Practices (GMPs), hygiene, and microbial quality in OFSP puree processing plant in Kenya. Intensive observation and interviews using a structured GMPs checklist, environmental sampling, and microbial analysis by standard microbiological methods were used in data collection. The results indicated low level of compliance to GMPs with an overall compliance score of 58%. Microbial counts on food equipment surfaces, installations, and personnel hands and in packaged OFSP puree were above the recommended microbial safety and quality legal limits. Steaming significantly ( P contamination. Total counts, yeasts and molds, Enterobacteriaceae, total coliforms, and E. coli and S. aureus counts in OFSP puree were 8.0, 4.0, 6.6, 5.8, 4.8, and 5.9 log 10 cfu/g, respectively. In conclusion, equipment surfaces, personnel hands, and processing water were major sources of contamination in OFSP puree processing and handling. Plant hygiene inspection, environmental monitoring, and food safety trainings are recommended to improve hygiene, microbial quality, and safety of OFSP puree.

  10. Targeted quantification of functional enzyme dynamics in environmental samples for microbially mediated biogeochemical processes: Targeted quantification of functional enzyme dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Li, Minjing [School of Environmental Studies, China University of Geosciences, Wuhan 430074 People' s Republic of China; Gao, Yuqian [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Qian, Wei-Jun [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Shi, Liang [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Liu, Yuanyuan [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Nelson, William C. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Nicora, Carrie D. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Resch, Charles T. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Thompson, Christopher [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Yan, Sen [School of Environmental Studies, China University of Geosciences, Wuhan 430074 People' s Republic of China; Fredrickson, James K. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Zachara, John M. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Liu, Chongxuan [Pacific Northwest National Laboratory, Richland, WA 99354 USA; School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055 People' s Republic of China

    2017-07-13

    Microbially mediated biogeochemical processes are catalyzed by enzymes that control the transformation of carbon, nitrogen, and other elements in environment. The dynamic linkage between enzymes and biogeochemical species transformation has, however, rarely been investigated because of the lack of analytical approaches to efficiently and reliably quantify enzymes and their dynamics in soils and sediments. Herein, we developed a signature peptide-based technique for sensitively quantifying dissimilatory and assimilatory enzymes using nitrate-reducing enzymes in a hyporheic zone sediment as an example. Moreover, the measured changes in enzyme concentration were found to correlate with the nitrate reduction rate in a way different from that inferred from biogeochemical models based on biomass or functional genes as surrogates for functional enzymes. This phenomenon has important implications for understanding and modeling the dynamics of microbial community functions and biogeochemical processes in environments. Our results also demonstrate the importance of enzyme quantification for the identification and interrogation of those biogeochemical processes with low metabolite concentrations as a result of faster enzyme-catalyzed consumption of metabolites than their production. The dynamic enzyme behaviors provide a basis for the development of enzyme-based models to describe the relationship between the microbial community and biogeochemical processes.

  11. Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases.

    Science.gov (United States)

    Welch, David; Buonanno, Manuela; Grilj, Veljko; Shuryak, Igor; Crickmore, Connor; Bigelow, Alan W; Randers-Pehrson, Gerhard; Johnson, Gary W; Brenner, David J

    2018-02-09

    Airborne-mediated microbial diseases such as influenza and tuberculosis represent major public health challenges. A direct approach to prevent airborne transmission is inactivation of airborne pathogens, and the airborne antimicrobial potential of UVC ultraviolet light has long been established; however, its widespread use in public settings is limited because conventional UVC light sources are both carcinogenic and cataractogenic. By contrast, we have previously shown that far-UVC light (207-222 nm) efficiently inactivates bacteria without harm to exposed mammalian skin. This is because, due to its strong absorbance in biological materials, far-UVC light cannot penetrate even the outer (non living) layers of human skin or eye; however, because bacteria and viruses are of micrometer or smaller dimensions, far-UVC can penetrate and inactivate them. We show for the first time that far-UVC efficiently inactivates airborne aerosolized viruses, with a very low dose of 2 mJ/cm 2 of 222-nm light inactivating >95% of aerosolized H1N1 influenza virus. Continuous very low dose-rate far-UVC light in indoor public locations is a promising, safe and inexpensive tool to reduce the spread of airborne-mediated microbial diseases.

  12. Stable, geochemically mediated biospheres in the Deep Mine Microbial Observatory, SD, USA

    Science.gov (United States)

    Osburn, M. R.; Casar, C. P.; Kruger, B.; Flynn, T. M.

    2017-12-01

    The terrestrial subsurface is a vast reservoir of life, hosting diverse microbial ecosystems with varying levels of connectivity to surface inputs. Understanding long term ecosystem dynamics within the subsurface biosphere is very challenging due to limitations in accessibility, sample availability, and slow microbial growth rates. The establishment of the Deep Mine Microbial Observatory (DeMMO) at the Sanford Underground Research Facility, SD, USA has allowed for bimonthly sampling for nearly two years at six sites spanning 250 to 1500 m below the surface. Here we present a time-resolved analysis of the geomicrobiology of the six DeMMO sites, which have been created from legacy mine boreholes modified to allow for controlled sampling. Our interdisciplinary approach includes analysis of passively draining fracture fluid for aqueous and gas geochemistry, DNA sequencing, microscopy, and isotopic measurements of organic and inorganic substrates. Fluid geochemistry varies significantly between sites, but is relatively stable over time for a given site, even through significant external perturbations such as drilling and installation of permanent sampling devices into the boreholes. The fluid-hosted microbial diversity follows these trends, with consistent populations present at each site through time, even through drilling events. For instance, the shallowest site (DeMMO 1) consistently hosts >30% uncharacterized phyla and >25% Omnitrophica whereas the deepest site (DeMMO 6) is dominated by Firmicutes and Bacterioidetes. Microbial diversity appears to respond to the availability of energy sources such as organic carbon, sulfate, sulfide, hydrogen, and iron. Carbon isotopic measurements reveal closed system behavior with significant recycling of organic carbon into the DIC pool. Together these observations suggest DeMMO hosts isolated subsurface microbial populations adapted to local geochemistry that are stable on yearlong timescales.

  13. Desert farming benefits from microbial potential in arid soils and promotes diversity and plant health.

    Directory of Open Access Journals (Sweden)

    Martina Köberl

    Full Text Available BACKGROUND: To convert deserts into arable, green landscapes is a global vision, and desert farming is a strong growing area of agriculture world-wide. However, its effect on diversity of soil microbial communities, which are responsible for important ecosystem services like plant health, is still not known. METHODOLOGY/PRINCIPAL FINDINGS: We studied the impact of long-term agriculture on desert soil in one of the most prominent examples for organic desert farming in Sekem (Egypt. Using a polyphasic methodological approach to analyse microbial communities in soil as well as associated with cultivated plants, drastic effects caused by 30 years of agriculture were detected. Analysing bacterial fingerprints, we found statistically significant differences between agricultural and native desert soil of about 60%. A pyrosequencing-based analysis of the 16S rRNA gene regions showed higher diversity in agricultural than in desert soil (Shannon diversity indices: 11.21/7.90, and displayed structural differences. The proportion of Firmicutes in field soil was significantly higher (37% than in the desert (11%. Bacillus and Paenibacillus play the key role: they represented 96% of the antagonists towards phytopathogens, and identical 16S rRNA sequences in the amplicon library and for isolates were detected. The proportion of antagonistic strains was doubled in field in comparison to desert soil (21.6%/12.4%; disease-suppressive bacteria were especially enriched in plant roots. On the opposite, several extremophilic bacterial groups, e.g., Acidimicrobium, Rubellimicrobium and Deinococcus-Thermus, disappeared from soil after agricultural use. The N-fixing Herbaspirillum group only occurred in desert soil. Soil bacterial communities were strongly driven by the a-biotic factors water supply and pH. CONCLUSIONS/SIGNIFICANCE: After long-term farming, a drastic shift in the bacterial communities in desert soil was observed. Bacterial communities in agricultural

  14. [Isolation of endophytic fungi from medicinal plant Brucea javanica and their microbial inhibition activity].

    Science.gov (United States)

    Liang, Zi-Ning; Zhu, Hua; Lai, Kai-Ping; Chen, Long

    2014-04-01

    To isolate and identify endophytic fungi from Brucea javanica, and to detect the antimicrobial activity of these strains. Endophytic fungi were isolated by tissue inoculation culture and identified by conventional morphological characteristic method. Seven kinds of pathogenic fungi and three kinds of bacteria were used as targeting microbes to test microbial inhibition activities by agar plate antagonistic action and modified agar gel diffusion methods, respectively. A total of 83 endophytic fungi strains were isolated from the root, stem, leaf and fruit of Brucea javanica. 34 strains were obtained from the stem, 32 strains were obtained from the leaf, 15 strains were isolated from the root and 2 strains came from the fruit. These 73 strains which had been identified attribute to 5 orders, 6 families and 12 genera. For the isolated strains, 14 strains had antifungal activities against at least one pathogenic fungi, 9 strains showed antibacterial activities against one or more bacteria. Especially, the strain YJ-17 which belonged to Phomopsis genus showed the best inhibitory effect on the targeting microbes. The endophytic fungi from Brucea javanica show diversity and microbial inhibition activity, and are worthy for further study on plant disease controlling.

  15. Effects of Plant Extracts on Microbial Population, Methane Emission and Ruminal Fermentation Characteristics in

    Directory of Open Access Journals (Sweden)

    E. T. Kim

    2012-06-01

    Full Text Available This study was conducted to evaluate effects of plant extracts on methanogenesis and rumen microbial diversity in in vitro. Plant extracts (Artemisia princeps var. Orientalis; Wormwood, Allium sativum for. Pekinense; Garlic, Allium cepa; Onion, Zingiber officinale; Ginger, Citrus unshiu; Mandarin orange, Lonicera japonica; Honeysuckle were obtained from the Plant Extract Bank at Korea Research Institute of Bioscience and Biotechnology. The rumen fluid was collected before morning feeding from a fistulated Holstein cow fed timothy and commercial concentrate (TDN; 73.5%, crude protein; 19%, crude fat; 3%, crude fiber; 12%, crude ash; 10%, Ca; 0.8%, P; 1.2% in the ratio of 3 to 2. The 30 ml of mixture, comprising McDougall buffer and rumen liquor in the ratio of 4 to 1, was dispensed anaerobically into serum bottles containing 0.3 g of timothy substrate and plant extracts (1% of total volume, respectively filled with O2-free N2 gas and capped with a rubber stopper. The serum bottles were held in a shaking incubator at 39°C for 24 h. Total gas production in all plant extracts was higher (p<0.05 than that of the control, and total gas production of ginger extract was highest (p<0.05. The methane emission was highest (p<0.05 at control, but lowest (p<0.05 at garlic extract which was reduced to about 20% of methane emission (40.2 vs 32.5 ml/g DM. Other plant extracts also resulted in a decrease in methane emissions (wormwood; 8%, onion; 16%, ginger; 16.7%, mandarin orange; 12%, honeysuckle; 12.2%. Total VFAs concentration and pH were not influenced by the addition of plant extracts. Acetate to propionate ratios from garlic and ginger extracts addition samples were lower (p<0.05, 3.36 and 3.38 vs 3.53 than that of the control. Real-time PCR indicted that the ciliate-associated methanogen population in all added plant extracts decreased more than that of the control, while the fibrolytic bacteria population increased. In particular, the F. succinogens

  16. Seasonal variations and effects of nutrient applications on N and P and microbial biomass under two temperate heathland plants

    DEFF Research Database (Denmark)

    Nielsen, Pia Lund; Andresen, Louise Christoffersen; Michelsen, Anders

    2009-01-01

    . The microbial biomass on the other hand was positively related to soil water content in fertilized plots indicating that this was due to an indirect effect of enhanced nutrient availability. Microbial N and P pools were respectively 1000 and 100 times higher than the pool of inorganic N and P, and microbes...... this process. In this study the soil properties under two dominant heathland plants, the dwarf shrub Calluna vulgaris and the grass Deschampsia flexuosa, were investigated, with focus on nutrient content in the organic top soil and soil microbes during the main growing season and effects of nutrient amendments...... therefore may play an important role in regulating plant nutrient supply. Judged from responses of inorganic and microbial N and P concentrations to added N and P, N seemed to limit C. vulgaris and soil microbes below while P seemed to limit D. flexuosa and soil microbes below this species. There were lower...

  17. Effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities

    Energy Technology Data Exchange (ETDEWEB)

    Liu Feng [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, Tianhe District, Guangzhou 510640 (China); Ying Guangguo, E-mail: guangguo.ying@gmail.co [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, Tianhe District, Guangzhou 510640 (China); Tao Ran; Zhao Jianliang; Yang Jifeng [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, Tianhe District, Guangzhou 510640 (China); Zhao Lanfeng [College of Resource and Environmental Science, South China Agricultural University, Guangzhou 510642 (China)

    2009-05-15

    The potential impact of six antibiotics (chlortetracycline, tetracycline and tylosin; sulfamethoxazole, sulfamethazine and trimethoprim) on plant growth and soil quality was studied by using seed germination test on filter paper and plant growth test in soil, soil respiration and phosphatase activity tests. The phytotoxic effects varied between the antibiotics and between plant species (sweet oat, rice and cucumber). Rice was most sensitive to sulfamethoxazole with the EC10 value of 0.1 mg/L. The antibiotics tested inhibited soil phosphatase activity during the 22 days' incubation. Significant effects on soil respiration were found for the two sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim, whereas little effects were observed for the two tetracyclines and tylosin. The effective concentrations (EC10 values) for soil respiration in the first 2 days were 7 mg/kg for sulfamethoxazole, 13 mg/kg for sulfamethazine and 20 mg/kg for trimethoprim. Antibiotic residues in manure and soils may affect soil microbial and enzyme activities. - Terrestrial ecotoxicological effects of antibiotics are related to their sorption and degradation behavior in soil.

  18. Effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities

    International Nuclear Information System (INIS)

    Liu Feng; Ying Guangguo; Tao Ran; Zhao Jianliang; Yang Jifeng; Zhao Lanfeng

    2009-01-01

    The potential impact of six antibiotics (chlortetracycline, tetracycline and tylosin; sulfamethoxazole, sulfamethazine and trimethoprim) on plant growth and soil quality was studied by using seed germination test on filter paper and plant growth test in soil, soil respiration and phosphatase activity tests. The phytotoxic effects varied between the antibiotics and between plant species (sweet oat, rice and cucumber). Rice was most sensitive to sulfamethoxazole with the EC10 value of 0.1 mg/L. The antibiotics tested inhibited soil phosphatase activity during the 22 days' incubation. Significant effects on soil respiration were found for the two sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim, whereas little effects were observed for the two tetracyclines and tylosin. The effective concentrations (EC10 values) for soil respiration in the first 2 days were 7 mg/kg for sulfamethoxazole, 13 mg/kg for sulfamethazine and 20 mg/kg for trimethoprim. Antibiotic residues in manure and soils may affect soil microbial and enzyme activities. - Terrestrial ecotoxicological effects of antibiotics are related to their sorption and degradation behavior in soil.

  19. More JAZ in the orchestration of jasmonate-mediated plant defense

    NARCIS (Netherlands)

    Zhou, Meiliang

    2014-01-01

    Jasmonates (JAs) are plant hormones that regulate defense against microbial pathogens and insect herbivores via two antagonistic branches of the JAs signaling pathway leading to activation of distinct sets of defense genes. In Arabidopsis thaliana defense against herbivores is regulated by JAs alone

  20. Chemical diversity of microbial volatiles and their potential for plant growth and productivity

    Directory of Open Access Journals (Sweden)

    CHIDANANDA NAGAMANGALA KANCHISWAMY

    2015-03-01

    Full Text Available Microbial volatile organic compounds (MVOCs are produced by a wide array of microorganisms ranging from bacteria to fungi. A growing body of evidence indicates that MVOCs are ecofriendly and can be exploited as a cost-effective sustainable strategy for use in agricultural practice as agents that enhance plant growth, productivity and disease resistance. As naturally occurring chemicals, MVOCs have potential as possible alternatives to harmful pesticides, fungicides and bactericides as well as genetic modification. Recent studies performed under open field conditions demonstrate that efficiently adopting MVOCs may contribute to sustainable crop protection and production. We review here the chemical diversity of MVOCs and their potential physiological effects on crops and analyze potential and actual limitations for MVOC use as a sustainable strategy for improving productivity and reducing pesticide use.

  1. Plant genetic variation mediates an indirect ecological effect between belowground earthworms and aboveground aphids.

    Science.gov (United States)

    Singh, Akanksha; Braun, Julia; Decker, Emilia; Hans, Sarah; Wagner, Agnes; Weisser, Wolfgang W; Zytynska, Sharon E

    2014-10-21

    Interactions between aboveground and belowground terrestrial communities are often mediated by plants, with soil organisms interacting via the roots and aboveground organisms via the shoots and leaves. Many studies now show that plant genetics can drive changes in the structure of both above and belowground communities; however, the role of plant genetic variation in mediating aboveground-belowground interactions is still unclear. We used an earthworm-plant-aphid model system with two aphid species (Aphis fabae and Acyrthosiphon pisum) to test the effect of host-plant (Vicia faba) genetic variation on the indirect interaction between the belowground earthworms (Eisenia veneta) on the aboveground aphid populations. Our data shows that host-plant variety mediated an indirect ecological effect of earthworms on generalist black bean aphids (A. fabae), with earthworms increasing aphid growth rate in three plant varieties but decreasing it in another variety. We found no effect of earthworms on the second aphid species, the pea aphid (A. pisum), and no effect of competition between the aphid species. Plant biomass was increased when earthworms were present, and decreased when A. pisum was feeding on the plant (mediated by plant variety). Although A. fabae aphids were influenced by the plants and worms, they did not, in turn, alter plant biomass. Previous work has shown inconsistent effects of earthworms on aphids, but we suggest these differences could be explained by plant genetic variation and variation among aphid species. This study demonstrates that the outcome of belowground-aboveground interactions can be mediated by genetic variation in the host-plant, but depends on the identity of the species involved.

  2. Microbial diversity in soil : Selection of microbial populations by plant and soil type and implications for disease suppressiveness

    NARCIS (Netherlands)

    Garbeva, P; van Veen, JA; van Elsas, JD

    2004-01-01

    An increasing interest has emerged with respect to the importance of microbial diversity in soil habitats. The extent of the diversity of microorganisms in soil is seen to be critical to the maintenance of soil health and quality, as a wide range of microorganisms is involved in important soil

  3. Assessment of WQI and Microbial pollution for two water treatment plants in Baghdad city

    Directory of Open Access Journals (Sweden)

    Mohammed AliAl-Hashimi

    2017-03-01

    Full Text Available Tigris River is the main water source for all water treatment plants in Baghdad city. In current study, Water Quality Index (WQI and microbial pollution was obtained for two water treatment plants and their networks in Baghdad city Al-Karama and Al-Wathba WTP for both raw and treated water, In order to assess water suitability as a source of domestic water supply. Physical, chemical, and Microbialparameters werestudied fora period of four months (March-June, 2014. The parameters which were taken into account for the present work are pH, turbidity (Nephelometric Turbidity Unit, Total Alkalinity (TA, Electrical Conductivity (EC, Calcium (Ca++, Magnesium (Mg++, Total Hardness (TH, Total Dissolved Solids (TDS,Chloride (Cl-, and Most Probable Number (MPN method as microbial pollution indicator. The results indicate that WQI for untreated Tigris water was classified as "unfit for human consumption" at both WTPs intakes and along study period and after water passing through the sequence treatment units in WTPs its quality is gradually increased and finally, the treated water quality ranged from "Good" to " Moderately polluted" at both All-Karama and Al-Wathba WTPs. In networks the quality of water ranged between "Good" to "moderately polluted" in Al-Karama WTP network and between "Moderately polluted" to "severely polluted" in Al-Wathba WTP network. For Microbiological pollution, MPN throughout the period of study was between (0-150 cell/100ml at Al-Karama WTP and between (0- 240 cell/100ml at Al-Wathba WTP. The highest value obtained was (240 cell/100ml at raw water in Al- Wathba WTP intake in June, while the lowest value obtained was (0 cell/100ml at all chlorinated samples.

  4. Disentangling mechanisms that mediate the balance between stochastic and deterministic processes in microbial succession

    NARCIS (Netherlands)

    Dini-Andreote, Francisco; Stegen, James C.; van Elsas, Jan Dirk; Salles, Joana Falcao

    2015-01-01

    Ecological succession and the balance between stochastic and deterministic processes are two major themes within microbial ecology, but these conceptual domains have mostly developed independent of each other. Here we provide a framework that integrates shifts in community assembly processes with

  5. Soil-derived microbial consortia enriched with different plant biomass reveal distinct players acting in lignocellulose degradation

    NARCIS (Netherlands)

    de Lima Brossi, Maria Julia; Jiménez Avella, Diego; Cortes Tolalpa, Larisa; van Elsas, Jan

    Here, we investigated how different plant biomass, and-for one substrate-pH, drive the composition of degrader microbial consortia. We bred such consortia from forest soil, incubated along nine aerobic sequential - batch enrichments with wheat straw (WS1, pH 7.2; WS2, pH 9.0), switchgrass (SG, pH

  6. Relationship of microbial processes to the fate and behavior of transuranic elements in soils, plants, and animals

    International Nuclear Information System (INIS)

    Wildung, R.E.; Garland, T.R.

    1980-01-01

    Soil physicochemical and microbial processes influence the long-term solubility, form, and bioavailability of plutonium and other transuranic elements important in the nuclear fuel cycle. Consideration is given to the chemistry/microbiology of the transuranic elements in soil, emphasizing possible organic complexation reactions in soils and plants and the relationship of these phenomena to gastrointestinal absorption

  7. Impact of a wastewater treatment plant on microbial community composition and function in a hyporheic zone of a eutrophic river

    NARCIS (Netherlands)

    Atashgahi, S.; Aydin, R.; Rocha Dimitrov, M.; Sipkema, D.; Hamonts, K.; Lahti, Leo; Maphosa, F.; Kruse, T.; Saccenti, E.; Springael, D.; Dejonghe, W.; Smidt, H.

    2015-01-01

    The impact of the installation of a technologically advanced wastewater treatment plant (WWTP) on the benthic microbial community of a vinyl chloride (VC) impacted eutrophic river was examined two years before, and three and four years after installation of the WWTP. Reduced dissolved organic carbon

  8. Microbial plant litter decomposition in aquatic and terrestrial boreal systems along a natural fertility gradient

    Science.gov (United States)

    Soares, A. Margarida P. M.; Kritzberg, Emma S.; Rousk, Johannes

    2017-04-01

    Plant litter decomposition is a global ecosystem process, with a crucial role in carbon and nutrient cycling. The majority of litter processing occurs in terrestrial systems, but an important fraction also takes place in inland waters. Among environmental factors, pH impacts the litter decomposition through its selective influence on microbial decomposers. Fungal communities are less affected by pH than bacteria, possibly owing to a wider pH tolerance by this group. On the other hand, bacterial pH optima are constrained to a narrower range of pH values. The microbial decomposition of litter is universally nutrient limited; but few comparisons exist between terrestrial and aquatic systems. We investigated the microbial colonisation and decomposition of plant litter along a fertility gradient, which varied in both pH and N availability in both soil and adjacent water. To do this we installed litterbags with birch (Betula pendula) in streams and corresponding soils in adjacent riparian areas in a boreal system, in Krycklan, Sweden. During the four months covering the ice-free growth season we monitored the successional dynamics of fungal (acetate incorporation into ergosterol) and bacterial growth (thymidine incorporation), microbial respiration in leaf litter, and quantitative and qualitative changes in litter over time. We observed that bacterial growth rates were initially higher in litter decomposing in streams than those in soils, but differences between terrestrial and aquatic bacterial production converged towards the end of the experiment. In litter bags installed in soils, bacterial growth was lower at sites with more acidic pH and lower N availability, while aquatic bacteria were relatively unaffected by the fertility level. Fungal growth rates were two-fold higher for litter decomposing in streams than in soils. In aquatic systems, fungal growth was initially lower in low fertility sites, but differences gradually disappeared over the time course. Fungal

  9. CRISPR/Cas9-mediated viral interference in plants

    KAUST Repository

    Ali, Zahir; Abulfaraj, Aala A.; Idris, Ali; Ali, Shawkat; Tashkandi, Manal; Mahfouz, Magdy M.

    2015-01-01

    These data establish the efficacy of the CRISPR/Cas9 system for viral interference in plants, thereby extending the utility of this technology and opening the possibility of producing plants resistant to multiple viral infections.

  10. Plant tolerance to diesel minimizes its impact on soil microbial characteristics during rhizoremediation of diesel-contaminated soils

    International Nuclear Information System (INIS)

    Barrutia, O.; Garbisu, C.; Epelde, L.; Sampedro, M.C.; Goicolea, M.A.; Becerril, J.M.

    2011-01-01

    Soil contamination due to petroleum-derived products is an important environmental problem. We assessed the impacts of diesel oil on plants (Trifolium repens and Lolium perenne) and soil microbial community characteristics within the context of the rhizoremediation of contaminated soils. For this purpose, a diesel fuel spill on a grassland soil was simulated under pot conditions at a dose of 12,000 mg diesel kg -1 DW soil. Thirty days after diesel addition, T. repens (white clover) and L. perenne (perennial ryegrass) were sown in the pots and grown under greenhouse conditions (temperature 25/18 o C day/night, relative humidity 60/80% day/night and a photosynthetic photon flux density of 400 μmol photon m -2 s -1 ) for 5 months. A parallel set of unplanted pots was also included. Concentrations of n-alkanes in soil were determined as an indicator of diesel degradation. Seedling germination, plant growth, maximal photochemical efficiency of photosystem II (F v /F m ), pigment composition and lipophylic antioxidant content were determined to assess the impacts of diesel on the studied plants. Soil microbial community characteristics, such as enzyme and community-level physiological profiles, were also determined and used to calculate the soil quality index (SQI). The presence of plants had a stimulatory effect on soil microbial activity. L. perenne was far more tolerant to diesel contamination than T. repens. Diesel contamination affected soil microbial characteristics, although its impact was less pronounced in the rhizosphere of L. perenne. Rhizoremediation with T. repens and L. perenne resulted in a similar reduction of total n-alkanes concentration. However, values of the soil microbial parameters and the SQI showed that the more tolerant species (L. perenne) was able to better maintain its rhizosphere characteristics when growing in diesel-contaminated soil, suggesting a better soil health. We concluded that plant tolerance is of crucial importance for the

  11. Preliminary screening of some traditional zulu medicinal plants for anti-inflammatory and anti-microbial activities.

    Science.gov (United States)

    Lin, J; Opoku, A R; Geheeb-Keller, M; Hutchings, A D; Terblanche, S E; Jäger, A K; van Staden, J

    1999-12-15

    Aqueous and methanolic extracts from different parts of nine traditional Zulu medicinal plants, of the Vitaceae from KwaZulu-Natal, South Africa were evaluated for therapeutic potential as anti-inflammatory and anti-microbial agents. Of the twenty-nine crude extracts assayed for prostaglandin synthesis inhibitors, only five methanolic extracts of Cyphostemma natalitium-root, Rhoicissus digitata-leaf, R. rhomboidea-root, R. tomentosa-leaf/stem and R. tridentata-root showed significant inhibition of cyclo-oxygenase (COX-1). The extracts of R. digitata-leaf and of R. rhomboidea-root exhibited the highest inhibition of prostaglandin synthesis with 53 and 56%, respectively. The results suggest that Rhoicissus digitata leaves and of Rhoicissus rhomboidea roots may have the potential to be used as anti-inflammatory agents. All the screened plant extracts showed some degrees of anti-microbial activity against gram-positive and gram-negative microorganisms. The methanolic extracts of C. natalitium-stem and root, R. rhomboidea-root, and R. tomentosa-leaf/stem, showed different anti-microbial activities against almost all micro-organisms tested. Generally, these plant extracts inhibited the gram-positive micro-organisms more than the gram-negative ones. Several plant extracts inhibited the growth of Candida albicans while only one plant extract showed inhibitory activity against Saccharomyces cerevisiae. All the plant extracts which demonstrated good anti-inflammatory activities also showed better inhibitory activity against Candida albicans.

  12. The Influence of Ecological and Conventional Plant Production Systems on Soil Microbial Quality under Hops (Humulus lupulus)

    Science.gov (United States)

    Oszust, Karolina; Frąc, Magdalena; Gryta, Agata; Bilińska, Nina

    2014-01-01

    The knowledge about microorganisms—activity and diversity under hop production is still limited. We assumed that, different systems of hop production (within the same soil and climatic conditions) significantly influence on the composition of soil microbial populations and its functional activity (metabolic potential). Therefore, we compared a set of soil microbial properties in the field experiment of two hop production systems (a) ecological based on the use of probiotic preparations and organic fertilization (b) conventional—with the use of chemical pesticides and mineral fertilizers. Soil analyses included following microbial properties: The total number microorganisms, a bunch of soil enzyme activities, the catabolic potential was also assessed following Biolog EcoPlates®. Moreover, the abundance of ammonia-oxidizing archaea (AOA) was characterized by terminal restriction fragment length polymorphism analysis (T-RFLP) of PCR ammonia monooxygenase α-subunit (amoA) gene products. Conventional and ecological systems of hop production were able to affect soil microbial state in different seasonal manner. Favorable effect on soil microbial activity met under ecological, was more probably due to livestock-based manure and fermented plant extracts application. No negative influence on conventional hopyard soil was revealed. Both type of production fulfilled fertilizing demands. Under ecological production it was due to livestock-based manure fertilizers and fermented plant extracts application. PMID:24897025

  13. The Influence of Ecological and Conventional Plant Production Systems on Soil Microbial Quality under Hops (Humulus lupulus

    Directory of Open Access Journals (Sweden)

    Karolina Oszust

    2014-06-01

    Full Text Available The knowledge about microorganisms—activity and diversity under hop production is still limited. We assumed that, different systems of hop production (within the same soil and climatic conditions significantly influence on the composition of soil microbial populations and its functional activity (metabolic potential. Therefore, we compared a set of soil microbial properties in the field experiment of two hop production systems (a ecological based on the use of probiotic preparations and organic fertilization (b conventional—with the use of chemical pesticides and mineral fertilizers. Soil analyses included following microbial properties: The total number microorganisms, a bunch of soil enzyme activities, the catabolic potential was also assessed following Biolog EcoPlates®. Moreover, the abundance of ammonia-oxidizing archaea (AOA was characterized by terminal restriction fragment length polymorphism analysis (T-RFLP of PCR ammonia monooxygenase α-subunit (amoA gene products. Conventional and ecological systems of hop production were able to affect soil microbial state in different seasonal manner. Favorable effect on soil microbial activity met under ecological, was more probably due to livestock-based manure and fermented plant extracts application. No negative influence on conventional hopyard soil was revealed. Both type of production fulfilled fertilizing demands. Under ecological production it was due to livestock-based manure fertilizers and fermented plant extracts application.

  14. The Physical, Chemical and Microbial Quality of Treated Water in Qom s Desalination Plants

    Directory of Open Access Journals (Sweden)

    A. R. Yari

    2007-04-01

    Full Text Available Background and objectivesWater is the basis of life and health. The health of food and water supply plays an important role in human health. One of the methods of water desalination is membrane filter reverse osmosis method. This method is used for desalination of drinking water supply in Qom.MethodsThis is a descriptive, cross-sectional study designed to determine the quality of treated water in Qom desalination plant in year 2002. Inlet and outlet water samples of this plant were examined by the standard examination methods and the collected data were compared with national and international standards. Excel software was used for statistical analysis.ResultsThe results showed that the residual chlorine concentration, total hardness and fluoride concentration were lower than the minimum standard limit set for drinking water. The pH was also lower than the minimum standard limit. Microbial contamination was detected in 6% of samples.ConclusionThe results show that the acidity of water was lower than standard in whole plant. This gives corrosive properties to the water and increases the dissolution of materials, which are in contact with this water. In order to eliminate the secondary contamination, the concentration of residual chlorine should be 1 mg/l. But, none of the measurements showed a concentration as high as this value. As fluoride is an important element for health and growth of bone and teeth, especially in growing children, fluoride should be added to the drinking water. As the relationship between hardness of water and cardiovascular diseases has been established, it can be concluded that this drinking water supply can increase the risk of cardiovascular diseases in long time. Dilution of this water is recommended to adjust various factors to the standard limits and keep the total dissolved solids low.Keywords: Qom ;Water; Reverse Osmosis; Desalination Plant; Water Quality

  15. The ecological effects of different loading rates of metalaxyl on microbial biomass in unplanted and planted soils under field conditions

    Directory of Open Access Journals (Sweden)

    M. Mansourzadeh

    2016-05-01

    Full Text Available Fungicides are most widely used pesticides in Iran and the world. Application of fungicides may affect the populations and activity of soil microorganisms, particularly fungi, with a consequence for soil fertility and crop growth. In the current study, the effects of different levels of metalaxyl on soil microbial biomass carbon (C and nitrogen (N, microbial biomass C/N ratio and metabolic quotient under field conditions were assessed. Two levels of metalaxyl (30 and 60 kg.ha-1 were applied in planted soils with corn and unplanted calcareous soils, using a split-plots experiment in a completely randomized design with three replications. The C and N contents in soil microbial biomass as well as metabolic quotient were measured at 30 and 90 days after the onset of the experiment. Results showed that in cultivated soils metalaxyl application at 30 kg.ha-1 increased (15-80% significantly (p≤0.01 the amounts of microbial biomass C and N at both intervals (except microbial biomass C at 90 days compared to the control soil (0 kg.ha-1, while in uncultivated soils both microbial biomass C and N reduced by almost 1-34%. Microbial biomass C/N ratios in unplanted soils decreased (15 and 53% with increasing loading rates of metalaxyl, without a clear effect in cultivated soils. On the other hand, metabolic quotient values reduced (48% at 30 and 60 kg.ha-1 metalaxyl in corn-cultivated soils when compared to untreated soils while in uncultivated soils metalaxyl rate at 30 kg.a-1 had the greatest values at 30 days, and increased with increasing the levels of metalaxyl at 90 days. In summary, application of metalaxyl can either reduce or increase soil biological indices, and the direction and changes are depended upon the application rate of metalaxyl, time elapsed since metalaxyl application and the presence or absence of plant.

  16. Chirality in microbial biofilms is mediated by close interactions between the cell surface and the substratum

    Science.gov (United States)

    Jauffred, Liselotte; Munk Vejborg, Rebecca; Korolev, Kirill S; Brown, Stanley; Oddershede, Lene B

    2017-01-01

    From microbial biofilms to human migrations, spatial competition is central to the evolutionary history of many species. The boundary between expanding populations is the focal point of competition for space and resources and is of particular interest in ecology. For all Escherichia coli strains studied here, these boundaries move in a counterclockwise direction even when the competing strains have the same fitness. We find that chiral growth of bacterial colonies is strongly suppressed by the expression of extracellular features such as adhesive structures and pili. Experiments with other microbial species show that chiral growth is found in other bacteria and exclude cell wall biosynthesis and anisotropic shape as the primary causes of chirality. Instead, intimate contact with the substratum is necessary for chirality. Our results demonstrate that through a handful of surface molecules cells can fundamentally reorganize their migration patterns, which might affect intra- and interspecific competitions through colony morphology or other mechanisms. PMID:28362723

  17. Ant-mediated effects on spruce litter decomposition, solution chemistry, and microbial activity

    DEFF Research Database (Denmark)

    Stadler, B.; Schramm, Andreas; Kalbitz, K.

    2006-01-01

    the effects of ants and aphid honeydew on litter solution of Norway spruce, microbial enzyme activities, and needle decomposition in a field and greenhouse experiment during summer 2003. In the field, low ant densities had relatively little effects on litter solution 30 cm away from a tree trunk...... and %N were not affected by ants or honeydew. Our results suggest that ants have a distinct and immediate effect on solution composition and microbial activity in the litter layer indicating accelerated litter decay whereas the effect of honeydew was insignificant. Keywords: Ants; Decomposition; Formica......Forest management practices often generate clear-cut patches, which may be colonized by ants not present in the same densities in mature forests. In addition to the associated changes in abiotic conditions ants can initiate processes, which do not occur in old-growth stands. Here, we analyse...

  18. Microbially mediated transformations of phosphorus in the sea: new views of an old cycle.

    Science.gov (United States)

    Karl, David M

    2014-01-01

    Phosphorus (P) is a required element for life. Its various chemical forms are found throughout the lithosphere and hydrosphere, where they are acted on by numerous abiotic and biotic processes collectively referred to as the P cycle. In the sea, microorganisms are primarily responsible for P assimilation and remineralization, including recently discovered P reduction-oxidation bioenergetic processes that add new complexity to the marine microbial P cycle. Human-induced enhancement of the global P cycle via mining of phosphate-bearing rock will likely influence the pace of P-cycle dynamics, especially in coastal marine habitats. The inextricable link between the P cycle and cycles of other bioelements predicts future impacts on, for example, nitrogen fixation and carbon dioxide sequestration. Additional laboratory and field research is required to build a comprehensive understanding of the marine microbial P cycle.

  19. Microbial composition in a deep saline aquifer in the North German Basin -microbiologically induced corrosion and mineral precipitation affecting geothermal plant operation and the effects of plant downtime

    Science.gov (United States)

    Lerm, Stephanie; Westphal, Anke; Miethling-Graff, Rona; Alawi, Mashal; Seibt, Andrea; Wolfgramm, Markus; Würdemann, Hilke

    2013-04-01

    The microbial composition in fluids of a deep saline geothermal used aquifer in the North German Basin was characterized over a period of five years. The genetic fingerprinting techniques PCR-SSCP and PCR-DGGE revealed distinct microbial communities in fluids produced from the cold and warm side of the aquifer. Direct cell counting and quantification of 16S rRNA genes and dissimilatory sulfite reductase (dsrA) genes by real-time PCR proved different population sizes in fluids, showing higher abundance of Bacteria and sulfate reducing bacteria (SRB) in cold fluids compared to warm fluids. Predominating SRB in the cold well probably accounted for corrosion damage to the submersible well pump, and iron sulfide precipitates in the near wellbore area and topside facility filters. This corresponded to a lower sulfate content in fluids produced from the cold well as well as higher content of hydrogen gas that was probably released from corrosion, and maybe favoured growth of hydrogenotrophic SRB. Plant downtime significantly influenced the microbial biocenosis in fluids. Samples taken after plant restart gave indications about the processes occurring downhole during those phases. High DNA concentrations in fluids at the beginning of the restart process with a decreasing trend over time indicated a higher abundance of microbes during plant downtime compared to regular plant operation. It is likely that a gradual drop in temperature as well as stagnant conditions favoured the growth of microbes and maturation of biofilms at the casing and in pores of the reservoir rock in the near wellbore area. Furthermore, it became obvious that the microorganisms were more associated to particles then free-living. This study reflects the high influence of microbial populations for geothermal plant operation, because microbiologically induced precipitative and corrosive processes adversely affect plant reliability. Those processes may favourably occur during plant downtime due to enhanced

  20. Effects of silver sulfide nanomaterials on mycorrhizal colonization of tomato plants and soil microbial communities in biosolid-amended soil

    International Nuclear Information System (INIS)

    Judy, Jonathan D.; Kirby, Jason K.; Creamer, Courtney; McLaughlin, Mike J.; Fiebiger, Cathy; Wright, Claire; Cavagnaro, Timothy R.; Bertsch, Paul M.

    2015-01-01

    We investigated effects of Ag_2S engineered nanomaterials (ENMs), polyvinylpyrrolidone (PVP) coated Ag ENMs (PVP-Ag), and Ag"+ on arbuscular mycorrhizal fungi (AMF), their colonization of tomato (Solanum lycopersicum), and overall microbial community structure in biosolids-amended soil. Concentration-dependent uptake was measured in all treatments. Plants exposed to 100 mg kg"−"1 PVP-Ag ENMs and 100 mg kg"−"1 Ag"+ exhibited reduced biomass and greatly reduced mycorrhizal colonization. Bacteria, actinomycetes and fungi were inhibited by all treatment classes, with the largest reductions measured in 100 mg kg"−"1 PVP-Ag ENMs and 100 mg kg"−"1 Ag"+. Overall, Ag_2S ENMs were less toxic to plants, less disruptive to plant-mycorrhizal symbiosis, and less inhibitory to the soil microbial community than PVP-Ag ENMs or Ag"+. However, significant effects were observed at 1 mg kg"−"1 Ag_2S ENMs, suggesting that the potential exists for microbial communities and the ecosystem services they provide to be disrupted by environmentally relevant concentrations of Ag_2S ENMs. - Highlights: • PVP-Ag and Ag"+ inhibited AMF colonization more readily than Ag_2S ENMs. • Impact of PVP-Ag ENMs and Ag"+ on microbial communities larger than for Ag_2S ENMs. • Significant changes in microbial communities in response to Ag_2S ENMs at 1 mg kg"−"1. - Although Ag_2S ENMs are less toxic to soil microorganisms than pristine nanomaterials or ions, some effects are observed on soil microbial communities at relevant concentrations.

  1. Enhanced microbial decolorization of methyl red with oxidized carbon fiber as redox mediator

    Energy Technology Data Exchange (ETDEWEB)

    Emilia Rios-Del Toro, E. [División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, SLP 78216 (Mexico); Celis, Lourdes B. [División de Geociencias Aplicadas, Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, SLP 78216 (Mexico); Cervantes, Francisco J. [División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, SLP 78216 (Mexico); Rangel-Mendez, J. Rene, E-mail: rene@ipicyt.edu.mx [División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, SLP 78216 (Mexico)

    2013-09-15

    Highlights: • Activated carbon fibers (ACFs) act as redox mediator. • Electron accepting capacity increased with oxidation time of ACF. •ACFs increased 8-fold the reduction of methyl red in biological assays. •Biofilm formed on the ACFs partly blocked their redox mediator capacity. -- Abstract: The anaerobic degradation of azo dyes under anaerobic conditions is possible but at a slow rate. Redox mediators (quinones, activated carbon) are used to improve the reduction rate. The aim of this work was to use activated carbon fiber (ACF) as a redox mediator for the anaerobic reduction of the azo dye methyl red. ACF was chemically modified with 8 M HNO{sub 3} to increase its redox-mediating capacity and used in chemical and anaerobic biological batch assays for the reduction of methyl red. ACF increased its redox-mediating capacity up to 3-fold in chemical assays; in biological assays ACF increased the reduction rate up to 8-fold compared to controls without ACF. However, since the ACF served as support for biomass, a biofilm formed on the fiber significantly reduced its redox-mediating capacity; substrate consumption suggested that the electron transport from ACF to methyl red was the rate-limiting step in the process. These results are the first evidence of the role of ACF as a redox mediator in the reductive decolorization of methyl red, in addition to the effect of biofilm attached to ACF on methyl red reduction. Due to the versatile characteristics of ACF and its redox-mediating capacity, carbon fibers could be used in biological wastewater treatment systems to accelerate the reductive transformation of pollutants commonly found in industrial effluents.

  2. Enhanced microbial decolorization of methyl red with oxidized carbon fiber as redox mediator

    International Nuclear Information System (INIS)

    Emilia Rios-Del Toro, E.; Celis, Lourdes B.; Cervantes, Francisco J.; Rangel-Mendez, J. Rene

    2013-01-01

    Highlights: • Activated carbon fibers (ACFs) act as redox mediator. • Electron accepting capacity increased with oxidation time of ACF. •ACFs increased 8-fold the reduction of methyl red in biological assays. •Biofilm formed on the ACFs partly blocked their redox mediator capacity. -- Abstract: The anaerobic degradation of azo dyes under anaerobic conditions is possible but at a slow rate. Redox mediators (quinones, activated carbon) are used to improve the reduction rate. The aim of this work was to use activated carbon fiber (ACF) as a redox mediator for the anaerobic reduction of the azo dye methyl red. ACF was chemically modified with 8 M HNO 3 to increase its redox-mediating capacity and used in chemical and anaerobic biological batch assays for the reduction of methyl red. ACF increased its redox-mediating capacity up to 3-fold in chemical assays; in biological assays ACF increased the reduction rate up to 8-fold compared to controls without ACF. However, since the ACF served as support for biomass, a biofilm formed on the fiber significantly reduced its redox-mediating capacity; substrate consumption suggested that the electron transport from ACF to methyl red was the rate-limiting step in the process. These results are the first evidence of the role of ACF as a redox mediator in the reductive decolorization of methyl red, in addition to the effect of biofilm attached to ACF on methyl red reduction. Due to the versatile characteristics of ACF and its redox-mediating capacity, carbon fibers could be used in biological wastewater treatment systems to accelerate the reductive transformation of pollutants commonly found in industrial effluents

  3. Microbial abundance in rhizosphere of medicinal and aromatic plant species in conventional and organic growing systems

    Directory of Open Access Journals (Sweden)

    Adamović Dušan

    2015-01-01

    Full Text Available This study was aimed at comparing the abundance of microorganisms in the rhizosphere of four different medicinal and aromatic plant species (basil, mint, dill and marigold grown under both conventional and organic management on the chernozem soil at the experimental field of Bački Petrovac (Institute of Field and Vegetable Crops, Novi Sad, Serbia. Two sampling terms (June 1 and July 18, 2012 were performed to collect samples for microbiological analyses. The microbial abundance was higher in organic than in conventional system while at the same time significant differences were obtained only with dill rhizosphere. The differences in number of microorganisms belonging to different groups relied upon both plant species and sampling term. Thus, in mint, the recorded number of azotobacters and fungi was significantly higher whereas the number of ammonifiers was significantly lower. The present results indicate that organic growing system affected the abundance of microorganisms in rhizosphere of species investigated, especially in the second term of sampling.

  4. A New Method for Sensing Soil Water Content in Green Roofs Using Plant Microbial Fuel Cells.

    Science.gov (United States)

    Tapia, Natalia F; Rojas, Claudia; Bonilla, Carlos A; Vargas, Ignacio T

    2017-12-28

    Green roofs have many benefits, but in countries with semiarid climates the amount of water needed for irrigation is a limiting factor for their maintenance. The use of drought-tolerant plants such as Sedum species, reduces the water requirements in the dry season, but, even so, in semiarid environments these can reach up to 60 L m -2 per day. Continuous substrate/soil water content monitoring would facilitate the efficient use of this critical resource. In this context, the use of plant microbial fuel cells (PMFCs) emerges as a suitable and more sustainable alternative for monitoring water content in green roofs in semiarid climates. In this study, bench and pilot-scale experiments using seven Sedum species showed a positive relationship between current generation and water content in the substrate. PMFC reactors with higher water content (around 27% vs. 17.5% v / v ) showed larger power density (114.6 and 82.3 μW m -2 vs. 32.5 μW m -2 ). Moreover, a correlation coefficient of 0.95 (±0.01) between current density and water content was observed. The results of this research represent the first effort of using PMFCs as low-cost water content biosensors for green roofs.

  5. Microbial community analysis of switchgrass planted and unplanted soil microcosms displaying PCB dechlorination.

    Science.gov (United States)

    Liang, Yi; Meggo, Richard; Hu, Dingfei; Schnoor, Jerald L; Mattes, Timothy E

    2015-08-01

    Polychlorinated biphenyls (PCBs) pose potential risks to human and environmental health because they are carcinogenic, persistent, and bioaccumulative. In this study, we investigated bacterial communities in soil microcosms spiked with PCB 52, 77, and 153. Switchgrass (Panicum virgatum) was employed to improve overall PCB removal, and redox cycling (i.e., sequential periods of flooding followed by periods of no flooding) was performed in an effort to promote PCB dechlorination. Lesser chlorinated PCB transformation products were detected in all microcosms, indicating the occurrence of PCB dechlorination. Terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis showed that PCB spiking, switchgrass planting, and redox cycling affected the microbial community structure. Putative organohalide-respiring Chloroflexi populations, which were not found in unflooded microcosms, were enriched after 2 weeks of flooding in the redox-cycled microcosms. Sequences classified as Geobacter sp. were detected in all microcosms and were most abundant in the switchgrass-planted microcosm spiked with PCB congeners. The presence of possible organohalide-respiring bacteria in these soil microcosms suggests that they play a role in PCB dechlorination therein.

  6. Plant communication: mediated by individual or blended VOCs?

    Science.gov (United States)

    Ueda, Hirokazu; Kikuta, Yukio; Matsuda, Kazuhiko

    2012-02-01

    Plants emit volatile organic compounds (VOCs) as a means to warn other plants of impending danger. Nearby plants exposed to the induced VOCs prepare their own defense weapons in response. Accumulated data supports this assertion, yet much of the evidence has been obtained in laboratories under artificial conditions where, for example, a single VOC might be applied at a concentration that plants do not actually experience in nature. Experiments conducted outdoors suggest that communication occurs only within a limited distance from the damaged plants. Thus, the question remains as to whether VOCs work as a single component or a specific blend, and at which concentrations VOCs elicit insect and pathogen defenses in undamaged plants. We discuss these issues based on available literature and our recent work, and propose future directions in this field.

  7. Constraining Biomarkers of Dissolved Organic Matter Sourcing Using Microbial Incubations of Vascular Plant Leachates of the California landscape

    Science.gov (United States)

    Harfmann, J.; Hernes, P.; Chuang, C. Y.; Kaiser, K.; Spencer, R. G.; Guillemette, F.

    2017-12-01

    Source origin of dissolved organic matter (DOM) is crucial in determining reactivity, driving chemical and biological processing of carbon. DOM source biomarkers such as lignin (a vascular plant marker) and D-amino acids (bacterial markers) are well-established tools in tracing DOM origin and fate. The development of high-resolution mass spectrometry and optical studies has expanded our toolkit; yet despite these advances, our understanding of DOM sources and fate remains largely qualitative. Quantitative data on DOM pools and fluxes become increasingly necessary as we refine our comprehension of its composition. In this study, we aim to calibrate and quantify DOM source endmembers by performing microbial incubations of multiple vascular plant leachates, where total DOM is constrained by initial vascular plant input and microbial production. Derived endmembers may be applied to endmember mixing models to quantify DOM source contributions in aquatic systems.

  8. Appraisal of medicinal plants used in alternative systems of medicines for microbial contamination, physiochemical parameters and heavy metals

    International Nuclear Information System (INIS)

    Malik, F.; Hussain, S.; Mahmood, S.

    2014-01-01

    The safety of herbal products has become a foremost apprehension in public health with their recognition and worldwide market growth and due in part to the widespread assumption that natural implies harmless. The global market of medicinal plants has been growing at a rate of 7-10% annually; capitalizing on the growing awareness of herbal and aromatic plants globally. The present study was conducted to assess the physiochemical parameters, microbial contamination and presence of heavy metals. The 24 medicinal plants were collected from open market places of various cities of Pakistan and tested by employing WHO and AOAC guidelines. Medicinal plants were found polluted with wide variety of potentially pathogenic bacterias. Microbial count and levels of arsenic and mercury in some plants were found elevated. The percentage (%) of physiochemical parameters i.e., foreign organic matter, total ash, acid insoluble ash, alcohol soluble extract, water soluble extract and moisture count of these medicinal plants were found statistically noteworthy. The nonexistence of quality control values for medicinal plants has been one of the key lacunas. Quality assurance system and WHO's guidelines on good agricultural and collection practices be methodically enforced in the medicinal plants supply chain i.e., cultivation, collection and distribution, although it is tricky task. (author)

  9. Scavenging Iron: A Novel Mechanism of Plant Immunity Activation by Microbial Siderophores1[C][W

    Science.gov (United States)

    Aznar, Aude; Chen, Nicolas W.G.; Rigault, Martine; Riache, Nassima; Joseph, Delphine; Desmaële, Didier; Mouille, Grégory; Boutet, Stéphanie; Soubigou-Taconnat, Ludivine; Renou, Jean-Pierre; Thomine, Sébastien; Expert, Dominique; Dellagi, Alia

    2014-01-01

    Siderophores are specific ferric iron chelators synthesized by virtually all microorganisms in response to iron deficiency. We have previously shown that they promote infection by the phytopathogenic enterobacteria Dickeya dadantii and Erwinia amylovora. Siderophores also have the ability to activate plant immunity. We have used complete Arabidopsis transcriptome microarrays to investigate the global transcriptional modifications in roots and leaves of Arabidopsis (Arabidopsis thaliana) plants after leaf treatment with the siderophore deferrioxamine (DFO). Physiological relevance of these transcriptional modifications was validated experimentally. Immunity and heavy-metal homeostasis were the major processes affected by DFO. These two physiological responses could be activated by a synthetic iron chelator ethylenediamine-di(o-hydroxyphenylacetic) acid, indicating that siderophores eliciting activities rely on their strong iron-chelating capacity. DFO was able to protect Arabidopsis against the pathogenic bacterium Pseudomonas syringae pv tomato DC3000. Siderophore treatment caused local modifications of iron distribution in leaf cells visible by ferrocyanide and diaminobenzidine-H2O2 staining. Metal quantifications showed that DFO causes a transient iron and zinc uptake at the root level, which is presumably mediated by the metal transporter iron regulated transporter1 (IRT1). Defense gene expression and callose deposition in response to DFO were compromised in an irt1 mutant. Consistently, plant susceptibility to D. dadantii was increased in the irt1 mutant. Our work shows that iron scavenging is a unique mechanism of immunity activation in plants. It highlights the strong relationship between heavy-metal homeostasis and immunity. PMID:24501001

  10. The Microbial Efficiency-Matrix Stabilization (MEMS) framework integrates plant litter decomposition with soil organic matter stabilization: do labile plant inputs form stable soil organic matter?

    Science.gov (United States)

    Cotrufo, M Francesca; Wallenstein, Matthew D; Boot, Claudia M; Denef, Karolien; Paul, Eldor

    2013-04-01

    The decomposition and transformation of above- and below-ground plant detritus (litter) is the main process by which soil organic matter (SOM) is formed. Yet, research on litter decay and SOM formation has been largely uncoupled, failing to provide an effective nexus between these two fundamental processes for carbon (C) and nitrogen (N) cycling and storage. We present the current understanding of the importance of microbial substrate use efficiency and C and N allocation in controlling the proportion of plant-derived C and N that is incorporated into SOM, and of soil matrix interactions in controlling SOM stabilization. We synthesize this understanding into the Microbial Efficiency-Matrix Stabilization (MEMS) framework. This framework leads to the hypothesis that labile plant constituents are the dominant source of microbial products, relative to input rates, because they are utilized more efficiently by microbes. These microbial products of decomposition would thus become the main precursors of stable SOM by promoting aggregation and through strong chemical bonding to the mineral soil matrix. © 2012 Blackwell Publishing Ltd.

  11. Plant-Mediated Systemic Interactions Between Pathogens, Parasitic Nematodes, and Herbivores Above- and Belowground

    NARCIS (Netherlands)

    Biere, A.; Goverse, A.

    2016-01-01

    Plants are important mediators of interactions between aboveground (AG) and belowground (BG) pathogens, arthropod herbivores, and nematodes (phytophages). We highlight recent progress in our understanding of within- and cross-compartment plant responses to these groups of phytophages in terms of

  12. Plant-mediated systemic interactions between pathogens, parasitic nematodes, and herbivores above- and belowground

    NARCIS (Netherlands)

    Biere, A.; Goverse, Aska

    2016-01-01

    Plants are important mediators of interactions between aboveground (AG) and belowground (BG) pathogens, arthropod herbivores, and nematodes (phytophages). We highlight recent progress in our understanding of within and cross-compartment plant responses to these groups of phytophages in terms of

  13. Mechanisms and ecological implications of plant-mediated interactions between belowground and aboveground insect herbivores

    NARCIS (Netherlands)

    Papadopoulou, G.V.; Dam, N.M. van

    2017-01-01

    Plant-mediated interactions between belowground (BG) and aboveground (AG) herbivores have received increasing interest recently. However, the molecular mechanisms underlying ecological consequences of BG–AG interactions are not fully clear yet. Herbivore-induced plant defenses are complex and

  14. Importance of Mediator complex in the regulation and integration of diverse signaling pathways in plants.

    Science.gov (United States)

    Samanta, Subhasis; Thakur, Jitendra K

    2015-01-01

    Basic transcriptional machinery in eukaryotes is assisted by a number of cofactors, which either increase or decrease the rate of transcription. Mediator complex is one such cofactor, and recently has drawn a lot of interest because of its integrative power to converge different signaling pathways before channeling the transcription instructions to the RNA polymerase II machinery. Like yeast and metazoans, plants do possess the Mediator complex across the kingdom, and its isolation and subunit analyses have been reported from the model plant, Arabidopsis. Genetic, and molecular analyses have unraveled important regulatory roles of Mediator subunits at every stage of plant life cycle starting from flowering to embryo and organ development, to even size determination. It also contributes immensely to the survival of plants against different environmental vagaries by the timely activation of its resistance mechanisms. Here, we have provided an overview of plant Mediator complex starting from its discovery to regulation of stoichiometry of its subunits. We have also reviewed involvement of different Mediator subunits in different processes and pathways including defense response pathways evoked by diverse biotic cues. Wherever possible, attempts have been made to provide mechanistic insight of Mediator's involvement in these processes.

  15. Extracellular Saccharide-Mediated Reduction of Au3+ to Gold Nanoparticles: New Insights for Heavy Metals Biomineralization on Microbial Surfaces.

    Science.gov (United States)

    Kang, Fuxing; Qu, Xiaolei; Alvarez, Pedro J J; Zhu, Dongqiang

    2017-03-07

    Biomineralization is a critical process controlling the biogeochemical cycling, fate, and potential environmental impacts of heavy metals. Despite the indispensability of extracellular polymeric substances (EPS) to microbial life and their ubiquity in soil and aquatic environments, the role played by EPS in the transformation and biomineralization of heavy metals is not well understood. Here, we used gold ion (Au 3+ ) as a model heavy metal ion to quantitatively assess the role of EPS in biomineralization and discern the responsible functional groups. Integrated spectroscopic analyses showed that Au 3+ was readily reduced to zerovalent gold nanoparticles (AuNPs, 2-15 nm in size) in aqueous suspension of Escherichia coli or dissolved EPS extracted from microbes. The majority of AuNPs (95.2%) was formed outside Escherichia coli cells, and the removal of EPS attached to cells pronouncedly suppressed Au 3+ reduction, reflecting the predominance of the extracellular matrix in Au 3+ reduction. XPS, UV-vis, and FTIR analyses corroborated that Au 3+ reduction was mediated by the hemiacetal groups (aldehyde equivalents) of reducing saccharides of EPS. Consistently, the kinetics of AuNP formation obeyed pseudo-second-order reaction kinetics with respect to the concentrations of Au 3+ and the hemiacetal groups in EPS, with minimal dependency on the source of microbial EPS. Our findings indicate a previously overlooked, universally significant contribution of EPS to the reduction, mineralization, and potential detoxification of metal species with high oxidation state.

  16. Morphogenetic and chemical stability of long-term maintained Agrobacterium-mediated transgenic Catharanthus roseus plants.

    Science.gov (United States)

    Verma, Priyanka; Sharma, Abhishek; Khan, Shamshad Ahmad; Mathur, Ajay Kumar; Shanker, Karuna

    2015-01-01

    Transgenic Catharanthus roseus plants (transgenic Dhawal [DT] and transgenic Nirmal [NT]) obtained from the Agrobacterium tumefaciens and Agrobacterium rhizognenes-mediated transformations, respectively, have been maintained in vitro for 5 years. Plants were studied at regular intervals for various parameters such as plant height, leaf size, multiplication rate, alkaloid profile and presence of marker genes. DT plant gradually lost the GUS gene expression and it was not detected in the fifth year while NT plant demonstrated the presence of genes rolA, rolB and rolC even in the fifth year, indicating the more stable nature of Ri transgene. Vindoline content in the DT was two times more than in non-transformed control plants. Alkaloid and tryptophan profiles were almost constant during the 5 years. The cluster analysis revealed that the DT plant is more close to the control Nirmal plant followed by NT plant.

  17. POTENTIAL USE OF MICROBIAL ELECTROLYSIS CELLS (MECs IN DOMESTIC WASTEWATER TREATMENT PLANTS FOR ENERGY RECOVERY

    Directory of Open Access Journals (Sweden)

    Adrian eEscapa

    2014-06-01

    Full Text Available Globally, large amounts of electrical energy are spent every year for domestic wastewater (dWW treatment. In the future, energy prices are expected to rise as the demand for energy resources increases and fossil fuel reserves become depleted. By using appropriate technologies, the potential chemical energy contained in the organic compounds present in dWWs might help to improve the energy and economic balance of dWW treatment plants. Bioelectrochemical Systems (BESs in general and microbial electrolysis cells (MECs in particular represent an emerging technology capable of harvesting part of this energy. This study offers an overview of the potential of using MEC technology in dWW treatment plants (dWWTPs to reduce the energy bill. It begins with a brief account of the basics of BESs, followed by an examination of how MECs can be integrated in dWW treatment plants (dWWTPs, identifying scaling-up bottlenecks and estimating potential energy savings. A simplified analysis showed that the use of MEC technology may help to reduce up to ~20% the energy consumption in a conventional dWWTP. The study concludes with a discussion of the future perspectives of MEC technology for dWW treatment. The growing rates of municipal water and wastewater treatment markets in Europe offer excellent business prospects and it is expected that the first generation of MECs could be ready within 1-4 years. However, before MEC technology may achieve practical implementation in dWWTPs, it needs not only to overcome important techno-economic challenges, but also to compete with other energy-producing technologies.

  18. The Physical, Chemical and Microbial Quality of Treated Water in Qom s Desalination Plants

    Directory of Open Access Journals (Sweden)

    A.R Yari

    2012-05-01

    Full Text Available

    Background and objectives

    Water is the basis of life and health. The health of food and water supply plays an important role in human health. One of the methods of water desalination is membrane filter reverse osmosis method. This method is used for desalination of drinking water supply in Qom.

    Methods

    This is a descriptive, cross-sectional study designed to determine the quality of treated water in Qom desalination plant in year 2002. Inlet and outlet water samples of this plant were examined by the standard examination methods and the collected data were compared with national and international standards. Excel software was used for statistical analysis.

    Results

    The results showed that the residual chlorine concentration, total hardness and fluoride concentration were lower than the minimum standard limit set for drinking water. The pH was also lower than the minimum standard limit. Microbial contamination was detected in 6% of samples.

    Conclusion

    The results show that the acidity of water was lower than standard in whole plant. This gives corrosive properties to the water and increases the dissolution of materials, which are in contact with this water. In order to eliminate the secondary contamination, the concentration of residual chlorine should be 1 mg/l. But, none of the measurements showed a concentration as high as this value. As fluoride is an important element for health and growth of bone and teeth, especially in growing children, fluoride should be added to the drinking water. As the relationship between hardness of water and cardiovascular diseases has been established, it can be concluded that this drinking water supply can increase the risk of cardiovascular diseases in long time. Dilution of this water is recommended to adjust various factors to the standard limits and keep the total dissolved solids low.

  19. Repressor-mediated tissue-specific gene expression in plants

    Science.gov (United States)

    Meagher, Richard B [Athens, GA; Balish, Rebecca S [Oxford, OH; Tehryung, Kim [Athens, GA; McKinney, Elizabeth C [Athens, GA

    2009-02-17

    Plant tissue specific gene expression by way of repressor-operator complexes, has enabled outcomes including, without limitation, male sterility and engineered plants having root-specific gene expression of relevant proteins to clean environmental pollutants from soil and water. A mercury hyperaccumulation strategy requires that mercuric ion reductase coding sequence is strongly expressed. The actin promoter vector, A2pot, engineered to contain bacterial lac operator sequences, directed strong expression in all plant vegetative organs and tissues. In contrast, the expression from the A2pot construct was restricted primarily to root tissues when a modified bacterial repressor (LacIn) was coexpressed from the light-regulated rubisco small subunit promoter in above-ground tissues. Also provided are analogous repressor operator complexes for selective expression in other plant tissues, for example, to produce male sterile plants.

  20. Plant-plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO2 : an experiment with plant populations from naturally high CO2 areas

    NARCIS (Netherlands)

    van Loon, Marloes P; Rietkerk, Max; Dekker, Stefan C; Hikosaka, Kouki; Ueda, Miki U; Anten, Niels P R

    2016-01-01

    Background and Aims The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant–plant interactions could mediate the trajectory of vegetation responses to elevated [CO2], because some plants may

  1. Disentangling mechanisms that mediate the balance between stochastic and deterministic processes in microbial succession.

    Science.gov (United States)

    Dini-Andreote, Francisco; Stegen, James C; van Elsas, Jan Dirk; Salles, Joana Falcão

    2015-03-17

    Ecological succession and the balance between stochastic and deterministic processes are two major themes within microbial ecology, but these conceptual domains have mostly developed independent of each other. Here we provide a framework that integrates shifts in community assembly processes with microbial primary succession to better understand mechanisms governing the stochastic/deterministic balance. Synthesizing previous work, we devised a conceptual model that links ecosystem development to alternative hypotheses related to shifts in ecological assembly processes. Conceptual model hypotheses were tested by coupling spatiotemporal data on soil bacterial communities with environmental conditions in a salt marsh chronosequence spanning 105 years of succession. Analyses within successional stages showed community composition to be initially governed by stochasticity, but as succession proceeded, there was a progressive increase in deterministic selection correlated with increasing sodium concentration. Analyses of community turnover among successional stages--which provide a larger spatiotemporal scale relative to within stage analyses--revealed that changes in the concentration of soil organic matter were the main predictor of the type and relative influence of determinism. Taken together, these results suggest scale-dependency in the mechanisms underlying selection. To better understand mechanisms governing these patterns, we developed an ecological simulation model that revealed how changes in selective environments cause shifts in the stochastic/deterministic balance. Finally, we propose an extended--and experimentally testable--conceptual model integrating ecological assembly processes with primary and secondary succession. This framework provides a priori hypotheses for future experiments, thereby facilitating a systematic approach to understand assembly and succession in microbial communities across ecosystems.

  2. Microbial mediation of radionuclide transport -significance for the nuclear fuel waste management program

    International Nuclear Information System (INIS)

    Champ, D.R.

    1984-08-01

    The role that microbially catalyzed processes may play in determining, or altering, radionuclide migration is an unresolved question in the Nuclear Fuel Waste Management Program. This report documents the results of a review of the available information on the existence and biochemical capabilities of micro-organisms and the potential for their involvement in processes affecting the migration of radionuclides of interest. The potential was judged sufficient to warrant conducting experiments to assess their role. The outline of an experimental program to address the role of micro-organisms is presented

  3. Peracetic Acid (PAA Disinfection: Inactivation of Microbial Indicators and Pathogenic Bacteria in a Municipal Wastewater Plant

    Directory of Open Access Journals (Sweden)

    Silvia Bonetta

    2017-06-01

    Full Text Available Several studies have noted that treated and untreated wastewaters are primary contributors of a variety of pathogenic microorganisms to the aquatic ecosystem. Conventional wastewater treatment may not be sufficient to achieve microbiologically safe effluent to be discharged into natural waters or reused, thus requiring wastewater effluents to be disinfected. In recent years, peracetic acid (PAA has been adopted as a disinfectant for wastewater effluents. The aim of this study was to evaluate the disinfection efficiency of PAA at low doses (range 0.99–2.10 mg/L against microbial indicators and pathogenic bacteria in a municipal wastewater plant. Samples of untreated sewage and effluents before and after PAA treatment were collected seasonally for 1 year and were analysed for pathogenic Campylobacter, Salmonella spp., E. coli O157:H7 and E. coli virulence genes using molecular methods; moreover, the detection of specific microbial indicators (E. coli, faecal coliforms, enterococci, C. perfringens and Salmonella spp. were carried out using culturing methods. Salmonella spp. DNA was found in all untreated sewage and effluent before PAA treatment, whereas it was recovered in 50% of the samples collected after PAA treatment. Although E. coli O157:H7 was never identified, the occurrence of Shiga-like toxin I amplicons was identified in 75% of the untreated sewage samples, in 50% of the effluents assayed before PAA treatment, and in 25% of the effluents assayed after PAA treatment, whereas the stx2 gene was never found. Campylobacter coli was only detected in one effluent sample before PAA treatment. In the effluents after PAA treatment, a lower load of indicator bacteria was observed compared to the effluents before treatment. The results of this study highlight that the use of low doses of PAA seems to lead to an improvement of the microbiological quality of the effluent, although it is not sufficient to guarantee its suitability for irrigation

  4. AGROBACTERIUM-MEDIATED TRANSFORMATION OF COMPOSITAE PLANTS. I. CONSTRUCTION OF TRANSGENIC PLANTS AND «HAIRY» ROOTS WITH NEW PROPERTIES

    Directory of Open Access Journals (Sweden)

    N. A.Matvieieva

    2013-02-01

    Full Text Available The review explores some of the recent advances and the author's own researchs concerning biotechnological approaches for Agrobacterium tumefaciens- and A. rhizogenes-mediated transformation of Compositae family plants. This paper reviews the results of genetic transformation of Compositae plants, including edible (Cichorium intybus, Lactuca sativa, oil (Helianthus annuus, decorative (Gerbera hybrida, medical (Bidens pilosa, Artemisia annua, Artemisia vulgaris, Calendula officinalis, Withania somnifera etc. plant species. Some Compositae genetic engineering areas are considered including creation of plants, resistant to pests, diseases and herbicides, to the effect of abiotic stress factors as well as plants with altered phenotype. The article also presents the data on the development of biotechnology for Compositae plants Cynara cardunculus, Arnica montana, Cichorium intybus, Artemisia annua "hairy" roots construction.

  5. Effects of Plant Functional Group Loss on Soil Microbial Community and Litter Decomposition in a Steppe Vegetation.

    Science.gov (United States)

    Xiao, Chunwang; Zhou, Yong; Su, Jiaqi; Yang, Fan

    2017-01-01

    Globally, many terrestrial ecosystems are experiencing a rapid loss of biodiversity. Continued improvements in our understanding of interrelationships between plant diversity and soil microbes are critical to address the concern over the consequences of the decline in biodiversity on ecosystem functioning and services. By removing forbs, or grasses, or, to an extreme scenario, both forbs and grasses in a steppe vegetation in Inner Mongolia, we studied how plant functional group (PFG) loss affects soil microbial community composition using phospholipid fatty acid analysis (PLFA) and litter decomposition using a litter-bag method. PFG loss significantly decreased above- and below-ground plant biomass, soil microbial biomass carbon (SMBC) and nitrogen (SMBN), but had no effect on the ratio of SMBC to SMBN. Although the ratio of fungal to bacterial PLFAs remained unaffected, PFG loss significantly reduced the amount of bacterial, fungal, and total PLFAs. PFG loss decreased litter monthly mass loss and decay constant, and such decrease was significant when both forbs and grasses were removed. Our results provide robust evidence that PFG loss in grassland ecosystem can lead to a rapid response of soil microbial activity which may affect litter decomposition and soil nutrient cycling, suggesting that the assessment of plant-microbe interactions in soils is an integral component of ecosystem response to biodiversity loss.

  6. Flow-through Column Experiments and Modeling of Microbially Mediated Cr(VI) Reduction at Hanford 100H

    Science.gov (United States)

    Yang, L.; Molins, S.; Beller, H. R.; Brodie, E. L.; Steefel, C.; Nico, P. S.; Han, R.

    2010-12-01

    Microbially mediated Cr(VI) reduction at the Hanford 100H area was investigated by flow-through column experiments. Three separate experiments were conducted to promote microbial activities associated with denitrification, iron and sulfate reduction, respectively. Replicate columns packed with natural sediments from the site under anaerobic environment were injected with 5mM Lactate as the electron donor and 5 μM Cr(VI) in all experiments. Sulfate and nitrate solutions were added to act as the main electron acceptors in the respective experiments, while iron columns relied on the indigenous sediment iron (and manganese) oxides as electron acceptors. Column effluent solutions were analyzed by IC and ICP-MS to monitor the microbial consumption/conversion of lactate and the associated Cr(VI) reduction. Biogeochemical reactive transport modeling was performed to gain further insights into the reaction mechanisms and Cr(VI) bioreduction rates. All experimental columns showed a reduction of the injected Cr(VI). Columns under denitrifying conditions showed the least Cr(VI) reduction at early stages (simulations indicated that biomass growth completely depleted influent ammonium, and called for an additional source of N to account for the measured reduction rates. Iron columns were the least active with undetectable consumption of the injected lactate, slowest cell growth, and the smallest change in Cr(VI) concentrations during the course of the experiment. In contrast, columns under sulfate-reducing/fermentative conditions exhibited the greatest Cr(VI) reduction capacity. Two sulfate columns evolved to complete lactate fermentation with acetate and propionate produced in the column effluent after 40 days of experiments. These fermenting columns showed a complete removal of injected Cr(VI), visible precipitation of sulfide minerals, and a significant increase in effluent Fe and Mn concentrations. Reactive transport simulations suggested that direct reduction of Cr(VI) by

  7. Nutrient Enrichment Mediates the Relationships of Soil Microbial Respiration with Climatic Factors in an Alpine Meadow

    Directory of Open Access Journals (Sweden)

    Ning Zong

    2015-01-01

    Full Text Available Quantifying the effects of nutrient additions on soil microbial respiration (Rm and its contribution to soil respiration (Rs are of great importance for accurate assessment ecosystem carbon (C flux. Nitrogen (N addition either alone (coded as LN and HN or in combination with phosphorus (P (coded as LN + P and HN + P were manipulated in a semiarid alpine meadow on the Tibetan Plateau since 2008. Either LN or HN did not affect Rm, while LN + P enhanced Rm during peak growing periods, but HN + P did not affect Rm. Nutrient addition also significantly affected Rm/Rs, and the correlations of Rm/Rs with climatic factors varied with years. Soil water content (Sw was the main factor controlling the variations of Rm/Rs. During the years with large rainfall variations, Rm/Rs was negatively correlated with Sw, while, in years with even rainfall, Rm/Rs was positively correlated with Sw. Meanwhile, in N + P treatments the controlling effects of climatic factors on Rm/Rs were more significant than those in CK. Our results indicate that the sensitivity of soil microbes to climatic factors is regulated by nutrient enrichment. The divergent effects of Sw on Rm/Rs suggest that precipitation distribution patterns are key factors controlling soil microbial activities and ecosystem C fluxes in semiarid alpine meadow ecosystems.

  8. Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Susan; Personna, Y.R.; Ntarlagiannis, D.; Slater, L.; Yee, N.; O' Brien, M.; Hubbard, S.

    2008-02-15

    Stimulated sulfate-reduction is a bioremediation technique utilized for the sequestration of heavy metals in the subsurface.We performed laboratory column experiments to investigate the geoelectrical response of iron sulfide transformations by Desulfo vibriovulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential measurements, were investigated. Aqueous geochemistry (sulfate, lactate, sulfide, and acetate), observations of precipitates (identified from electron microscopy as iron sulfide), and electrodic potentials on bisulfide ion (HS) sensitive silver-silver chloride (Ag-AgCl) electrodes (630 mV) were diagnostic of induced transitions between an aerobic iron sulfide forming conditions and aerobic conditions promoting iron sulfide dissolution. The SIP data showed 10m rad anomalies during iron sulfide mineralization accompanying microbial activity under an anaerobic transition. These anomalies disappeared during iron sulfide dissolution under the subsequent aerobic transition. SIP model parameters based on a Cole-Cole relaxation model of the polarization at the mineral-fluid interface were converted to (1) estimated biomineral surface area to pore volume (Sp), and (2) an equivalent polarizable sphere diameter (d) controlling the relaxation time. The temporal variation in these model parameters is consistent with filling and emptying of pores by iron sulfide biofilms, as the system transitions between anaerobic (pore filling) and aerobic (pore emptying) conditions. The results suggest that combined SIP and electrodic potential measurements might be used to monitor spatiotemporal variability in microbial iron sulfide transformations in the field.

  9. Prebiotics Mediate Microbial Interactions in a Consortium of the Infant Gut Microbiome.

    Science.gov (United States)

    Medina, Daniel A; Pinto, Francisco; Ovalle, Aline; Thomson, Pamela; Garrido, Daniel

    2017-10-04

    Composition of the gut microbiome is influenced by diet. Milk or formula oligosaccharides act as prebiotics, bioactives that promote the growth of beneficial gut microbes. The influence of prebiotics on microbial interactions is not well understood. Here we investigated the transformation of prebiotics by a consortium of four representative species of the infant gut microbiome, and how their interactions changed with dietary substrates. First, we optimized a culture medium resembling certain infant gut parameters. A consortium containing Bifidobacterium longum subsp. infantis , Bacteroides vulgatus , Escherichia coli and Lactobacillus acidophilus was grown on fructooligosaccharides (FOS) or 2'-fucosyllactose (2FL) in mono- or co-culture. While Bi. infantis and Ba. vulgatus dominated growth on 2FL, their combined growth was reduced. Besides, interaction coefficients indicated strong competition, especially on FOS. While FOS was rapidly consumed by the consortium, B. infantis was the only microbe displaying significant consumption of 2FL. Acid production by the consortium resembled the metabolism of microorganisms dominating growth in each substrate. Finally, the consortium was tested in a bioreactor, observing similar predominance but more pronounced acid production and substrate consumption. This study indicates that the chemical nature of prebiotics modulate microbial interactions in a consortium of infant gut species.

  10. Prebiotics Mediate Microbial Interactions in a Consortium of the Infant Gut Microbiome

    Directory of Open Access Journals (Sweden)

    Daniel A. Medina

    2017-10-01

    Full Text Available Composition of the gut microbiome is influenced by diet. Milk or formula oligosaccharides act as prebiotics, bioactives that promote the growth of beneficial gut microbes. The influence of prebiotics on microbial interactions is not well understood. Here we investigated the transformation of prebiotics by a consortium of four representative species of the infant gut microbiome, and how their interactions changed with dietary substrates. First, we optimized a culture medium resembling certain infant gut parameters. A consortium containing Bifidobacterium longum subsp. infantis, Bacteroides vulgatus, Escherichia coli and Lactobacillus acidophilus was grown on fructooligosaccharides (FOS or 2′-fucosyllactose (2FL in mono- or co-culture. While Bi. infantis and Ba. vulgatus dominated growth on 2FL, their combined growth was reduced. Besides, interaction coefficients indicated strong competition, especially on FOS. While FOS was rapidly consumed by the consortium, B. infantis was the only microbe displaying significant consumption of 2FL. Acid production by the consortium resembled the metabolism of microorganisms dominating growth in each substrate. Finally, the consortium was tested in a bioreactor, observing similar predominance but more pronounced acid production and substrate consumption. This study indicates that the chemical nature of prebiotics modulate microbial interactions in a consortium of infant gut species.

  11. Agrobacterium tumefaciens-mediated transformation of biofuel plant ...

    African Journals Online (AJOL)

    Yomi

    2010-09-27

    Sep 27, 2010 ... several plant species including Arabidopsis (Chang et al.,. 1994; Clough and Bent, ... and Technology Talents Scheme of Yunnan Province. (Grant no. .... of shoots and roots from Jatropha curcas L. explants. J. Horticult. Sci.

  12. CRISPR/Cas9-mediated viral interference in plants

    KAUST Repository

    Ali, Zahir

    2015-11-11

    Background The CRISPR/Cas9 system provides bacteria and archaea with molecular immunity against invading phages and conjugative plasmids. Recently, CRISPR/Cas9 has been used for targeted genome editing in diverse eukaryotic species. Results In this study, we investigate whether the CRISPR/Cas9 system could be used in plants to confer molecular immunity against DNA viruses. We deliver sgRNAs specific for coding and non-coding sequences of tomato yellow leaf curl virus (TYLCV) into Nicotiana benthamiana plants stably overexpressing the Cas9 endonuclease, and subsequently challenge these plants with TYLCV. Our data demonstrate that the CRISPR/Cas9 system targeted TYLCV for degradation and introduced mutations at the target sequences. All tested sgRNAs exhibit interference activity, but those targeting the stem-loop sequence within the TYLCV origin of replication in the intergenic region (IR) are the most effective. N. benthamiana plants expressing CRISPR/Cas9 exhibit delayed or reduced accumulation of viral DNA, abolishing or significantly attenuating symptoms of infection. Moreover, this system could simultaneously target multiple DNA viruses. Conclusions These data establish the efficacy of the CRISPR/Cas9 system for viral interference in plants, thereby extending the utility of this technology and opening the possibility of producing plants resistant to multiple viral infections.

  13. Importance of Mediator complex in the regulation and integration of diverse signaling pathways in plants

    Directory of Open Access Journals (Sweden)

    Subhasis eSamanta

    2015-09-01

    Full Text Available Basic transcriptional machinery in eukaryotes is assisted by a number of cofactors, which either increase or decrease the rate of transcription. Mediator complex is one such cofactor, and recently has drawn a lot of interest because of its integrative power to converge different signaling pathways before channelling the transcription instructions to the RNA polymerase II machinery. Like yeast and metazoans, plants do possess the Mediator complex across the kingdom, and its isolation and subunit analyses have been reported from the model plant, Arabidopsis. Genetic and molecular analyses have unravelled important regulatory roles of Mediator subunits at every stage of plant life cycle starting from flowering to embryo and organ development, to even size determination. It also contributes immensely to the survival of plants against different environmental vagaries by the timely activation of its resistance mechanisms. Here, we have provided an overview of plant Mediator complex starting from its discovery to regulation of stoichiometry of its subunits. We have also reviewed involvement of different Mediator subunits in different processes and pathways including defense response pathways evoked by diverse biotic cues. Wherever possible, attempts have been made to provide mechanistic insight of Mediator’s involvement in these processes.

  14. Potential Use of Microbial Electrolysis Cells in Domestic Wastewater Treatment Plants for Energy Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Escapa, Adrián; San-Martín, María Isabel; Morán, Antonio, E-mail: amorp@unileon.es [Chemical and Environmental Bioprocess Engineering Group, Natural Resources Institute (IRENA), University of León, León (Spain)

    2014-06-06

    Globally, large amounts of electrical energy are spent every year for domestic wastewater (dWW) treatment. In the future, energy prices are expected to rise as the demand for energy resources increases and fossil fuel reserves become depleted. By using appropriate technologies, the potential chemical energy contained in the organic compounds present in dWWs might help to improve the energy and economic balance of dWW treatment plants. Bioelectrochemical systems (BESs) in general and microbial electrolysis cells (MECs) in particular represent an emerging technology capable of harvesting part of this energy. This study offers an overview of the potential of using MEC technology in domestic wastewater treatment plants (dWWTPs) to reduce the energy bill. It begins with a brief account of the basics of BESs, followed by an examination of how MECs can be integrated in dWWTPs, identifying scaling-up bottlenecks and estimating potential energy savings. A simplified analysis showed that the use of MEC technology may help to reduce up to ~20% the energy consumption in a conventional dWWTP. The study concludes with a discussion of the future perspectives of MEC technology for dWW treatment. The growing rates of municipal water and wastewater treatment markets in Europe offer excellent business prospects and it is expected that the first generation of MECs could be ready within 1–4 years. However, before MEC technology may achieve practical implementation in dWWTPs, it need not only to overcome important techno-economic challenges, but also to compete with other energy-producing technologies.

  15. The Importance of the Microbial N Cycle in Soil for Crop Plant Nutrition.

    Science.gov (United States)

    Hirsch, Penny R; Mauchline, Tim H

    2015-01-01

    Nitrogen is crucial for living cells, and prior to the introduction of mineral N fertilizer, fixation of atmospheric N2 by diverse prokaryotes was the primary source of N in all ecosystems. Microorganisms drive the N cycle starting with N2 fixation to ammonia, through nitrification in which ammonia is oxidized to nitrate and denitrification where nitrate is reduced to N2 to complete the cycle, or partially reduced to generate the greenhouse gas nitrous oxide. Traditionally, agriculture has relied on rotations that exploited N fixed by symbiotic rhizobia in leguminous plants, and recycled wastes and manures that microbial activity mineralized to release ammonia or nitrate. Mineral N fertilizer provided by the Haber-Bosch process has become essential for modern agriculture to increase crop yields and replace N removed from the system at harvest. However, with the increasing global population and problems caused by unintended N wastage and pollution, more sustainable ways of managing the N cycle in soil and utilizing biological N2 fixation have become imperative. This review describes the biological N cycle and details the steps and organisms involved. The effects of various agricultural practices that exploit fixation, retard nitrification, and reduce denitrification are presented, together with strategies that minimize inorganic fertilizer applications and curtail losses. The development and implementation of new technologies together with rediscovering traditional practices are discussed to speculate how the grand challenge of feeding the world sustainably can be met. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Current trends and future requirements for the mass spectrometric investigation of microbial, mammalian and plant metabolomes

    International Nuclear Information System (INIS)

    Dunn, Warwick B

    2008-01-01

    The functional levels of biological cells or organisms can be separated into the genome, transcriptome, proteome and metabolome. Of these the metabolome offers specific advantages to the investigation of the phenotype of biological systems. The investigation of the metabolome (metabolomics) has only recently appeared as a mainstream scientific discipline and is currently developing rapidly for the study of microbial, plant and mammalian metabolomes. The metabolome pipeline or workflow encompasses the processes of sample collection and preparation, collection of analytical data, raw data pre-processing, data analysis and data storage. Of these processes the collection of analytical data will be discussed in this review with specific interest shown in the application of mass spectrometry in the metabolomics pipeline. The current developments in mass spectrometry platforms (GC–MS, LC–MS, DIMS and imaging MS) and applications of specific interest will be highlighted. The current limitations of these platforms and applications will be discussed with areas requiring further development also highlighted. These include the detectable coverage of the metabolome, the identification of metabolites and the process of converting raw data to biological knowledge. (review article)

  17. Ecological Insights into the Dynamics of Plant Biomass-Degrading Microbial Consortia.

    Science.gov (United States)

    Jiménez, Diego Javier; Dini-Andreote, Francisco; DeAngelis, Kristen M; Singer, Steven W; Salles, Joana Falcão; van Elsas, Jan Dirk

    2017-10-01

    Plant biomass (PB) is an important resource for biofuel production. However, the frequent lack of efficiency of PB saccharification is still an industrial bottleneck. The use of enzyme cocktails produced from PB-degrading microbial consortia (PB-dmc) is a promising approach to optimize this process. Nevertheless, the proper use and manipulation of PB-dmc depends on a sound understanding of the ecological processes and mechanisms that exist in these communities. This Opinion article provides an overview of arguments as to how spatiotemporal nutritional fluxes influence the successional dynamics and ecological interactions (synergism versus competition) between populations in PB-dmc. The themes of niche occupancy, 'sugar cheaters', minimal effective consortium, and the Black Queen Hypothesis are raised as key subjects that foster our appraisal of such systems. Here we provide a conceptual framework that describes the critical topics underpinning the ecological basis of PB-dmc, giving a solid foundation upon which further prospective experimentation can be developed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Recombinant production of plant lectins in microbial systems for biomedical application – the frutalin case study

    Directory of Open Access Journals (Sweden)

    Carla eOliveira

    2014-08-01

    Full Text Available Frutalin is a homotetrameric partly-glycosylated alpha-D-galactose-binding lectin of biomedical interest from Artocarpus incisa (breadfruit seeds, belonging to the jacalin-related lectins family. As other plant lectins, frutalin is a heterogeneous mixture of several isoforms possibly with distinct biological activities. The main problem of using such lectins as biomedical tools is that batch-to-batch variation in isoforms content may lead to inconstant results. The production of lectins by recombinant means has the advantage of obtaining high amounts of proteins with defined amino-acid sequences and more precise properties. In this mini review, we provide the strategies followed to produce two different forms of frutalin in two different microbial systems: Escherichia coli and Pichia pastoris. The processing and functional properties of the recombinant frutalin obtained from these hosts are compared to those of frutalin extracted from breadfruit. Emphasis is given particularly to recombinant frutalin produced in P. pastoris, which showed a remarkable capacity as biomarker of human prostate cancer and as apoptosis-inducer of cancer cells. Recombinant frutalin production opens perspectives for its development as a new tool in human medicine.

  19. Recombinant production of plant lectins in microbial systems for biomedical application – the frutalin case study

    Science.gov (United States)

    Oliveira, Carla; Teixeira, José A.; Domingues, Lucília

    2014-01-01

    Frutalin is a homotetrameric partly glycosylated α-D-galactose-binding lectin of biomedical interest from Artocarpus incisa (breadfruit) seeds, belonging to the jacalin-related lectins family. As other plant lectins, frutalin is a heterogeneous mixture of several isoforms possibly with distinct biological activities. The main problem of using such lectins as biomedical tools is that “batch-to-batch” variation in isoforms content may lead to inconstant results. The production of lectins by recombinant means has the advantage of obtaining high amounts of proteins with defined amino-acid sequences and more precise properties. In this mini review, we provide the strategies followed to produce two different forms of frutalin in two different microbial systems: Escherichia coli and Pichia pastoris. The processing and functional properties of the recombinant frutalin obtained from these hosts are compared to those of frutalin extracted from breadfruit. Emphasis is given particularly to recombinant frutalin produced in P. pastoris, which showed a remarkable capacity as biomarker of human prostate cancer and as apoptosis-inducer of cancer cells. Recombinant frutalin production opens perspectives for its development as a new tool in human medicine. PMID:25152749

  20. Development of an analytical microbial consortia method for enhancing performance monitoring at aerobic wastewater treatment plants.

    Science.gov (United States)

    Razban, Behrooz; Nelson, Kristina Y; McMartin, Dena W; Cullimore, D Roy; Wall, Michelle; Wang, Dunling

    2012-01-01

    An analytical method to produce profiles of bacterial biomass fatty acid methyl esters (FAME) was developed employing rapid agitation followed by static incubation (RASI) using selective media of wastewater microbial communities. The results were compiled to produce a unique library for comparison and performance analysis at a Wastewater Treatment Plant (WWTP). A total of 146 samples from the aerated WWTP, comprising 73 samples of each secondary and tertiary effluent, were included analyzed. For comparison purposes, all samples were evaluated via a similarity index (SI) with secondary effluents producing an SI of 0.88 with 2.7% variation and tertiary samples producing an SI 0.86 with 5.0% variation. The results also highlighted significant differences between the fatty acid profiles of the tertiary and secondary effluents indicating considerable shifts in the bacterial community profile between these treatment phases. The WWTP performance results using this method were highly replicable and reproducible indicating that the protocol has potential as a performance-monitoring tool for aerated WWTPs. The results quickly and accurately reflect shifts in dominant bacterial communities that result when processes operations and performance change.

  1. Microbially-mediated fluorescent organic matter transformations in the deep ocean

    DEFF Research Database (Denmark)

    Aparicio, Fran L.; Nieto-Cid, Mar; Borrull, Encarna

    2015-01-01

    The refractory nature of marine dissolved organic matter (DOM) increases while it travels from surface waters to the deep ocean. This resistant fraction is in part composed of fluorescent humic-like material, which is relatively difficult to metabolize by deep water prokaryotes, and it can also b....... These findings contribute to the understanding of FDOM variability in deep waters and provide valuable information for studies where fluorescent compounds are used in order to track water masses and/or microbial processes.......The refractory nature of marine dissolved organic matter (DOM) increases while it travels from surface waters to the deep ocean. This resistant fraction is in part composed of fluorescent humic-like material, which is relatively difficult to metabolize by deep water prokaryotes, and it can also...

  2. Plant-mediated restriction of Salmonella enterica on tomato and spinach leaves colonized with Pseudomonas plant growth-promoting rhizobacteria.

    Science.gov (United States)

    Hsu, Chiun-Kang; Micallef, Shirley A

    2017-10-16

    Reducing Salmonella enterica association with plants during crop production could reduce risks of fresh produce-borne salmonellosis. Plant growth-promoting rhizobacteria (PGPR) colonizing plant roots are capable of promoting plant growth and boosting resistance to disease, but the effects of PGPR on human pathogen-plant associations are not known. Two root-colonizing Pseudomonas strains S2 and S4 were investigated in spinach, lettuce and tomato for their plant growth-promoting properties and their influence on leaf populations of S. enterica serovar Newport. Plant roots were inoculated with Pseudomonas in the seedling stage. At four (tomato) and six (spinach and lettuce) weeks post-germination, plant growth promotion was assessed by shoot dry weight (SDW) and leaf chlorophyll content measurements. Leaf populations of S. Newport were measured after 24h of leaf inoculation with this pathogen by direct plate counts on Tryptic Soy Agar. Root inoculation of spinach cv. 'Tyee', with Pseudomonas strain S2 or S4 resulted in a 69% and 63% increase in SDW compared to non-inoculated controls (pgrowth by over 40% compared to controls (pgrowth promotion was detected in tomato cv. 'BHN602', but S2-inoculated plants had elevated leaf chlorophyll content (13%, pgrowth, but also reduce the fitness of epiphytic S. enterica in the phyllosphere. Plant-mediated effects induced by PGPR may be an effective strategy to minimize contamination of crops with S. enterica during cultivation. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. A saponin-detoxifying enzyme mediates suppression of plant defences

    Science.gov (United States)

    Bouarab, K.; Melton, R.; Peart, J.; Baulcombe, D.; Osbourn, A.

    2002-08-01

    Plant disease resistance can be conferred by constitutive features such as structural barriers or preformed antimicrobial secondary metabolites. Additional defence mechanisms are activated in response to pathogen attack and include localized cell death (the hypersensitive response). Pathogens use different strategies to counter constitutive and induced plant defences, including degradation of preformed antimicrobial compounds and the production of molecules that suppress induced plant defences. Here we present evidence for a two-component process in which a fungal pathogen subverts the preformed antimicrobial compounds of its host and uses them to interfere with induced defence responses. Antimicrobial saponins are first hydrolysed by a fungal saponin-detoxifying enzyme. The degradation product of this hydrolysis then suppresses induced defence responses by interfering with fundamental signal transduction processes leading to disease resistance.

  4. Comparing a microbial biocide and chlorine as zebra mussel control strategies in an Irish drinking water treatment plant

    OpenAIRE

    Sara Meehan; Frances E. Lucy; Bridget Gruber; Sarahann Rackl

    2013-01-01

    A need exists for an environmentally friendly mussel control method to replace chlorine and other traditional control methods currentlyutilised in drinking water plants and other infested facilities. Zequanox® is a newly commercialised microbial biocide for zebra and quaggamussels comprised of killed Pseudomonas fluorescens CL145A cells. The objective of this study was to compare the efficacy of adevelopmental formulation of Zequanox (referred to as MBI 401 FDP) and chlorine treatments on adu...

  5. Herbivory and eutrophication mediate grassland plant nutrient responses across a global climatic gradient

    Science.gov (United States)

    Anderson, T. Michael; Griffith, Daniel M.; Grace, James B.; Lind, Eric M.; Adler, Peter B.; Biederman, Lori A.; Blumenthal, Dana M.; Daleo, Pedro; Firn, Jennifer; Hagenah, Nicole; Harpole, W. Stanley; MacDougall, Andrew S.; McCulley, Rebecca L.; Prober, Suzanne M.; Risch, Anita C.; Sankaran, Mahesh; Schütz, Martin; Seabloom, Eric W.; Stevens, Carly J.; Sullivan, Lauren; Wragg, Peter; Borer, Elizabeth T.

    2018-01-01

    Plant stoichiometry, the relative concentration of elements, is a key regulator of ecosystem functioning and is also being altered by human activities. In this paper we sought to understand the global drivers of plant stoichiometry and compare the relative contribution of climatic vs. anthropogenic effects. We addressed this goal by measuring plant elemental (C, N, P and K) responses to eutrophication and vertebrate herbivore exclusion at eighteen sites on six continents. Across sites, climate and atmospheric N deposition emerged as strong predictors of plot‐level tissue nutrients, mediated by biomass and plant chemistry. Within sites, fertilization increased total plant nutrient pools, but results were contingent on soil fertility and the proportion of grass biomass relative to other functional types. Total plant nutrient pools diverged strongly in response to herbivore exclusion when fertilized; responses were largest in ungrazed plots at low rainfall, whereas herbivore grazing dampened the plant community nutrient responses to fertilization. Our study highlights (1) the importance of climate in determining plant nutrient concentrations mediated through effects on plant biomass, (2) that eutrophication affects grassland nutrient pools via both soil and atmospheric pathways and (3) that interactions among soils, herbivores and eutrophication drive plant nutrient responses at small scales, especially at water‐limited sites.

  6. Microbial Community Composition of Polyhydroxyalkanoate-Accumulating Organisms in Full-Scale Wastewater Treatment Plants Operated in Fully Aerobic Mode

    Science.gov (United States)

    Oshiki, Mamoru; Onuki, Motoharu; Satoh, Hiroyasu; Mino, Takashi

    2013-01-01

    The removal of biodegradable organic matter is one of the most important objectives in biological wastewater treatments. Polyhydroxyalkanoate (PHA)-accumulating organisms (PHAAOs) significantly contribute to the removal of biodegradable organic matter; however, their microbial community composition is mostly unknown. In the present study, the microbial community composition of PHAAOs was investigated at 8 full-scale wastewater treatment plants (WWTPs), operated in fully aerobic mode, by fluorescence in situ hybridization (FISH) analysis and post-FISH Nile blue A (NBA) staining techniques. Our results demonstrated that 1) PHAAOs were in the range of 11–18% in the total number of cells, and 2) the microbial community composition of PHAAOs was similar at the bacterial domain/phylum/class/order level among the 8 full-scale WWTPs, and dominant PHAAOs were members of the class Alphaproteobacteria and Betaproteobacteria. The microbial community composition of α- and β-proteobacterial PHAAOs was examined by 16S rRNA gene clone library analysis and further by applying a set of newly designed oligonucleotide probes targeting 16S rRNA gene sequences of α- or β-proteobacterial PHAAOs. The results demonstrated that the microbial community composition of PHAAOs differed in the class Alphaproteobacteria and Betaproteobacteria, which possibly resulted in a different PHA accumulation capacity among the WWTPs (8.5–38.2 mg-C g-VSS−1 h−1). The present study extended the knowledge of the microbial diversity of PHAAOs in full-scale WWTPs operated in fully aerobic mode. PMID:23257912

  7. The effect of salinity, redox mediators and temperature on anaerobic biodegradation of petroleum hydrocarbons in microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Adelaja, Oluwaseun, E-mail: o.adelaja@my.westminster.ac.uk; Keshavarz, Tajalli, E-mail: t.keshavarz@westminster.ac.uk; Kyazze, Godfrey, E-mail: g.kyazze@westminster.ac.uk

    2015-02-11

    Highlights: • Effective degradation of petroleum hydrocarbon mixtures was achieved using MFC. • Adapted anaerobic microbial consortium was used as inoculum. • Bio-electricity generation was enhanced by 30-fold when riboflavin, was added. • Optimum MFC performance was obtained at mesophilic and moderately saline conditions. • Stable MFC performance was obtained during prolonged fed-batch MFC operation. - Abstract: Microbial fuel cells (MFCs) need to be robust if they are to be applied in the field for bioremediation. This study investigated the effect of temperature (20–50 °C), salinity (0.5–2.5% (w/v) as sodium chloride), the use of redox mediators (riboflavin and anthraquinone-2-sulphonate, AQS) and prolonged fed-batch operation (60 days) on biodegradation of a petroleum hydrocarbon mix (i.e. phenanthrene and benzene) in MFCs. The performance criteria were degradation efficiency, % COD removal and electrochemical performance. Good electrochemical and degradation performance were maintained up to a salinity of 1.5% (w/v) but deteriorated by 35-fold and 4-fold respectively as salinity was raised to 2.5%w/v. Degradation rates and maximum power density were both improved by approximately 2-fold at 40 °C compared to MFC performance at 30 °C but decreased sharply by 4-fold when operating temperature was raised to 50 °C. The optimum reactor performance obtained at 40 °C was 1.15 mW/m{sup 2} maximum power density, 89.1% COD removal and a degradation efficiency of 97.10%; at moderately saline (1% w/v) conditions the maximum power density was 1.06 mW/m{sup 2}, 79.1% COD removal and 91.6% degradation efficiency. This work suggests the possible application of MFC technology in the effective treatment of petroleum hydrocarbons contaminated site and refinery effluents.

  8. The effect of salinity, redox mediators and temperature on anaerobic biodegradation of petroleum hydrocarbons in microbial fuel cells

    International Nuclear Information System (INIS)

    Adelaja, Oluwaseun; Keshavarz, Tajalli; Kyazze, Godfrey

    2015-01-01

    Highlights: • Effective degradation of petroleum hydrocarbon mixtures was achieved using MFC. • Adapted anaerobic microbial consortium was used as inoculum. • Bio-electricity generation was enhanced by 30-fold when riboflavin, was added. • Optimum MFC performance was obtained at mesophilic and moderately saline conditions. • Stable MFC performance was obtained during prolonged fed-batch MFC operation. - Abstract: Microbial fuel cells (MFCs) need to be robust if they are to be applied in the field for bioremediation. This study investigated the effect of temperature (20–50 °C), salinity (0.5–2.5% (w/v) as sodium chloride), the use of redox mediators (riboflavin and anthraquinone-2-sulphonate, AQS) and prolonged fed-batch operation (60 days) on biodegradation of a petroleum hydrocarbon mix (i.e. phenanthrene and benzene) in MFCs. The performance criteria were degradation efficiency, % COD removal and electrochemical performance. Good electrochemical and degradation performance were maintained up to a salinity of 1.5% (w/v) but deteriorated by 35-fold and 4-fold respectively as salinity was raised to 2.5%w/v. Degradation rates and maximum power density were both improved by approximately 2-fold at 40 °C compared to MFC performance at 30 °C but decreased sharply by 4-fold when operating temperature was raised to 50 °C. The optimum reactor performance obtained at 40 °C was 1.15 mW/m 2 maximum power density, 89.1% COD removal and a degradation efficiency of 97.10%; at moderately saline (1% w/v) conditions the maximum power density was 1.06 mW/m 2 , 79.1% COD removal and 91.6% degradation efficiency. This work suggests the possible application of MFC technology in the effective treatment of petroleum hydrocarbons contaminated site and refinery effluents

  9. Host-Plant Specialization Mediates the Influence of Plant Abundance on Host Use by Flower Head-Feeding Insects.

    Science.gov (United States)

    Nobre, Paola A F; Bergamini, Leonardo L; Lewinsohn, Thomas M; Jorge, Leonardo R; Almeida-Neto, Mário

    2016-02-01

    Among-population variation in host use is a common phenomenon in herbivorous insects. The simplest and most trivial explanation for such variation in host use is the among-site variation in plant species composition. Another aspect that can influence spatial variation in host use is the relative abundance of each host-plant species compared to all available hosts. Here, we used endophagous insects that develop in flower heads of Asteraceae species as a study system to investigate how plant abundance influences the pattern of host-plant use by herbivorous insects with distinct levels of host-range specialization. Only herbivores recorded on three or more host species were included in this study. In particular, we tested two related hypotheses: 1) plant abundance has a positive effect on the host-plant preference of herbivorous insects, and 2) the relative importance of plant abundance to host-plant preference is greater for herbivorous species that use a wider range of host-plant species. We analyzed 11 herbivore species in 20 remnants of Cerrado in Southeastern Brazil. For 8 out of 11 herbivore species, plant abundance had a positive influence on host use. In contrast to our expectation, both the most specialized and the most generalist herbivores showed a stronger positive effect of plant species abundance in host use. Thus, we found evidence that although the abundance of plant species is a major factor determining the preferential use of host plants, its relative importance is mediated by the host-range specialization of herbivores.

  10. Anti-microbial and anti-biofilm compounds from Indonesian medicinal plants

    NARCIS (Netherlands)

    Pratiwi, Sylvia U.T.

    2015-01-01

    Microbial biofilms causing elevated resistance to both most anti-microbial drugs and the host defense systems, which often results in persistent and difficult-to-treat infections. The discovery of anti-infective agents which are active against planktonic and biofilm microorganisms are therefore

  11. Reconstructing the Genetic Potential of the Microbially-Mediated Nitrogen Cycle in a Salt Marsh Ecosystem.

    Science.gov (United States)

    Dini-Andreote, Francisco; Brossi, Maria Julia de L; van Elsas, Jan Dirk; Salles, Joana F

    2016-01-01

    Coastal ecosystems are considered buffer zones for the discharge of land-derived nutrients without accounting for potential negative side effects. Hence, there is an urgent need to better understand the ecological assembly and dynamics of the microorganisms that are involved in nitrogen (N) cycling in such systems. Here, we employed two complementary methodological approaches (i.e., shotgun metagenomics and quantitative PCR) to examine the distribution and abundance of selected microbial genes involved in N transformations. We used soil samples collected along a well-established pristine salt marsh soil chronosequence that spans over a century of ecosystem development at the island of Schiermonnikoog, The Netherlands. Across the examined soil successional stages, the structure of the populations of genes involved in N cycling processes was strongly related to (shifts in the) soil nitrogen levels (i.e., [Formula: see text], [Formula: see text]), salinity and pH (explaining 73.8% of the total variation, R (2) = 0.71). Quantification of the genes used as proxies for N fixation, nitrification and denitrification revealed clear successional signatures that corroborated the taxonomic assignments obtained by metagenomics. Notably, we found strong evidence for niche partitioning, as revealed by the abundance and distribution of marker genes for nitrification (ammonia-oxidizing bacteria and archaea) and denitrification (nitrite reductase nirK, nirS and nitrous oxide reductase nosZ clades I and II). This was supported by a distinct correlation between these genes and soil physico-chemical properties, such as soil physical structure, pH, salinity, organic matter, total N, [Formula: see text], [Formula: see text] and [Formula: see text], across four seasonal samplings. Overall, this study sheds light on the successional trajectories of microbial N cycle genes along a naturally developing salt marsh ecosystem. The data obtained serve as a foundation to guide the formulation of

  12. Microbial- and isothiocyanate-mediated control of Phytophthora and Pythium species

    Science.gov (United States)

    M.F. Cohen; E. Yamamoto; E. Condeso; B.L. Anacker; N. Rank; M. Mazzola

    2008-01-01

    Plant pathogens of the oomycete lineage share common susceptibilities to many biotic and abiotic stresses. We are investigating the potential of antagonistic bacteria, isothiocyanates, and mycophagous amoebae to control diseases caused by Phytophthora spp., including the etiologic agent of sudden oak death, Phytophthora ramorum (...

  13. Potential pest transfer mediated by international ornamental plant trade.

    Science.gov (United States)

    Patoka, Jiří; Bláha, Martin; Kalous, Lukáš; Vrabec, Vladimír; Buřič, Miloš; Kouba, Antonín

    2016-05-25

    In recent years, the keeping of ornamental freshwater animals and plants in garden ponds has been growing in popularity. Water hyacinth (Eichhornia crassipes) is one of the preferred macrophytes seasonally imported mainly from South-eastern Asia throughout the world. This constitutes a secondary introduction inasmuch as the species is native to South America. Although many assemblages of aquatic invertebrates have been described as associated with this plant in the wild, there has been no research focused on their potential introduction via the international plant trade. We examined 216 specimens of water hyacinths imported for ornamental purposes from Indonesia into the Czech Republic. Numerous meio- and macroinvertebrates belonging to at least 39 species were captured. On the total number of individuals, the highest prevalence was of Tubulinea and Rotifera. Most of these were still alive and vital, including a caterpillar of the Indo-Australian invasive moth Spodoptera litura. Water hyacinths are usually placed into outdoor ponds immediately after import, which facilitates the release of non-target alien species. The present paper aims to draw attention to "hitchhikers" associated with the ornamental trade.

  14. MicroRNA-Mediated Gene Silencing in Plant Defense and Viral Counter-Defense

    Directory of Open Access Journals (Sweden)

    Sheng-Rui Liu

    2017-09-01

    Full Text Available MicroRNAs (miRNAs are non-coding RNAs of approximately 20–24 nucleotides in length that serve as central regulators of eukaryotic gene expression by targeting mRNAs for cleavage or translational repression. In plants, miRNAs are associated with numerous regulatory pathways in growth and development processes, and defensive responses in plant–pathogen interactions. Recently, significant progress has been made in understanding miRNA-mediated gene silencing and how viruses counter this defense mechanism. Here, we summarize the current knowledge and recent advances in understanding the roles of miRNAs involved in the plant defense against viruses and viral counter-defense. We also document the application of miRNAs in plant antiviral defense. This review discusses the current understanding of the mechanisms of miRNA-mediated gene silencing and provides insights on the never-ending arms race between plants and viruses.

  15. Microbial surfactant mediated degradation of anthracene in aqueous phase by marine Bacillus licheniformis MTCC 5514

    Directory of Open Access Journals (Sweden)

    Sreethar Swaathy

    2014-12-01

    Full Text Available The present study emphasizes the biosurfactant mediated anthracene degradation by a marine alkaliphile Bacillus licheniformis (MTCC 5514. The isolate, MTCC 5514 degraded >95% of 300 ppm anthracene in an aqueous medium within 22 days and the degradation percentage reduced significantly when the concentration of anthracene increased to above 500 ppm. Naphthalene, naphthalene 2-methyl, phthalic acid and benzene acetic acid are the products of degradation identified based on thin layer chromatography, high performance liquid chromatography, gas chromatography and mass analyses. It has been observed that the degradation is initiated by the biosurfactant of the isolate for solubilization through micellation and then the alkali pH and intra/extra cellular degradative enzymes accomplish the degradation process. Encoding of genes responsible for biosurfactant production (licA3 as well as catabolic reactions (C23O made with suitable primers designed. The study concludes in situ production of biosurfactant mediates the degradation of anthracene by B. licheniformis.

  16. Radiocesium storage in soil microbial biomass of undisturbed alpine meadow soils and its relation to 137Cs soil-plant transfer

    International Nuclear Information System (INIS)

    Stemmer, Michael; Hromatka, Angelika; Lettner, Herbert; Strebl, Friederike

    2005-01-01

    This study focuses on radiocesium storage in soil microbial biomass of undisturbed alpine meadow sites and its relation to the soil-to-plant transfer. Soil and plant samples were taken in August 1999 from an altitude transect (800-1600 m.a.s.l.) at Gastein valley, Austria. Soil samples were subdivided into 3-cm layers for analyses of total, K 2 SO 4 -extractable and microbially stored 137 Cs. Microbial biomass was measured by the fumigation extraction method, and fungal biomass was quantified using ergosterol as biomarker molecule. In general, the quantity of 137 Cs stored in the living soil microbial biomass was relatively small. At the high-altitude meadows, showing high amounts of fungal biomass, microbially stored 137 Cs amounted to 0.64 ± 0.14 kBq m -2 which corresponds to about 1.2-2.7% of the total 137 Cs soil inventory. At lower altitudes, microbial 137 Cs content was distinctly smaller and in most cases not measurable at all using the fumigation extraction method. However, a positive correlation between the observed soil-to-plant aggregated transfer factor, microbially stored 137 Cs and fungal biomass was found, which indicates a possible role of fungal biomass in the storage and turnover of 137 Cs in soils and in the 137 Cs uptake by plants

  17. Microbial gas generation under expected Waste Isolation Pilot Plant repository conditions

    International Nuclear Information System (INIS)

    Francis, A.J.; Gillow, J.B.; Giles, M.R.

    1997-03-01

    Gas generation from the microbial degradation of the organic constituents of transuranic waste under conditions expected at the Waste Isolation Pilot Plant (WIPP) repository was investigated at Brookhaven National Laboratory. The biodegradation of mixed cellulosics (various types of paper) and electron-beam irradiated plastic and rubber materials (polyethylene, polyvinylchloride, neoprene, hypalon, and leaded hypalon) was examined. The rate of gas production from cellulose biodegradation in inundated samples incubated for 1,228 days at 30 C was biphasic, with an initial rapid rate up to approximately 600 days incubation, followed by a slower rate. The rate of total gas production in anaerobic samples containing mixed inoculum was as follows: 0.002 mL/g cellulose/day without nutrients; 0.004 mL/g cellulose/day with nutrients; and 0.01 mL/g cellulose/day in the presence of excess nitrate. Carbon dioxide production proceeded at a rate of 0.009 micromol/g cellulose/day in anaerobic samples without nutrients, 0.05 micromol/g cellulose/day in the presence of nutrients, and 0.2 micromol/g cellulose/day with excess nitrate. Adding nutrients and excess nitrate stimulated denitrification, as evidenced by the accumulation of N 2 O in the headspace (200 micromol/g cellulose). The addition of the potential backfill bentonite increased the rate of CO 2 production to 0.3 micromol/g cellulose/day in anaerobic samples with excess nitrate. Analysis of the solution showed that lactic, acetic, propionic, butyric, and valeric acids were produced due to cellulose degradation. Samples incubated under anaerobic humid conditions for 415 days produced CO 2 at a rate of 0.2 micromol/g cellulose/day in the absence of nutrients, and 1 micromol/g cellulose/day in the presence of bentonite and nutrients. There was no evidence of biodegradation of electron-beam irradiated plastic and rubber

  18. Effects of Flavonoid-rich Plant Extracts on Ruminal Methanogenesis, Microbial Populations and Fermentation Characteristics

    Directory of Open Access Journals (Sweden)

    Eun T. Kim

    2015-04-01

    Full Text Available The objective of this study was to evaluate the in vitro effects of flavonoid-rich plant extracts (PE on ruminal fermentation characteristics and methane emission by studying their effectiveness for methanogenesis in the rumen. A fistulated Holstein cow was used as a donor of rumen fluid. The PE (Punica granatum, Betula schmidtii, Ginkgo biloba, Camellia japonica, and Cudrania tricuspidata known to have high concentrations of flavonoid were added to an in vitro fermentation incubated with rumen fluid. Total gas production and microbial growth with all PE was higher than that of the control at 24 h incubation, while the methane emission was significantly lower (p<0.05 than that of the control. The decrease in methane accumulation relative to the control was 47.6%, 39.6%, 46.7%, 47.9%, and 48.8% for Punica, Betula, Ginkgo, Camellia, and Cudrania treatments, respectively. Ciliate populations were reduced by more than 60% in flavonoid-rich PE treatments. The Fibrobacter succinogenes diversity in all added flavonoid-rich PE was shown to increase, while the Ruminoccocus albus and R. flavefaciens populations in all PE decreased as compared with the control. In particular, the F. succinogenes community with the addition of Birch extract increased to a greater extent than that of others. In conclusion, the results of this study showed that flavonoid-rich PE decreased ruminal methane emission without adversely affecting ruminal fermentation characteristics in vitro in 24 h incubation time, suggesting that the flavonoid-rich PE have potential possibility as bio-active regulator for ruminants.

  19. Microbial functional diversity associated with plant litter decomposition along a climatic gradient.

    Science.gov (United States)

    Sherman, Chen; Steinberger, Yosef

    2012-08-01

    Predicted changes in climate associated with increased greenhouse gas emissions can cause increases in global mean temperature and changes in precipitation regimes. These changes may affect key soil processes, e.g., microbial CO(2) evolution and biomass, mineralization rates, primary productivity, biodiversity, and litter decomposition, which play an important role in carbon and nutrient cycling in terrestrial ecosystems. Our study examined the changes in litter microbial communities and decomposition along a climatic gradient, ranging from arid desert to humid Mediterranean regions in Israel. Wheat straw litter bags were placed in arid, semi-arid, Mediterranean, and humid Mediterranean sites. Samples were collected seasonally over a 2-year period in order to evaluate mass loss, litter moisture, C/N ratio, bacterial colony-forming units (CFUs), microbial CO(2) evolution and biomass, microbial functional diversity, and catabolic profile. Decomposition rate was the highest during the first year of the study at the Mediterranean and arid sites. Community-level physiological profile and microbial biomass were the highest in summer, while bacterial CFUs were the highest in winter. Microbial functional diversity was found to be highest at the humid Mediterranean site, whereas substrate utilization increased at the arid site. Our results support the assumption that climatic factors control litter degradation and regulate microbial activity.

  20. Nitrate-Mediated Microbially Enhanced Oil Recovery (N-MEOR) from model upflow bioreactors.

    Science.gov (United States)

    Gassara, Fatma; Suri, Navreet; Voordouw, Gerrit

    2017-02-15

    Microbially Enhanced Oil Recovery (MEOR) can enhance oil production with less energy input and less costs than other technologies. The present study used different aqueous electron donors (acetate, glucose, molasses) and an aqueous electron acceptor (nitrate) to stimulate growth of heterotrophic nitrate reducing bacteria (hNRB) to improve production of oil. Initial flooding of columns containing heavy oil (viscosity of 3400cP at 20°C) with CSBK (Coleville synthetic brine medium) produced 0.5 pore volume (PV) of oil. Bioreactors were then inoculated with hNRB with 5.8g/L of molasses and 0, 10, 20, 40, 60 or 80mM nitrate, as well as with 17mM glucose or 57mM acetate and 80mM nitrate. During incubations no oil was produced in the bioreactors that received 5.8g/L of molasses and 0, 10, 20, 40 or 60mM nitrate. However, the bioreactors injected with 5.8g/L of molasses, 17mM glucose or 57mM acetate and 80mM nitrate produced 13.9, 11.3±3.1 and 17.8±6.6% of residual oil, respectively. The significant production of oil from these bioreactors may be caused by N 2 -CO 2 gas production. Following continued injection with CSBK without nitrate, subsequent elution of significant residual oil (5-30%) was observed. These results also indicate possible involvement of fermentation products (organic acids, alcohols) to enhance heavy oil recovery. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Biocontrol of Rhizoctonia solani disease and biostimulant effect by microbial products on bean plants

    Directory of Open Access Journals (Sweden)

    Roberta Roberti

    2015-12-01

    Full Text Available Microbial products containing a mixture of fungi and bacteria (EM Bokashi® 2-fi and EM-5 Sutociu® characterised by plant biostimulant activity, Trichoderma harzianum T22 (biofungicide and the antagonist fungus Trichoderma sp. TJ40 were tested for efficacy against R. solani disease and for their biostimulant effects on bean plants, in growth chamber experiments, and for their direct effect on the pathogen growth, through in vitro experiments. In growth chamber experiments, EM-5 Sutociu was applied to seed (Sut/Se, substrate (Sut/S and leaf (Sut/L many times, EM Bokashi 2-fi to substrare (Bok/S once and combined with Sut, T22 and TJ40 were applied once to substrate. The pathogen was inoculated to substrate at seeding time (first experiment or at seedling phase (second experiment. Under our experimental conditions, Bok/S+Sut/S+Sut/L, Sut/S+Sut/L, Sut/Se+Sut/S+Sut/L and T22, in the first experiment, and all treatments, with the exception of Bok/S applied alone in the second experiment, gave significantly disease severity reduction and increase of dry weight and leaf area with respect to the infected control. The TJ40 treatment reduced both disease incidence and disease severity only in the second experiment. In the experiment on the biostimulant effect, T22, Bok/S+Sut/S+Sut/L, Sut/S+Sut/L and Sut/Se+Sut/S+Sut/L showed significantly increases of both dry weight and leaf area. The direct effect of the treatment with T22, TJ40, Bok and Sut on R. solani growth in vitro was studied with two methods, submerged colony (SC and well diffusion (WD assays. The pathogen growth was completely inhibited by Trichoderma T22 in both assays, by Trichoderma TJ40 in a range of 80-50 % in SD assay, and 50-30 % in WD assay and slightly inhibited or not inhibited by Bok and Sut.

  2. Plant Mediated Green Synthesis of CuO Nanoparticles: Comparison of Toxicity of Engineered and Plant Mediated CuO Nanoparticles towards Daphnia magna

    Directory of Open Access Journals (Sweden)

    Sadia Saif

    2016-11-01

    Full Text Available Research on green production methods for metal oxide nanoparticles (NPs is growing, with the objective to overcome the potential hazards of these chemicals for a safer environment. In this study, facile, ecofriendly synthesis of copper oxide (CuO nanoparticles was successfully achieved using aqueous extract of Pterospermum acerifolium leaves. P. acerifolium-fabricated CuO nanoparticles were further characterized by UV-Visible spectroscopy, field emission scanning electron microscopy (FE-SEM, energy dispersive X-ray (EDX, Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS and dynamic light scattering (DLS. Plant-mediated CuO nanoparticles were found to be oval shaped and well dispersed in suspension. XPS confirmed the elemental composition of P. acerifolium-mediated copper nanoparticles as comprised purely of copper and oxygen. DLS measurements and ion release profile showed that P. acerifolium-mediated copper nanoparticles were more stable than the engineered CuO NPs. Copper oxide nanoparticles are used in many applications; therefore, their potential toxicity cannot be ignored. A comparative study was performed to investigate the bio-toxic impacts of plant-synthesized and engineered CuO nanoparticles on water flea Daphnia. Experiments were conducted to investigate the 48-h acute toxicity of engineered CuO NPs and plant-synthesized nanoparticles. Lower EC50 value 0.102 ± 0.019 mg/L was observed for engineered CuO NPs, while 0.69 ± 0.226 mg/L was observed for plant-synthesized CuO NPs. Additionally, ion release from CuO nanoparticles and 48-h accumulation of these nano CuOs in daphnids were also calculated. Our findings thus suggest that the contribution of released ions from nanoparticles and particles/ions accumulation in Daphnia needs to be interpreted with care.

  3. Genetic 'fingerprints' to characterise microbial communities during organic overloading and in large-scale biogas plants

    Energy Technology Data Exchange (ETDEWEB)

    Kleyboecker, A.; Lerm, S.; Vieth, A.; Wuerdemann, H. [GeoForschungsZentrum Potsdam, Bio-Geo-Engineering, Potsdam (Germany); Miethling-Graff, R. [Bundesforschungsanstalt fuer Landwirtschaft, Braunschweig (Germany). Inst. fuer Agraroekologie; Wittmaier, M. [Institut fuer Kreislaufwirtschaft, Bremen (Germany)

    2007-07-01

    Since fermentation is a complex process, biogas reactors are still known as 'black boxes'. Mostly they are not run at their maximum loading rate due to the possible failure in the process by organic overloading. This means that there are still unused capacities to produce more biogas in less time. Investigations of different large-scale biogas plants showed that fermenters are operated containing different amounts of volatile fatty acids. These amounts can vary so much that one of two digestors, both possessing the same VFA concentration, does not produce gas anymore while the other is still at work. A reason for this phenomenon might be found in the composition of the microbial communities or in differences in the operation of the plants. To gain a better understanding of the 'black box', structural changes in microbial communities during controlled organic overloading in a laboratory and biocenosis of large-scale reactors were investigated. A genetic fingerprint based on 16S rDNA (PCR-SSCP) was used to characterise the microbial community. (orig.)

  4. Micro-organisms behind the pollination scenes: microbial imprint on floral nectar sugar variation in a tropical plant community.

    Science.gov (United States)

    Canto, A; Herrera, C M

    2012-11-01

    Variation in the composition of floral nectar reflects intrinsic plant characteristics as well as the action of extrinsic factors. Micro-organisms, particularly yeasts, represent one extrinsic factor that inhabit the nectar of animal-pollinated flowers worldwide. In this study a 'microbial imprint hypothesis' is formulated and tested, in which it is proposed that natural community-wide variation in nectar sugar composition will partly depend on the presence of yeasts in flowers. Occurrence and density of yeasts were studied microscopically in single-flower nectar samples of 22 animal-pollinated species from coastal xeric and sub-humid tropical habitats of the Yucatán Peninsula, Mexico. Nectar sugar concentration and composition were concurrently determined on the same samples using high-performance liquid chromatography (HPLC) methods. Microscopical examination of nectar samples revealed the presence of yeasts in nearly all plant species (21 out of 22 species) and in about half of the samples examined (51·8 % of total, all species combined). Plant species and individuals differed significantly in nectar sugar concentration and composition, and also in the incidence of nectar yeasts. After statistically controlling for differences between plant species and individuals, nectar yeasts still accounted for a significant fraction of community-wide variance in all nectar sugar parameters considered. Significant yeast × species interactions on sugar parameters revealed that plant species differed in the nectar sugar correlates of variation in yeast incidence. The results support the hypothesis that nectar yeasts impose a detectable imprint on community-wide variation in nectar sugar composition and concentration. Since nectar sugar features influence pollinator attraction and plant reproduction, future nectar studies should control for yeast presence and examine the extent to which microbial signatures on nectar characteristics ultimately have some influence on

  5. Comparative plant uptake and microbial degradation of trichloroethylene in the rhizospheres of five plant species-- implications for bioremediation of contaminated surface soils

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, T. A. [Tennessee Univ., Knoxville, TN (United States); Walton, B. T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    1992-01-01

    The objective of this study was to collect data that would provide a foundation for the concept of using vegetation to enhance in situ bioremediation of contaminated surface soils. Soil and vegetation (Lespedeza cuneata, Paspalum notatum, Pinus taeda, and Solidago sp.) samples from the Miscellaneous Chemicals Basin (MCB) at the Savannah River Site were used in tests to identify critical plant and microbiological variables affecting the fate of trichloroethylene (TCE) in the root zone. Microbiological assays including phospholipid acid analyses, and 14C-acetate incorporation were conducted to elucidate differences in rhizosphere and nonvegetated soil microbial communities from the MCB. The microbial activity, biomass, and degradation of TCE in rhizosphere soils were significantly greater than corresponding nonvegetated soils. Vegetation had a positive effect on microbial degradation of 14C-TCE in whole-plant experiments. Soils from the MCB containing Lespedeza cuneata, Pinus taeda, and Glycine max mineralized greater than 25% of the 14C- TCE added compared with less than 20% in nonvegetated soils. Collectively, these results provide evidence for the positive role of vegetation in enhancing biodegradation.

  6. Comparative plant uptake and microbial degradation of trichloroethylene in the rhizospheres of five plant species-- implications for bioremediation of contaminated surface soils

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, T.A. (Tennessee Univ., Knoxville, TN (United States)); Walton, B.T. (Oak Ridge National Lab., TN (United States))

    1992-01-01

    The objective of this study was to collect data that would provide a foundation for the concept of using vegetation to enhance in situ bioremediation of contaminated surface soils. Soil and vegetation (Lespedeza cuneata, Paspalum notatum, Pinus taeda, and Solidago sp.) samples from the Miscellaneous Chemicals Basin (MCB) at the Savannah River Site were used in tests to identify critical plant and microbiological variables affecting the fate of trichloroethylene (TCE) in the root zone. Microbiological assays including phospholipid acid analyses, and {sup 14}C-acetate incorporation were conducted to elucidate differences in rhizosphere and nonvegetated soil microbial communities from the MCB. The microbial activity, biomass, and degradation of TCE in rhizosphere soils were significantly greater than corresponding nonvegetated soils. Vegetation had a positive effect on microbial degradation of {sup 14}C-TCE in whole-plant experiments. Soils from the MCB containing Lespedeza cuneata, Pinus taeda, and Glycine max mineralized greater than 25% of the {sup 14}C- TCE added compared with less than 20% in nonvegetated soils. Collectively, these results provide evidence for the positive role of vegetation in enhancing biodegradation.

  7. An Indirect Defence Trait Mediated through Egg-Induced Maize Volatiles from Neighbouring Plants.

    Directory of Open Access Journals (Sweden)

    Daniel M Mutyambai

    Full Text Available Attack of plants by herbivorous arthropods may result in considerable changes to the plant's chemical phenotype with respect to emission of herbivore-induced plant volatiles (HIPVs. These HIPVs have been shown to act as repellents to the attacking insects as well as attractants for the insects antagonistic to these herbivores. Plants can also respond to HIPV signals from other plants that warn them of impending attack. Recent investigations have shown that certain maize varieties are able to emit volatiles following stemborer egg deposition. These volatiles attract the herbivore's parasitoids and directly deter further oviposition. However, it was not known whether these oviposition-induced maize (Zea mays, L. volatiles can mediate chemical phenotypic changes in neighbouring unattacked maize plants. Therefore, this study sought to investigate the effect of oviposition-induced maize volatiles on intact neighbouring maize plants in 'Nyamula', a landrace known to respond to oviposition, and a standard commercial hybrid, HB515, that did not. Headspace volatile samples were collected from maize plants exposed to Chilo partellus (Swinhoe (Lepidoptera: Crambidae egg deposition and unoviposited neighbouring plants as well as from control plants kept away from the volatile emitting ones. Behavioural bioassays were carried out in a four-arm olfactometer using egg (Trichogramma bournieri Pintureau & Babault (Hymenoptera: Trichogrammatidae and larval (Cotesia sesamiae Cameron (Hymenoptera: Braconidae parasitoids. Coupled Gas Chromatography-Mass Spectrometry (GC-MS was used for volatile analysis. For the 'Nyamula' landrace, GC-MS analysis revealed HIPV production not only in the oviposited plants but also in neighbouring plants not exposed to insect eggs. Higher amounts of EAG-active biogenic volatiles such as (E-4,8-dimethyl-1,3,7-nonatriene were emitted from these plants compared to control plants. Subsequent behavioural assays with female T. bournieri and

  8. Intragenomic matching reveals a huge potential for miRNA-mediated regulation in plants

    DEFF Research Database (Denmark)

    Lindow, Morten; Jacobsen, Anders; Nygaard, Sanne

    2007-01-01

    indicates that only a few of the candidates are conserved between the species. We conclude that there is a large potential for miRNA-mediated regulatory interactions encoded in the genomes of the investigated plants. We hypothesize that some of these interactions may be realized under special environmental...

  9. Activity and specificity of TRV-mediated gene editing in plants

    KAUST Repository

    Ali, Zahir

    2015-06-03

    © 2015 Taylor and Francis Group, LLC. Plant trait engineering requires efficient targeted genome-editing technologies. Clustered regularly interspaced palindromic repeats (CRISPRs)/ CRISPR associated (Cas) type II system is used for targeted genome-editing applications across eukaryotic species including plants. Delivery of genome engineering reagents and recovery of mutants remain challenging tasks for in planta applications. Recently, we reported the development of Tobacco rattle virus (TRV)-mediated genome editing in Nicotiana benthamiana. TRV infects the growing points and possesses small genome size; which facilitate cloning, multiplexing, and agroinfections. Here, we report on the persistent activity and specificity of the TRV-mediated CRISPR/Cas9 system for targeted modification of the Nicotiana benthamiana genome. Our data reveal the persistence of the TRVmediated Cas9 activity for up to 30 d post-agroinefection. Further, our data indicate that TRV-mediated genome editing exhibited no off-target activities at potential off-targets indicating the precision of the system for plant genome engineering. Taken together, our data establish the feasibility and exciting possibilities of using virus-mediated CRISPR/Cas9 for targeted engineering of plant genomes.

  10. Flavonoids: a metabolic network mediating plants adaptation to their real estate.

    Science.gov (United States)

    Mouradov, Aidyn; Spangenberg, German

    2014-01-01

    From an evolutionary perspective, the emergence of the sophisticated chemical scaffolds of flavonoid molecules represents a key step in the colonization of Earth's terrestrial environment by vascular plants nearly 500 million years ago. The subsequent evolution of flavonoids through recruitment and modification of ancestors involved in primary metabolism has allowed vascular plants to cope with pathogen invasion and damaging UV light. The functional properties of flavonoids as a unique combination of different classes of compounds vary significantly depending on the demands of their local real estate. Apart from geographical location, the composition of flavonoids is largely dependent on the plant species, their developmental stage, tissue type, subcellular localization, and key ecological influences of both biotic and abiotic origin. Molecular and metabolic cross-talk between flavonoid and other pathways as a result of the re-direction of intermediate molecules have been well investigated. This metabolic plasticity is a key factor in plant adaptive strength and is of paramount importance for early land plants adaptation to their local ecosystems. In human and animal health the biological and pharmacological activities of flavonoids have been investigated in great depth and have shown a wide range of anti-inflammatory, anti-oxidant, anti-microbial, and anti-cancer properties. In this paper we review the application of advanced gene technologies for targeted reprogramming of the flavonoid pathway in plants to understand its molecular functions and explore opportunities for major improvements in forage plants enhancing animal health and production.

  11. Flavonoids: A Metabolic Network Mediating Plants Adaptation to Their Real Estate

    Directory of Open Access Journals (Sweden)

    Aidyn eMouradov

    2014-11-01

    Full Text Available From an evolutionary perspective, the emergence of the sophisticated chemical scaffolds of flavonoid molecules represents a key step in the colonization of Earth’s terrestrial environment by vascular plants nearly 500 million years ago. The subsequent evolution of flavonoids through recruitment and modification of ancestors involved in primary metabolism has allowed vascular plants to cope with pathogen invasion and damaging UV light. The functional properties of flavonoids as a unique combination of different classes of compounds vary significantly depending on the demands of their local real estate. Apart from geographical location, the composition of flavonoids is largely dependent on the plant species, their developmental stage, tissue type, subcellular localization, and key ecological influences of both biotic and abiotic origin. Molecular and metabolic cross-talk between flavonoid and other pathways as a result of the re-direction of intermediate molecules have been well investigated. This metabolic plasticity is a key factor in plant adaptive strength and is of paramount importance for early land plants adaptation to their local ecosystems. In human and animal health the biological and pharmacological activities of flavonoids have been investigated in great depth and have shown a wide range of anti-inflammatory, anti-oxidant, anti-microbial and anti-cancer properties. In this paper we review the application of advanced gene technologies for targeted reprogramming of the flavonoid pathway in plants to understand its molecular functions and explore opportunities for major improvements in forage plants enhancing animal health and production.

  12. Petroleum Contamination and Plant Identity Influence Soil and Root Microbial Communities While AMF Spores Retrieved from the Same Plants Possess Markedly Different Communities.

    Science.gov (United States)

    Iffis, Bachir; St-Arnaud, Marc; Hijri, Mohamed

    2017-01-01

    Phytoremediation is a promising in situ green technology based on the use of plants to cleanup soils from organic and inorganic pollutants. Microbes, particularly bacteria and fungi, that closely interact with plant roots play key roles in phytoremediation processes. In polluted soils, the root-associated microbes contribute to alleviation of plant stress, improve nutrient uptake and may either degrade or sequester a large range of soil pollutants. Therefore, improving the efficiency of phytoremediation requires a thorough knowledge of the microbial diversity living in the rhizosphere and in close association with plant roots in both the surface and the endosphere. This study aims to assess fungal ITS and bacterial 16S rRNA gene diversity using high-throughput sequencing in rhizospheric soils and roots of three plant species ( Solidago canadensis, Populus balsamifera , and Lycopus europaeus ) growing spontaneously in three petroleum hydrocarbon polluted sedimentation basins. Microbial community structures of rhizospheric soils and roots were compared with those of microbes associated with arbuscular mycorrhizal fungal (AMF) spores to determine the links between the root and rhizosphere communities and those associated with AMF. Our results showed a difference in OTU richness and community structure composition between soils and roots for both bacteria and fungi. We found that petroleum hydrocarbon pollutant (PHP) concentrations have a significant effect on fungal and bacterial community structures in both soils and roots, whereas plant species identity showed a significant effect only on the roots for bacteria and fungi. Our results also showed that the community composition of bacteria and fungi in soil and roots varied from those associated with AMF spores harvested from the same plants. This let us to speculate that in petroleum hydrocarbon contaminated soils, AMF may release chemical compounds by which they recruit beneficial microbes to tolerate or degrade the

  13. Petroleum Contamination and Plant Identity Influence Soil and Root Microbial Communities While AMF Spores Retrieved from the Same Plants Possess Markedly Different Communities

    Directory of Open Access Journals (Sweden)

    Bachir Iffis

    2017-08-01

    Full Text Available Phytoremediation is a promising in situ green technology based on the use of plants to cleanup soils from organic and inorganic pollutants. Microbes, particularly bacteria and fungi, that closely interact with plant roots play key roles in phytoremediation processes. In polluted soils, the root-associated microbes contribute to alleviation of plant stress, improve nutrient uptake and may either degrade or sequester a large range of soil pollutants. Therefore, improving the efficiency of phytoremediation requires a thorough knowledge of the microbial diversity living in the rhizosphere and in close association with plant roots in both the surface and the endosphere. This study aims to assess fungal ITS and bacterial 16S rRNA gene diversity using high-throughput sequencing in rhizospheric soils and roots of three plant species (Solidago canadensis, Populus balsamifera, and Lycopus europaeus growing spontaneously in three petroleum hydrocarbon polluted sedimentation basins. Microbial community structures of rhizospheric soils and roots were compared with those of microbes associated with arbuscular mycorrhizal fungal (AMF spores to determine the links between the root and rhizosphere communities and those associated with AMF. Our results showed a difference in OTU richness and community structure composition between soils and roots for both bacteria and fungi. We found that petroleum hydrocarbon pollutant (PHP concentrations have a significant effect on fungal and bacterial community structures in both soils and roots, whereas plant species identity showed a significant effect only on the roots for bacteria and fungi. Our results also showed that the community composition of bacteria and fungi in soil and roots varied from those associated with AMF spores harvested from the same plants. This let us to speculate that in petroleum hydrocarbon contaminated soils, AMF may release chemical compounds by which they recruit beneficial microbes to tolerate

  14. Petroleum Contamination and Plant Identity Influence Soil and Root Microbial Communities While AMF Spores Retrieved from the Same Plants Possess Markedly Different Communities

    Science.gov (United States)

    Iffis, Bachir; St-Arnaud, Marc; Hijri, Mohamed

    2017-01-01

    Phytoremediation is a promising in situ green technology based on the use of plants to cleanup soils from organic and inorganic pollutants. Microbes, particularly bacteria and fungi, that closely interact with plant roots play key roles in phytoremediation processes. In polluted soils, the root-associated microbes contribute to alleviation of plant stress, improve nutrient uptake and may either degrade or sequester a large range of soil pollutants. Therefore, improving the efficiency of phytoremediation requires a thorough knowledge of the microbial diversity living in the rhizosphere and in close association with plant roots in both the surface and the endosphere. This study aims to assess fungal ITS and bacterial 16S rRNA gene diversity using high-throughput sequencing in rhizospheric soils and roots of three plant species (Solidago canadensis, Populus balsamifera, and Lycopus europaeus) growing spontaneously in three petroleum hydrocarbon polluted sedimentation basins. Microbial community structures of rhizospheric soils and roots were compared with those of microbes associated with arbuscular mycorrhizal fungal (AMF) spores to determine the links between the root and rhizosphere communities and those associated with AMF. Our results showed a difference in OTU richness and community structure composition between soils and roots for both bacteria and fungi. We found that petroleum hydrocarbon pollutant (PHP) concentrations have a significant effect on fungal and bacterial community structures in both soils and roots, whereas plant species identity showed a significant effect only on the roots for bacteria and fungi. Our results also showed that the community composition of bacteria and fungi in soil and roots varied from those associated with AMF spores harvested from the same plants. This let us to speculate that in petroleum hydrocarbon contaminated soils, AMF may release chemical compounds by which they recruit beneficial microbes to tolerate or degrade the

  15. Estimating the Transfer Range of Plasmids Encoding Antimicrobial Resistance in a Wastewater Treatment Plant Microbial Community

    DEFF Research Database (Denmark)

    Li, Liguan; Dechesne, Arnaud; He, Zhiming

    2018-01-01

    sludge microbial community was challenged in standardized filter matings with one of three multidrug resistance plasmids (pKJK5, pB10, and RP4) harbored by Escherichia coli or Pseudomonas putida. Different donor–plasmid combinations had distinct transfer frequencies, ranging from 3 to 50 conjugation...... events per 100000 cells of the WWTP microbial community. In addition, transfer was observed to a broad phylogenetic range of 13 bacterial phyla with several taxa containing potentially pathogenic species. Preferential transfer to taxa belonging to the predicted evolutionary host range of the plasmids...... ARG transmission. However, the contribution of microbial communities in WWTPs to ARG dissemination remains poorly understood. Here, we examined for the first time plasmid permissiveness of an activated sludge microbial community by utilizing an established fluorescent bioreporter system. The activated...

  16. Metaproteomics reveals major microbial players and their biodegradation functions in a large-scale aerobic composting plant

    Science.gov (United States)

    Liu, Dongming; Li, Mingxiao; Xi, Beidou; Zhao, Yue; Wei, Zimin; Song, Caihong; Zhu, Chaowei

    2015-01-01

    Composting is an appropriate management alternative for municipal solid waste; however, our knowledge about the microbial regulation of this process is still scare. We employed metaproteomics to elucidate the main biodegradation pathways in municipal solid waste composting system across the main phases in a large-scale composting plant. The investigation of microbial succession revealed that Bacillales, Actinobacteria and Saccharomyces increased significantly with respect to abundance in composting process. The key microbiologic population for cellulose degradation in different composting stages was different. Fungi were found to be the main producers of cellulase in earlier phase. However, the cellulolytic fungal communities were gradually replaced by a purely bacterial one in active phase, which did not support the concept that the thermophilic fungi are active through the thermophilic phase. The effective decomposition of cellulose required the synergy between bacteria and fungi in the curing phase. PMID:25989417

  17. Plant Pathogenic Microbial Communication Affected by Elevated Temperature in Pectobacterium carotovorum subsp. carotovorum.

    Science.gov (United States)

    Saha, N D; Chaudhary, A; Singh, S D; Singh, D; Walia, S; Das, T K

    2015-11-01

    Gram-negative plant pathogenic bacteria regulate specific gene expression in a population density-dependent manner by sensing level of Acyl-Homoserine Lactone (HSL) molecules which they produce and liberate to the environment, called Quorum Sensing (QS). The production of virulence factors (extracellular enzyme viz. cellulase, pectinase, etc.) in Pectobacterium carotovorum subsp. carotovorum (Pcc) is under strong regulation of QS. The QS signal molecule, N-(3-oxohexanoyl)-L-Homoserine Lactone (OHHL) was found as the central regulatory system for the virulence factor production in Pcc and is also under strict regulation of external environmental temperature. Under seven different incubation temperatures (24, 26, 28, 30, 33, 35, and 37 °C) in laboratory condition, highest amount of OHHL (804 violacein unit) and highest (79 %) Disease Severity Index (DSI) were measured at 33 °C. The OHHL production kinetics showed accumulation of highest concentration of OHHL at late log phase of the growth but diminution in the concentration occurred during stationary phase onwards to death phase. At higher temperature (35 and 37 °C) exposure, OHHL was not at detectable range. The effect of temperature on virulence factor production is the concomitant effect of HSL production and degradation which justifies less disease severity index in cross-inoculated tomato fruits incubated at 35 and 37 °C. The nondetection of the OHHL in the elevated temperature may because of degradation as these signal molecules are quite sensitive and prone to get degraded under different physical factors. This result provides the rationale behind the highest disease severity up to certain elevated temperature and leaves opportunities for investigation on mutation, co-evolution of superior plant pathogen with more stable HSL signals-mediated pathogenesis under global warming context.

  18. Plant Cell Division Analyzed by Transient Agrobacterium-Mediated Transformation of Tobacco BY-2 Cells.

    Science.gov (United States)

    Buschmann, Henrik

    2016-01-01

    The continuing analysis of plant cell division will require additional protein localization studies. This is greatly aided by GFP-technology, but plant transformation and the maintenance of transgenic lines can present a significant technical bottleneck. In this chapter I describe a method for the Agrobacterium-mediated genetic transformation of tobacco BY-2 cells. The method allows for the microscopic analysis of fluorescence-tagged proteins in dividing cells in within 2 days after starting a coculture. This transient transformation procedure requires only standard laboratory equipment. It is hoped that this rapid method would aid researchers conducting live-cell localization studies in plant mitosis and cytokinesis.

  19. Microbial Biomass Changes during Decomposition of Plant Residues in a Lixisol

    Directory of Open Access Journals (Sweden)

    Kachaka, SK.

    2003-01-01

    Full Text Available A lixisol was amended with four different alley cropping species: Senna siamea, Leucaena leucocephala, Dactyladenia barteri and Flemingia macrophylla. Soil samples were incubated for 140 days at 25 °C and the soil microbial biomass was determined by the ninhydrin extraction method along the incubation period. The soil microbial biomass values ranged between 80 and 600 mg.kg-1 and followed, in all cases, the decreasing order: Leucaena> Senna> Flemingia> Dactyladenia.

  20. Soil Minerals: AN Overlooked Mediator of Plant-Microbe Competition for Organic Nitrogen in the Rhizosphere

    Science.gov (United States)

    Grandy, S.; Jilling, A.; Keiluweit, M.

    2016-12-01

    Recent research on the rate limiting steps in soil nitrogen (N) availability have shifted in focus from mineralization to soil organic matter (SOM) depolymerization. To that end, Schimel and Bennett (2004) argued that together with enzymatic breakdown of polymers to monomers, microsite processes and plant-microbial competition collectively drive N cycling. Here we present new conceptual models arguing that while depolymerization is a critical first step, mineral-organic associations may ultimately regulate the provisioning of bioavailable organic N, especially in the rhizosphere. Mineral-associated organic matter (MAOM) is a rich reservoir for N in soils and often holds 5-7x more N than particulate or labile fractions. However, MAOM is considered largely unavailable to plants as a source of N due to the physicochemical forces on mineral surfaces that stabilize organic matter. We argue that in rhizosphere hotspots, MAOM is in fact a potentially mineralizable and important source of nitrogen for plants. Several biochemical strategies enable plants and microbes to compete with mineral-organic interactions and effectively access MAOM. In particular, root-deposited low molecular weight compounds in the form of root exudates facilitate the biotic and abiotic destabilization and subsequent bioavailability of MAOM. We believe that the competitive balance between the potential fates of assimilable organic N — bound to mineral surfaces or dissolved and available for assimilation — depends on the specific interaction between and properties of the clay, soil solution, mineral-bound organic matter, and microbial community. For this reason, the plant-soil-MAOM interplay is enhanced in rhizosphere hotspots relative to non-rhizosphere environments, and likely strongly regulates plant-microbe competition for N. If these hypotheses are true, we need to reconsider potential soil N cycle responses to changes in climate and land use intensity, focusing on the processes by which

  1. Transient plant transformation mediated by Agrobacterium tumefaciens: Principles, methods and applications.

    Science.gov (United States)

    Krenek, Pavel; Samajova, Olga; Luptovciak, Ivan; Doskocilova, Anna; Komis, George; Samaj, Jozef

    2015-11-01

    Agrobacterium tumefaciens is widely used as a versatile tool for development of stably transformed model plants and crops. However, the development of Agrobacterium based transient plant transformation methods attracted substantial attention in recent years. Transient transformation methods offer several applications advancing stable transformations such as rapid and scalable recombinant protein production and in planta functional genomics studies. Herein, we highlight Agrobacterium and plant genetics factors affecting transfer of T-DNA from Agrobacterium into the plant cell nucleus and subsequent transient transgene expression. We also review recent methods concerning Agrobacterium mediated transient transformation of model plants and crops and outline key physical, physiological and genetic factors leading to their successful establishment. Of interest are especially Agrobacterium based reverse genetics studies in economically important crops relying on use of RNA interference (RNAi) or virus-induced gene silencing (VIGS) technology. The applications of Agrobacterium based transient plant transformation technology in biotech industry are presented in thorough detail. These involve production of recombinant proteins (plantibodies, vaccines and therapeutics) and effectoromics-assisted breeding of late blight resistance in potato. In addition, we also discuss biotechnological potential of recombinant GFP technology and present own examples of successful Agrobacterium mediated transient plant transformations. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Plant- and microbial-based mechanisms to improve the agronomic effectiveness of phosphate rock: a review

    Directory of Open Access Journals (Sweden)

    Melissa M. Arcand

    2006-12-01

    Full Text Available Deficiency in plant-available phosphorus is considered to be a major limiting factor to food production in many agricultural soils. Mineral resources are necessary to restore soil phosphorus content. In regions where conventional fertilizers are not used due to cost limitations or to mitigate adverse environmental effects, local sources of phosphate rock are being increasingly recognized for potential use as alternative phosphorus fertilizers. The main obstacle associated with using directly applied ground phosphate rock is that the phosphate released is often unable to supply sufficient plant-available phosphorus for crop uptake. Plantand microbial-based mechanisms are low-cost, appropriate technologies to enhance the solubilization and increase the agronomic effectiveness of phosphate rock. Common mechanisms of phosphate rock dissolution including proton and organic acid production will be reviewed for both plants and microorganisms. This review will also address possibilities for future research directions and applications to agriculture, as well as highlight ongoing research at the University of Guelph, Guelph, Canada.A deficiência de fósforo disponível nas plantas é considerada o maior fator de limitação na produção de alimentos em diversos solos agrícolas. São necessários recursos minerais para restaurar o conteúdo de fósforo no solo. Em regiões onde fertilizantes convencionais nãosão utilizados devido às limitações de custo ou de seus efeitos ambientais adversos, fontes locais de rocha fosfática estão sendo crescentemente reconhecidas por seu uso potencial como alternativa aos fertilizantes solúveis de fósforo. O principal obstáculo associado ao uso daaplicação direta da rocha fosfática no solo é que o fósforo liberado é, muitas vezes, incapaz de suprir as necessidades das plantas de forma a aumentar a produção. Mecanismos baseados no uso de plantas e micro-organismos são consideradas tecnologias

  3. Plasmodesmata-mediated intercellular signaling during plant growth and development

    Directory of Open Access Journals (Sweden)

    Shri Ram eYadav

    2014-02-01

    Full Text Available Plasmodesmata (PD are cytoplasmic channels that connect neighboring cells for cell-to-cell communication. PD structure and function vary temporally and spatially to allow formation of symplastic domains during different stages of plant development. Reversible deposition of callose at PD plays an important role in controlling molecular trafficking through PD by regulating their size exclusion limit (SEL. Previously, we reported several semi-dominant mutants for CALLOSE SYNTHASE 3 (CALS3 gene, which overproduce callose at PD in Arabidopsis. By combining two of these mutations in a LexA-VP16-ER (XVE-based estradiol inducible vector system, a tool known as the icals3m system was developed to temporally obstruct the symplastic connections in a specified spatial domain. The system has been successfully tested and used, in combination with other methods, to investigate the route for mobile signals such as the SHR protein, microRNA165/6, and cytokinins in Arabidopsis roots, and also to understand the role of symplastic domain formation during lateral root development. We envision that this tool may also be useful for identifying tissue-specific symplastic regulatory networks and to analyze symplastic movement of metabolites.

  4. Plasmodesmata-mediated intercellular signaling during plant growth and development.

    Science.gov (United States)

    Yadav, Shri R; Yan, Dawei; Sevilem, Iris; Helariutta, Ykä

    2014-01-01

    Plasmodesmata (PD) are cytoplasmic channels that connect neighboring cells for cell-to-cell communication. PD structure and function vary temporally and spatially to allow formation of symplastic domains during different stages of plant development. Reversible deposition of callose at PD plays an important role in controlling molecular trafficking through PD by regulating their size exclusion limit. Previously, we reported several semi-dominant mutants for CALLOSE SYNTHASE 3 (CALS3) gene, which overproduce callose at PD in Arabidopsis. By combining two of these mutations in a LexA-VP16-ER (XVE)-based estradiol inducible vector system, a tool known as the "icals3m system" was developed to temporally obstruct the symplastic connections in a specified spatial domain. The system has been successfully tested and used, in combination with other methods, to investigate the route for mobile signals such as the SHR protein, microRNA165/6, and cytokinins in Arabidopsis roots, and also to understand the role of symplastic domain formation during lateral root development. We envision that this tool may also be useful for identifying tissue-specific symplastic regulatory networks and to analyze symplastic movement of metabolites.

  5. Boron-Mediated Plant Somatic Embryogenesis: A Provocative Model

    Directory of Open Access Journals (Sweden)

    Dhananjay K. Pandey

    2012-01-01

    Full Text Available A central question in plant regeneration biology concerns the primary driving forces invoking the acquisition of somatic embryogenesis. Recently, the role of micronutrient boron (B in the initiation and perpetuation of embryogenesis has drawn considerable attention within the scientific community. This interest may be due in part to the bewildering observation that the system-wide induction of embryogenic potential significantly varied in response to a minimal to optimal supply of B (minimal ≤ 0.1 mM, optimal = 0.1 mM. At the cellular level, certain channel proteins and cell wall-related proteins important for the induction of embryogenesis have been shown to be transcriptionally upregulated in response to minimal B supply suggesting the vital role of B in the induction of embryogenesis. At the molecular level, minimal to no B supply increased the endogenous level of auxin, which subsequently influenced the auxin-inducible somatic embryogenesis receptor kinases, suggesting the role of B in the induction of embryogenesis. Also, minimal B concentration may “turn on” other genetic and/or cellular transfactors reported earlier to be essential for cell-restructuring and induction of embryogenesis. In this paper, both the direct and indirect roles of B in the induction of somatic embryogenesis are highlighted and suggested for future validation.

  6. Targeted viral-mediated plant genome editing using crispr/cas9

    KAUST Repository

    Mahfouz, Magdy M.

    2015-12-17

    The present disclosure provides a viral-mediated genome-editing platform that facilitates multiplexing, obviates stable transformation, and is applicable across plant species. The RNA2 genome of the tobacco rattle virus (TRV) was engineered to carry and systemically deliver a guide RNA molecules into plants overexpressing Cas9 endonuclease. High genomic modification frequencies were observed in inoculated as well as systemic leaves including the plant growing points. This system facilitates multiplexing and can lead to germinal transmission of the genomic modifications in the progeny, thereby obviating the requirements of repeated transformations and tissue culture. The editing platform of the disclosure is useful in plant genome engineering and applicable across plant species amenable to viral infections for agricultural biotechnology applications.

  7. Targeted viral-mediated plant genome editing using crispr/cas9

    KAUST Repository

    Mahfouz, Magdy M.; Ali, Zahir

    2015-01-01

    The present disclosure provides a viral-mediated genome-editing platform that facilitates multiplexing, obviates stable transformation, and is applicable across plant species. The RNA2 genome of the tobacco rattle virus (TRV) was engineered to carry and systemically deliver a guide RNA molecules into plants overexpressing Cas9 endonuclease. High genomic modification frequencies were observed in inoculated as well as systemic leaves including the plant growing points. This system facilitates multiplexing and can lead to germinal transmission of the genomic modifications in the progeny, thereby obviating the requirements of repeated transformations and tissue culture. The editing platform of the disclosure is useful in plant genome engineering and applicable across plant species amenable to viral infections for agricultural biotechnology applications.

  8. HKT transporters mediate salt stress resistance in plants: from structure and function to the field.

    Science.gov (United States)

    Hamamoto, Shin; Horie, Tomoaki; Hauser, Felix; Deinlein, Ulrich; Schroeder, Julian I; Uozumi, Nobuyuki

    2015-04-01

    Plant cells are sensitive to salinity stress and do not require sodium as an essential element for their growth and development. Saline soils reduce crop yields and limit available land. Research shows that HKT transporters provide a potent mechanism for mediating salt tolerance in plants. Knowledge of the molecular ion transport and regulation mechanisms and the control of HKT gene expression are crucial for understanding the mechanisms by which HKT transporters enhance crop performance under salinity stress. This review focuses on HKT transporters in monocot plants and in Arabidopsis as a dicot plant, as a guide to efforts toward improving salt tolerance of plants for increasing the production of crops and bioenergy feedstocks. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. CMEIAS bioimage informatics that define the landscape ecology of immature microbial biofilms developed on plant rhizoplane surfaces

    Directory of Open Access Journals (Sweden)

    Frank B Dazzo

    2015-10-01

    Full Text Available Colonization of the rhizoplane habitat is an important activity that enables certain microorganisms to promote plant growth. Here we describe various types of computer-assisted microscopy that reveal important ecological insights of early microbial colonization behavior within biofilms on plant root surfaces grown in soil. Examples of the primary data are obtained by analysis of processed images of rhizoplane biofilm landscapes analyzed at single-cell resolution using the emerging technology of CMEIAS bioimage informatics software. Included are various quantitative analyses of the in situ biofilm landscape ecology of microbes during their pioneer colonization of white clover roots, and of a rhizobial biofertilizer strain colonized on rice roots where it significantly enhances the productivity of this important crop plant. The results show that spatial patterns of immature biofilms developed on rhizoplanes that interface rhizosphere soil are highly structured (rather than distributed randomly when analyzed at the appropriate spatial scale, indicating that regionalized microbial cell-cell interactions and the local environment can significantly affect their cooperative and competitive colonization behaviors.

  10. Mapping the Centimeter-Scale Spatial Variability of PAHs and Microbial Populations in the Rhizosphere of Two Plants.

    Directory of Open Access Journals (Sweden)

    Amélia Bourceret

    Full Text Available Rhizoremediation uses root development and exudation to favor microbial activity. Thus it can enhance polycyclic aromatic hydrocarbon (PAH biodegradation in contaminated soils. Spatial heterogeneity of rhizosphere processes, mainly linked to the root development stage and to the plant species, could explain the contrasted rhizoremediation efficiency levels reported in the literature. Aim of the present study was to test if spatial variability in the whole plant rhizosphere, explored at the centimetre-scale, would influence the abundance of microorganisms (bacteria and fungi, and the abundance and activity of PAH-degrading bacteria, leading to spatial variability in PAH concentrations. Two contrasted rhizospheres were compared after 37 days of alfalfa or ryegrass growth in independent rhizotron devices. Almost all spiked PAHs were degraded, and the density of the PAH-degrading bacterial populations increased in both rhizospheres during the incubation period. Mapping of multiparametric data through geostatistical estimation (kriging revealed that although root biomass was spatially structured, PAH distribution was not. However a greater variability of the PAH content was observed in the rhizosphere of alfalfa. Yet, in the ryegrass-planted rhizotron, the Gram-positive PAH-degraders followed a reverse depth gradient to root biomass, but were positively correlated to the soil pH and carbohydrate concentrations. The two rhizospheres structured the microbial community differently: a fungus-to-bacterium depth gradient similar to the root biomass gradient only formed in the alfalfa rhizotron.

  11. Microbial gas generation under expected Waste Isolation Pilot Plant repository conditions

    Energy Technology Data Exchange (ETDEWEB)

    Francis, A.J.; Gillow, J.B.; Giles, M.R. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science

    1997-03-01

    Gas generation from the microbial degradation of the organic constituents of transuranic waste under conditions expected at the Waste Isolation Pilot Plant (WIPP) repository was investigated at Brookhaven National Laboratory. The biodegradation of mixed cellulosics (various types of paper) and electron-beam irradiated plastic and rubber materials (polyethylene, polyvinylchloride, neoprene, hypalon, and leaded hypalon) was examined. The rate of gas production from cellulose biodegradation in inundated samples incubated for 1,228 days at 30 C was biphasic, with an initial rapid rate up to approximately 600 days incubation, followed by a slower rate. The rate of total gas production in anaerobic samples containing mixed inoculum was as follows: 0.002 mL/g cellulose/day without nutrients; 0.004 mL/g cellulose/day with nutrients; and 0.01 mL/g cellulose/day in the presence of excess nitrate. Carbon dioxide production proceeded at a rate of 0.009 {micro}mol/g cellulose/day in anaerobic samples without nutrients, 0.05 {micro}mol/g cellulose/day in the presence of nutrients, and 0.2 {micro}mol/g cellulose/day with excess nitrate. Adding nutrients and excess nitrate stimulated denitrification, as evidenced by the accumulation of N{sub 2}O in the headspace (200 {micro}mol/g cellulose). The addition of the potential backfill bentonite increased the rate of CO{sub 2} production to 0.3 {micro}mol/g cellulose/day in anaerobic samples with excess nitrate. Analysis of the solution showed that lactic, acetic, propionic, butyric, and valeric acids were produced due to cellulose degradation. Samples incubated under anaerobic humid conditions for 415 days produced CO{sub 2} at a rate of 0.2 {micro}mol/g cellulose/day in the absence of nutrients, and 1 {micro}mol/g cellulose/day in the presence of bentonite and nutrients. There was no evidence of biodegradation of electron-beam irradiated plastic and rubber.

  12. Microbial assimilation of 14C of ground and unground plant materials decomposing in a loamy sand and a clay soil

    DEFF Research Database (Denmark)

    Sørensen, P.; Ladd, J.N.; Amato, M.

    1996-01-01

    The influence of grinding plant materials on the microbial decomposition and the distribution of plant-derived carbon in soil was measured. Ground and unground, C-14-labelled subclover leaves (Trifolium subterraneum) were added to a loamy sand and clay soil and incubated for 42 d at 25 degrees C....

  13. Effects of wastewater treatment plant effluent inputs on planktonic metabolic rates and microbial community composition in the Baltic Sea

    DEFF Research Database (Denmark)

    Vaquer-Sunyer, Raquel; Reader, Heather E.; Muthusamy, Saraladevi

    2016-01-01

    ) contribute to eutrophication as they are important sources of nitrogen to coastal areas. Here, we evaluated the effects of wastewater treatment plant effluent inputs on Baltic Sea planktonic communities in four experiments. We tested for effects of effluent inputs on chlorophyll a content, bacterial....... An increase in BP and decrease in CR could be caused by high lability of the DOM that can support secondary bacterial production, without an increase in respiration. Increases in bacterial production and simultaneous decreases of primary production lead to more carbon being consumed in the microbial loop...

  14. Virus infection mediates the effects of elevated CO2 on plants and vectors

    Science.gov (United States)

    Trębicki, Piotr; Vandegeer, Rebecca K.; Bosque-Pérez, Nilsa A.; Powell, Kevin S.; Dader, Beatriz; Freeman, Angela J.; Yen, Alan L.; Fitzgerald, Glenn J.; Luck, Jo E.

    2016-03-01

    Atmospheric carbon dioxide (CO2) concentration has increased significantly and is projected to double by 2100. To increase current food production levels, understanding how pests and diseases respond to future climate driven by increasing CO2 is imperative. We investigated the effects of elevated CO2 (eCO2) on the interactions among wheat (cv. Yitpi), Barley yellow dwarf virus and an important pest and virus vector, the bird cherry-oat aphid (Rhopalosiphum padi), by examining aphid life history, feeding behavior and plant physiology and biochemistry. Our results showed for the first time that virus infection can mediate effects of eCO2 on plants and pathogen vectors. Changes in plant N concentration influenced aphid life history and behavior, and N concentration was affected by virus infection under eCO2. We observed a reduction in aphid population size and increased feeding damage on noninfected plants under eCO2 but no changes to population and feeding on virus-infected plants irrespective of CO2 treatment. We expect potentially lower future aphid populations on noninfected plants but no change or increased aphid populations on virus-infected plants therefore subsequent virus spread. Our findings underscore the complexity of interactions between plants, insects and viruses under future climate with implications for plant disease epidemiology and crop production.

  15. Virus infection mediates the effects of elevated CO2 on plants and vectors

    Science.gov (United States)

    Trębicki, Piotr; Vandegeer, Rebecca K.; Bosque-Pérez, Nilsa A.; Powell, Kevin S.; Dader, Beatriz; Freeman, Angela J.; Yen, Alan L.; Fitzgerald, Glenn J.; Luck, Jo E.

    2016-01-01

    Atmospheric carbon dioxide (CO2) concentration has increased significantly and is projected to double by 2100. To increase current food production levels, understanding how pests and diseases respond to future climate driven by increasing CO2 is imperative. We investigated the effects of elevated CO2 (eCO2) on the interactions among wheat (cv. Yitpi), Barley yellow dwarf virus and an important pest and virus vector, the bird cherry-oat aphid (Rhopalosiphum padi), by examining aphid life history, feeding behavior and plant physiology and biochemistry. Our results showed for the first time that virus infection can mediate effects of eCO2 on plants and pathogen vectors. Changes in plant N concentration influenced aphid life history and behavior, and N concentration was affected by virus infection under eCO2. We observed a reduction in aphid population size and increased feeding damage on noninfected plants under eCO2 but no changes to population and feeding on virus-infected plants irrespective of CO2 treatment. We expect potentially lower future aphid populations on noninfected plants but no change or increased aphid populations on virus-infected plants therefore subsequent virus spread. Our findings underscore the complexity of interactions between plants, insects and viruses under future climate with implications for plant disease epidemiology and crop production. PMID:26941044

  16. Performance Assessment of Full-Scale Wastewater Treatment Plants Based on Seasonal Variability of Microbial Communities via High-Throughput Sequencing.

    Directory of Open Access Journals (Sweden)

    Tang Liu

    Full Text Available Microbial communities of activated sludge (AS play a key role in the performance of wastewater treatment processes. However, seasonal variability of microbial population in varying AS-based processes has been poorly correlated with operation of full-scale wastewater treatment systems (WWTSs. In this paper, significant seasonal variability of AS microbial communities in eight WWTSs located in the city of Guangzhou were revealed in terms of 16S rRNA-based Miseq sequencing. Furthermore, variation redundancy analysis (RDA demonstrated that the microbial community compositions closely correlated with WWTS operation parameters such as temperature, BOD, NH4+-N and TN. Consequently, support vector regression models which reasonably predicted effluent BOD, SS and TN in WWTSs were established based on microbial community compositions. This work provided an alternative tool for rapid assessment on performance of full-scale wastewater treatment plants.

  17. Characteristics of microbial community involved in early biofilms formation under the influence of wastewater treatment plant effluent.

    Science.gov (United States)

    Peng, Yuke; Li, Jie; Lu, Junling; Xiao, Lin; Yang, Liuyan

    2018-04-01

    Effluents from wastewater treatment plants (WWTPs) containing microorganisms and residual nutrients can influence the biofilm formation. Although the process and mechanism of bacterial biofilm formation have been well characterized, little is known about the characteristics and interaction of bacteria, archaea and eukaryotes in the early colonization, especially under the influence of WWTP effluent. The aim of this study was to characterize the important bacterial, archaeal and eukaryotic species in the early stage of biofilm formation downstream of the WWTP outlet. Water and biofilm samples were collected 24 and 48hr after the deposition of bio-cords in the stream. Illumina Miseq sequencing of the 16S and 18S rDNA showed that, among the three domains, the bacterial biofilm community had the largest alpha and beta diversity. The early bacterial colonizers appeared to be "biofilm-specific", with only a few dominant operational taxonomic units (OTUs) shared between the biofilm and the ambient water environment. Alpha-proteobacteria and Ciliophora tended to dominate the bacterial and eukaryotic communities, respectively, of the early biofilm already at 24hr, whereas archaea played only a minor role during the early stage of colonization. The network analysis showed that the three domains of microbial community connected highly during the early colonization and it might be a characteristic of the microbial communities in the biofilm formation process where co-occurrence relationships could drive coexistence and diversity maintenance within the microbial communities. Copyright © 2017. Published by Elsevier B.V.

  18. Characterization of three plant biomass-degrading microbial consortia by metagenomics- and metasecretomics-based approaches

    DEFF Research Database (Denmark)

    Jiménez, Diego Javier; Brossi, Maria Julia de Lima; Schückel, Julia

    2016-01-01

    ). The highest degradation rates of lignin (~59 %) were observed with SG-M, whereas CS-M showed a high consumption of cellulose and hemicellulose. Analyses of the carbohydrate-active enzymes in the three microbial consortia showed the dominance of glycosyl hydrolases (e.g. of families GH3, GH43, GH13, GH10, GH29......), switchgrass (SG-M) and corn stover (CS-M) under aerobic and mesophilic conditions. Molecular fingerprintings, bacterial 16S ribosomal RNA (rRNA) gene amplicon sequencing and metagenomic analyses showed that the three microbial consortia were taxonomically distinct. Based on the taxonomic affiliation...

  19. Inter-plant communication through mycorrhizal networks mediates complex adaptive behaviour in plant communities.

    Science.gov (United States)

    Gorzelak, Monika A; Asay, Amanda K; Pickles, Brian J; Simard, Suzanne W

    2015-05-15

    Adaptive behaviour of plants, including rapid changes in physiology, gene regulation and defence response, can be altered when linked to neighbouring plants by a mycorrhizal network (MN). Mechanisms underlying the behavioural changes include mycorrhizal fungal colonization by the MN or interplant communication via transfer of nutrients, defence signals or allelochemicals. We focus this review on our new findings in ectomycorrhizal ecosystems, and also review recent advances in arbuscular mycorrhizal systems. We have found that the behavioural changes in ectomycorrhizal plants depend on environmental cues, the identity of the plant neighbour and the characteristics of the MN. The hierarchical integration of this phenomenon with other biological networks at broader scales in forest ecosystems, and the consequences we have observed when it is interrupted, indicate that underground 'tree talk' is a foundational process in the complex adaptive nature of forest ecosystems. Published by Oxford University Press on behalf of the Annals of Botany Company.

  20. Host-plant-mediated effects of Nadefensin on herbivore and pathogen resistance in Nicotiana attenuata

    Directory of Open Access Journals (Sweden)

    Baldwin Ian T

    2008-10-01

    Full Text Available Abstract Background The adage from Shakespeare, "troubles, not as single spies, but in battalions come," holds true for Nicotiana attenuata, which is commonly attacked by both pathogens (Pseudomonas spp. and herbivores (Manduca sexta in its native habitats. Defense responses targeted against the pathogens can directly or indirectly influence the responses against the herbivores. Nadefensin is an effective induced defense gene against the bacterial pathogen Pseudomonas syringae pv tomato (PST DC3000, which is also elicited by attack from M. sexta larvae, but whether this defense protein influences M. sexta's growth and whether M. sexta-induced Nadefensin directly or indirectly influences PST DC3000 resistance are unknown. Results M. sexta larvae consumed less on WT and on Nadefensin-silenced N. attenuata plants that had previously been infected with PST DC3000 than on uninfected plants. WT plants infected with PST DC3000 showed enhanced resistance to PST DC3000 and decreased leaf consumption by M. sexta larvae, but larval mass gain was unaffected. PST DC3000-infected Nadefensin-silenced plants were less resistant to subsequent PST DC3000 challenge, and on these plants, M. sexta larvae consumed less and gained less mass. WT and Nadefensin-silenced plants previously damaged by M. sexta larvae were better able to resist subsequent PST DC3000 challenges than were undamaged plants. Conclusion These results demonstrate that Na-defensin directly mediates defense against PST DC3000 and indirectly against M. sexta in N. attenuata. In plants that were previously infected with PST DC3000, the altered leaf chemistry in PST DC3000-resistant WT plants and PST DC3000-susceptible Nadefensin-silenced plants differentially reduced M. sexta's leaf consumption and mass gain. In plants that were previously damaged by M. sexta, the combined effect of the altered host plant chemistry and a broad spectrum of anti-herbivore induced metabolomic responses was more

  1. The Salicylic Acid-Mediated Release of Plant Volatiles Affects the Host Choice of Bemisia tabaci

    Directory of Open Access Journals (Sweden)

    Xiaobin Shi

    2016-06-01

    Full Text Available The whitefly Bemisia tabaci (Gennadius (Hemiptera: Aleyrodidae causes serious crop losses worldwide by transmitting viruses. We have previously shown that salicylic acid (SA-related plant defenses directly affect whiteflies. In this study, we applied exogenous SA to tomato plants in order to investigate the interaction between SA-induced plant volatiles and nonviruliferous B. tabaci B and Q or B- and Q-carrying tomato yellow leaf curl virus (TYLCV. The results showed that exogenous SA caused plants to repel nonviruliferous whiteflies, but the effect was reduced when the SA concentration was low and when the whiteflies were viruliferous. Exogenous SA increased the number and quantity of plant volatiles—especially the quantity of methyl salicylate and δ-limonene. In Y-tube olfactometer assays, methyl salicylate and δ-limonene repelled the whiteflies, but the repellency was reduced for viruliferous Q. We suggest that the release of plant volatiles as mediated by SA affects the interaction between whiteflies, plants, and viruses. Further studies are needed to determine why viruliferous Q is less sensitive than nonviruliferous Q to repellent plant volatiles.

  2. Effects of Secondary Plant Metabolites on Microbial Populations: Changes in Community Structure and Metabolic Activity in Contaminated Environments

    Directory of Open Access Journals (Sweden)

    Lucie Musilova

    2016-07-01

    Full Text Available Secondary plant metabolites (SPMEs play an important role in plant survival in the environment and serve to establish ecological relationships between plants and other organisms. Communication between plants and microorganisms via SPMEs contained in root exudates or derived from litter decomposition is an example of this phenomenon. In this review, the general aspects of rhizodeposition together with the significance of terpenes and phenolic compounds are discussed in detail. We focus specifically on the effect of SPMEs on microbial community structure and metabolic activity in environments contaminated by polychlorinated biphenyls (PCBs and polyaromatic hydrocarbons (PAHs. Furthermore, a section is devoted to a complex effect of plants and/or their metabolites contained in litter on bioremediation of contaminated sites. New insights are introduced from a study evaluating the effects of SPMEs derived during decomposition of grapefruit peel, lemon peel, and pears on bacterial communities and their ability to degrade PCBs in a long-term contaminated soil. The presented review supports the “secondary compound hypothesis” and demonstrates the potential of SPMEs for increasing the effectiveness of bioremediation processes.

  3. Seasonal and episodic moisture controls on plant and microbial contributions to soil respiration.

    Science.gov (United States)

    Carbone, Mariah S; Still, Christopher J; Ambrose, Anthony R; Dawson, Todd E; Williams, A Park; Boot, Claudia M; Schaeffer, Sean M; Schimel, Joshua P

    2011-09-01

    Moisture inputs drive soil respiration (SR) dynamics in semi-arid and arid ecosystems. However, determining the contributions of root and microbial respiration to SR, and their separate temporal responses to periodic drought and water pulses, remains poorly understood. This study was conducted in a pine forest ecosystem with a Mediterranean-type climate that receives seasonally varying precipitation inputs from both rainfall (in the winter) and fog-drip (primarily in the summer). We used automated SR measurements, radiocarbon SR source partitioning, and a water addition experiment to understand how SR, and its separate root and microbial sources, respond to seasonal and episodic changes in moisture. Seasonal changes in SR were driven by surface soil water content and large changes in root respiration contributions. Superimposed on these seasonal patterns were episodic pulses of precipitation that determined the short-term SR patterns. Warm season precipitation pulses derived from fog-drip, and rainfall following extended dry periods, stimulated the largest SR responses. Microbial respiration dominated these SR responses, increasing within hours, whereas root respiration responded more slowly over days. We conclude that root and microbial respiration sources respond differently in timing and magnitude to both seasonal and episodic moisture inputs. These findings have important implications for the mechanistic representation of SR in models and the response of dry ecosystems to changes in precipitation patterns.

  4. Ontogenetic stage, plant vigor and sex mediate herbivory loads in a dioecious understory herb

    Science.gov (United States)

    Selaković, Sara; Vujić, Vukica; Stanisavljević, Nemanja; Jovanović, Živko; Radović, Svetlana; Cvetković, Dragana

    2017-11-01

    Plant-herbivore interactions can be mediated by plant apparency, defensive and nutritional quality traits that change through plant ontogeny, resulting in age-specific herbivory. In dioecious species, opposing allocation patterns in defense may lead to sex-biased herbivory. Here, we examine how onto stage and plant sex determine levels of herbivore damage in understory herb Mercurialis perennis under field conditions. We analyzed variation in plant size (height, total leaf area), physical (specific leaf area) and chemical (total phenolic and condensed tannins contents) defense, and nutritional quality (total water, soluble protein and nonstructural carbohydrate contents) during the shift from reproductive to post-reproductive stage. Furthermore, we explored correlations between the analyzed traits and levels of foliar damage. Post-reproductive plants had lower levels of chemical defense, and larger leaf area removed, in spite of having lower nutritive quality. Opposing patterns of intersexual differences were detected in protein and phenolic contents during reproductive stage, while in post-reproductive stage total leaf area was sexually dimorphic. Female-biased herbivory was apparent only after reproduction. Plant size parameters combined with condensed tannins content determined levels of foliar damage during post-reproductive stage, while the only trait covarying with herbivory in reproductive stage was total nonstructural carbohydrate content. Our results support claims of optimal defense theory - sensitive stage of reproduction was better defended. We conclude that different combinations of plant traits mediated interactions with herbivores in mature stages. Differences in reproductive allocation between the sexes may not immediately translate into different levels of damage, stressing the need for considering different ontogenetic stages when exploring sex bias in herbivory.

  5. Volatile-Mediated within-Plant Signaling in Hybrid Aspen: Required for Systemic Responses.

    Science.gov (United States)

    Li, Tao; Blande, James D

    2017-04-01

    Plant volatiles play crucial roles in signaling between plants and their associated community members, but their role in within-plant signaling remains largely unexplored, particularly under field conditions. Using a system comprising the hybrid aspen (Populus tremula x tremuloides) and the specialized herbivorous leaf beetle (Phratora laticollis) and, combining field, greenhouse and laboratory experiments, we examined whether local damage triggered systemic responses in undamaged branches that lack vascular connection to the damaged branches, and to what extent this was caused by airborne volatile signals versus internal signals. An experiment tracing dye through the vasculature of saplings revealed no downward movement of the dye from upper to lower branches, suggesting a lack of vascular connectivity among branches. However, we found under both field and laboratory conditions that herbivore feeding on upper branches elicited volatile emissions by undamaged lower branches. Greenhouse experiments manipulating air contact between damaged and undamaged branches showed that systemic induction of volatiles was almost eliminated when air contact was interrupted. Our findings clearly demonstrate that herbivore-induced volatiles overcome vascular constraints and mediate within-plant signaling. Further, we found that volatile signaling led to induction of different classes of volatiles under field and environment controlled conditions, with a weaker response observed in the field. This difference not only reflects the dose- and time-dependent nature of volatile signaling, but also points out that future studies should focus more on field observations to better understand the ecological role of volatile-mediated within-plant signaling.

  6. Serobactins-mediated iron acquisition systems optimize competitive fitness of Herbaspirillum seropedicae inside rice plants.

    Science.gov (United States)

    Rosconi, Federico; Trovero, María F; de Souza, Emanuel M; Fabiano, Elena

    2016-09-01

    Herbaspirillum seropedicae Z67 is a diazotrophic endophyte able to colonize the interior of many economically relevant crops such as rice, wheat, corn and sorghum. Under iron-deficient conditions, this organism secretes serobactins, a suite of lipopetide siderophores. The role of siderophores in the interaction between endophytes and their plant hosts are not well understood. In this work, we aimed to determine the importance of serobactins-mediated iron acquisition systems in the interaction of H. seropedicae with rice plants. First we provide evidence, by using a combination of genome analysis, proteomic and genetic studies, that the Hsero_2345 gene encodes a TonB-dependent receptor involved in iron-serobactin complex internalization when iron bioavailability is low. Our results show that survival of the Hsero_2345 mutant inside rice plants was not significantly different from that of the wild-type strain. However, when plants were co-inoculated at equal ratios with the wild-type strain and with a double mutant defective in serobactins synthesis and internalization, recovery of mutant was significantly impaired after 8 days post-inoculation. These results demonstrate that serobactins-mediated iron acquisition contributes to competitive fitness of H. seropedicae inside host plants. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  7. Loop-mediated Isothermal Amplification Assay to Rapidly Detect Wheat Streak Mosaic Virus in Quarantined Plants

    Directory of Open Access Journals (Sweden)

    Siwon Lee

    2015-12-01

    Full Text Available We developed a loop-mediated isothermal amplification (LAMP method to rapidly diagnose Wheat streak mosaic virus (WSMV during quarantine inspections of imported wheat, corn, oats, and millet. The LAMP method was developed as a plant quarantine inspection method for the first time, and its simplicity, quickness, specificity and sensitivity were verified compared to current reverse transcription-polymerase chain reaction (RT-PCR and nested PCR quarantine methods. We were able to quickly screen for WSMV at quarantine sites with many test samples; thus, this method is expected to contribute to plant quarantine inspections.

  8. Plant-mediated synthesis of nanoparticles: A newer and safer tool against mosquito-borne diseases?

    Directory of Open Access Journals (Sweden)

    Giovanni Benelli

    2016-04-01

    Full Text Available Prevention and control of mosquito-borne diseases is a key challenge of huge public health importance. Plant-mediated synthesis of nanoparticles has recently gained attention as a cheap, rapid and eco-friendly method to control mosquito vector populations, with special reference to young instars. Furthermore, plant-fabricated nanoparticles have been successfully employed as dengue virus growth inhibitors. In this Editorial, parasitologists, entomologists and researchers in drug nanosynthesis are encouraged to deal with a number of crucial challenges of public health importance.

  9. Integrated membrane and microbial fuel cell technologies for enabling energy-efficient effluent Re-use in power plants.

    Science.gov (United States)

    Shrestha, Namita; Chilkoor, Govinda; Xia, Lichao; Alvarado, Catalina; Kilduff, James E; Keating, John J; Belfort, Georges; Gadhamshetty, Venkataramana

    2017-06-15

    Municipal wastewater is an attractive alternative to freshwater sources to meet the cooling water needs of thermal power plants. Here we offer an energy-efficient integrated microbial fuel cell (MFC)/ultrafiltration (UF) process to purify primary clarifier effluent from a municipal wastewater treatment plant for use as cooling water. The microbial fuel cell was shown to significantly reduce chemical oxygen demand (COD) in the primary settled wastewater effluent upstream of the UF module, while eliminating the energy demand required to deliver dissolved oxygen in conventional aerobic treatment. We investigated surface modification of the UF membranes to control fouling. Two promising hydrophilic monomers were identified in a high-throughput search: zwitterion (2-(Methacryloyloxy)-ethyl-dimethyl-(3-sulfopropyl ammoniumhydroxide, abbreviated BET SO 3 - ), and amine (2-(Methacryloyloxy) ethyl trimethylammonium chloride, abbreviated N(CH 3 ) 3 + ). Monomers were grafted using UV-induced polymerization on commercial poly (ether sulfone) membranes. Filtration of MFC effluent by membranes modified with BET SO 3 - and N(CH 3 ) 3 + exhibited a lower rate of resistance increase and lower energy consumption than the commercially available membrane. The MFC/UF process produced high quality cooling water that meets the Electrical Power Research Institute (EPRI) recommendations for COD, a suite of metals (Fe, Al, Cu, Zn, Si, Mn, S, Ca and Mg), and offered extremely low corrosion rates (<0.05 mm/yr). A series of AC and DC diagnostic tests were used to evaluate the MFC performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Occurrence of the mcr-1 Colistin Resistance Gene and other Clinically Relevant Antibiotic Resistance Genes in Microbial Populations at Different Municipal Wastewater Treatment Plants in Germany

    Directory of Open Access Journals (Sweden)

    Norman Hembach

    2017-07-01

    Full Text Available Seven wastewater treatment plants (WWTPs with different population equivalents and catchment areas were screened for the prevalence of the colistin resistance gene mcr-1 mediating resistance against last resort antibiotic polymyxin E. The abundance of the plasmid-associated mcr-1 gene in total microbial populations during water treatment processes was quantitatively analyzed by qPCR analyses. The presence of the colistin resistance gene was documented for all of the influent wastewater samples of the seven WWTPs. In some cases the mcr-1 resistance gene was also detected in effluent samples of the WWTPs after conventional treatment reaching the aquatic environment. In addition to the occurrence of mcr-1 gene, CTX-M-32, blaTEM, CTX-M, tetM, CMY-2, and ermB genes coding for clinically relevant antibiotic resistances were quantified in higher abundances in all WWTPs effluents. In parallel, the abundances of Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli were quantified via qPCR using specific taxonomic gene markers which were detected in all influent and effluent wastewaters in significant densities. Hence, opportunistic pathogens and clinically relevant antibiotic resistance genes in wastewaters of the analyzed WWTPs bear a risk of dissemination to the aquatic environment. Since many of the antibiotic resistance gene are associated with mobile genetic elements horizontal gene transfer during wastewater treatment can't be excluded.

  11. Linking agricultural practices, mycorrhizal fungi, and traits mediating plant-insect interactions.

    Science.gov (United States)

    Barber, Nicholas A; Kiers, E Toby; Theis, Nina; Hazzard, Ruth V; Adler, Lynn S

    2013-10-01

    Agricultural management has profound effects on soil communities. Activities such as fertilizer inputs can modify the composition of arbuscular mycorrhizal fungi (AMF) communities, which form important symbioses with the roots of most crop plants. Intensive conventional agricultural management may select for less mutualistic AMF with reduced benefits to host plants compared to organic management, but these differences are poorly understood. AMF are generally evaluated based on their direct growth effects on plants. However, mycorrhizal colonization also may alter plant traits such as tissue nutrients, defensive chemistry, or floral traits, which mediate important plant-insect interactions like herbivory and pollination. To determine the effect of AMF from different farming practices on plant performance and traits that putatively mediate species interactions, we performed a greenhouse study by inoculating Cucumis sativus (cucumber, Cucurbitaceae) with AMF from conventional farms, organic farms, and a commercial AMF inoculum. We measured growth and a suite of plant traits hypothesized to be important predictors of herbivore resistance and pollinator attraction. Several leaf and root traits and flower production were significantly affected by AMF inoculum. Both conventional and organic AMF reduced leaf P content but increased Na content compared to control and commercial AMF. Leaf defenses were unaffected by AMF treatments, but conventional AMF increased root cucurbitacin C, the primary defensive chemical of C. sativus, compared to organic AMF. These effects may have important consequences for herbivore preference and population dynamics. AMF from both organic and conventional farms decreased flower production relative to commercial and control treatments, which may reduce pollinator attraction and plant reproduction. AMF from both farm types also reduced seed germination, but effects on plant growth were limited. Our results suggest that studies only considering AMF

  12. Soil microbial species loss affects plant biomass and survival of an introduced bacterial strain, but not inducible plant defences

    NARCIS (Netherlands)

    Kurm, Viola; Putten, Van Der Wim H.; Pineda, Ana; Hol, G.W.H.

    2018-01-01

    • Background and Aims: Plant growth-promoting rhizobacteria (PGPR) strains can influence plant-insect interactions. However, little is known about the effect of changes in the soil bacterial community in general and especially the loss of rare soil microbes on these interactions. Here, the influence

  13. A Bacterial Parasite Effector Mediates Insect Vector Attraction in Host Plants Independently of Developmental Changes

    Science.gov (United States)

    Orlovskis, Zigmunds; Hogenhout, Saskia A.

    2016-01-01

    Parasites can take over their hosts and trigger dramatic changes in host appearance and behavior that are typically interpreted as extended phenotypes that promote parasite survival and fitness. For example, Toxoplasma gondii is thought to manipulate the behaviors of infected rodents to aid transmission to cats and parasitic trematodes of the genus Ribeiroia alter limb development in their amphibian hosts to facilitate predation of the latter by birds. Plant parasites and pathogens also reprogram host development and morphology. However, whereas some parasite-induced morphological alterations may have a direct benefit to the fitness of the parasite and may therefore be adaptive, other host alterations may be side effects of parasite infections having no adaptive effects on parasite fitness. Phytoplasma parasites of plants often induce the development of leaf-like flowers (phyllody) in their host plants, and we previously found that the phytoplasma effector SAP54 generates these leaf-like flowers via the degradation of plant MADS-box transcription factors (MTFs), which regulate all major aspects of development in plants. Leafhoppers prefer to reproduce on phytoplasma-infected and SAP54-trangenic plants leading to the hypothesis that leafhopper vectors are attracted to plants with leaf-like flowers. Surprisingly, here we show that leafhopper attraction occurs independently of the presence of leaf-like flowers. First, the leafhoppers were also attracted to SAP54 transgenic plants without leaf-like flowers and to single leaves of these plants. Moreover, leafhoppers were not attracted to leaf-like flowers of MTF-mutant plants without the presence of SAP54. Thus, the primary role of SAP54 is to attract leafhopper vectors, which spread the phytoplasmas, and the generation of leaf-like flowers may be secondary or a side effect of the SAP54-mediated degradation of MTFs. PMID:27446117

  14. Protease inhibitors as a possible new factor in agricultural plant protection against microbial and fungal attack

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Oldřich; Kodrík, Dalibor; Kludkiewicz, Barbara; Vinokurov, Konstantin; Sehnal, František; Horáčková, V.

    2012-01-01

    Roč. 73, Jan 2012 (2012), s. 61-67 ISSN 1027-3115 R&D Projects: GA MŠk 1M06030; GA MZe QI91A229 Institutional research plan: CEZ:AV0Z50380511; CEZ:AV0Z50070508 Keywords : potato * transgenosis * microbial and fungal pathogens Subject RIV: EB - Genetics ; Molecular Biology http://home.ueb.cas.cz/publikace/2012_Navratil_IOBC_61-67.pdf

  15. Seasonal variations of microbial community in a full scale oil field produced water treatment plant

    Directory of Open Access Journals (Sweden)

    Q. Xie

    2016-01-01

    Full Text Available This study investigated the microbial community in a full scale anaerobic baffled reactor and sequencing batch reactor system for oil-produced water treatment in summer and winter. The community structures of fungi and bacteria were analyzed through polymerase chain reaction–denaturing gradient gel electrophoresis and Illumina high-throughput sequencing, respectively. Chemical oxygen demand effluent concentration achieved lower than 50 mg/L level after the system in both summer and winter, however, chemical oxygen demand removal rates after anaerobic baffled reactor treatment system were significant higher in summer than that in winter, which conformed to the microbial community diversity. Saccharomycotina, Fusarium, and Aspergillus were detected in both anaerobic baffled reactor and sequencing batch reactor during summer and winter. The fungal communities in anaerobic baffled reactor and sequencing batch reactor were shaped by seasons and treatment units, while there was no correlation between abundance of fungi and chemical oxygen demand removal rates. Compared to summer, the total amount of the dominant hydrocarbon degrading bacteria decreased by 10.2% in anaerobic baffled reactor, resulting in only around 23% of chemical oxygen demand was removed in winter. Although microbial community significantly varied in the three parallel sulfide reducing bacteria, the performance of these bioreactors had no significant difference between summer and winter.

  16. Microbial and plant ecology of a long-term TNT-contaminated site

    International Nuclear Information System (INIS)

    Travis, Emma R.; Bruce, Neil C.; Rosser, Susan J.

    2008-01-01

    The contamination of the environment with explosive residues presents a serious ecological problem at sites across the world, with the highly toxic compound trinitrotoluene (TNT) the most widespread contaminant. This study examines the soil microbial community composition across a long-term TNT-contaminated site. It also investigates the extent of nitroaromatic contamination and its effect on vegetation. Concentrations of TNT and its metabolites varied across the site and this was observed to dramatically impact on the extent and diversity of the vegetation, with the most heavily contaminated area completely devoid of vegetation. Bryophytes were seen to be particularly sensitive to TNT contamination. The microbial population experienced both a reduction in culturable bacterial numbers and a shift in composition at the high concentrations of TNT. DGGE and community-level physiological profiling (CLPP) revealed a clear change in both the genetic and functional diversity of the soil when soil was contaminated with TNT. - Long-term contamination of soil with TNT reduces the extent and diversity of vegetation, decreases culturable bacterial numbers and shifts the microbial community composition

  17. Seasonal variations of microbial community in a full scale oil field produced water treatment plant

    International Nuclear Information System (INIS)

    Xie, Q.; Bai, S.; Li, Y.; Liu, L.; Wang, S.; Xi, J.

    2016-01-01

    This study investigated the microbial community in a full scale anaerobic baffled reactor and sequencing batch reactor system for oil-produced water treatment in summer and winter. The community structures of fungi and bacteria were analyzed through polymerase chain reaction–denaturing gradient gel electrophoresis and Illumina high throughput sequencing, respectively. Chemical oxygen demand effluent concentration achieved lower than 50 mg/L level after the system in both summer and winter, however, chemical oxygen demand removal rates after anaerobic baffled reactor treatment system were significant higher in summer than that in winter, which conformed to the microbial community diversity. Saccharomycotina, Fusarium, and Aspergillus were detected in both anaerobic baffled reactor and sequencing batch reactor during summer and winter. The fungal communities in anaerobic baffled reactor and sequencing batch reactor were shaped by seasons and treatment units, while there was no correlation between abundance of fungi and chemical oxygen demand removal rates. Compared to summer, the total amount of the dominant hydrocarbon degrading bacteria decreased by 10.2% in anaerobic baffled reactor, resulting in only around 23% of chemical oxygen demand was removed in winter. Although microbial community significantly varied in the three parallel sulfide reducing bacteria, the performance of these bioreactors had no significant difference between summer and winter.

  18. Effect of seven Indian plant extracts on Fenton reaction-mediated damage to DNA constituents.

    Science.gov (United States)

    Kar, Indrani; Chattopadhyaya, Rajagopal

    2017-11-01

    The influences of substoichiometric amounts of seven plant extracts in the Fenton reaction-mediated damage to deoxynucleosides, deoxynucleoside monophosphates, deoxynucleoside triphosphates, and supercoiled plasmid DNA were studied to rationalize anticancer properties reported in some of these extracts. Extracts from Acacia catechu, Emblica officinalis, Spondias dulcis, Terminalia belerica, Terminalia chebula, as well as gallic acid, epicatechin, chebulagic acid and chebulinic acid enhance the extent of damage in Fenton reactions with all monomeric substrates but protect supercoiled plasmid DNA, compared to standard Fenton reactions. The damage to pyrimidine nucleosides/nucleotides is enhanced by these extracts and compounds to a greater extent than for purine ones in a concentration dependent manner. Dolichos biflorus and Hemidesmus indicus extracts generally do not show this enhancement for the monomeric substrates though they protect plasmid DNA. Compared to standard Fenton reactions for deoxynucleosides with ethanol, the presence of these five plant extracts render ethanol scavenging less effective as the radical is generated in the vicinity of the target. Since substoichiometric amounts of these extracts and the four compounds produce this effect, a catalytic mechanism involving the presence of a ternary complex of the nucleoside/nucleotide substrate, a plant compound and the hydroxyl radical is proposed. Such a mechanism cannot operate for plasmid DNA as the planar rings in the extract compounds cannot stack with the duplex DNA bases. These plant extracts, by enhancing Fenton reaction-mediated damage to deoxynucleoside triphosphates, slow down DNA replication in rapidly dividing cancer cells, thus contributing to their anticancer properties.

  19. Plant-plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO2: an experiment with plant populations from naturally high CO2 areas.

    Science.gov (United States)

    van Loon, Marloes P; Rietkerk, Max; Dekker, Stefan C; Hikosaka, Kouki; Ueda, Miki U; Anten, Niels P R

    2016-06-01

    The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant-plant interactions could mediate the trajectory of vegetation responses to elevated [CO2], because some plants may benefit more from [CO2] elevation than others. The relative contribution of plastic (within the plant's lifetime) and genotypic (over several generations) responses to elevated [CO2] on plant performance was investigated and how these patterns are modified by plant-plant interactions was analysed. Plantago asiatica seeds originating from natural CO2 springs and from ambient [CO2] sites were grown in mono stands of each one of the two origins as well as mixtures of both origins. In total, 1944 plants were grown in [CO2]-controlled walk-in climate rooms, under a [CO2] of 270, 450 and 750 ppm. A model was used for upscaling from leaf to whole-plant photosynthesis and for quantifying the influence of plastic and genotypic responses. It was shown that changes in canopy photosynthesis, specific leaf area (SLA) and stomatal conductance in response to changes in growth [CO2] were mainly determined by plastic and not by genotypic responses. We further found that plants originating from high [CO2] habitats performed better in terms of whole-plant photosynthesis, biomass and leaf area, than those from ambient [CO2] habitats at elevated [CO2] only when both genotypes competed. Similarly, plants from ambient [CO2] habitats performed better at low [CO2], also only when both genotypes competed. No difference in performance was found in mono stands. The results indicate that natural selection under increasing [CO2] will be mainly driven by competitive interactions. This supports the notion that plant-plant interactions have an important influence on future vegetation functioning and species distribution. Furthermore, plant performance was mainly driven by plastic and not by genotypic responses to changes in

  20. Nitro-fatty acids in plant signaling: New key mediators of nitric oxide metabolism

    Directory of Open Access Journals (Sweden)

    Capilla Mata-Pérez

    2017-04-01

    Full Text Available Recent studies in animal systems have shown that NO can interact with fatty acids to generate nitro-fatty acids (NO2-FAs. They are the product of the reaction between reactive nitrogen species and unsaturated fatty acids, and are considered novel mediators of cell signaling based mainly on a proven anti-inflammatory response. Although these signaling mediators have been described widely in animal systems, NO2-FAs have scarcely been studied in plants. Preliminary data have revealed the endogenous presence of free and protein-adducted NO2-FAs in extra-virgin olive oil (EVOO, which appear to be contributing to the cardiovascular benefits associated with the Mediterranean diet. Importantly, new findings have displayed the endogenous occurrence of nitro-linolenic acid (NO2-Ln in the model plant Arabidopsis thaliana and the modulation of NO2-Ln levels throughout this plant's development. Furthermore, a transcriptomic analysis by RNA-seq technology established a clear signaling role for this molecule, demonstrating that NO2-Ln was involved in plant-defense response against different abiotic-stress conditions, mainly by inducing the chaperone network and supporting a conserved mechanism of action in both animal and plant defense processes. Thus, NO2-Ln levels significantly rose under several abiotic-stress conditions, highlighting the strong signaling role of these molecules in the plant-protection mechanism. Finally, the potential of NO2-Ln as a NO donor has recently been described both in vitro and in vivo. Jointly, this ability gives NO2-Ln the potential to act as a signaling molecule by the direct release of NO, due to its capacity to induce different changes mediated by NO or NO-related molecules such as nitration and S-nitrosylation, or by the electrophilic capacity of these molecules through a nitroalkylation mechanism. Here, we describe the current state of the art regarding the advances performed in the field of NO2-FAs in plants and their

  1. Removal of the pharmaceuticals ibuprofen and iohexol by four wetland plant species in hydroponic culture: plant uptake and microbial degradation.

    Science.gov (United States)

    Zhang, Yang; Lv, Tao; Carvalho, Pedro N; Arias, Carlos A; Chen, Zhanghe; Brix, Hans

    2016-02-01

    We aimed at assessing the effects of four wetland plant species commonly used in constructed wetland systems: Typha, Phragmites, Iris and Juncus for removing ibuprofen (IBU) and iohexol (IOH) from spiked culture solution and exploring the mechanisms responsible for the removal. IBU was nearly completely removed by all plant species during the 24-day experiment, whereas the IOH removal varied between 13 and 80 %. Typha and Phragmites were the most efficient in removing IBU and IOH, respectively, with first-order removal rate constants of 0.38 and 0.06 day(-1), respectively. The pharmaceuticals were taken up by the roots and translocated to the aerial tissues. However, at the end of the experiment, plant accumulation constituted only up to 1.1 and 5.7 % of the amount of IBU and IOH spiked initially. The data suggest that the plants mainly function by facilitating pharmaceutical degradation in the rhizosphere through release of root exudates.

  2. Interplays between soil-borne plant viruses and RNA silencing-mediated antiviral defense in roots

    Directory of Open Access Journals (Sweden)

    Ida Bagus Andika

    2016-09-01

    Full Text Available Although the majority of plant viruses are transmitted by arthropod vectors and invade the host plants through the aerial parts, there is a considerable number of plant viruses that infect roots via soil-inhabiting vectors such as plasmodiophorids, chytrids, and nematodes. These soil-borne viruses belong to diverse families, and many of them cause serious diseases in major crop plants. Thus, roots are important organs for the life cycle of many viruses. Compared to shoots, roots have a distinct metabolism and particular physiological characteristics due to the differences in development, cell composition, gene expression patterns, and surrounding environmental conditions. RNA silencing is an important innate defense mechanism to combat virus infection in plants, but the specific information on the activities and molecular mechanism of RNA silencing-mediated viral defense in root tissue is still limited. In this review, we summarize and discuss the current knowledge regarding RNA silencing aspects of the interactions between soil-borne viruses and host plants. Overall, research evidence suggests that soil-borne viruses have evolved to adapt to the distinct mechanism of antiviral RNA silencing in roots.

  3. Mycorrhizal mediation of plant response to atmospheric change: Air quality concepts and research considerations.

    Science.gov (United States)

    Shafer, S R; Schoeneberger, M M

    1991-01-01

    The term 'global climate change' encompasses many physical and chemical changes in the atmosphere that have been induced by anthropogenic pollutants. Increases in concentrations of CO2 and CH4 enhance the 'greenhouse effect' of the atmosphere and may contribute to changes in temperature and precipitation patterns at the earth's surface. Nitrogen oxides and SO2 are phytotoxic and also react with other pollutants to produce other phytotoxins in the troposphere such as O3 and acidic substances. However, release of chlorofluorocarbons into the atmosphere may cause depletion of stratospheric O3, increasing the transmittance of ultraviolet-B (UV-B) radiation to the earth's surface. Increased intensities of UV-B could affect plants and enhance photochemical reactions that generate some phytotoxic pollutants. The role of mycorrhizae in plant responses to such stresses has received little attention. Although plans for several research programs have acknowledged the importance of drought tolerance and soil fertility in plant responses to atmospheric stresses, mycorrhizae are rarely targeted to receive specific investigation. Most vascular land plants form mycorrhizae, so the role of mycorrhizae in mediating plant responses to atmospheric change may be an important consideration in predicting effects of atmospheric changes on plants in managed and natural ecosystems.

  4. Enhanced Microbial, Functional and Sensory Properties of Herbal Yogurt Fermented with Korean Traditional Plant Extracts

    OpenAIRE

    Joung, Jae Yeon; Lee, Ji Young; Ha, Young Sik; Shin, Yong Kook; Kim, Younghoon; Kim, Sae Hun; Oh, Nam Su

    2016-01-01

    This study evaluated the effects of two Korean traditional plant extracts (Diospyros kaki THUNB. leaf; DK, and Nelumbo nucifera leaf; NN) on the fermentation, functional and sensory properties of herbal yogurts. Compared to control fermentation, all plant extracts increased acidification rate and reduced the time to complete fermentation (pH 4.5). Supplementation of plant extracts and storage time were found to influence the characteristics of the yogurts, contributing to increased viability ...

  5. Ultrasound-microbubble mediated cavitation of plant cells: effects on morphology and viability.

    Science.gov (United States)

    Qin, Peng; Xu, Lin; Zhong, Wenjing; Yu, Alfred C H

    2012-06-01

    The interaction between ultrasound pulses and microbubbles is known to generate acoustic cavitation that may puncture biological cells. This work presents new experimental findings on the bioeffects of ultrasound-microbubble mediated cavitation in plant cells with emphasis on direct observations of morphological impact and analysis of viability trends in tobacco BY-2 cells that are widely studied in higher plant physiology. The tobacco cell suspensions were exposed to 1 MHz ultrasound pulses in the presence of 1% v/v microbubbles (10% duty cycle; 1 kHz pulse repetition frequency; 70 mm between probe and cells; 1-min exposure time). Few bioeffects were observed at low peak negative pressures (cavitation presumably occurred. In contrast, at 0.9 MPa peak negative pressure (with more inertial cavitation activities according to our passive cavitation detection results), random pores were found on tobacco cell wall (observed via scanning electron microscopy) and enhanced exogenous uptake into the cytoplasm was evident (noted in our fluorescein isothiocyanate dextran uptake analysis). Also, instant lysis was observed in 23.4% of cells (found using trypan blue staining) and programmed cell death was seen in 23.3% of population after 12 h (determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling [TUNEL]). These bioeffects generally correspond in trend with those for mammalian cells. This raises the possibility of developing ultrasound-microbubble mediated cavitation into a targeted gene transfection paradigm for plant cells and, conversely, adopting plant cells as experimental test-beds for sonoporation-based gene therapy in mammalian cells. Copyright © 2012 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  6. Legacy effects overwhelm the short-term effects of exotic plant invasion and restoration on soil microbial community structure, enzyme activities, and nitrogen cycling.

    Science.gov (United States)

    Elgersma, Kenneth J; Ehrenfeld, Joan G; Yu, Shen; Vor, Torsten

    2011-11-01

    Plant invasions can have substantial consequences for the soil ecosystem, altering microbial community structure and nutrient cycling. However, relatively little is known about what drives these changes, making it difficult to predict the effects of future invasions. In addition, because most studies compare soils from uninvaded areas to long-established dense invasions, little is known about the temporal dependence of invasion impacts. We experimentally manipulated forest understory vegetation in replicated sites dominated either by exotic Japanese barberry (Berberis thunbergii), native Viburnums, or native Vacciniums, so that each vegetation type was present in each site-type. We compared the short-term effect of vegetation changes to the lingering legacy effects of the previous vegetation type by measuring soil microbial community structure (phospholipid fatty acids) and function (extracellular enzymes and nitrogen mineralization). We also replaced the aboveground litter in half of each plot with an inert substitute to determine if changes in the soil microbial community were driven by aboveground or belowground plant inputs. We found that after 2 years, the microbial community structure and function was largely determined by the legacy effect of the previous vegetation type, and was not affected by the current vegetation. Aboveground litter removal had only weak effects, suggesting that changes in the soil microbial community and nutrient cycling were driven largely by belowground processes. These results suggest that changes in the soil following either invasion or restoration do not occur quickly, but rather exhibit long-lasting legacy effects from previous belowground plant inputs.

  7. Enhanced Microbial, Functional and Sensory Properties of Herbal Yogurt Fermented with Korean Traditional Plant Extracts.

    Science.gov (United States)

    Joung, Jae Yeon; Lee, Ji Young; Ha, Young Sik; Shin, Yong Kook; Kim, Younghoon; Kim, Sae Hun; Oh, Nam Su

    2016-01-01

    This study evaluated the effects of two Korean traditional plant extracts (Diospyros kaki THUNB. leaf; DK, and Nelumbo nucifera leaf; NN) on the fermentation, functional and sensory properties of herbal yogurts. Compared to control fermentation, all plant extracts increased acidification rate and reduced the time to complete fermentation (pH 4.5). Supplementation of plant extracts and storage time were found to influence the characteristics of the yogurts, contributing to increased viability of starter culture and phenolic compounds. In particular, the increase in the counts of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was highest (2.95 and 1.14 Log CFU/mL respectively) in DK yogurt. Furthermore, supplementation of the plant extracts significantly influenced to increase the antioxidant activity and water holding capacity and to produce volatile compounds. The higher antioxidant activity and water holding capacity were observed in NN yogurt than DK yogurt. Moreover, all of the sensory characteristics were altered by the addition of plant extracts. Addition of plant extracts increased the scores related to flavor, taste, and texture from plain yogurt without a plant extract, as a result of volatile compounds analysis. Thus, the overall preference was increased by plant extracts. Consequently, supplementation of DK and NN extracts in yogurt enhanced the antioxidant activity and physical property, moreover increased the acceptability of yogurt. These findings demonstrate the possibility of using plant extracts as a functional ingredient in the manufacture of herbal yogurt.

  8. Enhanced Microbial, Functional and Sensory Properties of Herbal Yogurt Fermented with Korean Traditional Plant Extracts

    Science.gov (United States)

    Joung, Jae Yeon; Lee, Ji Young; Ha, Young Sik; Shin, Yong Kook; Kim, Younghoon; Kim, Sae Hun; Oh, Nam Su

    2016-01-01

    This study evaluated the effects of two Korean traditional plant extracts (Diospyros kaki THUNB. leaf; DK, and Nelumbo nucifera leaf; NN) on the fermentation, functional and sensory properties of herbal yogurts. Compared to control fermentation, all plant extracts increased acidification rate and reduced the time to complete fermentation (pH 4.5). Supplementation of plant extracts and storage time were found to influence the characteristics of the yogurts, contributing to increased viability of starter culture and phenolic compounds. In particular, the increase in the counts of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was highest (2.95 and 1.14 Log CFU/mL respectively) in DK yogurt. Furthermore, supplementation of the plant extracts significantly influenced to increase the antioxidant activity and water holding capacity and to produce volatile compounds. The higher antioxidant activity and water holding capacity were observed in NN yogurt than DK yogurt. Moreover, all of the sensory characteristics were altered by the addition of plant extracts. Addition of plant extracts increased the scores related to flavor, taste, and texture from plain yogurt without a plant extract, as a result of volatile compounds analysis. Thus, the overall preference was increased by plant extracts. Consequently, supplementation of DK and NN extracts in yogurt enhanced the antioxidant activity and physical property, moreover increased the acceptability of yogurt. These findings demonstrate the possibility of using plant extracts as a functional ingredient in the manufacture of herbal yogurt. PMID:27499669

  9. Microbial ecology of hot desert edaphic systems.

    Science.gov (United States)

    Makhalanyane, Thulani P; Valverde, Angel; Gunnigle, Eoin; Frossard, Aline; Ramond, Jean-Baptiste; Cowan, Don A

    2015-03-01

    A significant proportion of the Earth's surface is desert or in the process of desertification. The extreme environmental conditions that characterize these areas result in a surface that is essentially barren, with a limited range of higher plants and animals. Microbial communities are probably the dominant drivers of these systems, mediating key ecosystem processes. In this review, we examine the microbial communities of hot desert terrestrial biotopes (including soils, cryptic and refuge niches and plant-root-associated microbes) and the processes that govern their assembly. We also assess the possible effects of global climate change on hot desert microbial communities and the resulting feedback mechanisms. We conclude by discussing current gaps in our understanding of the microbiology of hot deserts and suggest fruitful avenues for future research. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Mediatization

    DEFF Research Database (Denmark)

    Hjarvard, Stig

    2017-01-01

    Mediatization research shares media effects studies' ambition of answering the difficult questions with regard to whether and how media matter and influence contemporary culture and society. The two approaches nevertheless differ fundamentally in that mediatization research seeks answers...... to these general questions by distinguishing between two concepts: mediation and mediatization. The media effects tradition generally considers the effects of the media to be a result of individuals being exposed to media content, i.e. effects are seen as an outcome of mediated communication. Mediatization...... research is concerned with long-term structural changes involving media, culture, and society, i.e. the influences of the media are understood in relation to how media are implicated in social and cultural changes and how these processes come to create new conditions for human communication and interaction...

  11. Optimization of Agrobacterium tumefaciens-Mediated Transformation Systems in Tea Plant (Camellia sinensis

    Directory of Open Access Journals (Sweden)

    Qianru LV

    2017-05-01

    Full Text Available In this study, an efficient plant regeneration protocol in vitro and transformation by Agrobacterium-mediated method of Camellia sinensis was achieved, which would lay the foundation for genetic improvement of tea plant by genetic engineering technology. The cotyledon callus of C. sinensis were used as the receptors for transformation by Agrobacterium tumefaciens EHA105 containing PS1aG-3. Some factors which affected the result of Agrobacterium-mediated transformation of C. sinensis were studied on the basis of GUS transient expression system. The optimum system of Agrobacterium-mediated transformation was that the cotyledon callus were pre-cultured for 3 d, and then infected by EHA105 for 15 min followed by 3 d co-culture in the dark on the YEB medium containing 150 µmol⋅L−1 acetosyringone (AS. The transient expression rate of GUS gene was 62.6%. After being delayed selective culture for 3 d, infected callus were transferred into the differentiation medium and the root induction medium both of which were supplemented with 100 mg⋅L−1 spectinomycin, and then resistant seedlings of C. sinensis were obtained. The conversion rate was 3.6%.

  12. SacB-SacR gene cassette as the negative selection marker to suppress Agrobacterium overgrowth in Agrobacterium-mediated plant transformation

    Science.gov (United States)

    Agrobacterium overgrowth is a common problem in Agrobacterium-mediated plant transformation. To suppress the Agrobacterium overgrowth, various antibiotics have been used during plant tissue culture steps. The antibiotics are expensive and may adversely affect plant cell differentiation and reduce ...

  13. Biological consilience of hydrogen sulfide and nitric oxide in plants: Gases of primordial earth linking plant, microbial and animal physiologies.

    Science.gov (United States)

    Yamasaki, Hideo; Cohen, Michael F

    2016-05-01

    Hydrogen sulfide (H2S) is produced in the mammalian body through the enzymatic activities of cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3MST). A growing number of studies have revealed that biogenic H2S produced in tissues is involved in a variety of physiological responses in mammals including vasorelaxation and neurotransmission. It is now evident that mammals utilize H2S to regulate multiple signaling systems, echoing the research history of the gaseous signaling molecules nitric oxide (NO) and carbon monoxide (CO) that had previously only been recognized for their cytotoxicity. In the human diet, meats (mammals, birds and fishes) and vegetables (plants) containing cysteine and other sulfur compounds are the major dietary sources for endogenous production of H2S. Plants are primary producers in ecosystems on the earth and they synthesize organic sulfur compounds through the activity of sulfur assimilation. Although plant H2S-producing activities have been known for a long time, our knowledge of H2S biology in plant systems has not been updated to the extent of mammalian studies. Here we review recent progress on H2S studies, highlighting plants and bacteria. Scoping the future integration of H2S, NO and O2 biology, we discuss a possible linkage between physiology, ecology and evolutional biology of gas metabolisms that may reflect the historical changes of the Earth's atmospheric composition. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. The Root-Associated Microbial Community of the World’s Highest Growing Vascular Plants

    Czech Academy of Sciences Publication Activity Database

    Angel, R.; Conrad, R.; Dvorský, Miroslav; Kopecký, Martin; Kotilínek, M.; Hiiesalu, Inga; Schweingruber, F. H.; Doležal, Jiří

    2016-01-01

    Roč. 72, č. 2 (2016), s. 394-406 ISSN 0095-3628 Institutional support: RVO:67985939 Keywords : vascular plants * upward migration * subnival soil * plant-associated bacteria Subject RIV: EF - Botanics Impact factor: 3.630, year: 2016

  15. Transient negative biochar effects on plant growth are strongest after microbial species loss

    NARCIS (Netherlands)

    Hol, (Gera) W.H.G.; Vestergård, M.; Ten Hooven, F.C.; Duyts, H.; Van de Voorde, T.F.J.; Bezemer, T. Martijn

    2017-01-01

    Biochar has been explored as an organic amendment to improve soil quality and benefit plant growth. The overall positive effects of biochar on crop yields are generally attributed to abiotic changes, while the alternative causal pathway via changes in soil biota is unexplored. We compared plant

  16. New Trends and Perspectives in the Evolution of Neurotransmitters in Microbial, Plant, and Animal Cells.

    Science.gov (United States)

    Roshchina, Victoria V

    2016-01-01

    The evolutionary perspective on the universal roles of compounds known as neurotransmitters may help in the analysis of relations between all organisms in biocenosis-from microorganisms to plant and animals. This phenomenon, significant for chemosignaling and cellular endocrinology, has been important in human health and the ability to cause disease or immunity, because the "living environment" influences every organism in a biocenosis relationship (microorganism-microorganism, microorganism-plant, microorganism-animal, plant-animal, plant-plant and animal-animal). Non-nervous functions of neurotransmitters (rather "biomediators" on a cellular level) are considered in this review and ample consideration is given to similarities and differences that unite, as well as distinguish, taxonomical kingdoms.

  17. The influence of microbial-based inoculants on N2O emissions from soil planted with corn (Zea mays L.) under greenhouse conditions with different nitrogen fertilizer regimens.

    Science.gov (United States)

    Calvo, Pamela; Watts, Dexter B; Kloepper, Joseph W; Torbert, H Allen

    2016-12-01

    Nitrous oxide (N 2 O) emissions are increasing at an unprecedented rate owing to the increased use of nitrogen (N) fertilizers. Thus, new innovative management tools are needed to reduce emissions. One potential approach is the use of microbial inoculants in agricultural production. In a previous incubation study, we observed reductions in N 2 O emissions when microbial-based inoculants were added to soil (no plants present) with N fertilizers under laboratory incubations. This present study evaluated the effects of microbial-based inoculants on N 2 O and carbon dioxide (CO 2 ) emissions when applied to soil planted with corn (Zea mays L.) under controlled greenhouse conditions. Inoculant treatments consisted of (i) SoilBuilder (SB), (ii) a metabolite extract of SoilBuilder (SBF), and (iii) a mixture of 4 strains of plant-growth-promoting Bacillus spp. (BM). Experiments included an unfertilized control and 3 N fertilizers: urea, urea - ammonium nitrate with 32% N (UAN-32), and calcium - ammonium nitrate with 17% N (CAN-17). Cumulative N 2 O fluxes from pots 41 days after planting showed significant reductions in N 2 O of 15% (SB), 41% (BM), and 28% (SBF) with CAN-17 fertilizer. When UAN-32 was used, reductions of 34% (SB), 35% (SBF), and 49% (BM) were obtained. However, no reductions in N 2 O emissions occurred with urea. Microbial-based inoculants did not affect total CO 2 emissions from any of the fertilized treatments or the unfertilized control. N uptake was increased by an average of 56% with microbial inoculants compared with the control (nonmicrobial-based treatments). Significant increases in plant height, SPAD chlorophyll readings, and fresh and dry shoot mass were also observed when the microbial-based treatments were applied (with and without N). Overall, results demonstrate that microbial inoculants can reduce N 2 O emissions following fertilizer application depending on the N fertilizer type used and can enhance N uptake and plant growth. Future

  18. Biosynthesis of silver nanoparticles by plants crude extracts and ...

    African Journals Online (AJOL)

    Aghomotsegin

    and bioactive silver-containing Na2O CaO 2SiO2 glass prepared by sol-gel method. J. Mater. Sci. Mater. Med. 15(7):831-837. Chanda S (2014). Silver nanoparticles (medicinal plants mediated): a new generation of antimicrobials to combat microbial pathogens – a review. In: Mendez-Vilas, A. (Ed.), Microbial Pathogens ...

  19. Houttuynia cordata modulates oral innate immune mediators: potential role of herbal plant on oral health.

    Science.gov (United States)

    Satthakarn, S; Chung, W O; Promsong, A; Nittayananta, W

    2015-05-01

    Epithelial cells play an active role in oral innate immunity by producing various immune mediators. Houttuynia cordata Thunb (H. cordata), a herbal plant found in Asia, possesses many activities. However, its impacts on oral innate immunity have never been reported. The aim of this study was to determine the effects of H. cordata extract on the expression of innate immune mediators produced by oral epithelial cells. Primary gingival epithelial cells (GECs) were treated with various concentrations of the extract for 18 h. The gene expression of hBD2, SLPI, cytokines, and chemokines was measured using quantitative real-time RT-PCR. The secreted proteins in the culture supernatants were detected by ELISA or Luminex assay. Cytotoxicity of the extract was assessed using CellTiter-Blue Assay. H. cordata significantly induced the expression of hBD2, SLPI, IL-8, and CCL20 in a dose-dependent manner without cytotoxicity. The secreted hBD2 and SLPI proteins were modulated, and the levels of IL-2, IL-6, IL-8, and IFN-γ were significantly induced by the extract. Our data indicated that H. cordata can modulate oral innate immune mediators. These findings may lead to the development of new topical agents from H. cordata for the prevention and treatment of immune-mediated oral diseases. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Herbivore-mediated ecological costs of reproduction shape the life history of an iteroparous plant.

    Science.gov (United States)

    Miller, Tom E X; Tenhumberg, Brigitte; Louda, Svata M

    2008-02-01

    Plant reproduction yields immediate fitness benefits but can be costly in terms of survival, growth, and future fecundity. Life-history theory posits that reproductive strategies are shaped by trade-offs between current and future fitness that result from these direct costs of reproduction. Plant reproduction may also incur indirect ecological costs if it increases susceptibility to herbivores. Yet ecological costs of reproduction have received little empirical attention and remain poorly integrated into life-history theory. Here, we provide evidence for herbivore-mediated ecological costs of reproduction, and we develop theory to examine how these costs influence plant life-history strategies. Field experiments with an iteroparous cactus (Opuntia imbricata) indicated that greater reproductive effort (proportion of meristems allocated to reproduction) led to greater attack by a cactus-feeding insect (Narnia pallidicornis) and that damage by this herbivore reduced reproductive success. A dynamic programming model predicted strongly divergent optimal reproductive strategies when ecological costs were included, compared with when these costs were ignored. Meristem allocation by cacti in the field matched the optimal strategy expected under ecological costs of reproduction. The results indicate that plant reproductive allocation can strongly influence the intensity of interactions with herbivores and that associated ecological costs can play an important selective role in the evolution of plant life histories.

  1. Abscisic Acid and Gibberellins Antagonistically Mediate Plant Development and Abiotic Stress Responses

    Directory of Open Access Journals (Sweden)

    Kai Shu

    2018-03-01

    Full Text Available Phytohormones regulate numerous important biological processes in plant development and biotic/abiotic stress response cascades. More than 50 and 100 years have passed since the initial discoveries of the phytohormones abscisic acid (ABA and gibberellins (GA, respectively. Over the past several decades, numerous elegant studies have demonstrated that ABA and GA antagonistically regulate many plant developmental processes, including seed maturation, seed dormancy and germination, root initiation, hypocotyl and stem elongation, and floral transition. Furthermore, as a well-established stress hormone, ABA plays a key role in plant responses to abiotic stresses, such as drought, flooding, salinity and low temperature. Interestingly, recent evidence revealed that GA are also involved in plant response to adverse environmental conditions. Consequently, the complex crosstalk networks between ABA and GA, mediated by diverse key regulators, have been extensively investigated and documented. In this updated mini-review, we summarize the most recent advances in our understanding of the antagonistically regulatory roles of ABA and GA in different stages of plant development and in various plant–environment interactions, focusing on the crosstalk between ABA and GA at the levels of phytohormone metabolism and signal transduction.

  2. Soil microbial species loss affects plant biomass and survival of an introduced bacterial strain, but not inducible plant defences

    NARCIS (Netherlands)

    Kurm, Viola; van der Putten, W.H.; Pineda, A.M.; Hol, W.H.G.

    2018-01-01

    • Background and Aims Plant growth-promoting rhizobacteria (PGPR) strains can influence plant–insect interactions. However, little is known about the effect of changes in the soil bacterial community in general and especially the loss of rare soil microbes on these interactions. Here, the influence

  3. Nectar chemistry mediates the behavior of parasitized bees: consequences for plant fitness.

    Science.gov (United States)

    Richardson, Leif L; Bowers, M Deane; Irwin, Rebecca E

    2016-02-01

    fitness. Taken together, these results demonstrate that nectar secondary metabolites can mediate the behavior of pollinators with subsequent benefits for estimates of plant reproduction.

  4. Using microbial community interactions within plant microbiomes to advance an evergreen agricultural revolution

    Science.gov (United States)

    Innovative plant breeding and technology transfer fostered the Green Revolution, which transformed agriculture worldwide by increasing grain yields in developing countries. The Green Revolution temporarily alleviated world hunger, but also reduced biodiversity, nutrient cycling, and carbon sequestr...

  5. Plants and their microbial assistants: Nature's answer to Earth's environmental pollution problems

    Science.gov (United States)

    Wolverton, B. C.

    1990-01-01

    The utilization of higher plants and their associated microorganisms to solve environmental pollution problems on Earth and in future space applications is briefly reviewed. If man is sealed inside closed facilities, he becomes a polluter of the environment. It is also common knowledge to most people that man cannot survive on Earth without green photosynthesizing plants and microorganisms. Therefore, it is vitally important to have a better understanding of the interactions of man with plants and microorganisms. Biosphere 2 and other related studies presently being conducted or planned, hopefully, will supply data that will help save planet Earth from impending environmental disaster. The development of means to utilize both air and water pollution as a nutrient source for growing green plants is examined.

  6. The role of cis-zeatin-type cytokinins in plant growth regulation and mediating responses to environmental interactions

    DEFF Research Database (Denmark)

    Schäfer, Martin; Brütting, Christoph; Meza-Canales, Ivan David

    2015-01-01

    -zeatin and isopentenyladenine-type CKs, have been studied in detail, the role of cis-zeatin-type CKs (cZs) in plant development and in mediating environmental interactions is less well defined. Here we provide a comprehensive summary of the current knowledge about abundance, metabolism and activities of cZs in plants. We...

  7. In situ stimulation vs. bioaugmentation: Can microbial inoculation of plant roots enhance biodegradation of organic compounds?

    Energy Technology Data Exchange (ETDEWEB)

    Kingsley, M.T.; Metting, F.B. Jr.; Fredrickson, J.K. [Pacific Northwest Lab., Richland, WA (United States); Seidler, R.J. [Environmental Protection Agency, Corvallis, OR (United States). Environmental Research Lab.

    1993-06-01

    The use of plant roots and their associated rhizosphere bacteria for biocontainment and biorestoration offers several advantages for treating soil-dispersed contaminants and for application to large land areas. Plant roots function as effective delivery systems, since root growth transports bacteria vertically and laterally along the root in the soil column (see [ 1,2]). Movement of microbes along roots and downward in the soil column can be enhanced via irrigation [1-4]. For example, Ciafardini et al. [3] increased the nodulation and the final yield of soybeans during pod filling by including Bradyrhizobium japonicum in the irrigation water. Using rhizosphere microorganisms is advantageous for biodegradation of compounds that are degraded mainly by cometabolic processes, e.g., trichloroethylene (TCE). The energy source for bacterial growth and metabolism is supplied by the plant in the form of root exudates and other sloughed organic material. Plants are inexpensive, and by careful choice of species that possess either tap or fibrous root growth patterns, they can be used to influence mass transport of soil contaminants to the root surface via the transpiration stream [5]. Cropping of plants to remove heavy metals from contaminated soils has been proposed as a viable, low-cost, low-input treatment option [6]. The interest in use of plants as a remediation strategy has even reached the popular press [7], where the use of ragweed for the reclamation of sites contaminated with tetraethyl lead and other heavy metals was discussed.

  8. The response of soil carbon storage and microbially mediated carbon turnover to simulated climatic disturbance in a northern peatland forest. Revisiting the concept of soil organic matter recalcitrance

    Energy Technology Data Exchange (ETDEWEB)

    Kostka, Joel [Georgia Inst. of Technology, Atlanta, GA (United States)

    2015-09-14

    closely paralleled the chemical evolution of peat, with large shifts in microbial populations occurring in the biogeochemical hotspot, the mesotelm, where the highest rates of decomposition were detected. Stable isotope geochemistry and potential rates of methane production paralleled vertical changes in methanogen community composition to indicate a predominance of acetoclastic methanogenesis mediated by the Methanosarcinales in the mesotelm, while hydrogen-utilizing methanogens dominated in the deeper catotelm. Evidence pointed to the availability of phosphorus as well as nitrogen limiting the microbially-mediated turnover of organic carbon at MEF. Prior to initiation of the experimental treatments, our study provided key baseline data for the SPRUCE site on the vertical stratification of peat decomposition, key enzymatic pathways, and microbial taxa containing these pathways. The sensitivity of soil carbon turnover to climate change is strongly linked to recalcitrant carbon stocks and the temperature sensitivity of decomposition is thought to increase with increasing molecular complexity of carbon substrates. This project delivered results on how climate change perturbations impact the microbially-mediated turnover of recalcitrant organic matter in peatland forest soils, both under controlled conditions in the laboratory and at the ecosystem-scale in the field. This project revisited the concept of “recalcitrance” in the regulation of soil carbon turnover using a combination of natural abundance radiocarbon and optical spectroscopic measurements on bulk DOM, and high resolution molecular characterization of DOM. The project elucidated how organic matter reactivity and decomposition will respond to climate change in a both a qualitative (organic matter lability) and quantitiative (increased rates) manner. An Aromaticity Index was developed to represent a more direct and accurate parameter for modeling of DOM reactivity in peatlands. The abundance and community

  9. Seawater quality and microbial communities at a desalination plant marine outfall. A field study at the Israeli Mediterranean coast.

    Science.gov (United States)

    Drami, Dror; Yacobi, Yosef Z; Stambler, Noga; Kress, Nurit

    2011-11-01

    Global desalination quadrupled in the last 15 years and the relative importance of seawater desalination by reverse osmosis (SWRO) increased as well. While the technological aspects of SWRO plants are extensively described, studies on the environmental impact of brine discharge are lacking, in particular in situ marine environmental studies. The Ashqelon SWRO plant (333,000 m(3) d(-1) freshwater) discharges brine and backwash of the pre-treatment filters (containing ferric hydroxide coagulant) at the seashore, next to the cooling waters of a power plant. At the time of this study brine and cooling waters were discharged continuously and the backwash discharge was pulsed, with a frequency dependent on water quality at the intake. The effects of the discharges on water quality and neritic microbial community were identified, quantified and attributed to the different discharges. The mixed brine-cooling waters discharge increased salinity and temperature at the outfall, were positively buoyant, and dispersed at the surface up to 1340 m south of the outfall. Nutrient concentrations were higher at the outfall while phytoplankton densities were lower. Chlorophyll-a and picophytoplankton cell numbers were negatively correlated with salinity, but more significantly with temperature probably as a result of thermal pollution. The discharge of the pulsed backwash increased turbidity, suspended particulate matter and particulate iron and decreased phytoplankton growth efficiency at the outfall, effects that declined with distance from the outfall. The discharges clearly reduced primary production but we could not attribute the effect to a specific component of the discharge. Bacterial production was also affected but differently in the three surveys. The combined and possible synergistic effects of SWRO desalination along the Israeli shoreline should be taken into account when the three existing plants and additional ones are expected to produce 2 Mm(3) d(-1) freshwater by

  10. Internal nitrogen removal from sediments by the hybrid system of microbial fuel cells and submerged aquatic plants.

    Directory of Open Access Journals (Sweden)

    Peng Xu

    Full Text Available Sediment internal nitrogen release is a significant pollution source in the overlying water of aquatic ecosystems. This study aims to remove internal nitrogen in sediment-water microcosms by coupling sediment microbial fuel cells (SMFCs with submerged aquatic plants. Twelve tanks including four treatments in triplicates were designed: open-circuit (SMFC-o, closed-circuit (SMFC-c, aquatic plants with open-circuit (P-SMFC-o and aquatic plants with closed-circuit (P-SMFC-c. The changes in the bio-electrochemical characteristics of the nitrogen levels in overlying water, pore water, sediments, and aquatic plants were documented to explain the migration and transformation pathways of internal nitrogen. The results showed that both electrogenesis and aquatic plants could facilitate the mineralization of organic nitrogen in sediments. In SMFC, electrogenesis promoted the release of ammonium from the pore water, followed by the accumulation of ammonium and nitrate in the overlying water. The increased redox potential of sediments due to electrogenesis also contributed to higher levels of nitrate in overlying water when nitrification in pore water was facilitated and denitrification at the sediment-water interface was inhibited. When the aquatic plants were introduced into the closed-circuit SMFC, the internal ammonium assimilation by aquatic plants was advanced by electrogenesis; nitrification in pore water and denitrification in sediments were also promoted. These processes might result in the maximum decrease of internal nitrogen with low nitrogen levels in the overlying water despite the lower power production. The P-SMFC-c reduced 8.1%, 16.2%, 24.7%, and 25.3% of internal total nitrogen compared to SMFC-o on the 55th, 82th, 136th, and 190th days, respectively. The smaller number of Nitrospira and the larger number of Bacillus and Pseudomonas on the anodes via high throughput sequencing may account for strong mineralization and denitrification in the

  11. Duckweed (Lemna minor) as a Model Plant System for the Study of Human Microbial Pathogenesis

    Science.gov (United States)

    Zhang, Yong; Hu, Yangbo; Yang, Baoyu; Ma, Fang; Lu, Pei; Li, Lamei; Wan, Chengsong; Rayner, Simon; Chen, Shiyun

    2010-01-01

    Background Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions. Methodology/Principal Findings We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor) plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS) mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species. Conclusions/Significance Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals. PMID:21049039

  12. Duckweed (Lemna minor as a model plant system for the study of human microbial pathogenesis.

    Directory of Open Access Journals (Sweden)

    Yong Zhang

    Full Text Available BACKGROUND: Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions. METHODOLOGY/PRINCIPAL FINDINGS: We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals.

  13. Soil microbial abundance, activity and diversity response in two different altitude-adapted plant communities affected by wildfire in Sierra Nevada National Park (Granada, Spain)

    Science.gov (United States)

    Bárcenas-Moreno, Gema; Zavala, Lorena; Jordan, Antonio; Bååth, Erland; Mataix-Beneyto, Jorge

    2013-04-01

    Plant communities can play an important role in fire severity and post-fire ecosystem recovery due to their role as combustible and different plant-soil microorganisms interactions. Possible differences induced by plant and microorganisms response after fire could affect the general ecosystem short and long-term response and its sustainability. The main objective of this work was the evaluation of the effect of wildfire on soil microbial abundance, activity and diversity in two different plant communities associated to different altitudes in Sierra Nevada National Park (Granada, Spain). Samples were collected in two areas located on the Sierra Nevada Mountain between 1700 and 2000 m above sea level which were affected by a large wildfire in 2005. Two samplings were carried out 8 and 20 months after fire and samples were collected in both burned and unburned (control) zones in each plant community area. Area A is located at 1700m and it is formed by Quercus rotundifolia forest while area B is located at 2000 m altitude and is composed of alpine vegetation formed by creeping bearing shrubs. Microbial biomass measured by Fumigation-Extraction method followed the same trend in both areas showing slight and no significant differences between burned and unburned area during the study period while viable and cultivable bacteria abundance were markedly higher in fire affected samples than in the control ones in both samplings. Viable and cultivable filamentous fungi had different behavior depending of plant vegetation community studied showing no differences between burned and unburned area in area A while was significantly higher in burned samples than in the control ones in area B. Microbial activity monitoring with soil microbial respiration appears to had been affected immediately after fire since microbial respiration was lower in burned samples from area A than in unburned one only 8 months after fire and no significant differences were observed between burned and

  14. Nanoporous Mo2C functionalized 3D carbon architecture anode for boosting flavins mediated interfacial bioelectrocatalysis in microbial fuel cells

    Science.gov (United States)

    Zou, Long; Lu, Zhisong; Huang, Yunhong; Long, Zhong-er; Qiao, Yan

    2017-08-01

    An efficient microbial electrocatalysis in microbial fuel cells (MFCs) needs both high loading of microbes (biocatalysts) and robust interfacial electron transfer from microbes to electrode. Herein a nanoporous molybdenum carbide (Mo2C) functionalized carbon felt electrode with rich 3D hierarchical porous architecture is applied as MFC anode to achieve superior electrocatalytic performance. The nanoporous Mo2C functionalized anode exhibits strikingly improved microbial electrocatalysis in MFCs with 5-fold higher power density and long-term stability of electricity production. The great enhancement is attributed to the introduction of rough Mo2C nanostructural interface into macroporous carbon architecture for promoting microbial growth with great excretion of endogenous electron shuttles (flavins) and rich available nanopores for enlarging electrochemically active surface area. Importantly, the nanoporous Mo2C functionalized anode is revealed for the first time to have unique electrocatalytic activity towards redox reaction of flavins with more negative redox potential, indicating a more favourable thermodynamic driving force for anodic electron transfer. This work not only provides a promising electrode for high performance MFCs but also brings up a new insight into the effect of nanostructured materials on interfacial bioelectrocatalysis.

  15. The Effects of Clinorotation on the Host Plant, Medicago truncatula, and Its Microbial Symbionts

    Energy Technology Data Exchange (ETDEWEB)

    Dauzart, Ariel J. C.; Vandenbrink, Joshua P.; Kiss, John Z., E-mail: jzkiss@olemiss.edu [Department of Biology, Graduate School, University of Mississippi, University, MS (United States)

    2016-02-26

    Understanding the outcome of the plant-microbe symbiosis in reduced or altered is vital to developing life support systems for long-distance space travel and colonization of other planets. Thus, the aim of this research was to understand mutualistic relationships between plants and endophytic microbes under the influence of altered gravity. This project utilized the model tripartite relationship among Medicago truncatula—Sinorhizobium meliloti—Rhizophagus irregularis. Plants were inoculated with rhizobial bacteria (S. meliloti), arbuscular mycorrhizal fungi (R. irregularis), or both microbes, and placed on a rotating clinostat. Vertical and horizontal static controls were also performed. Clinorotation significantly reduced M. truncatula dry mass and fresh mass compared to the static controls. The addition of rhizobia treatments under clinorotation also altered total root length and root-to-shoot fresh mass ratio. Nodule size decreased under rhizobia + clinorotation treatment, and nodule density was significantly decreased compared to the vertical treatment. However, inoculation with arbuscular mycorrhizal fungi was shown to increase biomass accumulation and nodule size. Thus, clinorotation significantly affected M. truncatula and its symbiotic relationships with S. meliloti and R. irregularis. In the long term, the results observed in this clinostat study on the changes of plant-microbe mutualism need to be investigated in spaceflight experiments. Thus, careful consideration of the symbiotic microbes of plants should be included in the design of bioregenerative life support systems needed for space travel.

  16. The Effects of Clinorotation on the Host Plant, Medicago truncatula, and Its Microbial Symbionts

    International Nuclear Information System (INIS)

    Dauzart, Ariel J. C.; Vandenbrink, Joshua P.; Kiss, John Z.

    2016-01-01

    Understanding the outcome of the plant-microbe symbiosis in reduced or altered is vital to developing life support systems for long-distance space travel and colonization of other planets. Thus, the aim of this research was to understand mutualistic relationships between plants and endophytic microbes under the influence of altered gravity. This project utilized the model tripartite relationship among Medicago truncatula—Sinorhizobium meliloti—Rhizophagus irregularis. Plants were inoculated with rhizobial bacteria (S. meliloti), arbuscular mycorrhizal fungi (R. irregularis), or both microbes, and placed on a rotating clinostat. Vertical and horizontal static controls were also performed. Clinorotation significantly reduced M. truncatula dry mass and fresh mass compared to the static controls. The addition of rhizobia treatments under clinorotation also altered total root length and root-to-shoot fresh mass ratio. Nodule size decreased under rhizobia + clinorotation treatment, and nodule density was significantly decreased compared to the vertical treatment. However, inoculation with arbuscular mycorrhizal fungi was shown to increase biomass accumulation and nodule size. Thus, clinorotation significantly affected M. truncatula and its symbiotic relationships with S. meliloti and R. irregularis. In the long term, the results observed in this clinostat study on the changes of plant-microbe mutualism need to be investigated in spaceflight experiments. Thus, careful consideration of the symbiotic microbes of plants should be included in the design of bioregenerative life support systems needed for space travel.

  17. The Effects of Clinorotation on the Host Plant, Medicago truncatula, and Its Microbial Symbionts

    Directory of Open Access Journals (Sweden)

    Ariel J.C. Dauzart

    2016-02-01

    Full Text Available Understanding the outcome of the plant-microbe symbiosis in altered gravity is vital to developing life support systems for long-distance space travel and colonization of other planets. Thus, the aim of this research was to understand mutualistic relationships between plants and endophytic microbes under the influence of altered gravity. This project utilized the model tripartite relationship among Medicago truncatula ¬– Sinorhizobium meliloti – Rhizophagus irregularis. Plants were inoculated with rhizobial bacteria (S. meliloti, arbuscular mycorrhizal fungi (R. irregularis, or both microbes, and placed on a rotating clinostat. Vertical and horizontal static controls were also performed. Clinorotation significantly reduced M. truncatula dry mass and fresh mass compared to the static controls. The addition of rhizobia treatments under clinorotation also altered total root length and root-to-shoot fresh mass ratio. Nodule size decreased under rhizobia + clinorotation treatment, and nodule density was significantly decreased compared to the vertical treatment. However, inoculation with arbuscular mycorrhizal fungi was shown to increase biomass accumulation and nodule size. Thus, clinorotation significantly affected M. truncatula and its symbiotic relationships with S. meliloti and R. irregularis. In the long term, the results observed in this clinostat study on the changes of plant-microbe mutualism need to be investigated in spaceflight experiments. Thus, careful consideration of the symbiotic microbes of plants should be included in the design of bioregenerative life support systems needed for space travel.

  18. ROS-mediated abiotic stress-induced programmed cell death in plants

    Directory of Open Access Journals (Sweden)

    Veselin ePetrov

    2015-02-01

    Full Text Available During the course of their ontogenesis, plants are continuously exposed to a large variety of abiotic stress factors which can damage tissues and jeopardize the survival of the organism unless properly countered. While animals can simply escape and thus evade stressors, plants as sessile organisms have developed complex strategies to withstand them. When the intensity of a detrimental factor is high, one of the defense programs employed by plants is the induction of programmed cell death (PCD. This is an active, genetically controlled process which is initiated to isolate and remove damaged tissues thereby ensuring the survival of the organism. The mechanism of PCD induction usually includes an increase in the levels of reactive oxygen species (ROS which are utilized as mediators of the stress signal. Abiotic stress-induced PCD is not only a process of fundamental biological importance, but also of considerable interest to agricultural practice as it has the potential to significantly influence crop yield. Therefore, numerous scientific enterprises have focused on elucidating the mechanisms leading to and controlling PCD in response to adverse conditions in plants. This knowledge may help to develop novel strategies to obtain more resilient crop varieties with improved tolerance and enhanced productivity. The aim of the present review is to summarize the recent advances in research on ROS-induced PCD related to abiotic stress and the role of the organelles in the process.

  19. Horizontal transmission of the insect symbiont Rickettsia is plant-mediated

    Science.gov (United States)

    Caspi-Fluger, Ayelet; Inbar, Moshe; Mozes-Daube, Netta; Katzir, Nurit; Portnoy, Vitaly; Belausov, Eduard; Hunter, Martha S.; Zchori-Fein, Einat

    2012-01-01

    Bacteria in the genus Rickettsia, best known as vertebrate pathogens vectored by blood-feeding arthropods, can also be found in phytophagous insects. The presence of closely related bacterial symbionts in evolutionarily distant arthropod hosts presupposes a means of horizontal transmission, but no mechanism for this transmission has been described. Using a combination of experiments with live insects, molecular analyses and microscopy, we found that Rickettsia were transferred from an insect host (the whitefly Bemisia tabaci) to a plant, moved inside the phloem, and could be acquired by other whiteflies. In one experiment, Rickettsia was transferred from the whitefly host to leaves of cotton, basil and black nightshade, where the bacteria were restricted to the phloem cells of the plant. In another experiment, Rickettsia-free adult whiteflies, physically segregated but sharing a cotton leaf with Rickettsia-plus individuals, acquired the Rickettsia at a high rate. Plants can serve as a reservoir for horizontal transmission of Rickettsia, a mechanism which may explain the occurrence of phylogenetically similar symbionts among unrelated phytophagous insect species. This plant-mediated transmission route may also exist in other insect–symbiont systems and, since symbionts may play a critical role in the ecology and evolution of their hosts, serve as an immediate and powerful tool for accelerated evolution. PMID:22113034

  20. Silicon-mediated Improvement in Plant Salinity Tolerance: The Role of Aquaporins

    Directory of Open Access Journals (Sweden)

    Juan J. Rios

    2017-06-01

    Full Text Available Silicon (Si is an abundant and differentially distributed element in soils that is believed to have important biological functions. However, the benefits of Si and its essentiality in plants are controversial due to differences among species in their ability to take up this element. Despite this, there is a consensus that the application of Si improves the water status of plants under abiotic stress conditions. Hence, plants treated with Si are able to maintain a high stomatal conductance and transpiration rate under salt stress, suggesting that a reduction in Na+ uptake occurs due to deposition of Si in the root. In addition, root hydraulic conductivity increases when Si is applied. As a result, a Si-mediated upregulation of aquaporin (PIP gene expression is observed in relation to increased root hydraulic conductivity and water uptake. Aquaporins of the subclass nodulin 26-like intrinsic proteins are further involved in allowing Si entry into the cell. Therefore, on the basis of available published results and recent developments, we propose a model to explain how Si absorption alleviates stress in plants grown under saline conditions through the conjugated action of different aquaporins.

  1. Dynamics of microbial communities in an integrated ultrafiltration–reverse osmosis desalination pilot plant located at the Arabian Gulf

    KAUST Repository

    Hong, Pei-Ying

    2015-08-27

    This study demonstrated the use of high-throughput sequencing to assess the efficacy of an integrated ultrafiltration (UF)–reverse osmosis (RO) desalination pilot plant located at the Arabian Gulf, and to identify potential microbial-associated problems that may arise in this plant. When integrated into the desalination treatment system, the UF membranes were able to serve as a good pretreatment strategy to delay RO fouling by achieving up to 1.96-log removal of cells from the seawater. Consequently, the differential pressure of the RO membrane remained around 1 bar for the entire six-month study, suggesting no significant biofouling performance issue identified for this RO system. Examples of microbial populations effectively removed by the UF membranes from the feed waters included Nitrosoarchaeum limnia and phototrophic eukaryotes. Microbial-associated problems observed in this pilot plant included the presence of Pseudomonas spp. in coexistence with Desulfovibrio spp. These two bacterial populations can reduce sulfate and produce hydrogen sulfide, which would in turn cause corrosion problems or compromise membrane integrities. Chemical-enhanced backwashing (CEB) can be used as an effective strategy to minimize the associated microbial problems by removing bacterial populations including sulfate reducers from the UF membranes.

  2. Dynamics of microbial communities in an integrated ultrafiltration–reverse osmosis desalination pilot plant located at the Arabian Gulf

    KAUST Repository

    Hong, Pei-Ying; Moosa, Nasir; Mink, Justine

    2015-01-01

    This study demonstrated the use of high-throughput sequencing to assess the efficacy of an integrated ultrafiltration (UF)–reverse osmosis (RO) desalination pilot plant located at the Arabian Gulf, and to identify potential microbial-associated problems that may arise in this plant. When integrated into the desalination treatment system, the UF membranes were able to serve as a good pretreatment strategy to delay RO fouling by achieving up to 1.96-log removal of cells from the seawater. Consequently, the differential pressure of the RO membrane remained around 1 bar for the entire six-month study, suggesting no significant biofouling performance issue identified for this RO system. Examples of microbial populations effectively removed by the UF membranes from the feed waters included Nitrosoarchaeum limnia and phototrophic eukaryotes. Microbial-associated problems observed in this pilot plant included the presence of Pseudomonas spp. in coexistence with Desulfovibrio spp. These two bacterial populations can reduce sulfate and produce hydrogen sulfide, which would in turn cause corrosion problems or compromise membrane integrities. Chemical-enhanced backwashing (CEB) can be used as an effective strategy to minimize the associated microbial problems by removing bacterial populations including sulfate reducers from the UF membranes.

  3. Dietary green-plant thylakoids decrease gastric emptying and gut transit, promote changes in the gut microbial flora, but does not cause steatorrhea

    DEFF Research Database (Denmark)

    Stenblom, Eva-Lena; Weström, Björn R.; Linninge, Caroline

    2016-01-01

    Green-plant thylakoids increase satiety by affecting appetite hormones such as ghrelin, cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1). The objective of this study was to investigate if thylakoids also affect gastrointestinal (GI) passage and microbial composition. To analyse the effects......, and specifically the Bacteriodes fragilis group, were increased by thylakoid treatment versus placebo, while thylakoids did not cause steatorrhea. Dietary supplementation with thylakoids thus affects satiety both via appetite hormones and GI fullness, and affects the microbial composition without causing GI...... adverse effects such as steatorrhea. This suggests thylakoids as a novel agent in prevention and treatment of obesity....

  4. Plant cell surface receptor-mediated signaling - a common theme amid diversity.

    Science.gov (United States)

    He, Yunxia; Zhou, Jinggeng; Shan, Libo; Meng, Xiangzong

    2018-01-29

    Sessile plants employ a diverse array of plasma membrane-bound receptors to perceive endogenous and exogenous signals for regulation of plant growth, development and immunity. These cell surface receptors include receptor-like kinases (RLKs) and receptor-like proteins (RLPs) that harbor different extracellular domains for perception of distinct ligands. Several RLK and RLP signaling pathways converge at the somatic embryogenesis receptor kinases (SERKs), which function as shared co-receptors. A repertoire of receptor-like cytoplasmic kinases (RLCKs) associate with the receptor complexes to relay intracellular signaling. Downstream of the receptor complexes, mitogen-activated protein kinase (MAPK) cascades are among the key signaling modules at which the signals converge, and these cascades regulate diverse cellular and physiological responses through phosphorylation of different downstream substrates. In this Review, we summarize the emerging common theme that underlies cell surface receptor-mediated signaling pathways in Arabidopsis thaliana : the dynamic association of RLKs and RLPs with specific co-receptors and RLCKs for signal transduction. We further discuss how signaling specificities are maintained through modules at which signals converge, with a focus on SERK-mediated receptor signaling. © 2018. Published by The Company of Biologists Ltd.

  5. The Microbial Database for Danish wastewater treatment plants with nutrient removal (MiDas-DK) - a tool for understanding activated sludge population dynamics and community stability.

    Science.gov (United States)

    Mielczarek, A T; Saunders, A M; Larsen, P; Albertsen, M; Stevenson, M; Nielsen, J L; Nielsen, P H

    2013-01-01

    Since 2006 more than 50 Danish full-scale wastewater treatment plants with nutrient removal have been investigated in a project called 'The Microbial Database for Danish Activated Sludge Wastewater Treatment Plants with Nutrient Removal (MiDas-DK)'. Comprehensive sets of samples have been collected, analyzed and associated with extensive operational data from the plants. The community composition was analyzed by quantitative fluorescence in situ hybridization (FISH) supported by 16S rRNA amplicon sequencing and deep metagenomics. MiDas-DK has been a powerful tool to study the complex activated sludge ecosystems, and, besides many scientific articles on fundamental issues on mixed communities encompassing nitrifiers, denitrifiers, bacteria involved in P-removal, hydrolysis, fermentation, and foaming, the project has provided results that can be used to optimize the operation of full-scale plants and carry out trouble-shooting. A core microbial community has been defined comprising the majority of microorganisms present in the plants. Time series have been established, providing an overview of temporal variations in the different plants. Interestingly, although most microorganisms were present in all plants, there seemed to be plant-specific factors that controlled the population composition thereby keeping it unique in each plant over time. Statistical analyses of FISH and operational data revealed some correlations, but less than expected. MiDas-DK (www.midasdk.dk) will continue over the next years and we hope the approach can inspire others to make similar projects in other parts of the world to get a more comprehensive understanding of microbial communities in wastewater engineering.

  6. Epipremnum aureum and Dracaena braunii as indoor plants for enhanced bio-electricity generation in a plant microbial fuel cell with electrochemically modified carbon fiber brush anode.

    Science.gov (United States)

    Sarma, Pranab Jyoti; Mohanty, Kaustubha

    2018-04-13

    In this study, two different unexploited indoor plants, Epipremnum aureum and Dracaena braunii were used to produce clean and sustainable bio-electricity in a plant microbial fuel cell (PMFC). Acid modified carbon fiber brush electrodes as well as bare electrodes were used in both the PMFCs. A bentonite based clay membrane was successfully integrated in the PMFCs. Maximum performance of E. aureum was 620 mV which was 188 mV higher potential than D. braunii. The bio-electricity generation using modified electrode was 154 mV higher than the bare carbon fiber, probably due to the effective bacterial attachment to the carbon fiber owing to hydrogen bonding. Maximum power output of 15.38 mW/m 2 was obtained by E. aureum with an internal resistance of 200 Ω. Higher biomass yield was also obtained in case of E. aureum during 60 days of experiment, which may correlate with the higher bio-electricity generation than D. braunii. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  7. The effect of chronic seaweed subsidies on herbivory: plant-mediated fertilization pathway overshadows lizard-mediated predator pathways.

    Science.gov (United States)

    Piovia-Scott, Jonah; Spiller, David A; Takimoto, Gaku; Yang, Louie H; Wright, Amber N; Schoener, Thomas W

    2013-08-01

    Flows of energy and materials link ecosystems worldwide and have important consequences for the structure of ecological communities. While these resource subsidies typically enter recipient food webs through multiple channels, most previous studies focussed on a single pathway of resource input. We used path analysis to evaluate multiple pathways connecting chronic marine resource inputs (in the form of seaweed deposits) and herbivory in a shoreline terrestrial ecosystem. We found statistical support for a fertilization effect (seaweed increased foliar nitrogen content, leading to greater herbivory) and a lizard numerical response effect (seaweed increased lizard densities, leading to reduced herbivory), but not for a lizard diet-shift effect (seaweed increased the proportion of marine-derived prey in lizard diets, but lizard diet was not strongly associated with herbivory). Greater seaweed abundance was associated with greater herbivory, and the fertilization effect was larger than the combined lizard effects. Thus, the bottom-up, plant-mediated effect of fertilization on herbivory overshadowed the top-down effects of lizard predators. These results, from unmanipulated shoreline plots with persistent differences in chronic seaweed deposition, differ from those of a previous experimental study of the short-term effects of a pulse of seaweed deposition: while the increase in herbivory in response to chronic seaweed deposition was due to the fertilization effect, the short-term increase in herbivory in response to a pulse of seaweed deposition was due to the lizard diet-shift effect. This contrast highlights the importance of the temporal pattern of resource inputs in determining the mechanism of community response to resource subsidies.

  8. Odd-numbered very-long-chain fatty acids from the microbial, animal and plant kingdoms

    Czech Academy of Sciences Publication Activity Database

    Řezanka, Tomáš; Sigler, Karel

    2009-01-01

    Roč. 48, 3-4 (2009), s. 206-238 ISSN 0163-7827 R&D Projects: GA MŠk 1M0570; GA MŠk 1M06011 Institutional research plan: CEZ:AV0Z50200510 Keywords : microorganism * plants * animals Subject RIV: EE - Microbiology, Virology Impact factor: 8.167, year: 2009

  9. Microbial pathogens in source and treated waters from drinking water treatment plants in the US

    Science.gov (United States)

    An occurrence survey was conducted on selected pathogens in source and treated drinking water collected from 25 drinking water treatment plants (DWTPs) in the United States. Water samples were analyzed for the protozoa Giardia and Cryptosporidium (EPA Method 1623); the fungi Asp...

  10. The Microbial Database for Danish wastewater treatment plants with nutrient removal (MiDas-DK) – a tool for understanding activated sludge population dynamics and community stability

    DEFF Research Database (Denmark)

    Mielczarek, Artur Tomasz; Saunders, Aaron Marc; Larsen, Poul

    2013-01-01

    Since 2006 more than 50 Danish full-scale wastewater treatment plants with nutrient removal have been investigated in a project called ‘The Microbial Database for Danish Activated Sludge Wastewater Treatment Plants with Nutrient Removal (MiDas-DK)’. Comprehensive sets of samples have been collected......, analyzed and associated with extensive operational data from the plants. The community composition was analyzed by quantitative fluorescence in situ hybridization (FISH) supported by 16S rRNA amplicon sequencing and deep metagenomics. MiDas-DK has been a powerful tool to study the complex activated sludge...

  11. Plant and Fungal Food Components with Potential Activity on the Development of Microbial Oral Diseases

    Directory of Open Access Journals (Sweden)

    Maria Daglia

    2011-01-01

    Full Text Available This paper reports the content in macronutrients, free sugars, polyphenols, and inorganic ions, known to exert any positive or negative action on microbial oral disease such as caries and gingivitis, of seven food/beverages (red chicory, mushroom, raspberry, green and black tea, cranberry juice, dark beer. Tea leaves resulted the richest material in all the detected ions, anyway tea beverages resulted the richest just in fluoride. The highest content in zinc was in chicory, raspberry and mushroom. Raspberry is the richest food in strontium and boron, beer in selenium, raspberry and mushroom in copper. Beer, cranberry juice and, especially green and black tea are very rich in polyphenols, confirming these beverages as important sources of such healthy substances. The fractionation, carried out on the basis of the molecular mass (MM, of the water soluble components occurring in raspberry, chicory, and mushroom extracts (which in microbiological assays revealed the highest potential action against oral pathogens, showed that both the high and low MM fractions are active, with the low MM fractions displaying the highest potential action for all the fractionated extracts. Our findings show that more compounds that can play a different active role occur in these foods.

  12. Comparing a microbial biocide and chlorine as zebra mussel control strategies in an Irish drinking water treatment plant

    Directory of Open Access Journals (Sweden)

    Sara Meehan

    2013-06-01

    Full Text Available A need exists for an environmentally friendly mussel control method to replace chlorine and other traditional control methods currentlyutilised in drinking water plants and other infested facilities. Zequanox® is a newly commercialised microbial biocide for zebra and quaggamussels comprised of killed Pseudomonas fluorescens CL145A cells. The objective of this study was to compare the efficacy of adevelopmental formulation of Zequanox (referred to as MBI 401 FDP and chlorine treatments on adult and juvenile zebra mussels byrunning a biobox trial in conjunction with chlorine treatments at an infested Irish drinking water treatment plant. Since 2009, the plantmanagement has used a residual chlorine concentration of 2 mg/L in autumn to control both adult zebra mussels and juvenile settlement intheir three concrete raw water chambers. Juvenile mussel settlement was monitored in three bioboxes as well as in three treatment chambersin the plant for three months prior to treatment. Adult mussels were seeded into the chambers and bioboxes four days before treatment. InOctober 2011, the bioboxes were treated with MBI 401 FDP at 200 mg active substance/L, while chlorine treatment took place in the waterchambers. The MBI 401 FDP treatment lasted only 8 hours while chlorine treatment lasted seven days. Juvenile numbers were reduced tozero in both the bioboxes and treated chambers within seven days. Adult mussel mortality reached 80% for both the chlorine and MBI 401FDP treatment; however, mortality was achieved faster in the chlorine treatment. These results provided important insights into zebra musselcontrol alternatives to chlorine and supported further development of the now commercial product, Zequanox.

  13. Development of an Agrobacterium-Mediated Stable Transformation Method for the Sensitive Plant Mimosa pudica

    Science.gov (United States)

    Mano, Hiroaki; Fujii, Tomomi; Sumikawa, Naomi; Hiwatashi, Yuji; Hasebe, Mitsuyasu

    2014-01-01

    The sensitive plant Mimosa pudica has long attracted the interest of researchers due to its spectacular leaf movements in response to touch or other external stimuli. Although various aspects of this seismonastic movement have been elucidated by histological, physiological, biochemical, and behavioral approaches, the lack of reverse genetic tools has hampered the investigation of molecular mechanisms involved in these processes. To overcome this obstacle, we developed an efficient genetic transformation method for M. pudica mediated by Agrobacterium tumefaciens (Agrobacterium). We found that the cotyledonary node explant is suitable for Agrobacterium-mediated transformation because of its high frequency of shoot formation, which was most efficiently induced on medium containing 0.5 µg/ml of a synthetic cytokinin, 6-benzylaminopurine (BAP). Transformation efficiency of cotyledonary node cells was improved from almost 0 to 30.8 positive signals arising from the intron-sGFP reporter gene by using Agrobacterium carrying a super-binary vector pSB111 and stabilizing the pH of the co-cultivation medium with 2-(N-morpholino)ethanesulfonic acid (MES) buffer. Furthermore, treatment of the explants with the detergent Silwet L-77 prior to co-cultivation led to a two-fold increase in the number of transformed shoot buds. Rooting of the regenerated shoots was efficiently induced by cultivation on irrigated vermiculite. The entire procedure for generating transgenic plants achieved a transformation frequency of 18.8%, which is comparable to frequencies obtained for other recalcitrant legumes, such as soybean (Glycine max) and pea (Pisum sativum). The transgene was stably integrated into the host genome and was inherited across generations, without affecting the seismonastic or nyctinastic movements of the plants. This transformation method thus provides an effective genetic tool for studying genes involved in M. pudica movements. PMID:24533121

  14. Development of an Agrobacterium-mediated stable transformation method for the sensitive plant Mimosa pudica.

    Directory of Open Access Journals (Sweden)

    Hiroaki Mano

    Full Text Available The sensitive plant Mimosa pudica has long attracted the interest of researchers due to its spectacular leaf movements in response to touch or other external stimuli. Although various aspects of this seismonastic movement have been elucidated by histological, physiological, biochemical, and behavioral approaches, the lack of reverse genetic tools has hampered the investigation of molecular mechanisms involved in these processes. To overcome this obstacle, we developed an efficient genetic transformation method for M. pudica mediated by Agrobacterium tumefaciens (Agrobacterium. We found that the cotyledonary node explant is suitable for Agrobacterium-mediated transformation because of its high frequency of shoot formation, which was most efficiently induced on medium containing 0.5 µg/ml of a synthetic cytokinin, 6-benzylaminopurine (BAP. Transformation efficiency of cotyledonary node cells was improved from almost 0 to 30.8 positive signals arising from the intron-sGFP reporter gene by using Agrobacterium carrying a super-binary vector pSB111 and stabilizing the pH of the co-cultivation medium with 2-(N-morpholinoethanesulfonic acid (MES buffer. Furthermore, treatment of the explants with the detergent Silwet L-77 prior to co-cultivation led to a two-fold increase in the number of transformed shoot buds. Rooting of the regenerated shoots was efficiently induced by cultivation on irrigated vermiculite. The entire procedure for generating transgenic plants achieved a transformation frequency of 18.8%, which is comparable to frequencies obtained for other recalcitrant legumes, such as soybean (Glycine max and pea (Pisum sativum. The transgene was stably integrated into the host genome and was inherited across generations, without affecting the seismonastic or nyctinastic movements of the plants. This transformation method thus provides an effective genetic tool for studying genes involved in M. pudica movements.

  15. Native fruit traits may mediate dispersal competition between native and non-native plants

    Directory of Open Access Journals (Sweden)

    Clare Aslan

    2012-02-01

    Full Text Available Seed disperser preferences may mediate the impact of invasive, non-native plant species on their new ecological communities. Significant seed disperser preference for invasives over native species could facilitate the spread of the invasives while impeding native plant dispersal. Such competition for dispersers could negatively impact the fitness of some native plants. Here, we review published literature to identify circumstances under which preference for non-native fruits occurs. The importance of fruit attraction is underscored by several studies demonstrating that invasive, fleshy-fruited plant species are particularly attractive to regional frugivores. A small set of studies directly compare frugivore preference for native vs. invasive species, and we find that different designs and goals within such studies frequently yield contrasting results. When similar native and non-native plant species have been compared, frugivores have tended to show preference for the non-natives. This preference appears to stem from enhanced feeding efficiency or accessibility associated with the non-native fruits. On the other hand, studies examining preference within existing suites of co-occurring species, with no attempt to maximize fruit similarity, show mixed results, with frugivores in most cases acting opportunistically or preferring native species. A simple, exploratory meta-analysis finds significant preference for native species when these studies are examined as a group. We illustrate the contrasting findings typical of these two approaches with results from two small-scale aviary experiments we conducted to determine preference by frugivorous bird species in northern California. In these case studies, native birds preferred the native fruit species as long as it was dissimilar from non-native fruits, while non-native European starlings preferred non-native fruit. However, native birds showed slight, non-significant preference for non-native fruit

  16. Arabidopsis cryptochrome 1 is a soluble protein mediating blue light-dependent regulation of plant growth and development

    International Nuclear Information System (INIS)

    Lin ChenTao; Ahmad, M.; Cashmore, A.R.

    1996-01-01

    Cryptochrome 1 (CRY1) is a flavin-type blue type receptor of Arabidopsis thaliana which mediates inhibition of hypocotyl elongation. In the work described in this report it is demonstrated that CRY1 is a soluble protein expressed in both young seedlings grown either in the dark or under light, and in different organs of adult plants. The functional role of CRY1 was further investigated using transgenic Arabidopsis plants overexpressing CRY1. It is demonstrated that overexpression of CRY1 resulted in hypersensitivity to blue, UV-A, and green light for the inhibition of hypocotyl elongation response. Transgenic plants overexpressing CRY1 also exhibited a dwarf phenotype with reduced size in almost every organ. This was in keeping with the previous observation of reciprocal alterations found in hy4 mutant plants and is consistent with a hypothesis that CRY1 mediates a light-dependent process resulting in a general inhibitory effect on plant growth. In addition, transgenic plants overexpressing CRY1 showed increased anthocyanin accumulation in response to blue, UV-A, and green light in a fluence rate-dependent manner. This increase in anthocyanin accumulation in transgenic plants was shown to be concomitant with increased blue light-induction of CHS gene expression. It is concluded that CRY1 is a photoreceptor mediating blue light-dependent regulation of gene expression in addition to its affect on plant growth. (author)

  17. Effects of plant density on recombinant hemagglutinin yields in an Agrobacterium-mediated transient gene expression system using Nicotiana benthamiana plants.

    Science.gov (United States)

    Fujiuchi, Naomichi; Matsuda, Ryo; Matoba, Nobuyuki; Fujiwara, Kazuhiro

    2017-08-01

    Agrobacterium-mediated transient expression systems enable plants to rapidly produce a wide range of recombinant proteins. To achieve economically feasible upstream production and downstream processing, it is beneficial to obtain high levels of two yield-related quantities of upstream production: recombinant protein content per fresh mass of harvested biomass (g gFM -1 ) and recombinant protein productivity per unit area-time (g m -2 /month). Here, we report that the density of Nicotiana benthamiana plants during upstream production had significant impacts on the yield-related quantities of recombinant hemagglutinin (HA). The two quantities were smaller at a high plant density of 400 plants m -2 than at a low plant density of 100 plants m -2 . The smaller quantities at the high plant density were attributed to: (i) a lower HA content in young leaves, which usually have high HA accumulation potentials; (ii) a lower biomass allocation to the young leaves; and (iii) a high area-time requirement for plants. Thus, plant density is a key factor for improving upstream production in Agrobacterium-mediated transient expression systems. Biotechnol. Bioeng. 2017;114: 1762-1770. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  18. An expression tag toolbox for microbial production of membrane bound plant cytochromes P450

    DEFF Research Database (Denmark)

    Vazquez Albacete, Dario; Cavaleiro, Mafalda; Christensen, Ulla

    2017-01-01

    of the intermediate and the final product of the pathway. Finally, the effect of a robustly performing expression tag was explored with a library of 49 different P450s from medicinal plants and nearly half of these were improved in expression by more than 2-fold. The developed toolbox serves as platform to tune P450...... tag chimeras of the model plant P450 CYP79A1 in different Escherichia coli strains. Using a high-throughput screening platform based on C-terminal GFP fusions, we identify several highly expressing and robustly performing chimeric designs. Analysis of long-term cultures by flow cytometry showed...... homogeneous populations for some of the conditions. Three chimeric designs were chosen for a more complex combinatorial assembly of a multigene pathway consisting of two P450s and a redox partner. Cells expressing these recombinant enzymes catalysed the conversion of the substrate to highly different ratios...

  19. Effect of microbial processes on transuranium elements behaviour in soil, plants and animal organism

    International Nuclear Information System (INIS)

    Uajldung, R.Eh.; Garlend, T.P.

    1985-01-01

    Results of preliminary studies discussed in the present paper bring about the supposition that concentration and chemical from of an element in a plant play an essential role in variation of its availability for animals consuming plants. That is why any assessment of long-term behaviour of transuranium elements in terrestrialenvironment should be based on determination of factors affecting solubility and forms of soluble compounds in soil. These factors include concentration and chemical form of the element migrating to soil; effect of the properties of soil on element distribution between solid and liquid phases; effect soil processes on kinetics of sorption reactions, concentration of transuranium elements, forms of soluble and non-soluble chemical compounds

  20. Effect of Arbuscular Mycorrhizal Fungi on Plant Biomass and the Rhizosphere Microbial Community Structure of Mesquite Grown in Acidic Lead/Zinc Mine Tailings

    Science.gov (United States)

    Solís-Domínguez, Fernando A.; Valentín-Vargas, Alexis; Chorover, Jon; Maier, Raina M.

    2011-01-01

    Mine tailings in arid and semi-arid environments are barren of vegetation and subject to eolian dispersion and water erosion. Revegetation is a cost-effective strategy to reduce erosion processes and has wide public acceptance. A major cost of revegetation is the addition of amendments, such as compost, to allow plant establishment. In this paper we explore whether arbuscular mycorrhizal fungi (AMF) can help support plant growth in tailings at a reduced compost concentration. A greenhouse experiment was performed to determine the effects of three AMF inocula on biomass, shoot accumulation of heavy metals, and changes in the rhizosphere microbial community structure of the native plant Prosopis juliflora (mesquite). Plants were grown in an acidic lead/zinc mine tailings amended with 10% (w/w) compost amendment, which is slightly sub-optimal for plant growth in these tailings. After two months, AMF-inoculated plants showed increased dry biomass and root length (p tailings. Mesquite shoot tissue lead and zinc concentrations did not exceed domestic animal toxicity limits regardless of whether AMF inoculation was used. The rhizosphere microbial community structure was assessed using denaturing gradient gel electrophoresis (DGGE) profiles of the small subunit RNA gene for bacteria and fungi. Canonical correspondence analysis (CCA) of DGGE profiles showed that the rhizosphere fungal community structure at the end of the experiment was significantly different from the community structure in the tailings, compost, and AMF inocula prior to planting. Further, CCA showed that AMF inoculation significantly influenced the development of both the fungal and bacterial rhizosphere community structures after two months. The changes observed in the rhizosphere microbial community structure may be either a direct effect of the AMF inocula, caused by changes in plant physiology induced by AMF, or a combination of both mechanisms. PMID:21211826

  1. Effect of arbuscular mycorrhizal fungi on plant biomass and the rhizosphere microbial community structure of mesquite grown in acidic lead/zinc mine tailings.

    Science.gov (United States)

    Solís-Domínguez, Fernando A; Valentín-Vargas, Alexis; Chorover, Jon; Maier, Raina M

    2011-02-15

    Mine tailings in arid and semi-arid environments are barren of vegetation and subject to eolian dispersion and water erosion. Revegetation is a cost-effective strategy to reduce erosion processes and has wide public acceptance. A major cost of revegetation is the addition of amendments, such as compost, to allow plant establishment. In this paper we explore whether arbuscular mycorrhizal fungi (AMF) can help support plant growth in tailings at a reduced compost concentration. A greenhouse experiment was performed to determine the effects of three AMF inocula on biomass, shoot accumulation of heavy metals, and changes in the rhizosphere microbial community structure of the native plant Prosopis juliflora (mesquite). Plants were grown in an acidic lead/zinc mine tailings amended with 10% (w/w) compost amendment, which is slightly sub-optimal for plant growth in these tailings. After two months, AMF-inoculated plants showed increased dry biomass and root length (p<0.05) and effective AMF colonization compared to controls grown in uninoculated compost-amended tailings. Mesquite shoot tissue lead and zinc concentrations did not exceed domestic animal toxicity limits regardless of whether AMF inoculation was used. The rhizosphere microbial community structure was assessed using denaturing gradient gel electrophoresis (DGGE) profiles of the small subunit RNA gene for bacteria and fungi. Canonical correspondence analysis (CCA) of DGGE profiles showed that the rhizosphere fungal community structure at the end of the experiment was significantly different from the community structure in the tailings, compost, and AMF inocula prior to planting. Further, CCA showed that AMF inoculation significantly influenced the development of both the fungal and bacterial rhizosphere community structures after two months. The changes observed in the rhizosphere microbial community structure may be either a direct effect of the AMF inocula, caused by changes in plant physiology induced by

  2. Fate of antibiotic resistance genes within the microbial communities of three waste water treatment plants

    OpenAIRE

    Di Cesare, Andrea; Eckert, Ester; D'Urso, Silvia; Doppelbauer, Julia; Corno, Gianluca

    2016-01-01

    Although Waste Water Treatment Plant (WWTP) are designed to reduce the biological pollution of urban waters, they lack a specific action against antibiotic resistance bacteria (ARB) or antibiotic resistance genes (ARGs). Nowadays, it is well documented that WWTPs constitute a reservoir of antibiotic resistances and, in some cases, they can be a favorable environment for the selection of ARB. This represent a serious concern for the public health, because the effluents of the WWTPs can be reus...

  3. Salt tolerant SUV3 overexpressing transgenic rice plants conserve physicochemical properties and microbial communities of rhizosphere.

    Science.gov (United States)

    Sahoo, Ranjan K; Ansari, Mohammad W; Tuteja, Renu; Tuteja, Narendra

    2015-01-01

    Key concerns in the ecological evaluation of GM crops are undesirably spread, gene flow, other environmental impacts, and consequences on soil microorganism's biodiversity. Numerous reports have highlighted the effects of transgenic plants on the physiology of non-targeted rhizospheric microbes and the food chain via causing adverse effects. Therefore, there is an urgent need to develop transgenics with insignificant toxic on environmental health. In the present study, SUV3 overexpressing salt tolerant transgenic rice evaluated in New Delhi and Cuttack soil conditions for their effects on physicochemical and biological properties of rhizosphere. Its cultivation does not affect soil properties viz., pH, Eh, organic C, P, K, N, Ca, Mg, S, Na and Fe(2+). Additionally, SUV3 rice plants do not cause any change in the phenotype, species characteristics and antibiotic sensitivity of rhizospheric bacteria. The population and/or number of soil organisms such as bacteria, fungi and nematodes were unchanged in the soil. Also, the activity of bacterial enzymes viz., dehydrogenase, invertase, phenol oxidases, acid phosphatases, ureases and proteases was not significantly affected. Further, plant growth promotion (PGP) functions of bacteria such as siderophore, HCN, salicylic acid, IAA, GA, zeatin, ABA, NH3, phosphorus metabolism, ACC deaminase and iron tolerance were, considerably, not influenced. The present findings suggest ecologically pertinent of salt tolerant SUV3 rice to sustain the health and usual functions of the rhizospheric organisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Effects of water stress, organic amendment and mycorrhizal inoculation on soil microbial community structure and activity during the establishment of two heavy metal-tolerant native plant species.

    Science.gov (United States)

    Fernández, D A; Roldán, A; Azcón, R; Caravaca, F; Bååth, E

    2012-05-01

    Our aim was to examine the effect of water stress on plant growth and development of two native plant species (Tetraclinis articulata and Crithmum maritimum) and on microbial community composition and activity in the rhizosphere soil, following the addition of an organic amendment, namely sugar beet residue (SBR), and/or the inoculation with an arbuscular mycorrhizal (AM) fungus, namely Glomus mosseae, in a non-sterile heavy metal-polluted soil. The AM inoculation did not have any significant effect on plant growth of both species. In T. articulata, SBR increased shoot growth, foliar P, total phospholipid fatty acids (PLFA), fungi-related PLFA, AM fungi-related neutral lipid fatty acid, bacterial gram-positive/gram-negative PLFA ratio and the β-glucosidase and dehydrogenase activities. SBR and AM inoculation increased phosphatase activity in T. articulata plants grown under drought conditions. In both plants, there was a synergistic effect between AM inoculation and SBR on mycorrhizal colonisation under drought conditions. In C. maritimum, the increase produced by the SBR on total amounts of PLFA, bacterial gram-positive-related PLFA and bacterial gram-negative-related PLFA was considerably higher under drought conditions. Our results suggest that the effectiveness of the amendment with regard to stimulating microbial communities and plant growth was largely limited by drought, particularly for plant species with a low degree of mycorrhizal colonisation.

  5. Hydrogen Peroxide- and Nitric Oxide-mediated Disease Control of Bacterial Wilt in Tomato Plants

    Directory of Open Access Journals (Sweden)

    Jeum Kyu Hong

    2013-12-01

    Full Text Available Reactive oxygen species (ROS generation in tomato plants by Ralstonia solanacearum infection and the role of hydrogen peroxide (H₂O₂ and nitric oxide in tomato bacterial wilt control were demonstrated. During disease development of tomato bacterial wilt, accumulation of superoxide anion (O₂− and H₂O₂ was observed and lipid peroxidation also occurred in the tomato leaf tissues. High doses of H₂O₂and sodium nitroprusside (SNP nitric oxide donor showed phytotoxicity to detached tomato leaves 1 day after petiole feeding showing reduced fresh weight. Both H₂O₂and SNP have in vitro antibacterial activities against R. solanacearum in a dose-dependent manner, as well as plant protection in detached tomato leaves against bacterial wilt by 10⁶ and 10⁷ cfu/ml of R. solanacearum. H₂O₂- and SNP-mediated protection was also evaluated in pots using soil-drench treatment with the bacterial inoculation, and relative ‘area under the disease progressive curve (AUDPC’ was calculated to compare disease protection by H₂O₂ and/or SNP with untreated control. Neither H₂O₂ nor SNP protect the tomato seedlings from the bacterial wilt, but H₂O₂+ SNP mixture significantly decreased disease severity with reduced relative AUDPC. These results suggest that H₂O₂ and SNP could be used together to control bacterial wilt in tomato plants as bactericidal agents.

  6. Treatment efficiency in wastewater treatment plant of Hat Yai Municipality by quantitative removal of microbial indicators

    Directory of Open Access Journals (Sweden)

    Duangporn Kantachote

    2009-11-01

    Full Text Available The efficiency of treatment in a wastewater treatment plant of Hat Yai Municipality through stabilization ponds and constructed wetlands was monitored by using the bacterial indicators, total coliforms (TC, fecal coliforms (FC, Escherichia coli and fecal streptococci (FS, and photosynthetic microbes. The sequence of water flow in the wastewater treatment plant is as follows: primary or anaerobic pond (P, facultative pond (F, maturation pond (M, constructed wetlands (W1, W2 and W3, and an effluent storage pond (S for the treated wastewater. The wastewater treatment plant has an approximate area of 3,264,000 m2 (2,040 rai and its dry weather flow was running at only 40,000 m3/ day. There were 10 sampling times used for all the 7 ponds during July-October, 2006.Statistical analysis using a Two-Factorial Design model, indicated that pond types significantly affected temperature, dissolved oxygen (DO, and pH (p<0.05, whereas the time of sampling during the day had a significant effect (p<0.05 only on the temperature and light intensity available to the ponds. There were also significant different removal efficiencies of the different bacterial indicator groups tested (p<0.05. The overall performance of the wastewater treatment plant effectively removed TC, FC, E. coli, and FS as follows, 99.8%, 99.8%, 75.8% and 98.8%, respectively. The amounts of bacterial indicators, except for E. coli, showed a negative correlation with levels of light intensity and DO, whereas there was no correlation between the pH and the different indicator bacteria. There was a positive middle level correlation between pHand chlorophyll a.There were five different divisions of photosynthetic organisms detected throughout the plant as follows, Cyanophyta, Chlorophyta, Bacillariophyta, Euglenophyta, and Pyrrhophyta. The least diversity was found in the anaerobic pond (P as there were only 15 genera. Euglena, an indicator of dirty water, was detected only in this pond. The

  7. Rhododendron aureum Georgi formed a special soil microbial community and competed with above-ground plants on the tundra of the Changbai Mountain, China.

    Science.gov (United States)

    Wang, Xiaolong; Li, Lin; Zhao, Wei; Zhao, Jiaxin; Chen, Xia

    2017-09-01

    Rhododendron aureum Georgi is a perennial evergreen dwarf shrub that grows at all elevations within the alpine tundra of northern China. Previous research has investigated the plant communities of R. aureum ; however, little information is available regarding interspecific competition and underground soil microbial community composition. The objective of our study was to determine whether the presence of R. aureum creates a unique soil microbiome and to investigate the relationship between R. aureum and other plant species. Our study site ranged from 1,800 to 2,600 m above sea level on the northern slope of the Changbai Mountain. The results show that the soil from sites with an R. aureum community had a higher abundance of nitrogen-fixing bacteria and a higher resistance to pathogens than soils from sites without R. aureum . We emphasize that R. aureum promotes a unique soil microbial community structure that is distinct from those associated with other plants. Elevation and microbial biomass were the main influencing factors for plant community structure. Analysis of interspecific relationships reveals that R. aureum is negatively associated with most other dominant shrubs and herbs, suggesting interspecific competition. It is necessary to focus on other dominant species if protection and restoration of the R. aureum competition is to occur. In the future, more is needed to prove whether R. aureum decreases species diversity in the tundra ecosystems of Changbai Mountain.

  8. Effects of plant species on soil microbial processes and CH4 emission from constructed wetlands

    International Nuclear Information System (INIS)

    Wang, Yanhua; Yang, Hao; Ye, Chun; Chen, Xia; Xie, Biao; Huang, Changchun; Zhang, Jixiang; Xu, Meina

    2013-01-01

    Methane (CH 4 ) emission from constructed wetland has raised environmental concern. This study evaluated the influence of mono and polyculture constructed wetland and seasonal variation on CH 4 fluxes. Methane emission data showed large temporal variation ranging from 0 to 249.29 mg CH 4 m −2 h −1 . Results indicated that the highest CH 4 flux was obtained in the polyculture system, planted with Phragmites australis, Zizania latifolia and Typha latifolia, reflecting polyculture system could stimulate CH 4 emission. FISH analysis showed the higher amount of methanotrophs in the profile of Z. latifolia in both mono and polyculture systems. The highest methanogens amount and relatively lower methanotrophs amount in the profile of polyculture system were obtained. The results support the characteristics of CH 4 fluxes. The polyculture constructed wetland has the higher potential of global warming. -- Highlights: ► The polyculture constructed wetland has the higher contribution to CH 4 emission. ► The CH 4 –C conversion ranged from 0 to 3.7%. ► The Z. latifolia played important roles in methanotrophs growth and CH 4 consumption. ► Major influence of T-N, TOC and plant cover on CH 4 emission was obtained. -- The polyculture constructed wetland has the higher contribution to global warming

  9. Generation of Electricity Using Spartina Patens with Stainless Steel Current Collectors in a Plant-Microbial Fuel Cell

    Science.gov (United States)

    Narula, Deep

    At present, the global energy infrastructure is highly dependent on (i) non-renewable fossil fuels with significant emissions of greenhouse gasses (ii) green fuels such as bioethanol and biodiesel with impact on current agricultural practices competing with food production for arable lands, fertilizers, also requiring additional energy input. Plant-based microbial fuel cell (PMFC) technology can be found as a promising alternative to produce electricity without any side effects with an advantage of using sunlight as an energy source. In the present study, we developed PMFCs using Spartina patens, a marshland grass, abundantly available in the coastal regions of the USA. Figure 1 is a schematic for a PMFC with the anode and cathode compartments where others have used carbon-based electrodes for current collection. In contrast, we attempted to utilize stainless steel wires with more surface area to enhance the current collection in the anode compartment as well as to increase the rate of reduction in the cathode chamber and thereby increase the amount of electricity produced. The study will give results on the periodic use of Spartina patens in PMFC along with the porous stainless steel electrodes which have never been employed in PMFCs before.

  10. Use of MgO to mitigate the effect of microbial CO2 production in the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    Wang, Y.; Brush, L.H.

    1997-01-01

    The Waste Isolation Pilot Plant (WIPP), located in a salt bed in southern New Mexico, is designed by US Department of Energy to demonstrate the safe and permanent disposal of design-basis transuranic waste. WIPP performance assessment requires consideration of radionuclide release in brines in the event of inadvertent human intrusion. The mobility of radionuclides depends on chemical factors such as brine pmH (-log molality of H + ) and CO 2 fugacity. According to current waste inventory estimates, a large quantity (∼ 10 9 moles C) of organic materials will be emplaced in the WIPP. Those organic material will potentially be degraded by halophilic or halotolerant microorganisms in the presence of liquid water in the repository, especially if a large volume of brine is introduced into the repository by human intrusions. Organic material biodegradation will produce a large amount of CO 2 , which will acidify the WIPP brine and thus significantly increase the mobility of actinides. This communication addresses (1) the rate of organic material biodegradation and the quantity of CO 2 to be possibly generated, (2) the effect of microbial CO 2 production on overall WIPP performance, and (3) the mechanism of using MgO to mitigate this effect

  11. Two-year microbial adaptation during hydrogen-mediated biogas upgrading process in a serial reactor configuration

    DEFF Research Database (Denmark)

    Treu, Laura; Kougias, Panagiotis; de Diego-Díaz, B.

    2018-01-01

    Microbial dynamics in an upgrading biogas reactor system undergoing a more than two years-period at stable operating conditions were explored. The carbon dioxide generated during biomass degradation in the first reactor of the system was converted to methane into the secondary reactor by addition...... of external hydrogen. Considering the overall efficiency, the long-term operation period resulted in an improved biogas upgrading performance (99% methane content). However, a remarkable accumulation of acetate was revealed, indicating the enhancement of homoacetogenic activity. For this reason, a shift...

  12. Effect of Plants Containing Secondary Compounds with Palm Oil on Feed Intake, Digestibility, Microbial Protein Synthesis and Microbial Population in Dairy Cows

    Directory of Open Access Journals (Sweden)

    N. Anantasook

    2013-06-01

    Full Text Available The objective of this study was to determine the effect of rain tree pod meal with palm oil supplementation on feed intake, digestibility, microbial protein synthesis and microbial populations in dairy cows. Four, multiparous early-lactation Holstein-Friesian crossbred (75% lactating dairy cows with an initial body weight (BW of 405±40 kg and 36±8 DIM were randomly assigned to receive dietary treatments according to a 4×4 Latin square design. The four dietary treatments were un-supplementation (control, supplementation with rain tree pod meal (RPM at 60 g/kg, supplementation with palm oil (PO at 20 g/kg, and supplementation with RPM at 60 g/kg and PO at 20 g/kg (RPO, of total dry matter intake. The cows were offered concentrates, at a ratio of concentrate to milk production of 1:2, and chopped 30 g/kg of urea treated rice straw was fed ad libitum. The RPM contained condensed tannins and crude saponins at 88 and 141 g/kg of DM, respectively. It was found that supplementation with RPM and/or PO to dairy cows diets did not show negative effects on feed intake and ruminal pH and BUN at any times of sampling (p>0.05. However, RPM supplementation resulted in lower crude protein digestibility, NH3-N concentration and number of proteolytic bacteria. It resulted in greater allantoin absorption and microbial crude protein (p<0.05. In addition, dairy cows showed a higher efficiency of microbial N supply (EMNS in both RPM and RPO treatments. Moreover, NDF digestibility and cellulolytic bacteria numbers were highest in RPO supplementation (p<0.05 while, supplementation with RPM and/or PO decreased the protozoa population in dairy cows. Based on this study, supplementation with RPM and/or PO in diets could improve fiber digestibility, microbial protein synthesis in terms of quantity and efficiency and microbial populations in dairy cows.

  13. Thermo-Regulation of Genes Mediating Motility and Plant Interactions in Pseudomonas syringae

    Science.gov (United States)

    Hockett, Kevin L.; Burch, Adrien Y.; Lindow, Steven E.

    2013-01-01

    Pseudomonas syringae is an important phyllosphere colonist that utilizes flagellum-mediated motility both as a means to explore leaf surfaces, as well as to invade into leaf interiors, where it survives as a pathogen. We found that multiple forms of flagellum-mediated motility are thermo-suppressed, including swarming and swimming motility. Suppression of swarming motility occurs between 28° and 30°C, which coincides with the optimal growth temperature of P. syringae. Both fliC (encoding flagellin) and syfA (encoding a non-ribosomal peptide synthetase involved in syringafactin biosynthesis) were suppressed with increasing temperature. RNA-seq revealed 1440 genes of the P. syringae genome are temperature sensitive in expression. Genes involved in polysaccharide synthesis and regulation, phage and IS elements, type VI secretion, chemosensing and chemotaxis, translation, flagellar synthesis and motility, and phytotoxin synthesis and transport were generally repressed at 30°C, while genes involved in transcriptional regulation, quaternary ammonium compound metabolism and transport, chaperone/heat shock proteins, and hypothetical genes were generally induced at 30°C. Deletion of flgM, a key regulator in the transition from class III to class IV gene expression, led to elevated and constitutive expression of fliC regardless of temperature, but did not affect thermo-regulation of syfA. This work highlights the importance of temperature in the biology of P. syringae, as many genes encoding traits important for plant-microbe interactions were thermo-regulated. PMID:23527276

  14. On the effects of the evolution of microbial mats and land plants on the Earth as a planet. Photometric and spectroscopic light curves of paleo-Earths

    OpenAIRE

    Sanromá, E.; Pallé, E.; García-Muñoz, A.

    2013-01-01

    Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of the utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non- uniformly from des...

  15. Bacterial mediated alleviation of heavy metal stress and decreased accumulation of metals in plant tissues: Mechanisms and future prospects.

    Science.gov (United States)

    Etesami, Hassan

    2018-01-01

    Heavy metal pollution of agricultural soils is one of main concerns causing some of the different ecological and environmental problems. Excess accumulation of these metals in soil has changed microbial community (e.g., structure, function, and diversity), deteriorated soil, decreased the growth and yield of plant, and entered into the food chain. Plants' tolerance to heavy metal stress needs to be improved in order to allow growth of crops with minimum or no accumulation of heavy metals in edible parts of plant that satisfy safe food demands for the world's rapidly increasing population. It is well known that PGPRs (plant growth-promoting rhizobacteria) enhance crop productivity and plant resistance to heavy metal stress. Many recent reports describe the application of heavy metal resistant-PGPRs to enhance agricultural yields without accumulation of metal in plant tissues. This review provides information about the mechanisms possessed by heavy metal resistant-PGPRs that ameliorate heavy metal stress to plants and decrease the accumulation of these metals in plant, and finally gives some perspectives for research on these bacteria in agriculture in the future. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2-keto-4-methylthiobutyric acid production.

    Directory of Open Access Journals (Sweden)

    Axel de Zélicourt

    2018-03-01

    Full Text Available Several plant species require microbial associations for survival under different biotic and abiotic stresses. In this study, we show that Enterobacter sp. SA187, a desert plant endophytic bacterium, enhances yield of the crop plant alfalfa under field conditions as well as growth of the model plant Arabidopsis thaliana in vitro, revealing a high potential of SA187 as a biological solution for improving crop production. Studying the SA187 interaction with Arabidopsis, we uncovered a number of mechanisms related to the beneficial association of SA187 with plants. SA187 colonizes both the surface and inner tissues of Arabidopsis roots and shoots. SA187 induces salt stress tolerance by production of bacterial 2-keto-4-methylthiobutyric acid (KMBA, known to be converted into ethylene. By transcriptomic, genetic and pharmacological analyses, we show that the ethylene signaling pathway, but not plant ethylene production, is required for KMBA-induced plant salt stress tolerance. These results reveal a novel molecular communication process during the beneficial microbe-induced plant stress tolerance.

  17. Insights into microbial communities mediating the bioremediation of hydrocarbon-contaminated soil from an Alpine former military site.

    Science.gov (United States)

    Siles, José A; Margesin, Rosa

    2018-05-01

    The study of microbial communities involved in soil bioremediation is important to identify the specific microbial characteristics that determine improved decontamination rates. Here, we characterized bacterial, archaeal, and fungal communities in terms of (i) abundance (using quantitative PCR) and (ii) taxonomic diversity and structure (using Illumina amplicon sequencing) during the bioremediation of long-term hydrocarbon-contaminated soil from an Alpine former military site during 15 weeks comparing biostimulation (inorganic NPK fertilization) vs. natural attenuation and considering the effect of temperature (10 vs. 20 °C). Although a considerable amount of total petroleum hydrocarbon (TPH) loss could be attributed to natural attenuation, significantly higher TPH removal rates were obtained with NPK fertilization and at increased temperature, which were related to the stimulation of the activities of indigenous soil microorganisms. Changing structures of bacterial and fungal communities significantly explained shifts in TPH contents in both natural attenuation and biostimulation treatments at 10 and 20 °C. However, archaeal communities, in general, and changing abundances and diversities in bacterial and fungal communities did not play a decisive role on the effectiveness of soil bioremediation. Gammaproteobacteria and Bacteroidia classes, within bacterial community, and undescribed/novel groups, within fungal community, proved to be actively involved in TPH removal in natural attenuation and biostimulation at both temperatures.

  18. Multitrophic microbial interactions for eco- and agro-biotechnological processes: theory and practice.

    Science.gov (United States)

    Saleem, Muhammad; Moe, Luke A

    2014-10-01

    Multitrophic level microbial loop interactions mediated by protist predators, bacteria, and viruses drive eco- and agro-biotechnological processes such as bioremediation, wastewater treatment, plant growth promotion, and ecosystem functioning. To what extent these microbial interactions are context-dependent in performing biotechnological and ecosystem processes remains largely unstudied. Theory-driven research may advance the understanding of eco-evolutionary processes underlying the patterns and functioning of microbial interactions for successful development of microbe-based biotechnologies for real world applications. This could also be a great avenue to test the validity or limitations of ecology theory for managing diverse microbial resources in an era of altering microbial niches, multitrophic interactions, and microbial diversity loss caused by climate and land use changes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Cysteine-rich peptides (CRPs) mediate diverse aspects of cell-cell communication in plant reproduction and development.

    Science.gov (United States)

    Marshall, Eleanor; Costa, Liliana M; Gutierrez-Marcos, Jose

    2011-03-01

    Cell-cell communication in plants is essential for the correct co-ordination of reproduction, growth, and development. Studies to dissect this mode of communication have previously focussed primarily on the action of plant hormones as mediators of intercellular signalling. In animals, peptide signalling is a well-documented intercellular communication system, however, relatively little is known about this system in plants. In recent years, numerous reports have emerged about small, secreted peptides controlling different aspects of plant reproduction. Interestingly, most of these peptides are cysteine-rich, and there is convincing evidence suggesting multiple roles for related cysteine-rich peptides (CRPs) as signalling factors in developmental patterning as well as during plant pathogen responses and symbiosis. In this review, we discuss how CRPs are emerging as key signalling factors in regulating multiple aspects of vegetative growth and reproductive development in plants.

  20. Plant-mediated horizontal transmission of Rickettsia endosymbiont between different whitefly species.

    Science.gov (United States)

    Li, Yi-Han; Ahmed, Muhammad Z; Li, Shao-Jian; Lv, Ning; Shi, Pei-Qiong; Chen, Xiao-Sheng; Qiu, Bao-Li

    2017-12-01

    A growing number of studies have revealed the presence of closely related endosymbionts in phylogenetically distant arthropods, indicating horizontal transmission of these bacteria. Here we investigated the interspecific horizontal transmission of Rickettsia between two globally invasive whitefly species, Bemisia tabaci MEAM1 and B. tabaci MED, via cotton plants. We found both scattered and confined distribution patterns of Rickettsia in these whiteflies. After entering cotton leaves, Rickettsia was restricted to the leaf phloem vessels and could be taken up by both species of the Rickettsia-free whitefly adults, but only the scattered pattern was observed in the recipient whiteflies. Both the relative quantity of Rickettsia and the efficiency of transmitting Rickettsia into cotton leaves were significantly higher in MEAM1 females than in MED females. The retention time of Rickettsia transmitted from MEAM1 into cotton leaves was at least 5 days longer than that of MED. Phylogenetic analysis based on 16S rRNA and gltA genes confirmed that the Rickettsia extracted from the donor MEAM1, the cotton leaves, the recipient MEAM1 and the recipient MED were all identical. We conclude that cotton plants can mediate horizontal transmission of Rickettsia between different insect species, and that the transmission dynamics of Rickettsia vary with different host whitefly species. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Investigating Gene Function in Cereal Rust Fungi by Plant-Mediated Virus-Induced Gene Silencing.

    Science.gov (United States)

    Panwar, Vinay; Bakkeren, Guus

    2017-01-01

    Cereal rust fungi are destructive pathogens, threatening grain production worldwide. Targeted breeding for resistance utilizing host resistance genes has been effective. However, breakdown of resistance occurs frequently and continued efforts are needed to understand how these fungi overcome resistance and to expand the range of available resistance genes. Whole genome sequencing, transcriptomic and proteomic studies followed by genome-wide computational and comparative analyses have identified large repertoire of genes in rust fungi among which are candidates predicted to code for pathogenicity and virulence factors. Some of these genes represent defence triggering avirulence effectors. However, functions of most genes still needs to be assessed to understand the biology of these obligate biotrophic pathogens. Since genetic manipulations such as gene deletion and genetic transformation are not yet feasible in rust fungi, performing functional gene studies is challenging. Recently, Host-induced gene silencing (HIGS) has emerged as a useful tool to characterize gene function in rust fungi while infecting and growing in host plants. We utilized Barley stripe mosaic virus-mediated virus induced gene silencing (BSMV-VIGS) to induce HIGS of candidate rust fungal genes in the wheat host to determine their role in plant-fungal interactions. Here, we describe the methods for using BSMV-VIGS in wheat for functional genomics study in cereal rust fungi.

  2. AGO/RISC-mediated antiviral RNA silencing in a plant in vitro system.

    Science.gov (United States)

    Schuck, Jana; Gursinsky, Torsten; Pantaleo, Vitantonio; Burgyán, Jozsef; Behrens, Sven-Erik

    2013-05-01

    AGO/RISC-mediated antiviral RNA silencing, an important component of the plant's immune response against RNA virus infections, was recapitulated in vitro. Cytoplasmic extracts of tobacco protoplasts were applied that supported Tombusvirus RNA replication, as well as the formation of RNA-induced silencing complexes (RISC) that could be functionally reconstituted with various plant ARGONAUTE (AGO) proteins. For example, when RISC containing AGO1, 2, 3 or 5 were programmed with exogenous siRNAs that specifically targeted the viral RNA, endonucleolytic cleavages occurred and viral replication was inhibited. Antiviral RNA silencing was disabled by the viral silencing suppressor p19 when this was present early during RISC formation. Notably, with replicating viral RNA, only (+)RNA molecules were accessible to RISC, whereas (-)RNA replication intermediates were not. The vulnerability of viral RNAs to RISC activity also depended on the RNA structure of the target sequence. This was most evident when we characterized viral siRNAs (vsiRNAs) that were particularly effective in silencing with AGO1- or AGO2/RISC. These vsiRNAs targeted similar sites, suggesting that accessible parts of the viral (+)RNA may be collectively attacked by different AGO/RISC. The in vitro system was, hence, established as a valuable tool to define and characterize individual molecular determinants of antiviral RNA silencing.

  3. Microbial Degradation of Lobster Shells to Extract Chitin Derivatives for Plant Disease Management

    Directory of Open Access Journals (Sweden)

    Gayathri Ilangumaran

    2017-05-01

    Full Text Available Biodegradation of lobster shells by chitinolytic microorganisms are an environment safe approach to utilize lobster processing wastes for chitin derivation. In this study, we report degradation activities of two microbes, “S223” and “S224” isolated from soil samples that had the highest rate of deproteinization, demineralization and chitinolysis among ten microorganisms screened. Isolates S223 and S224 had 27.3 and 103.8 protease units mg-1 protein and 12.3 and 11.2 μg ml-1 of calcium in their samples, respectively, after 1 week of incubation with raw lobster shells. Further, S223 contained 23.8 μg ml-1 of N-Acetylglucosamine on day 3, while S224 had 27.3 μg ml-1 on day 7 of incubation with chitin. Morphological observations and 16S rDNA sequencing suggested both the isolates were Streptomyces. The culture conditions were optimized for efficient degradation of lobster shells and chitinase (∼30 kDa was purified from crude extract by affinity chromatography. The digested lobster shell extracts induced disease resistance in Arabidopsis by induction of defense related genes (PR1 > 500-fold, PDF1.2 > 40-fold upon Pseudomonas syringae and Botrytis cinerea infection. The study suggests that soil microbes aid in sustainable bioconversion of lobster shells and extraction of chitin derivatives that could be applied in plant protection.

  4. Anti-microbial principles of selected remedial plants from Southern India.

    Science.gov (United States)

    Tirupathi, Rao G; Suresh, Babu K; Ujwal, Kumar J; Sujana, P; Raoa, A Veerabhadr; Sreedhar, A S

    2011-08-01

    To examine the anti-bacterial activity of leaf extracts of Morus alba L. (Moraceae) and Piper betel L. (Piperaceae), and seed extracts of Bombax ceiba L. (Borabacaceae). We have partially purified plant extracts by solvent extraction method, and evaluated the effect of individual fractions on bacterial growth using Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) bacterial strains. Compared with Morus and Bombax fractions, Piper fractions showed significant growth inhibition on all the three types of bacteria studied. The EtOAc-hexane fractions of Piper leaves exhibited significant anti-bacterial activity with minimum inhibitory concentrations (MIC) of 50 µg/mL culture against both gram-positive and gram-negative bacteria. The EtOAc-fractions I, II, and IV inhibited bacterial colony formation on soft agar in addition to growth inhibition. A combination treatment of piper fractions with ampicillin resulted in significant growth inhibition in E. coli and P. aeruginosa, and combination with anticancer drug geldanamycin (2µg/mL) showed selective growth inhibition against P. aeruginosa and S. aureus. Three major compounds, i.e., eugenol, 3-hexene-ol and stigmasterol, were primarily identified from Piper betel leaf extractions. Among the individual compounds, eugenol treatment showed improved growth inhibition compared with stigmasterol and 3-hexene-ol. We are reporting potential anti-bacterial compounds from Piper betel against both gram-positive and gram-negative bacteria either alone or in combination with drug treatment.

  5. The effect of hygienic treatment on the microbial flora of biowaste at biogas plants

    Energy Technology Data Exchange (ETDEWEB)

    Bagge, E.; Sahlstroem, L.; Albihn, A. [National Veterinary Institute, Uppsala (Sweden). Dept. of Bacteriology

    2005-12-15

    In Sweden, full-scale, commercial biogas plants (BGP), which process low-risk animal waste, operate a separate pre-pasteurisation at 70{sup o}C for 60 min as required by EEC regulation 1774/2002. The purpose of this study was to establish if, during pasteurisation and further processing and handling in full-scale BGPs, pathogens in biowaste could be sufficiently reduced to allow its use on arable land. Four BGPs were sampled on six occasions during 1 year. Sampling was performed from six locations during biogas production. The samples being analysed quantitatively to detect indicator bacteria (Escherichia coli, Enterococcus spp. and coliforms) and spore-forming bacteria (Clostridium spp. and Bacillus spp.) and qualitatively for bacterial pathogens (salmonella, listeria, campylobacter and VTEC O157). Salmonella was the most frequently isolated pathogen before pasteurisation In general, the treatment adequately reduced both indicator and pathogenic bacteria. Spore-forming bacteria were not reduced. However, recontamination and regrowth of bacteria in biowaste was frequently noted after pasteurisation and digestion. (author)

  6. The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History

    Directory of Open Access Journals (Sweden)

    Yiming Zhang

    2018-05-01

    Full Text Available Soil microbial abundance and diversity change constantly in continuous cropping systems, resulting in the prevalence of soil-borne pathogens and a decline in crop yield in solar greenhouses. To investigate the effects of rice straw and biochar on soil microbial abundance and diversity in soils with a history of continuous planting, three treatments were examined: mixed rice straw and biochar addition (RC, rice straw addition (R, and biochar addition (C. The amount of C added in each treatment group was 3.78 g kg−1 soil. Soil without rice straw and biochar addition was treated as a control (CK. Results showed that RC treatment significantly increased soil pH, available nitrogen (AN, available phosphorus (AP, and potassium (AK by 40.3%, 157.2%, and 24.2%, respectively, as compared to the CK soil. The amount of soil labile organic carbon (LOC, including readily oxidizable organic carbon (ROC, dissolved organic carbon (DOC, and light fraction organic carbon (LFOC, was significantly greater in the RC, R, and C treatment groups as compared to CK soil. LOC levels with RC treatment were higher than with the other treatments. Both rice straw and biochar addition significantly increased bacterial and total microbial abundance, whereas rice straw but not biochar addition improved soil microbial carbon metabolism and diversity. Thus, the significant effects of rice straw and biochar on soil microbial carbon metabolism and diversity were attributed to the quantity of DOC in the treatments. Therefore, our results indicated that soil microbial diversity is directly associated with DOC. Based on the results of this study, mixed rice straw and biochar addition, rather than their application individually, might be key to restoring degraded soil.

  7. Microbial effects

    International Nuclear Information System (INIS)

    Sharpe, V.J.

    1985-10-01

    The long term safety and integrity of radioactive waste disposal sites proposed for use by Ontario Hydro may be affected by the release of radioactive gases. Microbes mediate the primary pathways of waste degradation and hence an assessment of their potential to produce gaseous end products from the breakdown of low level waste was performed. Due to a number of unknown variables, assumptions were made regarding environmental and waste conditions that controlled microbial activity; however, it was concluded that 14 C and 3 H would be produced, albeit over a long time scale of about 1500 years for 14 C in the worst case situation

  8. Airborne microbial emissions and immissions on aerogic mechanical-biological waste treatment plants; Luftgetragene mikrobielle Emissionen und Immissionen an aeroben mechanisch-biologischen Abfallbehandlungsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Luft, C.

    2002-07-01

    During biological waste treatment it is important to consider the hygienic situation. One has to take care that citizens in the neighborhood and especially the work force complain about impairments caused by microbial immissions. Therefore it is important to evaluate microbial emissions and immissions of composting plants. This dissertation looked upon this topic. Microbial and endotoxin emissions of different biological waste treatment plants were measured with diverse sampling methods. The research was done on enclosed and open variants of plants. Measurements were taken from different composting techniques and also from a plant treating the rest fraction of household waste. Depending on the technique researched different concentrations of airborne microbes could be found. The size of the plant and degree of enclosure as well as the material input all affect the amount of airborne microbial emissions. At a small open composting plant (6 500 Mg/a) only low microbial concentrations could be found at the workplace, while at the totally enclosed plant (12 000 Mg/a) high concentrations of airborne microorganisms could be observed at the workplace. Seasonal differences in microbial concentrations could not be seen when considering the agitation of outdoor piles consisting of separated household waste. In contrast, measured concentrations of endotoxins at another composting plant showed seasonal differences. Using simulations based on the models of TA-Luft and VDI 3783 it could be calculated that emissions from enclosed plants with 12 000 Mg/a input and a biofilter have a minimal influence on the neighborhood of the composting plant. (orig.) [German] Beim Umgang mit biologischen Abfaellen spielt die hygienische Situation eine wichtige Rolle. Besonders im Bereich des Arbeitsschutzes, aber auch im Hinblick auf die in der Naehe von Abfallbehandlungsanlagen wohnenden Personen, ist Sorge zu tragen, dass es nicht zu gesundheitlichen Beeintraechtigungen durch Keimimmissionen

  9. An approach to mitigating soil CO2 emission by biochemically inhibiting cellulolytic microbial populations through mediation via the medicinal herb Isatis indigotica

    Science.gov (United States)

    Wu, Hong-Sheng; Chen, Su-Yun; Li, Ji; Liu, Dong-Yang; Zhou, Ji; Xu, Ya; Shang, Xiao-Xia; Wei, Dong-yang; Yu, Lu-ji; Fang, Xiao-hang; Li, Shun-yi; Wang, Ke-ke

    2017-06-01

    Greenhouse gases (GHGs, particularly carbon dioxide (CO2)) emissions from soil under wheat production are a significant source of agricultural carbon emissions that have not been mitigated effectively. A field experiment and a static incubation study in a lab were conducted to stimulate wheat growth and investigate its potential to reduce CO2 emissions from soil through intercropping with a traditional Chinese medicinal herb called Isatis indigotica. This work was conducted by adding I. indigotica root exudates based on the quantitative real-time PCR (qPCR) analysis of the DNA copy number of the rhizosphere or bulk soil microbial populations. This addition was performed in relation to the CO2 formation by cellulolytic microorganisms (Penicillium oxalicum, fungi and Ruminococcus albus) to elucidate the microbial ecological basis for the molecular mechanism that decreases CO2 emissions from wheat fields using I. indigotica. The results showed that the panicle weight and full grains per panicle measured through intercropping with I. indigotica (NPKWR) increased by 39% and 28.6%, respectively, compared to that of the CK (NPKW). Intercropping with I. indigotica significantly decreased the CO2 emissions from soil under wheat cultivation. Compared with CK, the total CO2 emission flux during the wheat growth period in the I. indigotica (NPKWR) intercropping treatment decreased by 29.26%. The intensity of CO2 emissions per kg of harvested wheat grain declined from 7.53 kg CO2/kg grain in the NPKW (CK) treatment to 5.55 kg CO2/kg grain in the NPKWR treatment. The qPCR analysis showed that the DNA copy number of the microbial populations of cellulolytic microorganisms (P. oxalicum, fungi and R. albus) in the field rhizosphere around I. indigotica or in the bulk soil under laboratory incubation was significantly lower than that of CK. This finding indicated that root exudates from I. indigotica inhibited the activity and number of cellulolytic microbial populations, which led

  10. Microbial mitigation-exacerbation continuum: a novel framework for microbiome effects on hosts in the face of stress.

    Science.gov (United States)

    David, Aaron S; Thapa-Magar, Khum B; Afkhami, Michelle E

    2018-03-01

    A key challenge to understanding microbiomes and their role in ecological processes is contextualizing their effects on host organisms, particularly when faced with environmental stress. One influential theory, the Stress Gradient Hypothesis, might predict that the frequency of positive interactions increases with stressful conditions such that microbial taxa would mitigate harmful effects on host performance. Yet, equally plausible is that microbial taxa could exacerbate these effects. Here, we introduce the Mitigation-Exacerbation Continuum as a novel framework to conceptualize microbial mediation of stress. We (1) use this continuum to quantify microbial mediation of stress for six plant species and (2) test the association between these continuum values and natural species' abundance. We factorially manipulated a common stress (allelopathy) and the presence of soil microbes to quantify microbial effects in benign and stressed environments for two critical early life-history metrics, seed germination and seedling biomass. Although we found evidence of both mitigation and exacerbation among the six species, exacerbation was more common. Across species, the degree of microbial-mediated effects on germination explained >80% of the variation of natural field abundances. Our results suggest a critical role of soil microbes in mediating plant stress responses, and a potential microbial mechanism underlying species abundance. © 2018 by the Ecological Society of America.

  11. ASSESSMENT OF THE BIODIVERSITY OF SAMPLES USED FOR ISOLATION OF MICROBIAL STRAINS CAPABLE OF CONVERTING STRAW DESTINED AS A SUBSTRATE FOR BIOGAS PLANT

    Directory of Open Access Journals (Sweden)

    Krystyna Cybulska

    2016-01-01

    Full Text Available In biogas plants, almost any type of organic matter can be used as a substrate to produce biogas. To make the process of methane fermentation more effective, these materials are pretreated. This applies in particular to a group of difficult substrates. Straw, due to its hemicellulose structure and saturation, is hardly fermented by biogas reactor microorganisms. The methods of post-harvest residue preparation for anaerobic digestion being applied so far are expensive, while their application has a negative effect on methanoegenic bacteria. Therefore, the microorganisms being able to degrade straw hemicellulose structure, utilisation of which could precede the proper fermentation process, have been searched for. This paper presents the results of microbial biodiversity analysis in the environmental samples being lupin, cereal, rape and maize straw as well as hay and haylage at different degradation stages. The analysis of biodiversity will help at a further stage of study to isolate active microbial strains showing cellulolytic, hemicellulolytic or ligninolytic activity which are desirable in the process of straw biodegradation. Analysis of the microbial count was performed by the method of deep inoculation on different microbiological culture media. The conducted tests include determination of the number of fungi, bacteria and actinomycetes. The results obtained confirm the usefulness of the analysed samples for isolation of microbial strains capable of converting straw preceding the biogas production.

  12. Full-scale agricultural biogas plant metal content and process parameters in relation to bacterial and archaeal microbial communities over 2.5 year span.

    Science.gov (United States)

    Repinc, Sabina Kolbl; Šket, Robert; Zavec, Domen; Mikuš, Katarina Vogel; Fermoso, Fernando G; Stres, Blaž

    2018-05-01

    A start-up of 4 MW agricultural biogas plant in Vučja vas, Slovenia, was monitored from 2011 to 2014. The start-up was carried out in 3 weeks with the intake of biomass from three operating full-scale 1-2 MW donor agricultural biogas plants. The samples were taken from donor digesters and from two serial digesters during the start-up over the course of 2.5 years. Bacterial and Archaeal microbial communities progressively diverged from the composition of donor digesters during the start-up phase. The rate of change of Bacterial community decreased exponentially over the first 2.5 years as dynamics within the first 70 days was comparable to that of the next 1.5 years, whereas approximately constant rate was observed for Archaea. Despite rearrangements, the microbial communities remained functionally stable and produced biogas throughout the whole 2.5 years of observation. All systems parameters measured were ordered according to their Kernel density (Gaussian function) ranging from the most dispersed (substrate categories used as cosubstrates, quantities of each cosubstrate, substate dry and volatile matter, process parameters) towards progressively least dispersed (trace metal and ion profiles, aromatic-polyphenolic compounds, biogas plant functional output (energy)). No deficiency was detected in trace metal content as the distribution of metals and elements fluctuated within the suggested limits for biogas over 2.5 year observation. In contrast to the recorded process variables, Bacterial and Archaeal microbial communities exhibited directed changes oriented in time. Variation partitioning showed that a large fraction of variability in the Bacterial and Archaeal microbial communities (55% and 61%, respectively) remained unexplained despite numerous measured variables (n = 44) and stable biogas production. Our results show that the observed reorganization of microbial communities was not directly associated with impact on the full-scale biogas reactor

  13. The effect of the Falcon 460 EC fungicide on soil microbial communities, enzyme activities and plant growth.

    Science.gov (United States)

    Baćmaga, Małgorzata; Wyszkowska, Jadwiga; Kucharski, Jan

    2016-10-01

    Fungicides are considered to be effective crop protection chemicals in modern agriculture. However, they can also exert toxic effects on non-target organisms, including soil-dwelling microbes. Therefore, the environmental fate of fungicides has to be closely monitored. The aim of this study was to evaluate the influence of the Falcon 460 EC fungicide on microbial diversity, enzyme activity and resistance, and plant growth. Samples of sandy loam with pH KCl 7.0 were collected for laboratory analyses on experimental days 30, 60 and 90. Falcon 460 EC was applied to soil in the following doses: control (soil without the fungicide), dose recommended by the manufacturer, 30-fold higher than the recommended dose, 150-fold higher than the recommended dose and 300-fold higher than the recommended dose. The observed differences in the values of the colony development index and the eco-physiological index indicate that the mixture of spiroxamine, tebuconazole and triadimenol modified the biological diversity of the analyzed groups of soil microorganisms. Bacteria of the genus Bacillus and fungi of the genera Penicillium and Rhizopus were isolated from fungicide-contaminated soil. The tested fungicide inhibited the activity of dehydrogenases, catalase, urease, acid phosphatase and alkaline phosphatase. The greatest changes were induced by the highest fungicide dose 300-fold higher than the recommended dose. Dehydrogenases were most resistant to soil contamination. The Phytotoxkit test revealed that the analyzed fungicide inhibits seed germination capacity and root elongation. The results of this study indicate that excessive doses of the Falcon 460 EC fungicide 30-fold higher than the recommended dose to 300-fold higher than the recommended dose) can induce changes in the biological activity of soil. The analyzed microbiological and biochemical parameters are reliable indicators of the fungicide's toxic effects on soil quality.

  14. Microbial Community Dynamics and Response to Plant Growth-Promoting Microorganisms in the Rhizosphere of Four Common Food Crops Cultivated in Hydroponics.

    Science.gov (United States)

    Sheridan, C; Depuydt, P; De Ro, M; Petit, C; Van Gysegem, E; Delaere, P; Dixon, M; Stasiak, M; Aciksöz, S B; Frossard, E; Paradiso, R; De Pascale, S; Ventorino, V; De Meyer, T; Sas, B; Geelen, D

    2017-02-01

    Plant growth promoting microorganisms (PGPMs) of the plant root zone microbiome have received limited attention in hydroponic cultivation systems. In the framework of a project aimed at the development of a biological life support system for manned missions in space, we investigated the effects of PGPMs on four common food crops (durum and bread wheat, potato and soybean) cultivated in recirculating hydroponic systems for a whole life cycle. Each crop was inoculated with a commercial PGPM mixture and the composition of the microbial communities associated with their root rhizosphere, rhizoplane/endosphere and with the recirculating nutrient solution was characterised through 16S- and ITS-targeted Illumina MiSeq sequencing. PGPM addition was shown to induce changes in the composition of these communities, though these changes varied both between crops and over time. Microbial communities of PGPM-treated plants were shown to be more stable over time. Though additional development is required, this study highlights the potential benefits that PGPMs may confer to plants grown in hydroponic systems, particularly when cultivated in extreme environments such as space.

  15. Senescence and programmed cell death in plants: polyamine action mediated by transglutaminase

    Directory of Open Access Journals (Sweden)

    Stefano eDel Duca

    2014-04-01

    Full Text Available Research on polyamines in plants laps a long way of about 50 years and many roles have been discovered for these aliphatic cations. Polyamines regulate cell division, differentiation, organogenesis, reproduction, dormancy-break and senescence, homeostatic adjustments in response to external stimuli and stresses. Nevertheless, the molecular mechanisms of their multiple activities are still matter of research. Polyamines are present in free and bound forms and interact with several important cell molecules; some of these interactions may occur by covalent linkages catalyzed by transglutaminase, giving rise to ‘cationisation’ or cross-links among specific proteins. Senescence and PCD can be delayed by polyamines; in order to re-interpret some of these effects and to obtain new insights into their molecular mechanisms, their conjugation has been revised here. The transglutaminase-mediated interactions between proteins and polyamines are the main target of this review. After an introduction on the characteristics of this enzyme, on its catalysis and role in PCD in animals, the plant senescence and PCD models in which TGase has been studied, are presented: the corolla of naturally senescing or excised flowers, the leaves senescing, either excised or not, the pollen during self-incompatible pollination, the hypersensitive response and the tuber storage parenchyma during dormancy release. In all the models examined, transglutaminase appears to be involved by a similar molecular mechanism as described during apoptosis in animal cells, even though several substrates are different. Its effect is probably related to the type of PCD, but mostly to the substrate to be modified in order to achieve the specific PCD program. As a cross-linker of polyamines and proteins, transglutaminase is an important factor involved in multiple, sometimes controversial, roles of polyamines during senescence and PCD.

  16. Microbial Inoculants and Their Impact on Soil Microbial Communities: A Review

    Directory of Open Access Journals (Sweden)

    Darine Trabelsi

    2013-01-01

    Full Text Available The knowledge of the survival of inoculated fungal and bacterial strains in field and the effects of their release on the indigenous microbial communities has been of great interest since the practical use of selected natural or genetically modified microorganisms has been developed. Soil inoculation or seed bacterization may lead to changes in the structure of the indigenous microbial communities, which is important with regard to the safety of introduction of microbes into the environment. Many reports indicate that application of microbial inoculants can influence, at least temporarily, the resident microbial communities. However, the major concern remains regarding how the impact on taxonomic groups can be related to effects on functional capabilities of the soil microbial communities. These changes could be the result of direct effects resulting from trophic competitions and antagonistic/synergic interactions with the resident microbial populations, or indirect effects mediated by enhanced root growth and exudation. Combination of inoculants will not necessarily produce an additive or synergic effect, but rather a competitive process. The extent of the inoculation impact on the subsequent crops in relation to the buffering capacity of the plant-soil-biota is still not well documented and should be the focus of future research.

  17. On the Effects of the Evolution of Microbial Mats and Land Plants on the Earth as a Planet. Photometric and Spectroscopic Light Curves of Paleo-Earths

    Science.gov (United States)

    Sanromá, E.; Pallé, E.; García Munõz, A.

    2013-04-01

    Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non-uniformly from deserts through microbial mats to land plants, modifying the reflective properties of the ground and most likely the distribution of moisture and cloudiness. Here, we used a radiative transfer model of the Earth, together with geological paleo-records of the continental distribution and a reconstructed cloud distribution, to simulate the visible and near-IR radiation reflected by our planet as a function of Earth's rotation. We found that the evolution from deserts to microbial mats and to land plants produces detectable changes in the globally averaged Earth's reflectance. The variability of each surface type is located in different bands and can induce reflectance changes of up to 40% in period of hours. We conclude that by using photometric observations of an Earth-like planet at different photometric bands it would be possible to discriminate between different surface types. While recent literature proposes the red-edge feature of vegetation near 0.7 μm as a signature for land plants, observations in near-IR bands can be equally or even better suited for this purpose.

  18. ON THE EFFECTS OF THE EVOLUTION OF MICROBIAL MATS AND LAND PLANTS ON THE EARTH AS A PLANET. PHOTOMETRIC AND SPECTROSCOPIC LIGHT CURVES OF PALEO-EARTHS

    International Nuclear Information System (INIS)

    Sanromá, E.; Pallé, E.; García Munõz, A.

    2013-01-01

    Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non-uniformly from deserts through microbial mats to land plants, modifying the reflective properties of the ground and most likely the distribution of moisture and cloudiness. Here, we used a radiative transfer model of the Earth, together with geological paleo-records of the continental distribution and a reconstructed cloud distribution, to simulate the visible and near-IR radiation reflected by our planet as a function of Earth's rotation. We found that the evolution from deserts to microbial mats and to land plants produces detectable changes in the globally averaged Earth's reflectance. The variability of each surface type is located in different bands and can induce reflectance changes of up to 40% in period of hours. We conclude that by using photometric observations of an Earth-like planet at different photometric bands it would be possible to discriminate between different surface types. While recent literature proposes the red-edge feature of vegetation near 0.7 μm as a signature for land plants, observations in near-IR bands can be equally or even better suited for this purpose.

  19. Microbial decomposers not constrained by climate history along a Mediterranean climate gradient in southern California.

    Science.gov (United States)

    Baker, Nameer R; Khalili, Banafshe; Martiny, Jennifer B H; Allison, Steven D

    2018-06-01

    Microbial decomposers mediate the return of CO 2 to the atmosphere by producing extracellular enzymes to degrade complex plant polymers, making plant carbon available for metabolism. Determining if and how these decomposer communities are constrained in their ability to degrade plant litter is necessary for predicting how carbon cycling will be affected by future climate change. We analyzed mass loss, litter chemistry, microbial biomass, extracellular enzyme activities, and enzyme temperature sensitivities in grassland litter transplanted along a Mediterranean climate gradient in southern California. Microbial community composition was manipulated by caging litter within bags made of nylon membrane that prevent microbial immigration. To test whether grassland microbes were constrained by climate history, half of the bags were inoculated with local microbial communities native to each gradient site. We determined that temperature and precipitation likely interact to limit microbial decomposition in the extreme sites along our gradient. Despite their unique climate history, grassland microbial communities were not restricted in their ability to decompose litter under different climate conditions across the gradient, although microbial communities across our gradient may be restricted in their ability to degrade different types of litter. We did find some evidence that local microbial communities were optimized based on climate, but local microbial taxa that proliferated after inoculation into litterbags did not enhance litter decomposition. Our results suggest that microbial community composition does not constrain C-cycling rates under climate change in our system, but optimization to particular resource environments may act as more general constraints on microbial communities. © 2018 by the Ecological Society of America.

  20. Inside out: high-efficiency plant regeneration and Agrobacterium-mediated transformation of upland and lowland switchgrass cultivars.

    Science.gov (United States)

    Liu, Yan-Rong; Cen, Hui-Fang; Yan, Jian-Ping; Zhang, Yun-Wei; Zhang, Wan-Jun

    2015-07-01

    Selection of pre-embryogenic callus from a core structure from mature seed-derived callus is the key for high-efficiency plant regeneration and transformation of switchgrass different cultivars. Switchgrass (Panicum virgatum L.) has been identified as a dedicated biofuel crop. For its trait improvement through biotechnological approaches, we have developed a highly efficient plant regeneration and genetic transformation protocol for both lowland and upland cultivars. We identified and separated a pre-embryogenic "core" structure from the seed-derived callus, which often leads to development of highly regenerative type II calluses. From the type II callus, plant regeneration rate of lowland cultivars Alamo and Performer reaches 95%, and upland cultivars Blackwell and Dacotah, 50 and 76%, respectively. The type II callus was also amenable for Agrobacterium-mediated transformation. Transformation efficiency of 72.8% was achieved for lowland cultivar Alamo, and 8.0% for upland cultivar Dacotah. PCR, Southern blot and GUS staining assays were performed to verify the transgenic events. High regenerative callus lines could be established in 3 months, and transgenic plants could be obtained in 2 months after Agrobacterium infection. To our knowledge, this is the first report on successful plant regeneration and recovery of transgenic plants from upland switchgrass cultivars by Agrobacterium-mediated transformation. The method presented here could be helpful in breaking through the bottleneck of regeneration and transformation of lowland and upland switchgrass cultivars and probably other recalcitrant grass crops.

  1. Disruption of Ethylene Responses by Turnip mosaic virus Mediates Suppression of Plant Defense against the Green Peach Aphid Vector.

    Science.gov (United States)

    Casteel, Clare L; De Alwis, Manori; Bak, Aurélie; Dong, Haili; Whitham, Steven A; Jander, Georg

    2015-09-01

    Plants employ diverse responses mediated by phytohormones to defend themselves against pathogens and herbivores. Adapted pathogens and herbivores often manipulate these responses to their benefit. Previously, we demonstrated that Turnip mosaic virus (TuMV) infection suppresses callose deposition, an important plant defense induced in response to feeding by its aphid vector, the green peach aphid (Myzus persicae), and increases aphid fecundity compared with uninfected control plants. Further, we determined that production of a single TuMV protein, Nuclear Inclusion a-Protease (NIa-Pro) domain, was responsible for changes in host plant physiology and increased green peach aphid reproduction. To characterize the underlying molecular mechanisms of this phenomenon, we examined the role of three phytohormone signaling pathways, jasmonic acid, salicylic acid, and ethylene (ET), in TuMV-infected Arabidopsis (Arabidopsis thaliana), with or without aphid herbivory. Experiments with Arabidopsis mutants ethylene insensitive2 and ethylene response1, and chemical inhibitors of ET synthesis and perception (aminoethoxyvinyl-glycine and 1-methylcyclopropene, respectively), show that the ET signaling pathway is required for TuMV-mediated suppression of Arabidopsis resistance to the green peach aphid. Additionally, transgenic expression of NIa-Pro in Arabidopsis alters ET responses and suppresses aphid-induced callose formation in an ET-dependent manner. Thus, disruption of ET responses in plants is an additional function of NIa-Pro, a highly conserved potyvirus protein. Virus-induced changes in ET responses may mediate vector-plant interactions more broadly and thus represent a conserved mechanism for increasing transmission by insect vectors across generations. © 2015 American Society of Plant Biologists. All Rights Reserved.

  2. Mechanism of plant-mediated synthesis of silver nanoparticles - A review on biomolecules involved, characterisation and antibacterial activity.

    Science.gov (United States)

    Rajeshkumar, S; Bharath, L V

    2017-08-01

    Engineering a reliable and eco-accommodating methodology for the synthesis of metal nanoparticles is a crucial step in the field of nanotechnology. Plant-mediated synthesis of metal nanoparticles has been developed as a substitute to defeat the limitations of conventional synthesis approaches such as physical and chemical methods. Biomolecules, such as proteins, amino acids, enzymes, flavonoids, and terpenoids from several plant extracts have been used as a stabilising and reducing agents for the synthesis of AgNPs. Regardless of an extensive range of biomolecules assistance in the synthesis procedure, researchers are facing a significant challenge to synthesise stable and geometrically controlled AgNPs. In the past decade, several efforts were made to develop Plant-mediated synthesis methods to produce stable, cost effective and eco-friendly AgNPs. More than hundred different plants extract sources for synthesising AgNPs were described in the last decade by several researchers. Most of the reviews were focused on various plant sources for synthesis, various characterization techniques for characteristic analysis, and antibacterial activity against bacterial. There are many reviews are available for the plant-mediated synthesis of AgNPs as well as antibacterial activity of AgNPs but this is the first review article mainly focused on biomolecules of plants and its various parts and operating conditions involved in the synthesis. Apart from, this review includes the characterisation of AgNPs and antibacterial activity of such nanoparticles with size, shape and method used for this study. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Soil mineral composition matters: response of microbial communities to phenanthrene and plant litter addition in long-term matured artificial soils.

    Science.gov (United States)

    Babin, Doreen; Vogel, Cordula; Zühlke, Sebastian; Schloter, Michael; Pronk, Geertje Johanna; Heister, Katja; Spiteller, Michael; Kögel-Knabner, Ingrid; Smalla, Kornelia

    2014-01-01

    The fate of polycyclic aromatic hydrocarbons (PAHs) in soil is determined by a suite of biotic and abiotic factors, and disentangling their role in the complex soil interaction network remains challenging. Here, we investigate the influence of soil composition on the microbial community structure and its response to the spiked model PAH compound phenanthrene and plant litter. We used long-term matured artificial soils differing in type of clay mineral (illite, montmorillonite) and presence of charcoal or ferrihydrite. The soils received an identical soil microbial fraction and were incubated for more than two years with two sterile manure additions. The matured artificial soils and a natural soil were subjected to the following spiking treatments: (I) phenanthrene, (II) litter, (III) litter + phenanthrene, (IV) unspiked control. Total community DNA was extracted from soil sampled on the day of spiking, 7, 21, and 63 days after spiking. Bacterial 16S rRNA gene and fungal internal transcribed spacer amplicons were quantified by qPCR and subjected to denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed that the bacterial community composition, which was strongly shaped by clay minerals after more than two years of incubation, changed in response to spiked phenanthrene and added litter. DGGE and qPCR showed that soil composition significantly influenced the microbial response to spiking. While fungal communities responded only in presence of litter to phenanthrene spiking, the response of the bacterial communities to phenanthrene was less pronounced when litter was present. Interestingly, microbial communities in all artificial soils were more strongly affected by spiking than in the natural soil, which might indicate the importance of higher microbial diversity to compensate perturbations. This study showed the influence of soil composition on the microbiota and their response to phenanthrene and litter, which may increase our understanding of

  4. Topography- and management-mediated resource gradients maintain rare and common plant diversity around paddy terraces.

    Science.gov (United States)

    Uematsu, Yuta; Ushimaru, Atushi

    2013-09-01

    Examining the causes of interspecific differences in susceptibility to bidirectional land-use changes (land abandonment and use-intensification) is important for understanding the mechanisms of global biodiversity loss in agricultural landscapes. We tested the hypothesis that rare (endangered) plant species prefer wet and oligotrophic areas within topography- and management-mediated resource (soil water content, nutrient, and aboveground biomass) gradients, making them more susceptible to both abandonment and use-intensification of agricultural lands. We demonstrated that topography and management practices generated resource gradients in seminatural grasslands around traditional paddy terraces. Terraced topography and management practices produced a soil moisture gradient within levees and a nutrient gradient within paddy terraces. Both total and rare species diversity increased with soil water content. Total species diversity increased in more eutrophied areas with low aboveground biomass, whereas rare species diversity was high under oligotrophic conditions. Rare and common species were differentially distributed along the human-induced nutrient gradient, with rare species preferring wet, nutrient-poor environments in the agricultural landscapes studied. We suggest that conservation efforts should concentrate on wet, nutrient-poor areas within such landscapes, which can be located easily using land-use and topography maps. This strategy would reduce the costs of finding and conserving rare grassland species in a given agricultural landscape.

  5. Plant-Mediated Changes in Soil N-Cycling Genes during Revegetation of Copper Mine Tailings

    Directory of Open Access Journals (Sweden)

    Yang Li

    2017-11-01

    Full Text Available Nitrogen limitation represents a major bottleneck during the revegetation of mine tailings. However, controls over key nitrogen-cycling genes in rhizospheric soils under differential vegetation management remain poorly understood. The abundance and transcriptional activity of nitrogen-cycling genes and the enzymatic activity of nitrogen transformation are mediated differentially during revegetation of mine tailings by Imperata cylindrica and Chrysopogon zizanioides plants. Results showed that the highest total organic carbon (TOC, total nitrogen (TN, and NH4+-N contents were found in the rhizosphere of I. cylindrica. The nifH gene abundances differed between I. cylindrica and C. zizanioides, and were higher in I. cylindrica which demonstrated by 3.39-fold higher mRNA transcript abundance of the nifH gene and a 2.15-fold higher nitrogen fixation rate in the rhizosphere. In addition, C. zizanioides exhibited a 4.94-fold higher transcript abundance of the archaeal amoA gene and the highest nitrification rate (1.706 ± 0.293 μg N-NO2- g−1 h−1 in the rhizosphere. In conclusion, I. cylindrica and C. zizanioides stimulated the abundances and activities of nifH gene and archaeal amoA gene, respectively. In addition, I. cylindrica appears to be capable of enhancing nitrogen fixation and exhibited accelerated nitrogen accumulation, which may be particularly useful for the rehabilitation of mine tailings.

  6. Crop resistance traits modify the effects of an aboveground herbivore, brown planthopper, on soil microbial biomass and nematode community via changes to plant performance.

    NARCIS (Netherlands)

    Huang, J.; Liu, M.; Chen, F.; Griffiths, B.S.; Chen, X.; Johnson, S.N.; Hu, F.

    2012-01-01

    Plant-mediated effects of aboveground herbivory on the belowground ecosystem are well documented, but less attention has been paid to agro-ecosystems and in particular how crop cultivars with different traits (i.e. resistance to pests) shape such interactions. A fully factorial experiment was

  7. Allopurinol-mediated lignocellulose-derived microbial inhibitor tolerance by Clostridium beijerinckii during acetone-butanol-ethanol (ABE) fermentation.

    Science.gov (United States)

    Ujor, Victor; Agu, Chidozie Victor; Gopalan, Venkat; Ezeji, Thaddeus Chukwuemeka

    2015-04-01

    In addition to glucans, xylans, and arabinans, lignocellulosic biomass hydrolysates contain significant levels of nonsugar components that are toxic to the microbes that are typically used to convert biomass to biofuels and chemicals. To enhance the tolerance of acetone-butanol-ethanol (ABE)-generating Clostridium beijerinckii NCIMB 8052 to these lignocellulose-derived microbial inhibitory compounds (LDMICs; e.g., furfural), we have been examining different metabolic perturbation strategies to increase the cellular reductant pools and thereby facilitate detoxification of LDMICs. As part of these efforts, we evaluated the effect of allopurinol, an inhibitor of NAD(P)H-generating xanthine dehydrogenase (XDH), on C. beijerinckii grown in furfural-supplemented medium and found that it unexpectedly increased the rate of detoxification of furfural by 1.4-fold and promoted growth, butanol, and ABE production by 1.2-, 2.5-, and 2-fold, respectively. Since NAD(P)H/NAD(P)(+) levels in C. beijerinckii were largely unchanged upon allopurinol treatment, we postulated and validated a possible basis in DNA repair to account for the solventogenic gains with allopurinol. Following the observation that supplementation of allopurinol in the C. beijerinckii growth media mitigates the toxic effects of nalidixic acid, a DNA-damaging antibiotic, we found that allopurinol elicited 2.4- and 6.7-fold increase in the messenger RNA (mRNA) levels of xanthine and hypoxanthine phosphoribosyltransferases, key purine-salvage enzymes. Consistent with this finding, addition of inosine (a precursor of hypoxanthine) and xanthine led to 1.4- and 1.7-fold increase in butanol production in furfural-challenged cultures of C. beijerinckii. Taken together, our results provide a purine salvage-based rationale for the unanticipated effect of allopurinol in improving furfural tolerance of the ABE-fermenting C. beijerinckii.

  8. Conservation and variability in the structure and function of the Cas5d endoribonuclease in the CRISPR-mediated microbial immune system.

    Science.gov (United States)

    Koo, Yoon; Ka, Donghyun; Kim, Eun-Jin; Suh, Nayoung; Bae, Euiyoung

    2013-10-23

    Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins form an RNA-mediated microbial immune system against invading foreign genetic elements. Cas5 proteins constitute one of the most prevalent Cas protein families in CRISPR-Cas systems and are predicted to have RNA recognition motif (RRM) domains. Cas5d is a subtype I-C-specific Cas5 protein that can be divided into two distinct subgroups, one of which has extra C-terminal residues while the other contains a longer insertion in the middle of its N-terminal RRM domain. Here, we report crystal structures of Cas5d from Streptococcus pyogenes and Xanthomonas oryzae, which respectively represent the two Cas5d subgroups. Despite a common domain architecture consisting of an N-terminal RRM domain and a C-terminal β-sheet domain, the structural differences between the two Cas5d proteins are highlighted by the presence of a unique extended helical region protruding from the N-terminal RRM domain of X. oryzae Cas5d. We also demonstrate that Cas5d proteins possess not only specific endoribonuclease activity for CRISPR RNAs but also nonspecific double-stranded DNA binding affinity. These findings suggest that Cas5d may play multiple roles in CRISPR-mediated immunity. Furthermore, the specific RNA processing was also observed between S. pyogenes Cas5d protein and X. oryzae CRISPR RNA and vice versa. This cross-species activity of Cas5d provides a special opportunity for elucidating conserved features of the CRISPR RNA processing event. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Method of inhibiting plant virus pathogen infections by crispr/cas9-mediated interference

    KAUST Repository

    Mahfouz, Magdy M.; Ali, Zahir

    2016-01-01

    A genetically modified tobacco plant or tomato plant resistant to at least one pathogenic geminiviridae virus species is provided. The plant comprises a heterologous CRISPR/Cas9 system and at least one heterologous nucleotide sequence

  10. Redox Homeostasis in Plants under Abiotic Stress: Role of electron carriers, energy metabolism mediators and proteinaceous thiols

    Directory of Open Access Journals (Sweden)

    Dhriti Kapoor

    2015-03-01

    Full Text Available Contemporaneous presence of both oxidized and reduced forms of electron carriers is mandatory in efficient flux by plant electron transport cascades. This requirement is considered as redox poising that involves the movement of electron from multiple sites in respiratory and photosynthetic electron transport chains to molecular oxygen. This flux triggers the formation of superoxide, consequently give rise to other reactive oxygen species (ROS under adverse environmental conditions like drought, high or low temperature, heavy metal stress etc. that plants owing during their life span. Plant cells synthesize ascorbate, an additional hydrophilic redox buffer, which protect the plants against oxidative challenge. Large pools of antioxidants also preside over the redox homeostasis. Besides, tocopherol is a liposoluble redox buffer, which efficiently scavenges the ROS like singlet oxygen. In addition, proteinaceous thiol members such as thioredoxin, peroxiredoxin and glutaredoxin, electron carriers and energy metabolism mediators phosphorylated (NADP and non-phosphorylated (NAD+ coenzyme forms interact with ROS, metabolize and maintain redox homeostasis.

  11. Biodegradation of isopropanol and acetone under denitrifying conditions by Thauera sp. TK001 for nitrate-mediated microbially enhanced oil recovery.

    Science.gov (United States)

    Fida, Tekle Tafese; Gassara, Fatma; Voordouw, Gerrit

    2017-07-15

    Amendment of reservoir fluid with injected substrates can enhance the growth and activity of microbes. The present study used isopropyl alcohol (IPA) or acetone to enhance the indigenous anaerobic nitrate-reducing bacterium Thauera sp. TK001. The strain was able to grow on IPA or acetone and nitrate. To monitor effects of strain TK001 on oil recovery, sand-packed columns containing heavy oil were flooded with minimal medium at atmospheric or high (400psi) pressure. Bioreactors were then inoculated with 0.5 pore volume (PV) of minimal medium containing Thauera sp. TK001 with 25mM of acetone or 22.2mM of IPA with or without 80mM nitrate. Incubation without flow for two weeks and subsequent injection with minimal medium gave an additional 17.0±6.7% of residual oil in place (ROIP) from low-pressure bioreactors and an additional 18.3% of ROIP from the high-pressure bioreactors. These results indicate that acetone or IPA, which are commonly used organic solvents, are good substrates for nitrate-mediated microbial enhanced oil recovery (MEOR), comparable to glucose, acetate or molasses, tested previously. This technology may be used for coupling biodegradation of IPA and/or acetone in waste streams to MEOR where these waste streams are generated in close proximity to an oil field. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Application of a qualitative image analysis on the evaluation of microbial process parameters of biogas plants; Einsatz einer quantitativen Bildanalyse zur Beurteilung mikrobieller Prozessparameter von Biogasanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Sung; Scherer, Paul [Hamburg Univ. of Applied Sciences, Hamburg-Bergedorf (Germany). Faculty of Life Sciences

    2013-10-01

    To evaluate efficiency and microbial activity of biogas or anaerobic waste water treatment plants, the number of microorganisms per gram or per milliliter is supposed to be a crucial factor. Since some years ago our research group at HAW-Hamburg has struggled to develop a simple and rapid technique for quantification and classification of environmental microbes with a semi-automatic digital image analysis. For detection of methanogens, the methanogenic fluorescence coenzyme F420 was used, which represents the vitality of methanogens. Furthermore this technique has been supplemented with morphological classification resulting in a Quantitative Microscopic Fingerprinting (QMF). The technique facilitates to find out microbial reasons for some problems of reactor performances. In addition QMF allows differentiating between H{sub 2}-CO{sub 2} and acetate consuming methanogens according to their morphology. At the moment, this study focusses on some relationships between QMF and plant operation parameters. As an example, a thermophilic biogas plant fed by 65% liquid cow manure, maize silage, grass silage and solid cow manure was analyzed for more than 22 weeks. Here some basic background and methodical procedures were presented as well as validation of this technique. (orig.)

  13. Pharmacological synergism of bee venom and melittin with antibiotics and plant secondary metabolites against multi-drug resistant microbial pathogens.

    Science.gov (United States)

    Al-Ani, Issam; Zimmermann, Stefan; Reichling, Jürgen; Wink, Michael

    2015-02-15

    The goal of this study was to investigate the antimicrobial activity of bee venom and its main component, melittin, alone or in two-drug and three-drug combinations with antibiotics (vancomycin, oxacillin, and amikacin) or antimicrobial plant secondary metabolites (carvacrol, benzyl isothiocyanate, the alkaloids sanguinarine and berberine) against drug-sensitive and antibiotic-resistant microbial pathogens. The secondary metabolites were selected corresponding to the molecular targets to which they are directed, being different from those of melittin and the antibiotics. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were evaluated by the standard broth microdilution method, while synergistic or additive interactions were assessed by checkerboard dilution and time-kill curve assays. Bee venom and melittin exhibited a broad spectrum of antibacterial activity against 51 strains of both Gram-positive and Gram-negative bacteria with strong anti-MRSA and anti-VRE activity (MIC values between 6 and 800 µg/ml). Moreover, bee venom and melittin showed significant antifungal activity (MIC values between 30 and 100 µg/ml). Carvacrol displayed bactericidal activity, while BITC exhibited bacteriostatic activity against all MRSA and VRE strains tested (reference strains and clinical isolates), both compounds showed a remarkable fungicidal activity with minimum fungicidal concentration (MFC) values between 30 and 200 µg/ml. The DNA intercalating alkaloid sanguinarine showed bactericidal activity against MRSA NCTC 10442 (MBC 20 µg/ml), while berberine exhibited bacteriostatic activity against MRSA NCTC 10442 (MIC 40 µg/ml). Checkerboard dilution tests mostly revealed synergism of two-drug combinations against all the tested microorganisms with FIC indexes between 0.24 and 0.50, except for rapidly growing mycobacteria in which combinations exerted an additive effect (FICI = 0.75-1). In time-kill assays all three

  14. Altered Plant Litter and Microbial Composition Lead to Topsoil Organic Carbon Loss Over a Shrub-encroachment Gradient in an Inner Mongolia Grassland

    Science.gov (United States)

    Zhou, L.; Li, H.; Shen, H.; Xu, Y.; Wang, Y.; Xing, A.; Fang, J.

    2017-12-01

    Over the past 150 years, shrub encroachment has occurred in arid and semi-arid ecosystems resulting from climate change and increased human disturbance. Previous studies have revealed that shrub encroachment has substantial effects on habitat heterogeneity, aboveground biomass and bulk carbon content of grasslands, thereby affecting the regional carbon balance. Soil organic carbon (SOC) is mainly derived from aboveground litter, root litter and root exudates and is metabolized by microorganisms. The quality and quantity of plant litter together with soil microbial biomass are important drivers of SOC accumulation. However, the mechanisms regulating soil carbon accumulation by the shrub encroachment remain unclear and molecular evidence is particularly lacking. We use the data of the chemical composition of plant tissues and SOC, and the soil microbial communities to identify the effects of shrub encroachment on SOC accumulation in the top layer along a gradient of natural shrub cover in the grasslands of Inner Mongolia. Our finding indicates that nitrogen-rich legume-shrub encroachment led to soil carbon accumulation in the shrub patch, with more extensive carbon loss observed in the grassy matrix, which resulted in an overall carbon loss. In the pure grassland, a higher abundance of cutin and suberin and a lower concentration of free lipids were detected, suggesting the preservation of recalcitrant polymers derived from herb inputs. In the shrub-encroached grasslands, the labile shrub leaves did not decompose alone but were mixed with herb litter to promote the degradation of SOC via the priming of microbial activities. The SOC remained unchanged in the shrub patches with the increasing shrub cover, which might have been caused by the replacement of prior carbon decompositions with the fresh input of shrub leaves. Similarly, the SOC decreased significantly with increasing shrub cover in the grassy matrix, which likely resulted from insufficient fresh plant inputs

  15. A method for the production and expedient screening of CRISPR/Cas9-mediated non-transgenic mutant plants.

    Science.gov (United States)

    Chen, Longzheng; Li, Wei; Katin-Grazzini, Lorenzo; Ding, Jing; Gu, Xianbin; Li, Yanjun; Gu, Tingting; Wang, Ren; Lin, Xinchun; Deng, Ziniu; McAvoy, Richard J; Gmitter, Frederick G; Deng, Zhanao; Zhao, Yunde; Li, Yi

    2018-01-01

    Developing CRISPR/Cas9-mediated non-transgenic mutants in asexually propagated perennial crop plants is challenging but highly desirable. Here, we report a highly useful method using an Agrobacterium -mediated transient CRISPR/Cas9 gene expression system to create non-transgenic mutant plants without the need for sexual segregation. We have also developed a rapid, cost-effective, and high-throughput mutant screening protocol based on Illumina sequencing followed by high-resolution melting (HRM) analysis. Using tetraploid tobacco as a model species and the phytoene desaturase ( PDS ) gene as a target, we successfully created and expediently identified mutant plants, which were verified as tetra-allelic mutants. We produced pds mutant shoots at a rate of 47.5% from tobacco leaf explants, without the use of antibiotic selection. Among these pds plants, 17.2% were confirmed to be non-transgenic, for an overall non-transgenic mutation rate of 8.2%. Our method is reliable and effective in creating non-transgenic mutant plants without the need to segregate out transgenes through sexual reproduction. This method should be applicable to many economically important, heterozygous, perennial crop species that are more difficult to regenerate.

  16. Natural history-driven, plant-mediated RNAi-based study reveals CYP6B46's role in a nicotine-mediated antipredator herbivore defense.

    Science.gov (United States)

    Kumar, Pavan; Pandit, Sagar S; Steppuhn, Anke; Baldwin, Ian T

    2014-01-28

    Manduca sexta (Ms) larvae are known to efficiently excrete ingested nicotine when feeding on their nicotine-producing native hostplant, Nicotiana attenuata. Here we describe how ingested nicotine is co-opted for larval defense by a unique mechanism. Plant-mediated RNAi was used to silence a midgut-expressed, nicotine-induced cytochrome P450 6B46 (CYP6B46) in larvae consuming transgenic N. attenuata plants producing MsCYP6B46 dsRNA. These and transgenic nicotine-deficient plants were planted into native habitats to study the phenotypes of larvae feeding on these plants and the behavior of their predators. The attack-behavior of a native wolf spider (Camptocosa parallela), a major nocturnal predator, provided the key to understanding MsCYP6B46's function: spiders clearly preferred CYP6B46-silenced larvae, just as they had preferred larvae fed nicotine-deficient plants. MsCYP6B46 redirects a small amount (0.65%) of ingested nicotine from the midgut into hemolymph, from which nicotine is exhaled through the spiracles as an antispider signal. CYP6B46-silenced larvae were more susceptible to spider-attack because they exhaled less nicotine because of lower hemolymph nicotine concentrations. CYP6B46-silenced larvae were impaired in distributing ingested nicotine from midgut to hemolymph, but not in the clearing of hemolymph nicotine or in the exhalation of nicotine from hemolymph. MsCYP6B46 could be a component of a previously hypothesized pump that converts nicotine to a short-lived, transportable, metabolite. Other predators, big-eyed bugs, and antlion larvae were insensitive to this defense. Thus, chemical defenses, too toxic to sequester, can be repurposed for defensive functions through respiration as a form of defensive halitosis, and predators can assist the functional elucidation of herbivore genes.

  17. Considering a Threshold Energy in Reactive Transport Modeling of Microbially Mediated Redox Reactions in an Arsenic-Affected Aquifer

    Directory of Open Access Journals (Sweden)

    Marco Rotiroti

    2018-01-01

    Full Text Available The reductive dissolution of Fe-oxide driven by organic matter oxidation is the primary mechanism accepted for As mobilization in several alluvial aquifers. These processes are often mediated by microorganisms that require a minimum Gibbs energy available to conduct the reaction in order to sustain their life functions. Implementing this threshold energy in reactive transport modeling is rarely used in the existing literature. This work presents a 1D reactive transport modeling of As mobilization by the reductive dissolution of Fe-oxide and subsequent immobilization by co-precipitation in iron sulfides considering a threshold energy for the following terminal electron accepting processes: (a Fe-oxide reduction, (b sulfate reduction, and (c methanogenesis. The model is then extended by implementing a threshold energy on both reaction directions for the redox reaction pairs Fe(III reduction/Fe(II oxidation and methanogenesis/methane oxidation. The optimal threshold energy fitted in 4.50, 3.76, and 1.60 kJ/mol e− for sulfate reduction, Fe(III reduction/Fe(II oxidation, and methanogenesis/methane oxidation, respectively. The use of models implementing bidirectional threshold energy is needed when a redox reaction pair can be transported between domains with different redox potentials. This may often occur in 2D or 3D simulations.

  18. Microbial Ecology of Soil Aggregation in Agroecosystems

    Science.gov (United States)

    Hofmockel, K. S.; Bell, S.; Tfailly, M.; Thompson, A.; Callister, S.

    2017-12-01

    Crop selection and soil texture influence the physicochemical attributes of the soil, which structures microbial communities and influences soil C cycling storage. At the molecular scale, microbial metabolites and necromass alter the soil environment, which creates feedbacks that influence ecosystem functions, including soil C accumulation. By integrating lab to field studies we aim to identify the molecules, organisms and metabolic pathways that control carbon cycling and stabilization in bioenergy soils. We investigated the relative influence of plants, microbes, and minerals on soil aggregate ecology at the Great Lakes Bioenergy Research experiment. Sites in WI and MI, USA have been in corn and switchgrass cropping systems for a decade. By comparing soil aggregate ecology across sites and cropping systems we are able to test the relative importance of plant, microbe, mineral influences on soil aggregate dynamics. Soil