Phylogenomics of 2,4-Diacetylphloroglucinol-Producing Pseudomonas and Novel Antiglycation Endophytes from Piper auritum.

PubMed

Gutiérrez-García, Karina; Neira-González, Adriana; Pérez-Gutiérrez, Rosa Martha; Granados-Ramírez, Giovana; Zarraga, Ramon; Wrobel, Kazimierz; Barona-Gómez, Francisco; Flores-Cotera, Luis B

2017-07-28

2,4-Diacetylphloroglucinol (DAPG) (1) is a phenolic polyketide produced by some plant-associated Pseudomonas species, with many biological activities and ecological functions. Here, we aimed at reconstructing the natural history of DAPG using phylogenomics focused at its biosynthetic gene cluster or phl genes. In addition to around 1500 publically available genomes, we obtained and analyzed the sequences of nine novel Pseudomonas endophytes isolated from the antidiabetic medicinal plant Piper auritum. We found that 29 organisms belonging to six Pseudomonas species contain the phl genes at different frequencies depending on the species. The evolution of the phl genes was then reconstructed, leading to at least two clades postulated to correlate with the known chemical diversity surrounding DAPG biosynthesis. Moreover, two of the newly obtained Pseudomonas endophytes with high antiglycation activity were shown to exert their inhibitory activity against the formation of advanced glycation end-products via DAPG and related congeners. Its isomer, 5-hydroxyferulic acid (2), detected during bioactivity-guided fractionation, together with other DAPG congeners, were found to enhance the detected inhibitory activity. This report provides evidence of a link between the evolution and chemical diversity of DAPG and congeners.

Endophytic bacterial community living in roots of healthy and 'Candidatus Phytoplasma mali'-infected apple (Malus domestica, Borkh.) trees.

PubMed

Bulgari, Daniela; Bozkurt, Adem I; Casati, Paola; Cağlayan, Kadriye; Quaglino, Fabio; Bianco, Piero A

2012-11-01

'Candidatus Phytoplasma mali', the causal agent of apple proliferation (AP) disease, is a quarantine pathogen controlled by chemical treatments against insect vectors and eradication of diseased plants. In accordance with the European Community guidelines, novel strategies should be developed for sustainable management of plant diseases by using resistance inducers (e.g. endophytes). A basic point for the success of this approach is the study of endophytic bacteria associated with plants. In the present work, endophytic bacteria living in healthy and 'Ca. Phytoplasma mali'-infected apple trees were described by cultivation-dependent and independent methods. 16S rDNA sequence analysis showed the presence of the groups Proteobacteria, Acidobacteria, Bacteroidetes, Actinobacteria, Chlamydiae, and Firmicutes. In detail, library analyses underscored 24 and 17 operational taxonomic units (OTUs) in healthy and infected roots, respectively, with a dominance of Betaproteobacteria. Moreover, differences in OTUs number and in CFU/g suggested that phytoplasmas could modify the composition of endophytic bacterial communities associated with infected plants. Intriguingly, the combination of culturing methods and cloning analysis allowed the identification of endophytic bacteria (e.g. Bacillus, Pseudomonas, and Burkholderia) that have been reported as biocontrol agents. Future research will investigate the capability of these bacteria to control 'Ca. Phytoplasma mali' in order to develop sustainable approaches for managing AP.

Screening mycotoxins for quorum inhibition in a biocontrol bacterial endophyte

USDA-ARS?s Scientific Manuscript database

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

Diversity of endophytic Pseudomonas in Halimione portulacoides from metal(loid)-polluted salt marshes.

PubMed

Rocha, Jaqueline; Tacão, Marta; Fidalgo, Cátia; Alves, Artur; Henriques, Isabel

2016-07-01

Phytoremediation assisted by bacteria is seen as a promising alternative to reduce metal contamination in the environment. The main goal of this study was to characterize endophytic Pseudomonas isolated from Halimione portulacoides, a metal-accumulator plant, in salt marshes contaminated with metal(loid)s. Phylogenetic analysis based on 16S rRNA and gyrB genes showed that isolates affiliated with P. sabulinigri (n = 16), P. koreensis (n = 10), P. simiae (n = 5), P. seleniipraecipitans (n = 2), P. guineae (n = 2), P. migulae (n = 1), P. fragi (n = 1), P. xanthomarina (n = 1), and Pseudomonas sp. (n = 1). Most of these species have never been described as endophytic. The majority of the isolates were resistant to three or more metal(loid)s. Antibiotic resistance was frequent among the isolates but most likely related to species-intrinsic features. Common acquired antibiotic resistance genes and integrons were not detected. Plasmids were detected in 43.6 % of the isolates. Isolates that affiliated with different species shared the same plasmid profile but attempts to transfer metal resistance to receptor strains were not successful. Phosphate solubilization and IAA production were the most prevalent plant growth promoting traits, and 20 % of the isolates showed activity against phytopathogenic bacteria. Most isolates produced four or more extracellular enzymes. Preliminary results showed that two selected isolates promote Arabidopsis thaliana root elongation. Results highlight the diversity of endophytic Pseudomonas in H. portulacoides from contaminated sites and their potential to assist phytoremediation by acting as plant growth promoters and as environmental detoxifiers.

Endophytic colonization of olive roots by the biocontrol strain Pseudomonas fluorescens PICF7.

PubMed

Prieto, Pilar; Mercado-Blanco, Jesús

2008-05-01

Confocal microscopy combined with three-dimensional olive root tissue sectioning was used to provide evidence of the endophytic behaviour of Pseudomonas fluorescens PICF7, an effective biocontrol strain against Verticillium wilt of olive. Two derivatives of the green fluorescent protein (GFP), the enhanced green and the red fluorescent proteins, have been used to visualize simultaneously two differently fluorescently tagged populations of P. fluorescens PICF7 within olive root tissues at the single cell level. The time-course of colonization events of olive roots cv. Arbequina by strain PICF7 and the localization of tagged bacteria within olive root tissues are described. First, bacteria rapidly colonized root surfaces and were predominantly found in the differentiation zone. Thereafter, microscopy observations showed that PICF7-tagged populations eventually disappeared from the root surface, and increasingly colonized inner root tissues. Localized and limited endophytic colonization by the introduced bacteria was observed over time. Fluorescent-tagged bacteria were always visualized in the intercellular spaces of the cortex region, and no colonization of the root xylem vessels was detected at any time. To the best of our knowledge, this is the first time this approach has been used to demonstrate endophytism of a biocontrol Pseudomonas spp. strain in a woody host such as olive using a nongnotobiotic system.

Bacterial endophyte communities of three agricultural important grass species differ in their response towards management regimes

NASA Astrophysics Data System (ADS)

Wemheuer, Franziska; Kaiser, Kristin; Karlovsky, Petr; Daniel, Rolf; Vidal, Stefan; Wemheuer, Bernd

2017-01-01

Endophytic bacteria are critical for plant growth and health. However, compositional and functional responses of bacterial endophyte communities towards agricultural practices are still poorly understood. Hence, we analyzed the influence of fertilizer application and mowing frequency on bacterial endophytes in three agriculturally important grass species. For this purpose, we examined bacterial endophytic communities in aerial plant parts of Dactylis glomerata L., Festuca rubra L., and Lolium perenne L. by pyrotag sequencing of bacterial 16S rRNA genes over two consecutive years. Although management regimes influenced endophyte communities, observed responses were grass species-specific. This might be attributed to several bacteria specifically associated with a single grass species. We further predicted functional profiles from obtained 16S rRNA data. These profiles revealed that predicted abundances of genes involved in plant growth promotion or nitrogen metabolism differed between grass species and between management regimes. Moreover, structural and functional community patterns showed no correlation to each other indicating that plant species-specific selection of endophytes is driven by functional rather than phylogenetic traits. The unique combination of 16S rRNA data and functional profiles provided a holistic picture of compositional and functional responses of bacterial endophytes in agricultural relevant grass species towards management practices.

Influences of Plant Species, Season and Location on Leaf Endophytic Bacterial Communities of Non-Cultivated Plants

PubMed Central

Ding, Tao; Melcher, Ulrich

2016-01-01

Bacteria are known to be associated endophytically with plants. Research on endophytic bacteria has identified their importance in food safety, agricultural production and phytoremediation. However, the diversity of endophytic bacterial communities and the forces that shape their compositions in non-cultivated plants are largely uncharacterized. In this study, we explored the diversity, community structure, and dynamics of endophytic bacteria in different plant species in the Tallgrass Prairie Preserve of northern Oklahoma, USA. High throughput sequencing of amplified segments of bacterial rDNA from 81 samples collected at four sampling times from five plant species at four locations identified 335 distinct OTUs at 97% sequence similarity, representing 16 phyla. Proteobacteria was the dominant phylum in the communities, followed by the phyla Bacteriodetes and Actinobacteria. Bacteria from four classes of Proteobacteria were detected with Alphaproteobacteria as the dominant class. Analysis of molecular variance revealed that host plant species and collecting date had significant influences on the compositions of the leaf endophytic bacterial communities. The proportion of Alphaproteobacteria was much higher in the communities from Asclepias viridis than from other plant species and differed from month to month. The most dominant bacterial groups identified in LDA Effect Size analysis showed host-specific patterns, indicating mutual selection between host plants and endophytic bacteria and that leaf endophytic bacterial compositions were dynamic, varying with the host plant’s growing season in three distinct patterns. In summary, next generation sequencing has revealed variations in the taxonomic compositions of leaf endophytic bacterial communities dependent primarily on the nature of the plant host species. PMID:26974817

Influences of Plant Species, Season and Location on Leaf Endophytic Bacterial Communities of Non-Cultivated Plants.

PubMed

Ding, Tao; Melcher, Ulrich

2016-01-01

Bacteria are known to be associated endophytically with plants. Research on endophytic bacteria has identified their importance in food safety, agricultural production and phytoremediation. However, the diversity of endophytic bacterial communities and the forces that shape their compositions in non-cultivated plants are largely uncharacterized. In this study, we explored the diversity, community structure, and dynamics of endophytic bacteria in different plant species in the Tallgrass Prairie Preserve of northern Oklahoma, USA. High throughput sequencing of amplified segments of bacterial rDNA from 81 samples collected at four sampling times from five plant species at four locations identified 335 distinct OTUs at 97% sequence similarity, representing 16 phyla. Proteobacteria was the dominant phylum in the communities, followed by the phyla Bacteriodetes and Actinobacteria. Bacteria from four classes of Proteobacteria were detected with Alphaproteobacteria as the dominant class. Analysis of molecular variance revealed that host plant species and collecting date had significant influences on the compositions of the leaf endophytic bacterial communities. The proportion of Alphaproteobacteria was much higher in the communities from Asclepias viridis than from other plant species and differed from month to month. The most dominant bacterial groups identified in LDA Effect Size analysis showed host-specific patterns, indicating mutual selection between host plants and endophytic bacteria and that leaf endophytic bacterial compositions were dynamic, varying with the host plant's growing season in three distinct patterns. In summary, next generation sequencing has revealed variations in the taxonomic compositions of leaf endophytic bacterial communities dependent primarily on the nature of the plant host species.

Serpentine endophytic bacterium Pseudomonas azotoformans ASS1 accelerates phytoremediation of soil metals under drought stress.

PubMed

Ma, Ying; Rajkumar, Mani; Moreno, António; Zhang, Chang; Freitas, Helena

2017-10-01

This study evaluates the potential of serpentine endophytic bacterium to foster phytoremediation efficiency of Trifolium arvense grown on multi-metal (Cu, Zn and Ni) contaminated soils under drought stress. A drought resistant endophytic bacterial strain ASS1 isolated from the leaves of Alyssum serpyllifolium grown in serpentine soils was identified as Pseudomonas azotoformans based on biochemical tests and partial 16S rRNA gene sequencing. P. azotoformans ASS1 possessed abiotic stress resistance (heavy metals, drought, salinity, antibiotics and extreme temperature) and plant growth promoting (PGP) properties (phosphate solubilization, nitrogen fixation, production of 1-aminocyclopropane-1-carboxylate deaminase, siderophore and ammonia). Inoculation of T. arvense with ASS1 considerably increased the plant biomass and leaf relative water content in both roll towel assay and pot experiments in the absence and presence of drought stress (DS). In the pot experiments, ASS1 greatly enhanced chlorophyll content, catalase, peroxidase, superoxide dismutase activities, and proline content (only in the absence of drought) in plant leaves, whereas they decreased the concentrations of malondialdehyde. Irrespective of water stress, ASS1 significantly improved accumulation, total removal, bio-concentration factor and biological accumulation coefficient of metals (Cu, Zn and Ni), while decreased translocation factors of Cu. The effective colonization and survival in the rhizosphere and tissue interior assured improved plant growth and successful metal phytoremediation under DS. These results demonstrate the potential of serpentine endophytic bacterium ASS1 for protecting plants against abiotic stresses and helping plants to thrive in semiarid ecosystems and accelerate phytoremediation process in metal polluted soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cultivable endophytic bacteria from leaf bases of Agave tequilana and their role as plant growth promoters

PubMed Central

Martínez-Rodríguez, Julia del C.; la Mora-Amutio, Marcela De; Plascencia-Correa, Luis A.; Audelo-Regalado, Esmeralda; Guardado, Francisco R.; Hernández-Sánchez, Elías; Peña-Ramírez, Yuri J.; Escalante, Adelfo; Beltrán-García, Miguel J.; Ogura, Tetsuya

2014-01-01

Agave tequilana Weber var. ‘Azul’ is grown for the production of tequila, inulin and syrup. Diverse bacteria inhabit plant tissues and play a crucial role for plant health and growth. In this study culturable endophytic bacteria were extracted from leaf bases of 100 healthy Agave tequilana plants. In plant tissue bacteria occurred at mean population densities of 3 million CFU/g of fresh plant tissue. Three hundred endophytic strains were isolated and 16s rDNA sequences grouped the bacteria into eight different taxa that shared high homology with other known sequences. Bacterial endophytes were identified as Acinectobacter sp., A. baumanii, A. bereziniae, Cronobacter sakazakii, Enterobacter hormaechei, Bacillus sp. Klebsiella oxytoca, Pseudomonas sp., Enterococcus casseliflavus, Leuconostoc mesenteroides subsp. mesenteroides and Gluconobacter oxydans. Isolates were confirmed to be plant growth promoting bacteria (PGPB) by their capacities for nitrogen fixation, auxin production, phosphate solubilization, or antagonism against Fusarium oxysporum AC132. E. casseliflavus JM47 and K. oxytoca JM26 secreted the highest concentrations of IAA. The endophyte Acinectobacter sp. JM58 exhibited the maximum values for nitrogen fixation and phosphate solubilization index (PSI). Inhibition of fungi was found in Pseudomonas sp. JM9p and K. oxytoca JM26. Bacterial endophytes show promise for use as bio-inoculants for agave cultivation. Use of endophytes to enhance cultivation of agave may be particularly important for plants produced by micropropagation techniques, where native endophytes may have been lost. PMID:25763038

Cultivable endophytic bacteria from leaf bases of Agave tequilana and their role as plant growth promoters.

PubMed

Martínez-Rodríguez, Julia del C; De la Mora-Amutio, Marcela; Plascencia-Correa, Luis A; Audelo-Regalado, Esmeralda; Guardado, Francisco R; Hernández-Sánchez, Elías; Peña-Ramírez, Yuri J; Escalante, Adelfo; Beltrán-García, Miguel J; Ogura, Tetsuya

2014-01-01

Agave tequilana Weber var. 'Azul' is grown for the production of tequila, inulin and syrup. Diverse bacteria inhabit plant tissues and play a crucial role for plant health and growth. In this study culturable endophytic bacteria were extracted from leaf bases of 100 healthy Agave tequilana plants. In plant tissue bacteria occurred at mean population densities of 3 million CFU/g of fresh plant tissue. Three hundred endophytic strains were isolated and 16s rDNA sequences grouped the bacteria into eight different taxa that shared high homology with other known sequences. Bacterial endophytes were identified as Acinectobacter sp., A. baumanii, A. bereziniae, Cronobacter sakazakii, Enterobacter hormaechei, Bacillus sp. Klebsiella oxytoca, Pseudomonas sp., Enterococcus casseliflavus, Leuconostoc mesenteroides subsp. mesenteroides and Gluconobacter oxydans. Isolates were confirmed to be plant growth promoting bacteria (PGPB) by their capacities for nitrogen fixation, auxin production, phosphate solubilization, or antagonism against Fusarium oxysporum AC132. E. casseliflavus JM47 and K. oxytoca JM26 secreted the highest concentrations of IAA. The endophyte Acinectobacter sp. JM58 exhibited the maximum values for nitrogen fixation and phosphate solubilization index (PSI). Inhibition of fungi was found in Pseudomonas sp. JM9p and K. oxytoca JM26. Bacterial endophytes show promise for use as bio-inoculants for agave cultivation. Use of endophytes to enhance cultivation of agave may be particularly important for plants produced by micropropagation techniques, where native endophytes may have been lost.

Application of Endophytic Pseudomonas fluorescens and a Bacterial Consortium to Brassica napus Can Increase Plant Height and Biomass under Greenhouse and Field Conditions

PubMed Central

Lally, Richard D.; Galbally, Paul; Moreira, António S.; Spink, John; Ryan, David; Germaine, Kieran J.; Dowling, David N.

2017-01-01

Plant associated bacteria with plant growth promotion (PGP) properties have been proposed for use as environmentally friendly biofertilizers for sustainable agriculture; however, analysis of their efficacy in the field is often limited. In this study, greenhouse and field trials were carried out using individual endophytic Pseudomonas fluorescens strains, the well characterized rhizospheric P. fluorescens F113 and an endophytic microbial consortium of 10 different strains. These bacteria had been previously characterized with respect to their PGP properties in vitro and had been shown to harbor a range of traits associated with PGP including siderophore production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and inorganic phosphate solubilization. In greenhouse experiments individual strains tagged with gfp and Kmr were applied to Brassica napus as a seed coat and were shown to effectively colonize the rhizosphere and root of B. napus and in addition they demonstrated a significant increase in plant biomass compared with the non-inoculated control. In the field experiment, the bacteria (individual and consortium) were spray inoculated to winter oilseed rape B. napus var. Compass which was grown under standard North Western European agronomic conditions. Analysis of the data provides evidence that the application of the live bacterial biofertilizers can enhance aspects of crop development in B. napus at field scale. The field data demonstrated statistically significant increases in crop height, stem/leaf, and pod biomass, particularly, in the case of the consortium inoculated treatment. However, although seed and oil yield were increased in the field in response to inoculation, these data were not statistically significant under the experimental conditions tested. Future field trials will investigate the effectiveness of the inoculants under different agronomic conditions. PMID:29312422

Antimicrobial activity of Ulva reticulata and its endophytes

NASA Astrophysics Data System (ADS)

Dhanya, K. I.; Swati, V. I.; Vanka, Kanth Swaroop; Osborne, W. J.

2016-04-01

Seaweeds are known to exhibit various antimicrobial properties, since it harbours an enormous range of indigenous bioactive compounds. The emergence of drug resistant strains has directed to the identification of prospective metabolites from seaweed and its endophytes, thereby exploiting the properties in resisting bacterial diseases. The current study was aimed to assess the antimicrobial activity of extracts obtained from Ulva reticulate, for which metabolites of Ulva reticulata and its endophytes were extracted and assessed against human pathogens like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Bacillus subtilis. It was observed that the hexane extract of isolate VITDSJ2 was effective against all the tested pathogens but a significant inhibition was observed for Staphylococcus aureus and Escherichia coli. Further, Gas chromatography coupled with Mass spectroscopy (GC-MS) revealed the existence of phenol, 3, 5-bis (1, 1-dimethylethyl) in the crude hexane extract which is well-known to possess antibacterial activity. The effective isolate VITDSJ2 was identified to be the closest neighbour of Pseudomonas stutzeri by phenotypic and genotypic methods. The crude extracts of the seaweed Ulva reticulata was also screened for antibacterial activity and the hexane extract was effective in showing inhibition against all the tested pathogens. The compound in the crude extract of Ulva reticulata was identified as hentriacontane using GC-MS. The extracts obtained from dichloromethane did not show significant activity in comparison with the hexane extracts. Hence the metabolites of Ulva reticulata and the bacterial secondary metabolites of the endophytes could be used in the treatment of bacterial infections.

Microgravity effect on endophytic bacteria communities of Triticum aestivum

NASA Astrophysics Data System (ADS)

Qin, Youcai; Fu, Yuming; Chen, Huiwen; Liu, Hong; Sun, Yi

2018-02-01

Under normal gravity conditions, endophytic bacteria, one of the key bacterial community that inhabit in plant tissues, are well-known in promoting the plant growth and health, which are essential for long-term and long-distance manned microgravity space exploration. Here, we report how the Triticum aestivum endophytic bacterial communities behave differently under the simulated microgravity conditions. We demonstrate that, under simulated microgravity conditions, the microbial diversity in wheat seedling leaf increases while that in root decreases, compared to that cultivated under normal gravity conditions. We found that the dominant bacteria genus such as Pseudomonas, Paenibacillus and Bacillus significantly changes with gravity. The findings of this study provide important insight for space research, especially in terms of the Triticum aestivum cultivation in space.

Biodegradation of phenol and benzene by endophytic bacterial strains isolated from refinery wastewater-fed Cannabis sativa.

PubMed

Iqbal, Aneela; Arshad, Muhammad; Hashmi, Imran; Karthikeyan, Raghupathy; Gentry, Terry J; Schwab, Arthur Paul

2017-06-13

The presence of benzene and phenol in the environment can lead to serious health effects in humans and warrant development of efficient cleanup strategies. The aim of the present work was to assess the potential of indigenous endophytic bacterial strains to degrade benzene and phenol. Seven strains were successfully isolated from Cannabis sativa plants irrigated with oil refinery wastewater. Molecular characterization was performed by 16S rRNA gene sequencing. Phenol was biodegraded almost completely with Achromobacter sp. (AIEB-7), Pseudomonas sp. (AIEB-4), and Alcaligenes sp. (AIEB-6) at 250, 500, and 750 mg L -1 ; however, the degradation was only 81%, 72%, and 69%, respectively, when exposed to 1000 mg L -1 . Bacillus sp. (AIEB-1), Enterobacter sp. (AIEB-3), and Acinetobacter sp. (AIEB-2) degraded benzene significantly at 250, 500, and 750 mg L -1 . However, these strains showed 80%, 72%, and 68% benzene removal at 1000 mg L -1 exposure, respectively. Rates of degradation could be modeled with first-order kinetics with rate constant values of 1.86 × 10 -2 for Pseudomonas sp. (AIEB-4) and 1.80 × 10 -2  h -1 for Bacillus sp. (AIEB-1) and half-lives of 1.5 and 1.6 days, respectively. These results establish a foundation for further testing of the phytoremediation of hydrocarbon-contaminated soils in the presence of these endophytic bacteria.

Restructuring of endophytic bacterial communities in grapevine yellows-diseased and recovered Vitis vinifera L. plants.

PubMed

Bulgari, Daniela; Casati, Paola; Crepaldi, Paola; Daffonchio, Daniele; Quaglino, Fabio; Brusetti, Lorenzo; Bianco, Piero Attilio

2011-07-01

Length heterogeneity-PCR assays, combined with statistical analyses, highlighted that the endophytic bacterial community associated with healthy grapevines was characterized by a greater diversity than that present in diseased and recovered plants. The findings suggest that phytoplasmas can restructure the bacterial community by selecting endophytic strains that could elicit a plant defense response.

Endophytic bacterial community of grapevine leaves influenced by sampling date and phytoplasma infection process

PubMed Central

2014-01-01

Background Endophytic bacteria benefit host plant directly or indirectly, e.g. by biocontrol of the pathogens. Up to now, their interactions with the host and with other microorganisms are poorly understood. Consequently, a crucial step for improving the knowledge of those relationships is to determine if pathogens or plant growing season influence endophytic bacterial diversity and dynamic. Results Four healthy, four phytoplasma diseased and four recovered (symptomatic plants that spontaneously regain a healthy condition) grapevine plants were sampled monthly from June to October 2010 in a vineyard in north-western Italy. Metagenomic DNA was extracted from sterilized leaves and the endophytic bacterial community dynamic and diversity were analyzed by taxon specific real-time PCR, Length-Heterogeneity PCR and genus-specific PCR. These analyses revealed that both sampling date and phytoplasma infection influenced the endophytic bacterial composition. Interestingly, in June, when the plants are symptomless and the pathogen is undetectable (i) the endophytic bacterial community associated with diseased grapevines was different from those in the other sampling dates, when the phytoplasmas are detectable inside samples; (ii) the microbial community associated with recovered plants differs from that living inside healthy and diseased plants. Interestingly, LH-PCR database identified bacteria previously reported as biocontrol agents in the examined grapevines. Of these, Burkholderia, Methylobacterium and Pantoea dynamic was influenced by the phytoplasma infection process and seasonality. Conclusion Results indicated that endophytic bacterial community composition in grapevine is correlated to both phytoplasma infection and sampling date. For the first time, data underlined that, in diseased plants, the pathogen infection process can decrease the impact of seasonality on community dynamic. Moreover, based on experimental evidences, it was reasonable to hypothesize that

Endophytic bacterial community of grapevine leaves influenced by sampling date and phytoplasma infection process.

PubMed

Bulgari, Daniela; Casati, Paola; Quaglino, Fabio; Bianco, Piero A

2014-07-21

Endophytic bacteria benefit host plant directly or indirectly, e.g. by biocontrol of the pathogens. Up to now, their interactions with the host and with other microorganisms are poorly understood. Consequently, a crucial step for improving the knowledge of those relationships is to determine if pathogens or plant growing season influence endophytic bacterial diversity and dynamic. Four healthy, four phytoplasma diseased and four recovered (symptomatic plants that spontaneously regain a healthy condition) grapevine plants were sampled monthly from June to October 2010 in a vineyard in north-western Italy. Metagenomic DNA was extracted from sterilized leaves and the endophytic bacterial community dynamic and diversity were analyzed by taxon specific real-time PCR, Length-Heterogeneity PCR and genus-specific PCR. These analyses revealed that both sampling date and phytoplasma infection influenced the endophytic bacterial composition. Interestingly, in June, when the plants are symptomless and the pathogen is undetectable (i) the endophytic bacterial community associated with diseased grapevines was different from those in the other sampling dates, when the phytoplasmas are detectable inside samples; (ii) the microbial community associated with recovered plants differs from that living inside healthy and diseased plants. Interestingly, LH-PCR database identified bacteria previously reported as biocontrol agents in the examined grapevines. Of these, Burkholderia, Methylobacterium and Pantoea dynamic was influenced by the phytoplasma infection process and seasonality. Results indicated that endophytic bacterial community composition in grapevine is correlated to both phytoplasma infection and sampling date. For the first time, data underlined that, in diseased plants, the pathogen infection process can decrease the impact of seasonality on community dynamic. Moreover, based on experimental evidences, it was reasonable to hypothesize that after recovery the restructured

Impact of grassland management regimes on bacterial endophyte diversity differs with grass species.

PubMed

Wemheuer, F; Wemheuer, B; Kretzschmar, D; Pfeiffer, B; Herzog, S; Daniel, R; Vidal, S

2016-04-01

Most plant species are colonized by endophytic bacteria. Despite their importance for plant health and growth, the response of these bacteria to grassland management regimes is still not understood. Hence, we investigated the bacterial community structure in three agricultural important grass species Dactylis glomerata L., Festuca rubra L. and Lolium perenne L. with regard to fertilizer application and different mowing frequencies. For this purpose, above-ground plant material was collected from the Grassland Management Experiment (GrassMan) in Germany in September 2010 and 2011. DNA was extracted from surface-sterilized plant tissue and subjected to 16S rRNA gene PCRs. Endophytic community structures were assessed by denaturing gradient gel electrophoresis (DGGE)-based analysis of obtained PCR products. DGGE fingerprints revealed that fertilizer application significantly altered the endophytic communities in L. perenne and F. rubra but not in D. glomerata. Although no direct effect of mowing was observed, mowing frequencies in combination with fertilizer application had a significant impact on endophyte bacterial community structures. However, this effect was not observed for all three grass species in both years. Therefore, our results showed that management regimes changed the bacterial endophyte communities, but this effect was plant-specific and varied over time. Endophytic bacteria play an important role in plant health and growth. However, studies addressing the influence of grassland management regimes on these bacteria in above-ground plant parts are still missing. In this study, we present first evidence that fertilizer application significantly impacted bacterial community structures in three agricultural important grass species, whereas mowing had only a minor effect. Moreover, this effect was plant-specific and thus not visible for all grass species in each year. Consequently, this study sheds new light into the complex interaction of microbes and

Culturable bacterial endophytes isolated from Mangrove tree (Rhizophora apiculata Blume) enhance seedling growth in Rice.

PubMed

Deivanai, Subramanian; Bindusara, Amitraghata Santhanam; Prabhakaran, Guruswamy; Bhore, Subhash Janardhan

2014-07-01

Endophytic bacteria do have several potential applications in medicine and in other various sectors of biotechnology including agriculture. Bacterial endophytes need to be explored for their potential applications in agricultural biotechnology. One of the potential applications of bacterial endophytes in agricultural is to enhance the growth of the agricultural crops. Hence, this study was undertaken to explore the plant growth promoting potential application of bacterial endophytes. The objective of this study was to examine the effect of endophytic bacteria from mangrove tree (Rhizophora apiculata Blume) for their efficacy in promoting seedling growth in rice. Eight endophytic bacterial isolates (EBIs) isolated from twig and petiole tissues of the mangrove were identified based on their 16S ribosomal ribonucleic acid (rRNA) gene sequence homology. Separately, surface sterilized paddy seeds were treated with cell-free broth and cell suspension of the EBIs. Rice seedlings were analyzed by various bioassays and data was recorded. The gene sequences of the isolates were closely related to two genera namely, Bacillus and Pantoea. Inoculation of EBIs from R. apiculata with rice seeds resulted in accelerated root and shoot growth with significant increase in chlorophyll content. Among the isolates, Pantoea ananatis (1MSE1) and Bacillus amyloliquefaciens (3MPE1) had shown predominance of activity. Endophytic invasion was recognized by the non-host by rapid accumulation of reactive oxygen species (ROS) and was counteracted by the production of hydrogen peroxide (H2O2) and lipid peroxide. The results demonstrated that EBIs from mangrove tree can increase the fitness of the rice seedlings under controlled conditions. These research findings could be useful to enhance the seedling growth and could serve as foundation in further research on enhancing the growth of the rice crop using endophytic bacteria.

Root bacterial endophytes alter plant phenotype, but not physiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henning, Jeremiah A.; Weston, David J.; Pelletier, Dale A.

Plant traits, such as root and leaf area, influence how plants interact with their environment and the diverse microbiota living within plants can influence plant morphology and physiology. Here, we explored how three bacterial strains isolated from the Populus root microbiome, influenced plant phenotype. Here, we chose three bacterial strains that differed in predicted metabolic capabilities, plant hormone production and metabolism, and secondary metabolite synthesis. We inoculated each bacterial strain on a single genotype of Populus trichocarpa and measured the response of plant growth related traits (root:shoot, biomass production, root and leaf growth rates) and physiological traits (chlorophyll content, netmore » photosynthesis, net photosynthesis at saturating light–A sat, and saturating CO 2–A max). Overall, we found that bacterial root endophyte infection increased root growth rate up to 184% and leaf growth rate up to 137% relative to non-inoculated control plants, evidence that plants respond to bacteria by modifying morphology. However, endophyte inoculation had no influence on total plant biomass and photosynthetic traits (net photosynthesis, chlorophyll content). In sum, bacterial inoculation did not significantly increase plant carbon fixation and biomass, but their presence altered where and how carbon was being allocated in the plant host.« less

Root bacterial endophytes alter plant phenotype, but not physiology

DOE PAGES

Henning, Jeremiah A.; Weston, David J.; Pelletier, Dale A.; ...

2016-11-01

Plant traits, such as root and leaf area, influence how plants interact with their environment and the diverse microbiota living within plants can influence plant morphology and physiology. Here, we explored how three bacterial strains isolated from the Populus root microbiome, influenced plant phenotype. Here, we chose three bacterial strains that differed in predicted metabolic capabilities, plant hormone production and metabolism, and secondary metabolite synthesis. We inoculated each bacterial strain on a single genotype of Populus trichocarpa and measured the response of plant growth related traits (root:shoot, biomass production, root and leaf growth rates) and physiological traits (chlorophyll content, netmore » photosynthesis, net photosynthesis at saturating light–A sat, and saturating CO 2–A max). Overall, we found that bacterial root endophyte infection increased root growth rate up to 184% and leaf growth rate up to 137% relative to non-inoculated control plants, evidence that plants respond to bacteria by modifying morphology. However, endophyte inoculation had no influence on total plant biomass and photosynthetic traits (net photosynthesis, chlorophyll content). In sum, bacterial inoculation did not significantly increase plant carbon fixation and biomass, but their presence altered where and how carbon was being allocated in the plant host.« less

Restructuring of Endophytic Bacterial Communities in Grapevine Yellows-Diseased and Recovered Vitis vinifera L. Plants ▿

PubMed Central

Bulgari, Daniela; Casati, Paola; Crepaldi, Paola; Daffonchio, Daniele; Quaglino, Fabio; Brusetti, Lorenzo; Bianco, Piero Attilio

2011-01-01

Length heterogeneity-PCR assays, combined with statistical analyses, highlighted that the endophytic bacterial community associated with healthy grapevines was characterized by a greater diversity than that present in diseased and recovered plants. The findings suggest that phytoplasmas can restructure the bacterial community by selecting endophytic strains that could elicit a plant defense response. PMID:21622794

Indoleacetic acid production and plant growth promoting potential of bacterial endophytes isolated from rice (Oryza sativa L.) seeds.

PubMed

Shahzad, Raheem; Waqas, Muhammad; Khan, Abdul Latif; Al-Hosni, Khadija; Kang, Sang-Mo; Seo, Chang-Woo; Lee, In-Jung

2017-06-01

Bacterial endophytes from the phyllosphere and rhizosphere have been used to produce bioactive metabolites and to promote plant growth. However, little is known about the endophytes residing in seeds. This study aimed to isolate and identify seed-borne bacterial endophytes from rice and elucidate their potential for phytohormone production and growth enhancement. The isolated endophytes included Micrococcus yunnanensis RWL-2, Micrococcus luteus RWL-3, Enterobacter soli RWL-4, Leclercia adecarboxylata RWL-5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7, which were identified using 16S rRNA sequencing and phylogenetic analysis. These strains were analyzed for indoleacetic acid (IAA) production by using GC-MS and IAA was found in the range of 11.50 ± 0.77 μg ml -1 to 38.80 ± 1.35 μg ml -1 . We also assessed the strains for plant growth promoting potential because these isolates were able to produce IAA in pure culture. Most of the growth attributes of rice plants (shoot and root length, fresh and dry biomass, and chlorophyll content) were significantly increased by bacterial endophytes compared to the controls. These results show that IAA producing bacterial endophytes can improve hostplant growth traits and can be used as bio-fertilizers.

The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots.

PubMed

Gómez-Lama Cabanás, Carmen; Schilirò, Elisabetta; Valverde-Corredor, Antonio; Mercado-Blanco, Jesús

2014-01-01

Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA) against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH) cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets), many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR) experiments aiming to: (1) validate the induction of these genes, and (2) shed light on their expression pattern along time (from 1 to 15 days). Induction of olive genes potentially coding for lipoxygenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase, and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e., JERF, bHLH, WRKY), as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mounts a wide array of systemic defense responses in distant tissues (stems, leaves). This sheds light on how olive plants respond to the "non-hostile" colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7.

The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots

PubMed Central

Gómez-Lama Cabanás, Carmen; Schilirò, Elisabetta; Valverde-Corredor, Antonio; Mercado-Blanco, Jesús

2014-01-01

Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA) against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH) cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets), many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR) experiments aiming to: (1) validate the induction of these genes, and (2) shed light on their expression pattern along time (from 1 to 15 days). Induction of olive genes potentially coding for lipoxygenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase, and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e., JERF, bHLH, WRKY), as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mounts a wide array of systemic defense responses in distant tissues (stems, leaves). This sheds light on how olive plants respond to the “non-hostile” colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7. PMID:25250017

Diversity of endophytic fungal and bacterial communities in Ilex paraguariensis grown under field conditions.

PubMed

Pérez, María Laura; Collavino, Mónica Mariana; Sansberro, Pedro Alfonso; Mroginski, Luis Amado; Galdeano, Ernestina

2016-04-01

The composition and diversity of the endophytic community associated with yerba mate (Ilex paraguariensis) was investigated using culture-depending methods. Fungi were identified based on their micromorphological characteristics and internal transcribed spacer rDNA sequence analysis; for bacteria 16S rDNA sequence analysis was used. Fungal and bacterial diversity did not show significant differences between organ age. The highest fungal diversity was registered during fall season and the lowest in winter. Bacterial diversity was higher in stems and increased from summer to winter, in contrast with leaves, which decreased. The most frequently isolated fungus was Fusarium, followed by Colletotrichum; they were both present in all the sampling seasons and organ types assayed. Actinobacteria represented 57.5 % of all bacterial isolates. The most dominant bacterial taxa were Curtobacterium and Microbacterium. Other bacteria frequently found were Methylobacterium, Sphingomonas, Herbiconiux and Bacillus. Nitrogen fixation and phosphate solubilization activity, ACC deaminase production and antagonism against plant fungal pathogens were assayed in endophytic bacterial strains. In the case of fungi, strains of Trichoderma, Penicillium and Aspergillus were assayed for antagonism against pathogenic Fusarium sp. All microbial isolates assayed showed at least one growth promoting activity. Strains of Bacillus, Pantoea, Curtobacterium, Methylobacterium, Brevundimonas and Paenibacillus had at least two growth-promoting activities, and Bacillus, Paenibacillus and the three endophytic fungi showed high antagonistic activity against Fusarium sp. In this work we have made a wide study of the culturable endophytic community within yerba mate plants and found that several microbial isolates could be considered as potential inoculants useful for improving yerba mate production.

Linking Bacterial Endophytic Communities to Essential Oils: Clues from Lavandula angustifolia Mill

PubMed Central

Emiliani, Giovanni; Maida, Isabel; Perrin, Elena; Chiellini, Carolina; Fondi, Marco; Gallo, Eugenia; Gori, Luigi; Maggini, Valentina; Vannacci, Alfredo; Biffi, Sauro; Firenzuoli, Fabio; Fani, Renato

2014-01-01

Endophytic bacteria play a crucial role in plant life and are also drawing much attention for their capacity to produce bioactive compounds of relevant biotechnological interest. Here we present the characterisation of the cultivable endophytic bacteria of Lavandula angustifolia Mill.—a species used since antiquity for its therapeutic properties—since the production of bioactive metabolites from medical plants may reside also in the activity of bacterial endophytes through their direct production, PGPR activity on host, and/or elicitation of plant metabolism. Lavender tissues are inhabited by a tissue specific endophytic community dominated by Proteobacteria, highlighting also their difference from the rhizosphere environment where Actinobacteria and Firmicutes are also found. Leaves' endophytic community resulted as the most diverse from the other ecological niches. Overall, the findings reported here suggest: (i) the existence of different entry points for the endophytic community, (ii) its differentiation on the basis of the ecological niche variability, and (iii) a two-step colonization process for roots endophytes. Lastly, many isolates showed a strong inhibition potential against human pathogens and the molecular characterization demonstrated also the presence of not previously described isolates that may constitute a reservoir of bioactive compounds relevant in the field of pathogen control, phytoremediation, and human health. PMID:24971151

Bacterial endophyte communities in the foliage of coast redwood and giant sequoia.

PubMed

Carrell, Alyssa A; Frank, Anna C

2015-01-01

The endophytic bacterial microbiome, with an emerging role in plant nutrient acquisition and stress tolerance, is much less studied in natural plant populations than in agricultural crops. In a previous study, we found consistent associations between trees in the pine family and acetic acid bacteria (AAB) occurring at high relative abundance inside their needles. Our objective here was to determine if that pattern may be general to conifers, or alternatively, is more likely restricted to pines or conifers growing in nutrient limited and exposed environments. We used 16S rRNA pyrosequencing to characterize the foliar endophyte communities of two conifers in the Cupressaceae family: Two coast redwood (CR; Sequoia sempervirens) populations and one giant sequoia (GS; Sequoiadendron giganteum) population were sampled. Similar to the pines, the endophyte communities of the giant trees were dominated by Proteobacteria, Firmicutes, Acidobacteria, and Actinobacteria. However, although some major operational taxonomic units (OTUs) occurred at a high relative abundance of 10-40% in multiple samples, no specific group of bacteria dominated the endophyte community to the extent previously observed in high-elevation pines. Several of the dominating bacterial groups in the CR and GS foliage (e.g., Bacillus, Burkholderia, Actinomycetes) are known for disease- and pest suppression, raising the possibility that the endophytic microbiome protects the giant trees against biotic stress. Many of the most common and abundant OTUs in our dataset were most similar to 16S rRNA sequences from bacteria found in lichens or arctic plants. For example, an OTU belonging to the uncultured Rhizobiales LAR1 lineage, which is commonly associated with lichens, was observed at high relative abundance in many of the CR samples. The taxa shared between the giant trees, arctic plants, and lichens may be part of a broadly defined endophyte microbiome common to temperate, boreal, and tundra ecosystems.

Bacterial endophyte communities in the foliage of coast redwood and giant sequoia

PubMed Central

Carrell, Alyssa A.; Frank, Anna C.

2015-01-01

The endophytic bacterial microbiome, with an emerging role in plant nutrient acquisition and stress tolerance, is much less studied in natural plant populations than in agricultural crops. In a previous study, we found consistent associations between trees in the pine family and acetic acid bacteria (AAB) occurring at high relative abundance inside their needles. Our objective here was to determine if that pattern may be general to conifers, or alternatively, is more likely restricted to pines or conifers growing in nutrient limited and exposed environments. We used 16S rRNA pyrosequencing to characterize the foliar endophyte communities of two conifers in the Cupressaceae family: Two coast redwood (CR; Sequoia sempervirens) populations and one giant sequoia (GS; Sequoiadendron giganteum) population were sampled. Similar to the pines, the endophyte communities of the giant trees were dominated by Proteobacteria, Firmicutes, Acidobacteria, and Actinobacteria. However, although some major operational taxonomic units (OTUs) occurred at a high relative abundance of 10–40% in multiple samples, no specific group of bacteria dominated the endophyte community to the extent previously observed in high-elevation pines. Several of the dominating bacterial groups in the CR and GS foliage (e.g., Bacillus, Burkholderia, Actinomycetes) are known for disease- and pest suppression, raising the possibility that the endophytic microbiome protects the giant trees against biotic stress. Many of the most common and abundant OTUs in our dataset were most similar to 16S rRNA sequences from bacteria found in lichens or arctic plants. For example, an OTU belonging to the uncultured Rhizobiales LAR1 lineage, which is commonly associated with lichens, was observed at high relative abundance in many of the CR samples. The taxa shared between the giant trees, arctic plants, and lichens may be part of a broadly defined endophyte microbiome common to temperate, boreal, and tundra ecosystems

Bacterial endophyte communities in the foliage of coast redwood and giant sequoia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carrell, Alyssa A.; Frank, Anna C.

The endophytic bacterial microbiome, with an emerging role in plant nutrient acquisition and stress tolerance, is much less studied in natural plant populations than in agricultural crops. In a previous study, we found consistent associations between trees in the pine family and acetic acid bacteria (AAB) occurring at high relative abundance inside their needles. Our objective here was to determine if that pattern may be general to conifers, or alternatively, is more likely restricted to pines or conifers growing in nutrient limited and exposed environments. We used 16S rRNA pyrosequencing to characterize the foliar endophyte communities of two conifers inmore » the Cupressaceae family: Two coast redwood (CR; Sequoia sempervirens) populations and one giant sequoia (GS; Sequoiadendron giganteum) population were sampled. Similar to the pines, the endophyte communities of the giant trees were dominated by Proteobacteria, Firmicutes, Acidobacteria, and Actinobacteria. However, although some major operational taxonomic units (OTUs) occurred at a high relative abundance of 10–40% in multiple samples, no specific group of bacteria dominated the endophyte community to the extent previously observed in high-elevation pines. Several of the dominating bacterial groups in the CR and GS foliage (e.g., Bacillus, Burkholderia, Actinomycetes) are known for disease- and pest suppression, raising the possibility that the endophytic microbiome protects the giant trees against biotic stress. Many of the most common and abundant OTUs in our dataset were most similar to 16S rRNA sequences from bacteria found in lichens or arctic plants. For example, an OTU belonging to the uncultured Rhizobiales LAR1 lineage, which is commonly associated with lichens, was observed at high relative abundance in many of the CR samples. Lastly, the taxa shared between the giant trees, arctic plants, and lichens may be part of a broadly defined endophyte microbiome common to temperate, boreal, and

Bacterial endophyte communities in the foliage of coast redwood and giant sequoia

DOE PAGES

Carrell, Alyssa A.; Frank, Anna C.

2015-09-22

The endophytic bacterial microbiome, with an emerging role in plant nutrient acquisition and stress tolerance, is much less studied in natural plant populations than in agricultural crops. In a previous study, we found consistent associations between trees in the pine family and acetic acid bacteria (AAB) occurring at high relative abundance inside their needles. Our objective here was to determine if that pattern may be general to conifers, or alternatively, is more likely restricted to pines or conifers growing in nutrient limited and exposed environments. We used 16S rRNA pyrosequencing to characterize the foliar endophyte communities of two conifers inmore » the Cupressaceae family: Two coast redwood (CR; Sequoia sempervirens) populations and one giant sequoia (GS; Sequoiadendron giganteum) population were sampled. Similar to the pines, the endophyte communities of the giant trees were dominated by Proteobacteria, Firmicutes, Acidobacteria, and Actinobacteria. However, although some major operational taxonomic units (OTUs) occurred at a high relative abundance of 10–40% in multiple samples, no specific group of bacteria dominated the endophyte community to the extent previously observed in high-elevation pines. Several of the dominating bacterial groups in the CR and GS foliage (e.g., Bacillus, Burkholderia, Actinomycetes) are known for disease- and pest suppression, raising the possibility that the endophytic microbiome protects the giant trees against biotic stress. Many of the most common and abundant OTUs in our dataset were most similar to 16S rRNA sequences from bacteria found in lichens or arctic plants. For example, an OTU belonging to the uncultured Rhizobiales LAR1 lineage, which is commonly associated with lichens, was observed at high relative abundance in many of the CR samples. Lastly, the taxa shared between the giant trees, arctic plants, and lichens may be part of a broadly defined endophyte microbiome common to temperate, boreal, and

The effect of different growth regimes on the endophytic bacterial communities of the fern, Dicksonia sellowiana hook (Dicksoniaceae).

PubMed

de Araújo Barros, Irene; Luiz Araújo, Welington; Lúcio Azevedo, João

2010-10-01

Endophytic bacteria associated with the fern Dicksonia sellowiana were investigated. The bacterial communities from the surface-sterilized pinnae and rachis segments of the plants from the Brazilian Atlantic Rainforest that grew in native field conditions were compared with the bacterial communities from plants grown in greenhouses and plants that were initially grown in greenhouses and then transferred to the forest. From 540 pinnae and 540 rachis segments, 163 (30.2%) and 346 (64.2%) were colonized by bacteria, respectively. The main bacterial genera and species that were isolated included Bacillus spp. ( B. cereus, B. megaterium, B. pumilus and B. subtilis ) , Paenibacillus sp. , Amphibacillus sp. , Gracilibacillus sp. , Micrococcus sp. and Stenotrophomonas spp. ( S. maltophilia and S. nitroreducens ). B. pumilus was the most frequently isolated bacterial species . Amphibacillus and Gracilibacillus were reported as endophytes for the first time. Other commonly found bacterial genera were not observed in D. sellowiana , which may reflect preferences of specific bacterial communities inside this fern or detection limitations due to the isolation procedures. Plants that were grown in greenhouses and plants that were reintroduced into the forest displayed more bacterial genera and species diversity than native field plants, suggesting that reintroduction shifts the bacterial diversity. Endophytic bacteria that displayed antagonistic properties against different microorganisms were detected, but no obvious correlation was found between their frequencies with plant tissues or with plants from different growth regimes. This paper reports the first isolation of endophytic bacteria from a fern.

The effect of different growth regimes on the endophytic bacterial communities of the fern, Dicksonia sellowiana hook (Dicksoniaceae)

PubMed Central

de Araújo Barros, Irene; Luiz Araújo, Welington; Lúcio Azevedo, João

2010-01-01

Endophytic bacteria associated with the fern Dicksonia sellowiana were investigated. The bacterial communities from the surface-sterilized pinnae and rachis segments of the plants from the Brazilian Atlantic Rainforest that grew in native field conditions were compared with the bacterial communities from plants grown in greenhouses and plants that were initially grown in greenhouses and then transferred to the forest. From 540 pinnae and 540 rachis segments, 163 (30.2%) and 346 (64.2%) were colonized by bacteria, respectively. The main bacterial genera and species that were isolated included Bacillus spp. ( B. cereus, B. megaterium, B. pumilus and B. subtilis ) , Paenibacillus sp. , Amphibacillus sp. , Gracilibacillus sp. , Micrococcus sp. and Stenotrophomonas spp. ( S. maltophilia and S. nitroreducens ). B. pumilus was the most frequently isolated bacterial species . Amphibacillus and Gracilibacillus were reported as endophytes for the first time. Other commonly found bacterial genera were not observed in D. sellowiana , which may reflect preferences of specific bacterial communities inside this fern or detection limitations due to the isolation procedures. Plants that were grown in greenhouses and plants that were reintroduced into the forest displayed more bacterial genera and species diversity than native field plants, suggesting that reintroduction shifts the bacterial diversity. Endophytic bacteria that displayed antagonistic properties against different microorganisms were detected, but no obvious correlation was found between their frequencies with plant tissues or with plants from different growth regimes. This paper reports the first isolation of endophytic bacteria from a fern. PMID:24031575

Seed-vectored endophytic bacteria modulate development of rice seedlings.

PubMed

Verma, S K; Kingsley, K; Irizarry, I; Bergen, M; Kharwar, R N; White, J F

2017-06-01

The aim of the present study was to evaluate the effects of the removal of indigenous bacteria from rice seeds on seedling growth and development. Here we report the presence of three indigenous endophytic bacteria in rice seeds that play important roles in modulating seedling development (shoot and root lengths, and formation of root hairs and secondary roots) and defence against pathogens. Seed-associated bacteria were removed using surface sterilization with NaOCl (bleach) followed by antibiotic treatment. When bacteria were absent, growth of seedlings in terms of root hair development and overall seedling size was less than that of seedlings that contained bacteria. Reactive oxygen staining of seedlings showed that endophytic bacteria became intracellular in root parenchyma cells and root hairs. Roots containing endophytic bacteria were seen to stain densely for reactive oxygen, while roots free of bacteria stained lightly for reactive oxygen. Bacteria were isolated and identified as Enterobacter asburiae (VWB1), Pantoea dispersa (VWB2) and Pseudomonas putida (VWB3) by 16S rDNA sequencing. Bacteria were found to produce indole acetic acid (auxins), inhibited the pathogen Fusarium oxysporum and solubilized phosphate. Reinoculation of bacteria onto seedlings derived from surface-disinfected rice and Bermuda grass seeds significantly restored seedling growth and development. Rice seeds harbour indigenous bacterial endophytes that greatly influence seedling growth and development, including root and shoot lengths, root hair formation and disease susceptibility of rice seedlings. This study shows that seeds of rice naturally harbour bacterial endophytes that play key roles in modulation of seedling development. © 2017 The Society for Applied Microbiology.

Diversity and distribution of the endophytic bacterial community at different stages of Eucalyptus growth.

PubMed

Miguel, Paulo Sérgio Balbino; de Oliveira, Marcelo Nagem Valério; Delvaux, Júlio César; de Jesus, Guilherme Luiz; Borges, Arnaldo Chaer; Tótola, Marcos Rogério; Neves, Júlio César Lima; Costa, Maurício Dutra

2016-06-01

The relationships between plants and endophytic bacteria significantly contribute to plant health and yield. However, the microbial diversity in leaves of Eucalyptus spp. is still poorly characterized. Here, we investigated the endophytic diversity in leaves of hybrid Eucalyptus grandis x E. urophylla (Eucalyptus "urograndis") by using culture-independent and culture-dependent approaches, to better understand their ecology in leaves at different stages of Eucalyptus development, including bacteria with N2 fixation potential. Firmicutes, Proteobacteria (classes alpha-, beta- and gamma-) and Actinobacteria were identified in the Eucalyptus "urograndis" endophytic bacterial community. Within this community, the species Novosphingobium barchaimii, Rhizobium grahamii, Stenotrophomonas panacihumi, Paenibacillus terrigena, P. darwinianus and Terrabacter lapilli represent the first report these bacteria as endophytes. The diversity of the total endophytic bacteria was higher in the leaves from the 'field' (the Shannon-Wiener index, 2.99), followed by the indices obtained in the 'clonal garden' (2.78), the 'recently out from under shade (2.68), 'under shade' (2.63) and 'plants for dispatch' (2.51). In contrast, for diazotrophic bacteria, the highest means of these indices were obtained from the leaves of plants in the 'under shade' (2.56), 'recently out from under shade (2.52)' and 'field' stages (2.54). The distribution of the endophytic bacterial species in Eucalyptus was distinct and specific to the development stages under study, and many of the species had the potential for nitrogen fixation, raising the question of whether these bacteria could contribute to overall nitrogen metabolism of Eucalyptus.

Isolation and identification of local bacteria endophyte and screening of its antimicrobial property against pathogenic bacteria and fungi

NASA Astrophysics Data System (ADS)

Fikri, Ahmad Syairazie Ibrahim; Rahman, Irman Abdul; Nor, Norefrina Shafinaz Md; Hamzah, Ainon

2018-04-01

Endophytes are organisms, often fungi and bacteria that live in living plant cells. These organisms reside in the living tissues of the host plant in a variety of relationships, ranging from symbiotic to slightly pathogenic. The endophytes may produce a plethora of substances that have potential to be used in modern medicine, agriculture and industry. The aims of this study are to isolate, identify and screening antimicrobial activity of bacterial endophytes. The endophytes were isolated using nutrient agar, incubated at 37°C for 48 hours. Identification of the isolates were done based on morphological characteristics, biochemical tests and 16S rDNA molecular analysis. Disk diffusion method was used to screen for antimicrobial activity of metabolites from endophytes against pathogenic bacteria. Screening for antifungal activity of selected endophytes was done using dual culture method againts pathogenic fungi followed by Kirby-Bauer method. Results showed endophytes designated as B2c and B7b have positive antimicrobial activity. The metabolites from isolate B2c showed antimicrobial activity against pathogenic bacteria methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus and Staphylococcus epidermis, while isolate B7b have positive activities againts MRSA, S. aureus and Pseudomonas aeruginosa. Isolates B2c displayed antifungal activity against Fusarium oxysporum, Fusarium solani, Phytophthora palmivora and Colletotrichum gloeosporioides. Identification using biochemical tests and 16S rDNA sequences identified isolate B2c as Pseudomonas resinovorans with 97% homology and isolate B7b as Bacillus subtilis with 98% homology.

Endophytic bacterial diversity in grapevine (Vitis vinifera L.) leaves described by 16S rRNA gene sequence analysis and length heterogeneity-PCR.

PubMed

Bulgari, Daniela; Casati, Paola; Brusetti, Lorenzo; Quaglino, Fabio; Brasca, Milena; Daffonchio, Daniele; Bianco, Piero Attilio

2009-08-01

Diversity of bacterial endophytes associated with grapevine leaf tissues was analyzed by cultivation and cultivation-independent methods. In order to identify bacterial endophytes directly from metagenome, a protocol for bacteria enrichment and DNA extraction was optimized. Sequence analysis of 16S rRNA gene libraries underscored five diverse Operational Taxonomic Units (OTUs), showing best sequence matches with gamma-Proteobacteria, family Enterobacteriaceae, with a dominance of the genus Pantoea. Bacteria isolation through cultivation revealed the presence of six OTUs, showing best sequence matches with Actinobacteria, genus Curtobacterium, and with Firmicutes genera Bacillus and Enterococcus. Length Heterogeneity-PCR (LH-PCR) electrophoretic peaks from single bacterial clones were used to setup a database representing the bacterial endophytes identified in association with grapevine tissues. Analysis of healthy and phytoplasma-infected grapevine plants showed that LH-PCR could be a useful complementary tool for examining the diversity of bacterial endophytes especially for diversity survey on a large number of samples.

Associations between Ectomycorrhizal Fungi and Bacterial Needle Endophytes in Pinus radiata: Implications for Biotic Selection of Microbial Communities

PubMed Central

Rúa, Megan A.; Wilson, Emily C.; Steele, Sarah; Munters, Arielle R.; Hoeksema, Jason D.; Frank, Anna C.

2016-01-01

Studies of the ecological and evolutionary relationships between plants and their associated microbes have long been focused on single microbes, or single microbial guilds, but in reality, plants associate with a diverse array of microbes from a varied set of guilds. As such, multitrophic interactions among plant-associated microbes from multiple guilds represent an area of developing research, and can reveal how complex microbial communities are structured around plants. Interactions between coniferous plants and their associated microbes provide a good model system for such studies, as conifers host a suite of microorganisms including mutualistic ectomycorrhizal (ECM) fungi and foliar bacterial endophytes. To investigate the potential role ECM fungi play in structuring foliar bacterial endophyte communities, we sampled three isolated, native populations of Monterey pine (Pinus radiata), and used constrained analysis of principal coordinates to relate the community matrices of the ECM fungi and bacterial endophytes. Our results suggest that ECM fungi may be important factors for explaining variation in bacterial endophyte communities but this effect is influenced by population and environmental characteristics, emphasizing the potential importance of other factors — biotic or abiotic — in determining the composition of bacterial communities. We also classified ECM fungi into categories based on known fungal traits associated with substrate exploration and nutrient mobilization strategies since variation in these traits allows the fungi to acquire nutrients across a wide range of abiotic conditions and may influence the outcome of multi-species interactions. Across populations and environmental factors, none of the traits associated with fungal foraging strategy types significantly structured bacterial assemblages, suggesting these ECM fungal traits are not important for understanding endophyte-ECM interactions. Overall, our results suggest that both biotic

Quorum signaling mycotoxins: A new risk strategy for bacterial biocontrol of Fusarium verticillioides and other endophytic fungal species?

USDA-ARS?s Scientific Manuscript database

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

Antimicrobial Activity of Medicinal Plants Correlates with the Proportion of Antagonistic Endophytes

PubMed Central

Egamberdieva, Dilfuza; Wirth, Stephan; Behrendt, Undine; Ahmad, Parvaiz; Berg, Gabriele

2017-01-01

Medicinal plants are known to harbor potential endophytic microbes, due to their bioactive compounds. In a first study of ongoing research, endophytic bacteria were isolated from two medicinal plants, Hypericum perforatum and Ziziphora capitata with contrasting antimicrobial activities from the Chatkal Biosphere Reserve of Uzbekistan, and their plant-specific traits involved in biocontrol and plant growth promotion were evaluated. Plant extracts of H. perforatum exhibited a remarkable activity against bacterial and fungal pathogens, whereas extracts of Z. capitata did not exhibit any potential antimicrobial activity. Matrix-assisted laser desorption ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) was used to identify plant associated culturable endophytic bacteria. The isolated culturable endophytes associated with H. perforatum belong to eight genera (Arthrobacter, Achromobacter, Bacillus, Enterobacter, Erwinia, Pseudomonas, Pantoea, Serratia, and Stenotrophomonas). The endophytic isolates from Z. capitata also contain those genera except Arthrobacter, Serratia, and Stenotrophomonas. H. perforatum with antibacterial activity supported more bacteria with antagonistic activity, as compared to Z. capitata. The antagonistic isolates were able to control tomato root rot caused by Fusarium oxysporum and stimulated plant growth under greenhouse conditions and could thus be a cost-effective source for agro-based biological control agents. PMID:28232827

Synergistic plant-microbe interactions between endophytic bacterial communities and the medicinal plant Glycyrrhiza uralensis F.

PubMed

Li, Li; Mohamad, Osama Abdalla Abdelshafy; Ma, Jinbiao; Friel, Ariel D; Su, Yangui; Wang, Yun; Musa, Zulpiya; Liu, Yonghong; Hedlund, Brian P; Li, Wenjun

2018-03-07

Little is known about the composition, diversity, and geographical distribution of bacterial communities associated with medicinal plants in arid lands. To address this, a collection of 116 endophytic bacteria were isolated from wild populations of the herb Glycyrrhiza uralensis Fisch (licorice) in Xinyuan, Gongliu, and Tekesi of Xinjiang Province, China, and identified based on their 16S rRNA gene sequences. The endophytes were highly diverse, including 20 genera and 35 species. The number of distinct bacterial genera obtained from root tissues was higher (n = 14) compared to stem (n = 9) and leaf (n = 6) tissue. Geographically, the diversity of culturable endophytic genera was higher at the Tekesi (n = 14) and Xinyuan (n = 12) sites than the Gongliu site (n = 4), reflecting the extremely low organic carbon content, high salinity, and low nutrient status of Gongliu soils. The endophytic bacteria exhibited a number of plant growth-promoting activities ex situ, including diazotrophy, phosphate and potassium solubilization, siderophore production, auxin synthesis, and production of hydrolytic enzymes. Twelve endophytes were selected based on their ex situ plant growth-promoting activities for growth chamber assays to test for their ability to promote growth of G. uralensis F. and Triticum aestivum (wheat) plants. Several strains belonging to the genera Bacillus (n = 6) and Achromobacter (n = 1) stimulated total biomass production in both G. uralensis and T. aestivum under low-nutrient conditions. This work is the first report on the isolation and characterization of endophytes associated with G. uralensis F. in arid lands. The results demonstrate the broad diversity of endophytes associated with wild licorice and suggest that some Bacillus strains may be promising candidates for biofertilizers to promote enhanced survival and growth of licorice and other valuable crops in arid environments.

Bacterial Endophyte Colonization and Distribution within Plants

PubMed Central

Kandel, Shyam L.; Joubert, Pierre M.

2017-01-01

The plant endosphere contains a diverse group of microbial communities. There is general consensus that these microbial communities make significant contributions to plant health. Both recently adopted genomic approaches and classical microbiology techniques continue to develop the science of plant-microbe interactions. Endophytes are microbial symbionts residing within the plant for the majority of their life cycle without any detrimental impact to the host plant. The use of these natural symbionts offers an opportunity to maximize crop productivity while reducing the environmental impacts of agriculture. Endophytes promote plant growth through nitrogen fixation, phytohormone production, nutrient acquisition, and by conferring tolerance to abiotic and biotic stresses. Colonization by endophytes is crucial for providing these benefits to the host plant. Endophytic colonization refers to the entry, growth and multiplication of endophyte populations within the host plant. Lately, plant microbiome research has gained considerable attention but the mechanism allowing plants to recruit endophytes is largely unknown. This review summarizes currently available knowledge about endophytic colonization by bacteria in various plant species, and specifically discusses the colonization of maize plants by Populus endophytes. PMID:29186821

Effect of bacterial antagonists on lettuce: active biocontrol of Rhizoctonia solani and negligible, short-term effects on nontarget microorganisms.

PubMed

Scherwinski, Katja; Grosch, Rita; Berg, Gabriele

2008-04-01

The aim of this study was to assess the biocontrol efficacy against Rhizoctonia solani of three bacterial antagonists introduced into naturally Rhizoctonia-infested lettuce fields and to analyse their impact on the indigenous plant-associated bacteria and fungi. Lettuce seedlings were inoculated with bacterial suspensions of two endophytic strains, Serratia plymuthica 3Re4-18 and Pseudomonas trivialis 3Re2-7, and with the rhizobacterium Pseudomonas fluorescens L13-6-12 7 days before and 5 days after planting in the field. Similar statistically significant biocontrol effects were observed for all applied bacterial antagonists compared with the uninoculated control. Single-strand conformation polymorphism analysis of 16S rRNA gene or ITS1 fragments revealed a highly diverse rhizosphere and a less diverse endophytic microbial community for lettuce. Representatives of several bacterial (Alpha-, Beta- and Gammaproteobacteria, Firmicutes, Bacteriodetes), fungal (Ascomycetes, Basidiomycetes) and protist (Oomycetes) groups were present inside or on lettuce plants. Surprisingly, given that lettuce is a vegetable that is eaten raw, species of genera such as Flavobacterium, Burkholderia, Staphylococcus, Cladosporium and Aspergillus, which contain potentially human pathogenic strains, were identified. Analysis of the indigenous bacterial and endophytic fungal populations revealed only negligible, short-term effects resulting from the bacterial treatments, and that they were more influenced by field site, plant growth stage and microenvironment.

Isolation and Identification of Endophytic Bacteria with Plant Growth Promoting Activity and Biocontrol Potential from Wild Pistachio Trees.

PubMed

Etminani, Faegheh; Harighi, Behrouz

2018-06-01

In this study, samples were collected from the leaves and stems of healthy wild Pistachio trees ( Pistacia atlantica L.) from various locations of Baneh and Marivan regions, Iran. In total, 61 endophytic bacteria were isolated and grouped according to phenotypic properties. Ten selected isolates from each group were further identified by partial sequencing of the 16S rRNA gene. Based on the results, isolates were identified as bacteria belonging to Pseudomonas , Stenotrophomonas , Bacillus , Pantoea and Serratia genus. The ability of these isolates was evaluated to phytohormone production such as auxin and gibberellin, siderophore production, phosphate solubilization, atmospheric nitrogen fixation, protease and hydrogen cyanide production. All strains were able to produce the plant growth hormone auxin and gibberellin in different amounts. The majority of strains were able to solubilize phosphate. The results of atmospheric nitrogen fixation ability, protease and siderophore production were varied among strains. Only Ba66 could produce a low amount of hydrogen cyanide. The results of biocontrol assay showed that Pb78 and Sp15 strains had the highest and lowest inhibition effects on bacterial plant pathogens, Pseudomonas syringae pv. syringae Pss20 and Pseudomonas tolaasii Pt18 under in vitro condition. Pb3, Pb24 and Pb71 strains significantly promote root formation on carrot slices. To our knowledge this is the first report of the isolation of endophytic bacterial strains belonging to Pantoea , Bacillus , Pseudomonas , Serratia and Stenotrophomonas genus from wild pistachio trees with plant growth promoting potential and biocontrol activity.

Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew.

PubMed

Khalaf, Eman M; Raizada, Manish N

2018-01-01

The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soil-borne pathogens ( Rhizoctonia solani , Fusarium graminearum , Phytophthora capsici , Pythium aphanideratum ). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea , the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus . All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro , respectively. These results show that seeds of cultivated

Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew

PubMed Central

Khalaf, Eman M.; Raizada, Manish N.

2018-01-01

The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soil-borne pathogens (Rhizoctonia solani, Fusarium graminearum, Phytophthora capsici, Pythium aphanidermatum). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea, the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus. All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro, respectively. These results show that seeds of cultivated cucurbits

Investigation of Endophytic Bacterial Community in Supposedly Axenic Cultures of Pineapple and Orchids with Evidence on Abundant Intracellular Bacteria.

PubMed

Esposito-Polesi, Natalia Pimentel; de Abreu-Tarazi, Monita Fiori; de Almeida, Cristina Vieira; Tsai, Siu Mui; de Almeida, Marcílio

2017-01-01

Asepsis, defined as the absence of microbial contamination, is one of the most important requirements of plant micropropagation. In long-term micropropagated cultures, there may occasionally occur scattered microorganism growth in the culture medium. These microorganisms are common plant components and are known as latent endophytes. Thus, the aim of this research was to investigate the presence of endophytic bacteria in asymptomatic pineapple and orchid microplants, which were cultivated in three laboratories for 1 year. Isolation and characterization of bacterial isolates, PCR-DGGE from total genomic DNA of microplants and ultrastructural analysis of leaves were performed. In the culture-dependent technique, it was only possible to obtain bacterial isolates from pineapple microplants. In this case, the bacteria genera identified in the isolation technique were Bacillus, Acinetobacter, and Methylobacterium. The scanning electron microscopy and transmission electron microscopy (SEM and TEM) analyses revealed the presence of endophytic bacteria in intracellular spaces in the leaves of pineapple and orchid microplants, independent of the laboratory or cultivation protocol. Our results strongly indicate that there are endophytic bacterial communities inhabiting the microplants before initiation of the in vitro culture and that some of these endophytes persist in their latent form and can also grow in the culture medium even after long-term micropropagation, thus discarding the concept of "truly axenic plants."

Culture dependent and independent analysis of bacterial communities associated with commercial salad leaf vegetables.

PubMed

Jackson, Colin R; Randolph, Kevin C; Osborn, Shelly L; Tyler, Heather L

2013-12-01

Plants harbor a diverse bacterial community, both as epiphytes on the plant surface and as endophytes within plant tissue. While some plant-associated bacteria act as plant pathogens or promote plant growth, others may be human pathogens. The aim of the current study was to determine the bacterial community composition of organic and conventionally grown leafy salad vegetables at the point of consumption using both culture-dependent and culture-independent methods. Total culturable bacteria on salad vegetables ranged from 8.0 × 10(3) to 5.5 × 10(8) CFU g(-1). The number of culturable endophytic bacteria from surface sterilized plants was significantly lower, ranging from 2.2 × 10(3) to 5.8 × 10(5) CFU g(-1). Cultured isolates belonged to six major bacterial phyla, and included representatives of Pseudomonas, Pantoea, Chryseobacterium, and Flavobacterium. Eleven different phyla and subphyla were identified by culture-independent pyrosequencing, with Gammaproteobacteria, Betaproteobacteria, and Bacteroidetes being the most dominant lineages. Other bacterial lineages identified (e.g. Firmicutes, Alphaproteobacteria, Acidobacteria, and Actinobacteria) typically represented less than 1% of sequences obtained. At the genus level, sequences classified as Pseudomonas were identified in all samples and this was often the most prevalent genus. Ralstonia sequences made up a greater portion of the community in surface sterilized than non-surface sterilized samples, indicating that it was largely endophytic, while Acinetobacter sequences appeared to be primarily associated with the leaf surface. Analysis of molecular variance indicated there were no significant differences in bacterial community composition between organic versus conventionally grown, or surface-sterilized versus non-sterilized leaf vegetables. While culture-independent pyrosequencing identified significantly more bacterial taxa, the dominant taxa from pyrosequence data were also detected by traditional

Culture dependent and independent analysis of bacterial communities associated with commercial salad leaf vegetables

PubMed Central

2013-01-01

Background Plants harbor a diverse bacterial community, both as epiphytes on the plant surface and as endophytes within plant tissue. While some plant-associated bacteria act as plant pathogens or promote plant growth, others may be human pathogens. The aim of the current study was to determine the bacterial community composition of organic and conventionally grown leafy salad vegetables at the point of consumption using both culture-dependent and culture-independent methods. Results Total culturable bacteria on salad vegetables ranged from 8.0 × 103 to 5.5 × 108 CFU g-1. The number of culturable endophytic bacteria from surface sterilized plants was significantly lower, ranging from 2.2 × 103 to 5.8 × 105 CFU g-1. Cultured isolates belonged to six major bacterial phyla, and included representatives of Pseudomonas, Pantoea, Chryseobacterium, and Flavobacterium. Eleven different phyla and subphyla were identified by culture-independent pyrosequencing, with Gammaproteobacteria, Betaproteobacteria, and Bacteroidetes being the most dominant lineages. Other bacterial lineages identified (e.g. Firmicutes, Alphaproteobacteria, Acidobacteria, and Actinobacteria) typically represented less than 1% of sequences obtained. At the genus level, sequences classified as Pseudomonas were identified in all samples and this was often the most prevalent genus. Ralstonia sequences made up a greater portion of the community in surface sterilized than non-surface sterilized samples, indicating that it was largely endophytic, while Acinetobacter sequences appeared to be primarily associated with the leaf surface. Analysis of molecular variance indicated there were no significant differences in bacterial community composition between organic versus conventionally grown, or surface-sterilized versus non-sterilized leaf vegetables. While culture-independent pyrosequencing identified significantly more bacterial taxa, the dominant taxa from pyrosequence data were also detected by

Exposure of Cucurbita pepo to DDE-contamination alters the endophytic community: A cultivation dependent vs a cultivation independent approach.

PubMed

Eevers, N; Hawthorne, J R; White, J C; Vangronsveld, J; Weyens, N

2016-02-01

2,2-bis(p-chlorophenyl)-1,1-dichloro-ethylene (DDE) is the most abundant and persistent degradation product of the pesticide 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) and is encountered in contaminated soils worldwide. Both DDE and DDT are classified as Persistent Organic Pollutants (POPs) due to their high hydrophobicity and potential for bioaccumulation and biomagnification in the food chain. Zucchini (Cucurbita pepo ssp. pepo) has been shown to accumulate high concentrations of DDE and other POPs and has been proposed as a phytoremediation tool for contaminated soils. The endophytic bacteria associated with this plant may play an important role in the remedial process. Therefore, this research focuses on changes in endophytic bacterial communities caused by the exposure of C. pepo to DDE. The total bacterial community was investigated using cultivation-independent 454 pyrosequencing, while the cultivable community was identified using cultivation-dependent isolation procedures. For both procedures, increasing numbers of endophytic bacteria, as well as higher diversities of genera were observed when plants were exposed to DDE. Several bacterial genera such as Stenotrophomonas sp. and Sphingomonas sp. showed higher abundance when DDE was present, while, for example Pseudomonas sp. showed a significantly lower abundance in the presence of DDE. These findings suggest tolerance of different bacterial strains to DDE, which might be incorporated in further investigations to optimize phytoremediation with the possible use of DDE-degrading endophytes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Isolation and Identification of Endophytic Bacteria with Plant Growth Promoting Activity and Biocontrol Potential from Wild Pistachio Trees

PubMed Central

Etminani, Faegheh; Harighi, Behrouz

2018-01-01

In this study, samples were collected from the leaves and stems of healthy wild Pistachio trees (Pistacia atlantica L.) from various locations of Baneh and Marivan regions, Iran. In total, 61 endophytic bacteria were isolated and grouped according to phenotypic properties. Ten selected isolates from each group were further identified by partial sequencing of the 16S rRNA gene. Based on the results, isolates were identified as bacteria belonging to Pseudomonas, Stenotrophomonas, Bacillus, Pantoea and Serratia genus. The ability of these isolates was evaluated to phytohormone production such as auxin and gibberellin, siderophore production, phosphate solubilization, atmospheric nitrogen fixation, protease and hydrogen cyanide production. All strains were able to produce the plant growth hormone auxin and gibberellin in different amounts. The majority of strains were able to solubilize phosphate. The results of atmospheric nitrogen fixation ability, protease and siderophore production were varied among strains. Only Ba66 could produce a low amount of hydrogen cyanide. The results of biocontrol assay showed that Pb78 and Sp15 strains had the highest and lowest inhibition effects on bacterial plant pathogens, Pseudomonas syringae pv. syringae Pss20 and Pseudomonas tolaasii Pt18 under in vitro condition. Pb3, Pb24 and Pb71 strains significantly promote root formation on carrot slices. To our knowledge this is the first report of the isolation of endophytic bacterial strains belonging to Pantoea, Bacillus, Pseudomonas, Serratia and Stenotrophomonas genus from wild pistachio trees with plant growth promoting potential and biocontrol activity. PMID:29887777

The contribution of endophytic bacteria to Albizia lebbeck-mediated phytoremediation of tannery effluent contaminated soil.

PubMed

Manikandan, Muthu; Kannan, Vijayaraghavan; Mendoza, Ordetta Hannah; Kanimozhi, Mahalingam; Chun, Sechul; Pašić, Lejla

2016-01-01

Toxicity of chromium often impairs the remediation capacity of plants used in phytoremediation of polluted soils. In this study, we have identified Albizia lebbeck as a prospective chromium hyperaccumulator and examined cultivable diversity of endophytes present in chromium-treated and control saplings. High numbers (22-100%) of endophytic bacteria, isolated from root, stem, and leaf tissues, could tolerate elevated (1-3 mM) concentrations of K2CrO7. 16S rRNA gene sequence-based phylogenetic analysis showed that the 118 isolates obtained comprised of 17 operational taxonomic units affiliated with the proteobacterial genera Rhizobium (18%), Marinomonas (1%), Pseudomonas (16%), and Xanthomonas (7%) but also with members of Firmicutes genera, such as Bacillus (35%) and Salinococcus (3%). The novel isolates belonging to Salinococcus and Bacillus could tolerate high K2CrO7 concentrations (3 mM) and also showed elevated activity of chromate reductase. In addition, majority (%) of the endophytic isolates also showed production of indole-3-acetic acid. Taken together, our results indicate that the innate endophytic bacterial community assists plants in reducing heavy metal toxicity.

[Isolation, identification and characterization of ACC deaminase-containing endophytic bacteria from halophyte Suaeda salsa].

PubMed

Teng, Songshan; Liu, Yanping; Zhao, Lei

2010-11-01

We Isolated and characterized 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing endophytic bacteria from halophyte Suaeda salsa to understand the interactions between endophytes and halophyte. ACC deaminase-containing endophytic bacteria were isolated from root, stalk and leaf of Suaeda salsa and were identified based on morphological, physiological-biochemical properties, API and 16S rRNA sequence analysis. Isolates were evaluated for their ACC deaminase, antifungal, protease activity, siderophores and phytohormones, such as indole-3-acetic acid, gibberellic acid and abscisic acid production, as well as atmospheric nitrogen fixation and phosphate solubilization. Four ACC deaminase-containing endophytic bacteria strains named as LP11, SS12, TW1 and TW2 were isolated and identified as Pseudomonas oryzihabitans, Pseudomonas sp., Pantoea agglomerans and Pseudomonas putida respectively. All the strains possessed the phosphate-solubilizing ability and could produce siderophores and phytohormones more or less. None of them could fix atmospheric nitrogen or produce protease. Only strain SS12 showed antagonism against two phytopathogenic fungi viz Fusarium oxysporum f. sp. conglutinans and F. oxysporum f. sp. cucumerinum. ACC deaminase-containing endophytic bacteria of Pseudomonas sp. and Pantoea sp. isolated from halophyte Suaeda salsa have abundant biological characteristics related to plant growth promotion, stress homeostasis regulation and biocontrol activity.

Endophytes as sources of antibiotics.

PubMed

Martinez-Klimova, Elena; Rodríguez-Peña, Karol; Sánchez, Sergio

2017-06-15

Until a viable alternative can be accessible, the emergence of resistance to antimicrobials requires the constant development of new antibiotics. Recent scientific efforts have been aimed at the bioprospecting of microorganisms' secondary metabolites, with special emphasis on the search for antimicrobial natural products derived from endophytes. Endophytes are microorganisms that inhabit the internal tissues of plants without causing apparent harm to the plant. The present review article compiles recent (2006-2016) literature to provide an update on endophyte research aimed at finding metabolites with antibiotic activities. We have included exclusively information on endophytes that produce metabolites capable of inhibiting the growth of bacterial, fungal and protozoan pathogens of humans, animals and plants. Where available, the identified metabolites have been listed. In this review, we have also compiled a list of the bacterial and fungal phyla that have been isolated as endophytes as well as the plant families from which the endophytes were isolated. The majority of endophytes that produce antibiotic metabolites belong to either phylum Ascomycota (kingdom Fungi) or to phylum Actinobacteria (superkingdom Bacteria). Endophytes that produce antibiotic metabolites were predominant, but certainly not exclusively, from the plant families Fabaceae, Lamiaceae, Asteraceae and Araceae, suggesting that endophytes that produce antimicrobial metabolites are not restricted to a reduced number of plant families. The locations where plants (and inhabiting endophytes) were collected from, according to the literature, have been mapped, showing that endophytes that produce bioactive compounds have been collected globally. Copyright © 2016 Elsevier Inc. All rights reserved.

Chemoprofile and functional diversity of fungal and bacterial endophytes and role of ecofactors - A review.

PubMed

Shah, Aiyatullah; Hassan, Qazi Parvaiz; Mushtaq, Saleem; Shah, Aabid Manzoor; Hussain, Aehtesham

2017-10-01

Endophytes represent a hidden world within plants. Almost all plants that are studied harbor one or more endophytes, which help their host to survive against pathogens and changing adverse environmental conditions. Fungal and bacterial endophytes with distinct ecological niches show important biological activities and ecological functions. Their unique physiological and biochemical characteristics lead to the production of niche specific secondary metabolites that may have pharmacological potential. Identification of specific secondary metabolites in adverse environment can also help us in understanding mechanisms of host tolerance against stress condition such as biological invasions, salt, drought, temperature. These metabolites include micro as well as macromolecules, which they produce through least studied yet surprising mechanisms like xenohormesis, toxin-antitoxin system, quorum sensing. Therefore, future studies should focus on unfolding all the underlying molecular mechanisms as well as the impact of physical and biochemical environment of a specific host over endophytic function and metabolite elicitation. Need of the hour is to reshape the focus of research over endophytes and scientifically drive their ecological role toward prospective pharmacological as well as eco-friendly biological applications. This may help to manage these endophytes especially from untapped ecoregions as a useful undying biological tool to meet the present challenges as well as lay a strong and logical basis for any impending challenges. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel antibacterial and antifungal phenolic compound from the endophytic fungus Pestalotiopsis mangiferae.

PubMed

Subban, Kamalraj; Subramani, Ramesh; Johnpaul, Muthumary

2013-01-01

A novel phenolic compound, 4-(2,4,7-trioxa-bicyclo[4.1.0]heptan-3-yl) phenol (1), was isolated from Pestalotiopsis mangiferae, an endophytic fungus associated with Mangifera indica Linn. The structure of the compound was elucidated on the basis of comprehensive spectral analysis (UV, IR, ¹H-, ¹³C- and 2D-NMR, as well as HRESI-MS). Compound (1) shows potent antibacterial and antifungal activity against Bacillus subtilis, Klebsiella pneumoniae, Escherichia coli, Micrococcus luteus, Pseudomonas aeruginosa and Candida albicans. The transmission electron microscope study for the mode of inhibition of compound (1) on bacterial pathogens revealed the destruction of bacterial cells by cytoplasm agglutination with the formation of pores in cell wall membranes.

Bacterial mutation affecting plasmid maintenance in Pseudomonas aeruginosa.

PubMed Central

Chang, B J; Holloway, B W

1977-01-01

A bacterial mutation, risA, in Pseudomonas aeruginosa caused growth inhibition at 43 degrees C of risA strains containing P2 plasmids. Incubation at 43 degrees C resulted in selection for clones that had lost P2 plasmids. PMID:122513

Endophytic bacteria take the challenge to improve Cu phytoextraction by sunflower.

PubMed

Kolbas, Aliaksandr; Kidd, Petra; Guinberteau, Jacques; Jaunatre, Renaud; Herzig, Rolf; Mench, Michel

2015-04-01

Endophytic bacteria from roots and crude seed extracts of a Cu-tolerant population of Agrostis capillaris were inoculated to a sunflower metal-tolerant mutant line, and their influence on Cu tolerance and phytoextraction was assessed using a Cu-contaminated soil series. Ten endophytic bacterial strains isolated from surface-sterilized A. capillaris roots were mixed to prepare the root endophyte inoculant (RE). In parallel, surface-sterilized seeds of A. capillaris were crushed in MgSO4 to prepare a crude seed extract containing seed endophytes (SE). An aliquot of this seed extract was filtered at 0.2 μm to obtain a bacterial cell-free seed extract (SEF). After surface sterilization, germinated sunflower seeds were separately treated with one of five modalities: no treatment (C), immersion in MgSO4 (CMg) or SEF solutions and inoculation with RE or SE. All plants were cultivated on a Cu-contaminated soil series (13-1020 mg Cu kg(-1)). Cultivable RE strains were mostly members of the Pseudomonas genera, and one strain was closely related to Labrys sp. The cultivable SE strains belonged mainly to the Bacillus genera and some members of the Rhodococcus genera. The treatment effects depended on the soil Cu concentration. Both SE and SEF plants had a higher Cu tolerance in the 13-517 mg Cu kg(-1) soil range as reflected by increased shoot and root DW yields compared to control plants. This was accompanied by a slight decrease in shoot Cu concentration and increase in root Cu concentration. Shoot and root DW yields were more promoted by SE than SEF in the 13-114 mg Cu kg(-1) soil range, which could reflect the influence of seed-located bacterial endophytes. At intermediate soil Cu (416-818 mg Cu kg(-1) soil), the RE and CMg plants had lower shoot Cu concentrations than the control, SE and SEF plants. At high total soil Cu (617-1020 mg Cu kg(-1)), root DW yield of RE plants slightly increased and their root Cu concentration rose by up to 1.9-fold. In terms

Bacterial Microbiota of Rice Roots: 16S-Based Taxonomic Profiling of Endophytic and Rhizospheric Diversity, Endophytes Isolation and Simplified Endophytic Community.

PubMed

Moronta-Barrios, Felix; Gionechetti, Fabrizia; Pallavicini, Alberto; Marys, Edgloris; Venturi, Vittorio

2018-02-11

Rice is currently the most important food crop in the world and we are only just beginning to study the bacterial associated microbiome. It is of importance to perform screenings of the core rice microbiota and also to develop new plant-microbe models and simplified communities for increasing our understanding about the formation and function of its microbiome. In order to begin to address this aspect, we have performed a 16S rDNA taxonomic bacterial profiling of the rhizosphere and endorhizosphere of two high-yield rice cultivars-Pionero 2010 FL and DANAC SD20A-extensively grown in Venezuela in 2014. Fifteen putative bacterial endophytes were then isolated from surface-sterilized roots and further studied in vitro and in planta . We have then performed inoculation of rice seedlings with a simplified community composed by 10 of the isolates and we have tracked them in the course of 30 days in greenhouse cultivation. The results obtained suggest that a set was able to significantly colonize together the rice endorhizospheres, indicating possible cooperation and the ability to form a stable multispecies community. This approach can be useful in the development of microbial solutions for a more sustainable rice production.

Plant species affect colonization patterns and metabolic activity of associated endophytes during phytoremediation of crude oil-contaminated soil.

PubMed

Fatima, K; Imran, A; Amin, I; Khan, Q M; Afzal, M

2016-04-01

Plants coupled with endophytic bacteria hold great potential for the remediation of polluted environment. The colonization patterns and activity of inoculated endophytes in rhizosphere and endosphere of host plant are among the primary factors that may influence the phytoremediation process. However, these colonization patterns and metabolic activity of the inoculated endophytes are in turn controlled by none other than the host plant itself. The present study aims to determine such an interaction specifically for plant-endophyte systems remediating crude oil-contaminated soil. A consortium (AP) of two oil-degrading endophytic bacteria (Acinetobacter sp. strain BRSI56 and Pseudomonas aeruginosa strain BRRI54) was inoculated to two grasses, Brachiaria mutica and Leptochloa fusca, vegetated in crude oil-contaminated soil. Colonization patterns and metabolic activity of the endophytes were monitored in the rhizosphere and endosphere of the plants. Bacterial augmentation enhanced plant growth and crude oil degradation. Maximum crude oil degradation (78%) was achieved with B. mutica plants inoculated with AP consortium. This degradation was significantly higher than those treatments, where plants and bacteria were used individually or L. fusca and endophytes were used in combination. Moreover, colonization and metabolic activity of the endophytes were higher in the rhizosphere and endosphere of B. mutica than L. fusca. The plant species affected not only colonization pattern and biofilm formation of the inoculated bacteria in the rhizosphere and endosphere of the host plant but also affected the expression of alkane hydroxylase gene, alkB. Hence, the investigation revealed that plant species can affect colonization patterns and metabolic activity of inoculated endophytic bacteria and ultimately the phytoremediation process.

Antimicrobial activity of pyrrocidines from Acremonium zeae against endophytes and pathogens of maize.

PubMed

Wicklow, Donald T; Poling, Stephen M

2009-01-01

Acremonium zeae produces pyrrocidines A and B, which are polyketide-amino acid-derived antibiotics, and is recognized as a seedborne protective endophyte of maize which augments host defenses against microbial pathogens causing seedling blights and stalk rots. Pyrrocidine A displayed significant in vitro activity against Aspergillus flavus and Fusarium verticillioides in assays performed using conidia as inoculum, with pyrrocidine A being more active than B. In equivalent assays performed with conidia or hyphal cells as inoculum, pyrrocidine A revealed potent activity against major stalk and ear rot pathogens of maize, including F. graminearum, Nigrospora oryzae, Stenocarpella (Diplodia) maydis, and Rhizoctonia zeae. Pyrrocidine A displayed significant activity against seed-rotting saprophytes A. flavus and Eupenicillium ochrosalmoneum, as well as seed-infecting colonists of the phylloplane Alternaria alternata, Cladosporium cladosporioides, and Curvularia lunata, which produces a damaging leaf spot disease. Protective endophytes, including mycoparasites which grow asymptomatically within healthy maize tissues, show little sensitivity to pyrrocidines. Pyrrocidine A also exhibited potent activity against Clavibacter michiganense subsp. nebraskense, causal agent of Goss's bacterial wilt of maize, and Bacillus mojaviense and Pseudomonas fluorescens, maize endophytes applied as biocontrol agents, but were ineffective against the wilt-producing bacterium Pantoea stewartii.

Biodegradation of chlorpyrifos by bacterial genus Pseudomonas.

PubMed

Gilani, Razia Alam; Rafique, Mazhar; Rehman, Abdul; Munis, Muhammad Farooq Hussain; Rehman, Shafiq Ur; Chaudhary, Hassan Javed

2016-02-01

Chlorpyrifos is an organophosphorus pesticide commonly used in agriculture. It is noxious to a variety of organisms that include living soil biota along with beneficial arthropods, fish, birds, humans, animals, and plants. Exposure to chlorpyrifos may cause detrimental effects as delayed seedling emergence, fruit deformities, and abnormal cell division. Contamination of chlorpyrifos has been found about 24 km from the site of its application. There are many physico-chemical and biological approaches to remove organophosphorus pesticides from the ecosystem, among them most promising is biodegradation. The 3,5,6-trichloro-2-pyridinol (TCP) and diethylthiophosphate (DETP) as primary products are made when chlorpyrifos is degraded by soil microorganisms which further break into nontoxic metabolites as CO(2), H(2)O, and NH(3). Pseudomonas is a diversified genus possessing a series of catabolic pathways and enzymes involved in pesticide degradation. Pseudomonas putida MAS-1 is reported to be more efficient in chlorpyrifos degradation by a rate of 90% in 24 h among Pseudomonas genus. The current review analyzed the comparative potential of bacterial species in Pseudomonas genus for degradation of chlorpyrifos thus, expressing an ecofriendly approach for the treatment of environmental contaminants like pesticides. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metagenomics workflow analysis of endophytic bacteria from oil palm fruits

NASA Astrophysics Data System (ADS)

Tanjung, Z. A.; Aditama, R.; Sudania, W. M.; Utomo, C.; Liwang, T.

2017-05-01

Next-Generation Sequencing (NGS) has become a powerful sequencing tool for microbial study especially to lead the establishment of the field area of metagenomics. This study described a workflow to analyze metagenomics data of a Sequence Read Archive (SRA) file under accession ERP004286 deposited by University of Sao Paulo. It was a direct sequencing data generated by 454 pyrosequencing platform originated from oil palm fruits endophytic bacteria which were cultured using oil-palm enriched medium. This workflow used SortMeRNA to split ribosomal reads sequence, Newbler (GS Assembler and GS Mapper) to assemble and map reads into genome reference, BLAST package to identify and annotate contigs sequence, and QualiMap for statistical analysis. Eight bacterial species were identified in this study. Enterobacter cloacae was the most abundant species followed by Citrobacter koseri, Seratia marcescens, Latococcus lactis subsp. lactis, Klebsiella pneumoniae, Citrobacter amalonaticus, Achromobacter xylosoxidans, and Pseudomonas sp. respectively. All of these species have been reported as endophyte bacteria in various plant species and each has potential as plant growth promoting bacteria or another application in agricultural industries.

Biodegradation of Mixed PAHs by PAH-Degrading Endophytic Bacteria.

PubMed

Zhu, Xuezhu; Ni, Xue; Waigi, Michael Gatheru; Liu, Juan; Sun, Kai; Gao, Yanzheng

2016-08-09

Endophytic bacteria can promote plant growth, induce plant defence mechanisms, and increase plant resistance to organic contaminants. The aims of the present study were to isolate highly PAH-degrading endophytic bacteria from plants growing at PAH-contaminated sites and to evaluate the capabilities of these bacteria to degrade polycyclic aromatic hydrocarbons (PAHs) in vitro, which will be beneficial for re-colonizing target plants and reducing plant PAH residues through the inoculation of plants with endophytic bacteria. Two endophytic bacterial strains P₁ (Stenotrophomonas sp.) and P₃ (Pseudomonas sp.), which degraded more than 90% of phenanthrene (PHE) within 7 days, were isolated from Conyza canadensis and Trifolium pretense L., respectively. Both strains could use naphthalene (NAP), PHE, fluorene (FLR), pyrene (PYR), and benzo(a)pyrene (B(a)P) as the sole sources of carbon and energy. Moreover, these bacteria reduced the contamination of mixed PAHs at high levels after inoculation for 7 days; strain P₁ degraded 98.0% NAP, 83.1% FLR, 87.8% PHE, 14.4% PYR, and 1.6% B(a)P, and strain P₃ degraded 95.3% NAP, 87.9% FLR, 90.4% PHE, 6.9% PYR, and negligible B(a)P. Notably, the biodegradation of PAHs could be promoted through additional carbon and nitrogen nutrients; therein, beef extract was suggested as the optimal co-substrate for the degradation of PAHs by these two strains (99.1% PHE was degraded within 7 days). Compared with strain P₁, strain P₃ has more potential for the use in the removal of PAHs from plant tissues. These results provide a novel perspective in the reduction of plant PAH residues in PAH-contaminated sites through inoculating plants with highly PAH-degrading endophytic bacteria.

Isolation, plant colonization potential, and phenanthrene degradation performance of the endophytic bacterium Pseudomonas sp. Ph6-gfp

PubMed Central

Sun, Kai; Liu, Juan; Gao, Yanzheng; Jin, Li; Gu, Yujun; Wang, Wanqing

2014-01-01

This investigation provides a novel method of endophyte-aided removal of polycyclic aromatic hydrocarbons (PAHs) from plant bodies. A phenanthrene-degrading endophytic bacterium Pseudomonas sp. Ph6 was isolated from clover (Trifolium pratense L.) grown in a PAH-contaminated site. After being marked with the GFP gene, the colonization and distribution of strain Ph6-gfp was directly visualized in plant roots, stems, and leaves for the first time. After ryegrass (Lolium multiflorum Lam.) roots inoculation, strain Ph6-gfp actively and internally colonized plant roots and transferred vertically to the shoots. Ph6-gfp had a natural capacity to cope with phenanthrene in vitro and in planta. Ph6-gfp degraded 81.1% of phenanthrene (50 mg·L−1) in a culture solution within 15 days. The inoculation of plants with Ph6-gfp reduced the risks associated with plant phenanthrene contamination based on observations of decreased concentration, accumulation, and translocation factors of phenanthrene in ryegrass. Our results will have important ramifications in the assessment of the environmental risks of PAHs and in finding ways to circumvent plant PAH contamination. PMID:24964867

Endophyte-Mediated Modulation of Defense-Related Genes and Systemic Resistance in Withania somnifera (L.) Dunal under Alternaria alternata Stress.

PubMed

Mishra, Aradhana; Singh, Satyendra Pratap; Mahfooz, Sahil; Singh, Surendra Pratap; Bhattacharya, Arpita; Mishra, Nishtha; Nautiyal, C S

2018-04-15

Endophytes have been explored and found to perform an important role in plant health. However, their effects on the host physiological function and disease management remain elusive. The present study aimed to assess the potential effects of endophytes, singly as well as in combination, in Withania somnifera (L.) Dunal, on various physiological parameters and systemic defense mechanisms against Alternaria alternata Seeds primed with the endophytic bacteria Bacillus amyloliquefaciens and Pseudomonas fluorescens individually and in combination demonstrated an enhanced vigor index and germination rate. Interestingly, plants treated with the two-microbe combination showed the lowest plant mortality rate (28%) under A. alternata stress. Physiological profiling of treated plants showed improved photosynthesis, respiration, transpiration, and stomatal conductance under pathogenic stress. Additionally, these endophytes not only augmented defense enzymes and antioxidant activity in treated plants but also enhanced the expression of salicylic acid- and jasmonic acid-responsive genes in the stressed plants. Reductions in reactive oxygen species (ROS) and reactive nitrogen species (RNS) along with enhanced callose deposition in host plant leaves corroborated well with the above findings. Altogether, the study provides novel insights into the underlying mechanisms behind the tripartite interaction of endophyte- A. alternata - W. somnifera and underscores their ability to boost plant health under pathogen stress. IMPORTANCE W. somnifera is well known for producing several medicinally important secondary metabolites. These secondary metabolites are required by various pharmaceutical sectors to produce life-saving drugs. However, the cultivation of W. somnifera faces severe challenge from leaf spot disease caused by A. alternata To keep pace with the rising demand for this plant and considering its capacity for cultivation under field conditions, the present study was undertaken

Elimination and molecular identification of endophytic bacterial contaminants during in vitro propagation of Bambusa balcooa.

PubMed

Ray, Syandan Sinha; Ali, Md Nasim; Mukherjee, Shibasis; Chatterjee, Gautam; Banerjee, Maitreyi

2017-02-01

Bambusa balcooa is an economically important, multipurpose bamboo species, decidedly used in construction industry. Availability of natural bamboo is depleting very rapidly due to accelerated deforestation and its unrestrained use. The large number and timely supply of saplings are the need of the hour for the restoration of bamboo stands. Micropropagation, being the potent alternative for season independent rapid regeneration, is restricted in bamboo because of endophytic contamination. An in vitro attempt has been taken to overcome the endophytic contamination by using broad spectrum antibiotics as surface sterilant as well as a media component. Ampicillin sodium salt (5 mg/ml for 30 min) as a surface sterilant was found as the best treatment for high bud breaking (80%) coupled with high branching and low contamination (20%) but it was found ineffective to control the contamination during multiplication stage. Then, two endophytes were isolated and minimum inhibitory concentration was determined through antibiotic susceptibility test for successful eradication at multiplication stage. Finally, contamination free cultures were obtained when streptocycline (100 μg/ml) and gentamicin sulphate (75 μg/ml) were added into the medium. The two isolated endophytes, BB1 and BB2, were identified through 16S rDNA techniques and NCBI-BLAST algorithm with 99% sequence similarity with those of Janibacter sp. (KX423734) and Serratia marcescens strain (KX423735). To our knowledge, this is the first report for B. balcooa where antibiotics were used as surface sterilant as well as medium component, to control endophytic bacterial contaminants, followed by their identification.

Distribution of bacterial endophytes in peanut seeds obtained from axenic and control plant material under field conditions

USDA-ARS?s Scientific Manuscript database

Since endophytic bacteria may play a role in the defense mechanism of peanut from fungal invasion, the internal bacterial colonization of peanut seeds was investigated. Bacteria-free young peanut plants from seed embryos were successfully grown to maturity in the field. Mature seeds from these pla...

Novel components of leaf bacterial communities of field-grown tomato plants and their potential for plant growth promotion and biocontrol of tomato diseases.

PubMed

Romero, Fernando M; Marina, María; Pieckenstain, Fernando L

2016-04-01

This work aimed to characterize potentially endophytic culturable bacteria from leaves of cultivated tomato and analyze their potential for growth promotion and biocontrol of diseases caused by Botrytis cinerea and Pseudomonas syringae. Bacteria were obtained from inner tissues of surface-disinfected tomato leaves of field-grown plants. Analysis of 16S rRNA gene sequences identified bacterial isolates related to Exiguobacterium aurantiacum (isolates BT3 and MT8), Exiguobacterium spp. (isolate GT4), Staphylococcus xylosus (isolate BT5), Pantoea eucalypti (isolate NT6), Bacillus methylotrophicus (isolate MT3), Pseudomonas veronii (isolates BT4 and NT2), Pseudomonas rhodesiae (isolate BT2) and Pseudomonas cichorii (isolate NT3). After seed inoculation, BT2, BT4, MT3, MT8, NT2 and NT6 were re-isolated from leaf extracts. NT2, BT2, MT3 and NT6 inhibited growth of Botrytis cinerea and Pseudomonas syringae pv. tomato in vitro, produced antimicrobial compounds and reduced leaf damage caused by B. cinerea. Some of these isolates also promoted growth of tomato plants, produced siderophores, the auxin indole-3-acetic and solubilized inorganic phosphate. Thus, bacterial communities of leaves from field-grown tomato plants were found to harbor potentially endophytic culturable beneficial bacteria capable of antagonizing pathogenic microorganisms and promoting plant growth, which could be used as biological control agents and biofertilizers/biostimulators for promotion of tomato plant growth. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Evaluation of endophytic colonization of Citrus sinensis and Catharanthus roseus seedlings by endophytic bacteria.

PubMed

Lacava, Paulo Teixeira; Araújo, Welington Luiz; Azevedo, João Lúcio

2007-02-01

Over the last few years, the endophytic bacterial community associated with citrus has been studied as an important component interacting with Xylella fastidiosa, the causal agent of citrus variegated chlorosis (CVC). This bacterium may also colonize some model plants, such as Catharanthus roseus and Nicotiana clevelandii. In the present study, we compared the endophytic colonization of Citrus sinensis and Catharanthus roseus using the endophytic bacteria Klebsiella pneumoniae. We chose an appropriate strain, K. pneumoniae 342 (Kp342), labeled with the GFP gene. This strain was inoculated onto seedlings of C. sinensis and C. roseus. The isolation frequency was determined one week after the inoculation and the endophytic colonization of K. pneumoniae was observed using fluorescence microscopy. Although the endophytic bacterium was more frequently isolated from C. roseus than from C. sinensis, the colonization profiles for both host plants were similar, suggesting that C. roseus could be used as a model plant to study the interaction between endophytic bacteria and X. fastidiosa.

Genome Survey and Characterization of Endophytic Bacteria Exhibiting a Beneficial Effect on Growth and Development of Poplar Trees ▿ †

PubMed Central

Taghavi, Safiyh; Garafola, Craig; Monchy, Sébastien; Newman, Lee; Hoffman, Adam; Weyens, Nele; Barac, Tanja; Vangronsveld, Jaco; van der Lelie, Daniel

2009-01-01

The association of endophytic bacteria with their plant hosts has a beneficial effect for many different plant species. Our goal is to identify endophytic bacteria that improve the biomass production and the carbon sequestration potential of poplar trees (Populus spp.) when grown in marginal soil and to gain an insight in the mechanisms underlying plant growth promotion. Members of the Gammaproteobacteria dominated a collection of 78 bacterial endophytes isolated from poplar and willow trees. As representatives for the dominant genera of endophytic gammaproteobacteria, we selected Enterobacter sp. strain 638, Stenotrophomonas maltophilia R551-3, Pseudomonas putida W619, and Serratia proteamaculans 568 for genome sequencing and analysis of their plant growth-promoting effects, including root development. Derivatives of these endophytes, labeled with gfp, were also used to study the colonization of their poplar hosts. In greenhouse studies, poplar cuttings (Populus deltoides × Populus nigra DN-34) inoculated with Enterobacter sp. strain 638 repeatedly showed the highest increase in biomass production compared to cuttings of noninoculated control plants. Sequence data combined with the analysis of their metabolic properties resulted in the identification of many putative mechanisms, including carbon source utilization, that help these endophytes to thrive within a plant environment and to potentially affect the growth and development of their plant hosts. Understanding the interactions between endophytic bacteria and their host plants should ultimately result in the design of strategies for improved poplar biomass production on marginal soils as a feedstock for biofuels. PMID:19060168

Population diversity of bacterial endophytes from jute (Corchorus olitorius) and evaluation of their potential role as bioinoculants.

PubMed

Haidar, Badrul; Ferdous, Mahbuba; Fatema, Babry; Ferdous, Ahlan Sabah; Islam, Mohammad Riazul; Khan, Haseena

2018-03-01

Endophytes are bacterial or fungal organisms associated with plants in an obligate or facultative manner. In order to maintain a stable symbiosis, many of the endophytes produce compounds that promote plant growth and help them adapt better to the environment. This study was conducted to explore the potential of jute bacterial endophytes for their growth promotion ability in direct and indirect ways. A total of 27 different bacterial species were identified from different varieties of a jute plant (Corchorus olitorius) and different parts of the plant (leaf, root, seed, and seedling) based on 16S rRNA gene sequence. Two of the isolates showed ACC deaminase activity with Staphylococcus pasteuri strain MBL_B3 and Ralstonia solanacearum strain MBL_B6 producing 18.1 and 8.08 μM mg -1  h -1 α-ketobutyrate respectively while eighteen had the ACC deaminase gene (acdS). Fourteen were positive for siderophore activity while Kocuria sp. strain MBL_B19 (133.36 μg/ml) and Bacillus sp. strain MBL_B17 (124.72 μg/ml) showed high IAA production ability. Seven bacterial strains were able to fix nitrogen with only one testing positive for nifH gene. Five isolates exhibited phosphorus utilization ability with Bacillus sp. strain MBL_B17 producing 218.47 μg P/ml. Three bacteria were able to inhibit the growth of a phytopathogen, Macrophomina phaseolina and among them Bacillus subtilis strain MBL_B4 was found to be the most effective, having 82% and 53% of relative inhibition ratio (RIR) and percent growth inhibition (PGI) values respectively. Nine bacteria were tested for their in vivo growth promotion ability and most of these isolates increased seed germination potential and vigour index significantly. Bacillus subtilis strain MBL_B13 showed 26.8% more vigour index than the control in which no bacterial inoculum was used. All inoculants were found to increase the dry weight of jute seedlings in comparison to the control plants and the most increase in fresh weight

Characterization of rhizosphere and endophytic bacterial communities from leaves, stems and roots of medicinal Stellera chamaejasme L.

PubMed

Jin, Hui; Yang, Xiao-Yan; Yan, Zhi-Qiang; Liu, Quan; Li, Xiu-Zhuang; Chen, Ji-Xiang; Zhang, Deng-Hong; Zeng, Li-Ming; Qin, Bo

2014-07-01

A diverse array of bacteria that inhabit the rhizosphere and different plant organs play a crucial role in plant health and growth. Therefore, a general understanding of these bacterial communities and their diversity is necessary. Using the 16S rRNA gene clone library technique, the bacterial community structure and diversity of the rhizosphere and endophytic bacteria in Stellera chamaejasme compartments were compared and clarified for the first time. Grouping of the sequences obtained showed that members of the Proteobacteria (43.2%), Firmicutes (36.5%) and Actinobacteria (14.1%) were dominant in both samples. Other groups that were consistently found, albeit at lower abundance, were Bacteroidetes (2.1%), Chloroflexi (1.9%), and Cyanobacteria (1.7%). The habitats (rhizosphere vs endophytes) and organs (leaf, stem and root) structured the community, since the Wilcoxon signed rank test indicated that more varied bacteria inhabited the rhizosphere compared to the organs of the plant. In addition, correspondence analysis also showed that differences were apparent in the bacterial communities associated with these distinct habitats. Moreover, principal component analysis revealed that the profiles obtained from the rhizosphere and roots were similar, whereas leaf and stem samples clustered together on the opposite side of the plot from the rhizosphere and roots. Taken together, these results suggested that, although the communities associated with the rhizosphere and organs shared some bacterial species, the associated communities differed in structure and diversity. Copyright © 2014 Elsevier GmbH. All rights reserved.

[Screening and identification of an endophytic bacterium with 1-aminocyclopropane-1-carboxylate deaminase activity from Panax ginseng and its effect on host growth].

PubMed

Tian, Lei; Jiang, Yun; Chen, Changqing; Zhang, Guanjun; Li, Tong; Tong, Bin; Xu, Peng

2014-07-04

This study aimed to screen endophytic bacteria with 1-aminocyclopropane-1-carboxylate deaminase activity from Panax ginseng and test the capability of growth promotion to its host. In total 120 endophytic bacterial strains isolated from Panax ginseng were screened for 1-aminocyclopropane-1-carboxylate deaminase activity using the qualitative and quantitative methods. The obtained strain was also tested for its ability of nitrogen fixation using the Ashby agar plates and the gene of nifH, for its ability of phosphate solubilization using the Pikovaskaia's plates and quantitative analysis of Mo-Sb-Ascrobiology acid colorimetry, for its ability of producing siderophores using the method of Chrome azurol S detecting, and its effect on promoting growth of Panax ginseng by laboratory and field experiments. The bacterial strain with ACC deaminase was identified based on morphology, physiological and biochemical traits, and 16S rRNA sequence analysis. The bacterial stain JJ8-3 with the ability of producing ACC deaminase activity was obtained through screening, which its ACC deaminase activity was alpha-ketobutyric acid 6.7 micromol/(mg x h). Strain JJ8-3 had other traits of phosphate solubilizing, nitrogen fixation, producing siderophores, and the ability of promoting growth of Panax ginseng. Strain JJ8-3 was identified as Pseudomonas fluorescens. Strain JJ8-3 of endophytic bacterium with ACC deaminase activity from Panax ginseng was obtained and would lay the foundation for its further study and application on plant growth promotion.

Inoculating plants with the endophytic bacterium Pseudomonas sp. Ph6-gfp to reduce phenanthrene contamination.

PubMed

Sun, Kai; Liu, Juan; Gao, Yanzheng; Sheng, Yuehui; Kang, Fuxing; Waigi, Michael Gatheru

2015-12-01

Plant organic contamination poses a serious threat to the safety of agricultural products and human health worldwide, and the association of endophytic bacteria with host plants may decrease organic pollutants in planta. In this study, we firstly determined the growth response and biofilm formation of endophytic Pseudomonas sp. Ph6-gfp, and then systematically evaluated the performance of different plant colonization methods (seed soaking (SS), root soaking (RS), leaf painting (LP)) for circumventing the risk of plant phenanthrene (PHE) contamination. After inoculation for 48 h, strain Ph6-gfp grew efficiently with PHE, oxalic acid, or malic acid as the sole sources of carbon and energy. Moreover, strain Ph6-gfp could form robust biofilms in LB medium. In greenhouse hydroponic experiments, strain Ph6-gfp could actively colonize inoculated plants internally, and plants colonized with Ph6-gfp showed a higher capacity for PHE removal. Compared with the Ph6-gfp-free treatment, the accumulations of PHE in Ph6-gfp-colonized plants via SS, RS, and LP were 20.1, 33.1, and 7.1 %, respectively, lower. Our results indicate that inoculating plants with Ph6-gfp could lower the risk of plant PHE contamination. RS was most efficient for improving PHE removal in whole plant bodies by increasing the cell numbers of Ph6-gfp in plant roots. The findings in this study provide an optimized method to strain Ph6-gfp reduce plant PAH residues, which may be applied to agricultural production in PAH-contaminated soil.

Root bacterial endophytes confer drought resistance and enhance expression and activity of a vacuolar H+ -pumping pyrophosphatase in pepper plants.

PubMed

Vigani, Gianpiero; Rolli, Eleonora; Marasco, Ramona; Dell'Orto, Marta; Michoud, Grégoire; Soussi, Asma; Raddadi, Noura; Borin, Sara; Sorlini, Claudia; Zocchi, Graziano; Daffonchio, Daniele

2018-05-22

It has been previously shown that the transgenic overexpression of the plant root vacuolar proton pumps H + -ATPase (V-ATPase) and H + -PPase (V-PPase) confer tolerance to drought. Since plant-root endophytic bacteria can also promote drought tolerance, we hypothesize that such promotion can be associated to the enhancement of the host vacuolar proton pumps expression and activity. To test this hypothesis, we selected two endophytic bacteria endowed with an array of in vitro plant growth promoting traits. Their genome sequences confirmed the presence of traits previously shown to confer drought resistance to plants, such as the synthesis of nitric oxide and of organic volatile organic compounds. We used the two strains on pepper (Capsicuum annuum L.) because of its high sensitivity to drought. Under drought conditions, both strains stimulated a larger root system and enhanced the leaves' photosynthetic activity. By testing the expression and activity of the vacuolar proton pumps, H + -ATPase (V-ATPase) and H + -PPase (V-PPase), we found that bacterial colonization enhanced V-PPase only. We conclude that the enhanced expression and activity of V-PPase can be favoured by the colonization of drought-tolerance-inducing bacterial endophytes. This article is protected by copyright. All rights reserved. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

NASA Astrophysics Data System (ADS)

Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

2015-12-01

The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

Impact of Soil Salinity on the Structure of the Bacterial Endophytic Community Identified from the Roots of Caliph Medic (Medicago truncatula)

PubMed Central

Al-Lawati, Abbas; Jana, Gerry Aplang; Vishwas Patankar, Himanshu; Glick, Bernard R.

2016-01-01

In addition to being a forage crop, Caliph medic (Medicago truncatula) is also a model legume plant and is used for research focusing on the molecular characterization of the interaction between rhizobia and plants. However, the endophytic microbiome in this plant is poorly defined. Endophytic bacteria play a role in supplying plants with the basic requirements necessary for growth and development. Moreover, these bacteria also play a role in the mechanism of salinity stress adaptation in plants. As a prelude to the isolation and utilization of these bacteria in Caliph medic farming, 41 bacterial OTUs were identified in this project from within the interior of the roots of this plant by pyrosequencing of the small ribosomal subunit gene (16S rDNA) using a cultivation-independent approach. In addition, the differential abundance of these bacteria was studied following exposure of the plants to salinity stress. About 29,064 high-quality reads were obtained from the sequencing of six libraries prepared from control and salinity-treated tissues. Statistical analysis revealed that the abundance of ~70% of the OTUs was significantly (p ≤ 0.05) altered in roots that were exposed to salinity stress. Sequence analysis showed a similarity between some of the identified species and other, known, growth-promoting bacteria, marine and salt-stressed soil-borne bacteria, and nitrogen-fixing bacterial isolates. Determination of the amendments to the bacterial community due to salinity stress in Caliph medic provides a crucial step toward developing an understanding of the association of these endophytes, under salt stress conditions, in this model plant. To provide direct evidence regarding their growth promoting activity, a group of endophytic bacteria were isolated from inside of plant roots using a cultivation-dependent approach. Several of these isolates were able to produce ACC-deaminase, ammonia and IAA; and to solubilize Zn+2 and PO4-3. This data is consistent with the

Molecular and phenotypic characterization of endophytic bacteria isolated from sulla nodules.

PubMed

Beghalem, Hamida; Aliliche, Khadidja; Chriki, Ali; Landoulsi, Ahmed

2017-10-01

In the current study, bacterial diversity was investigated in root nodules of Sulla pallida and Sulla capitata. The isolates were analyzed on the basis of their phenotypic and molecular characteristics. The phylogenetic analysis based on 16S rRNA and housekeeping genes (recA and atpD) showed that the isolated bacteria related to Sinorhizobium, Neorhizobium, Phyllobacterium, Arthrobacter, Variovorax and Pseudomonas genera. This is the first report of Neorhizobium genus associated with Hedysarum genus. Phenotypically, all strains tolerate the elevated temperature of 40 °C, and salt stress at a concentration of 2%. In addition, the isolates failed to induce nodulation on their original host; and the symbiotic genes could not be amplified, suggesting that these strains are endophytic bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cultivar and Metal-Specific Effects of Endophytic Bacteria in Helianthus tuberosus Exposed to Cd and Zn

PubMed Central

Thijs, Sofie; Lobo, Mª Carmen; Weyens, Nele; Pérez-Sanz, Araceli

2017-01-01

Plant growth promoting endophytic bacteria (PGPB) isolated from Brassica napus were inoculated in two cultivars of Helianthus tuberosus (VR and D19) growing on sand supplemented with 0.1 mM Cd or 1 mM Zn. Plant growth, concentrations of metals and thiobarbituric acid (TBA) reactive compounds were determined. Colonization of roots of H. tuberosus D19 by Pseudomonas sp. 262 was evaluated using confocal laser scanning microscopy. Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 significantly enhanced growth of H. tuberosus D19 exposed to Cd or Zn. Pseudomonas sp. 228 significantly increased Cd concentrations in roots. Serratia sp. 246, and Pseudomonas sp. 256 and 228 resulted in significantly decreased contents of TBA reactive compounds in roots of Zn exposed D19 plants. Growth improvement and decrease of metal-induced stress were more pronounced in D19 than in VR. Pseudomonas sp. 262-green fluorescent protein (GFP) colonized the root epidermis/exodermis and also inside root hairs, indicating that an endophytic interaction was established. H. tuberosus D19 inoculated with Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 holds promise for sustainable biomass production in combination with phytoremediation on Cd and Zn contaminated soils. PMID:28934107

Cultivar and Metal-Specific Effects of Endophytic Bacteria in Helianthus tuberosus Exposed to Cd and Zn.

PubMed

Montalbán, Blanca; Thijs, Sofie; Lobo, Mª Carmen; Weyens, Nele; Ameloot, Marcel; Vangronsveld, Jaco; Pérez-Sanz, Araceli

2017-09-21

Plant growth promoting endophytic bacteria (PGPB) isolated from Brassica napus were inoculated in two cultivars of Helianthus tuberosus (VR and D19) growing on sand supplemented with 0.1 mM Cd or 1 mM Zn. Plant growth, concentrations of metals and thiobarbituric acid (TBA) reactive compounds were determined. Colonization of roots of H. tuberosus D19 by Pseudomonas sp. 262 was evaluated using confocal laser scanning microscopy. Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 significantly enhanced growth of H. tuberosus D19 exposed to Cd or Zn. Pseudomonas sp. 228 significantly increased Cd concentrations in roots. Serratia sp. 246, and Pseudomonas sp. 256 and 228 resulted in significantly decreased contents of TBA reactive compounds in roots of Zn exposed D19 plants. Growth improvement and decrease of metal-induced stress were more pronounced in D19 than in VR. Pseudomonas sp. 262 - green fluorescent protein (GFP) colonized the root epidermis/exodermis and also inside root hairs, indicating that an endophytic interaction was established. H. tuberosus D19 inoculated with Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 holds promise for sustainable biomass production in combination with phytoremediation on Cd and Zn contaminated soils.

Nanoindentation of Pseudomonas aeruginosa bacterial biofilm using atomic force microscopy

NASA Astrophysics Data System (ADS)

Baniasadi, Mahmoud; Xu, Zhe; Gandee, Leah; Du, Yingjie; Lu, Hongbing; Zimmern, Philippe; Minary-Jolandan, Majid

2014-12-01

Bacterial biofilms are a source of many chronic infections. Biofilms and their inherent resistance to antibiotics are attributable to a range of health issues including affecting prosthetic implants, hospital-acquired infections, and wound infection. Mechanical properties of biofilm, in particular, at micro- and nano-scales, are governed by microstructures and porosity of the biofilm, which in turn may contribute to their inherent antibiotic resistance. We utilize atomic force microscopy (AFM)-based nanoindentation and finite element simulation to investigate the nanoscale mechanical properties of Pseudomonas aeruginosa bacterial biofilm. This biofilm was derived from human samples and represents a medically relevant model.

Hydrocarbon degradation potential and plant growth-promoting activity of culturable endophytic bacteria of Lotus corniculatus and Oenothera biennis from a long-term polluted site.

PubMed

Pawlik, Małgorzata; Cania, Barbara; Thijs, Sofie; Vangronsveld, Jaco; Piotrowska-Seget, Zofia

2017-08-01

Many endophytic bacteria exert beneficial effects on their host, but still little is known about the bacteria associated with plants growing in areas heavily polluted by hydrocarbons. The aim of the study was characterization of culturable hydrocarbon-degrading endophytic bacteria associated with Lotus corniculatus L. and Oenothera biennis L. collected in long-term petroleum hydrocarbon-polluted site using culture-dependent and molecular approaches. A total of 26 hydrocarbon-degrading endophytes from these plants were isolated. Phylogenetic analyses classified the isolates into the phyla Proteobacteria and Actinobacteria. The majority of strains belonged to the genera Rhizobium, Pseudomonas, Stenotrophomonas, and Rhodococcus. More than 90% of the isolates could grow on medium with diesel oil, approximately 20% could use n-hexadecane as a sole carbon and energy source. PCR analysis revealed that 40% of the isolates possessed the P450 gene encoding for cytochrome P450-type alkane hydroxylase (CYP153). In in vitro tests, all endophytic strains demonstrated a wide range of plant growth-promoting traits such as production of indole-3-acetic acid, hydrogen cyanide, siderophores, and phosphate solubilization. More than 40% of the bacteria carried the gene encoding for the 1-aminocyclopropane-1-carboxylic acid deaminase (acdS). Our study shows that the diversity of endophytic bacterial communities in tested plants was different. The results revealed also that the investigated plants were colonized by endophytic bacteria possessing plant growth-promoting features and a clear potential to degrade hydrocarbons. The properties of isolated endophytes indicate that they have the high potential to improve phytoremediation of petroleum hydrocarbon-polluted soils.

Endophytic colonization and biocontrol performance of Pseudomonas fluorescens PICF7 in olive (Olea europaea L.) are determined neither by pyoverdine production nor swimming motility.

PubMed

Maldonado-González, M Mercedes; Schilirò, Elisabetta; Prieto, Pilar; Mercado-Blanco, Jesús

2015-09-01

Pseudomonas fluorescens PICF7 is an indigenous inhabitant of olive (Olea europaea L.) rhizosphere, able to display endophytic lifestyle in roots, to induce a wide range of defence responses upon colonization of this organ and to exert effective biological control against Verticillium wilt of olive (VWO) (Verticillium dahliae). We aimed to evaluate the involvement of specific PICF7 phenotypes in olive root colonization and VWO biocontrol effectiveness by generating mutants impaired in swimming motility (fliI) or siderophore pyoverdine production (pvdI). Besides, the performance of mutants with diminished in vitro growth in potato dextrose agar medium (gltA) and cysteine (Cys) auxotrophy was also assessed. Results showed that olive root colonization and VWO biocontrol ability of the fliI, pvdI and gltA mutants did not significantly differ from that displayed by the parental strain PICF7. Consequently, altered in vitro growth, swimming motility and pyoverdine production contribute neither to PICF7 VWO suppressive effect nor to its colonization ability. In contrast, the Cys auxotroph mutant showed reduced olive root colonization capacity and lost full biocontrol efficacy. Moreover, confocal laser scanning microscopy revealed that all mutants tested were able to endophytically colonize root tissue to the same extent as wild-type PICF7, discarding these traits as relevant for its endophytic lifestyle. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

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

PubMed

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

2016-01-01

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

Quorum quenching activity in cell-free lysate of endophytic bacteria isolated from Pterocarpus santalinus Linn., and its effect on quorum sensing regulated biofilm in Pseudomonas aeruginosa PAO1.

PubMed

Rajesh, P S; Ravishankar Rai, V

2014-01-01

Quorum sensing mechanism allows the microorganisms to resist the antibiotic treatment by forming biofilms. Quorum quenching is one of the mechanisms to control the development of drug resistance in microbes. Endophyte bacteria are beneficial to plant growth as they support the immune system against the pathogen attack. The endophytic bacteria present in Pterocarpus santalinus were screened for the presence of N-acyl homoserine lactones (AHLs) degrading bacteria using biosensor strains and further confirmed by quantifying the violacein production. Cell-free lysate of endophytic bacteria, Bacillus firmus PT18 and Enterobacter asburiae PT39 exhibited potent AHL degrading ability by inhibiting about 80% violacein production in biosensor strain. Furthermore, when the cell-free lysate was applied to Pseudomonas aeruginosa PAO1 and PAO1-JP2 biofilm it resulted in significant (p<0.01) inhibition of biofilm formation. The biofilm inhibition was confirmed by visualization of biofilm slides under fluorescence microscopy, which showed decrease in total biomass formation in treated slides. Isolation and amplification of the gene (aiiA) indicated that the presence of AHL lactonase in cell-free lysate and sequence alignment indicated that AiiA contains a "HXHXDH" zinc-binding motif that is being conserved in several groups of metallohydrolases. Therefore, the study shows the potential of AHLs degradation by AHL lactonase present in cell-free lysate of isolated endophytic bacteria and inhibition of quorum sensing regulated biofilm formation in P. aeruginosa PAO1. Copyright © 2013 Elsevier GmbH. All rights reserved.

Endophytes are hidden producers of maytansine in Putterlickia roots.

PubMed

Kusari, Souvik; Lamshöft, Marc; Kusari, Parijat; Gottfried, Sebastian; Zühlke, Sebastian; Louven, Kathrin; Hentschel, Ute; Kayser, Oliver; Spiteller, Michael

2014-12-26

Several recent studies have lent evidence to the fact that certain so-called plant metabolites are actually biosynthesized by associated microorganisms. In this work, we show that the original source organism(s) responsible for the biosynthesis of the important anticancer and cytotoxic compound maytansine is the endophytic bacterial community harbored specifically within the roots of Putterlickia verrucosa and P. retrospinosa plants. Evaluation of the root endophytic community by chemical characterization of their fermentation products using HPLC-HRMS(n), along with a selective microbiological assay using the maytansine-sensitive type strain Hamigera avellanea revealed the endophytic production of maytansine. This was further confirmed by the presence of AHBA synthase genes in the root endophytic communities. Finally, MALDI-imaging-HRMS was used to demonstrate that maytansine produced by the endophytes is typically accumulated mainly in the root cortex of both plants. Our study, thus, reveals that maytansine is actually a biosynthetic product of root-associated endophytic microorganisms. The knowledge gained from this study provides fundamental insights on the biosynthesis of so-called plant metabolites by endophytes residing in distinct ecological niches.

Colonization process of olive tissues by Verticillium dahliae and its in planta interaction with the biocontrol root endophyte Pseudomonas fluorescens PICF7

PubMed Central

Prieto, Pilar; Navarro‐Raya, Carmen; Valverde‐Corredor, Antonio; Amyotte, Stefan G.; Dobinson, Katherine F.; Mercado‐Blanco, Jesús

2009-01-01

Summary The colonization process of Olea europaea by the defoliating pathotype of Verticillium dahliae, and the in planta interaction with the endophytic, biocontrol strain Pseudomonas fluorescens PICF7 were determined. Differential fluorescent protein tagging was used for the simultaneous visualization of P. fluorescens PICF7 and V. dahliae in olive tissues. Olive plants were bacterized with PICF7 and then transferred to V. dahliae‐infested soil. Monitoring olive colonization events by V. dahliae and its interaction with PICF7 was conducted using a non‐gnotobiotic system, confocal laser scanner microscopy and tissue vibratoming sections. A yellow fluorescently tagged V. dahliae derivative (VDAT‐36I) was obtained by Agrobacterium tumefaciens‐mediated transformation. Isolate VDAT‐36I quickly colonized olive root surface, successfully invaded root cortex and vascular tissues via macro‐ and micro‐breakages, and progressed to the aerial parts of the plant through xylem vessel cells. Strain PICF7 used root hairs as preferred penetration site, and once established on/in root tissues, hindered pathogen colonization. For the first time using this approach, the entire colonization process of a woody plant by V. dahliae is reported. Early and localized root surface and root endophytic colonization by P. fluorescens PICF7 is needed to impair full progress of verticillium wilt epidemics in olive. PMID:21255281

Pseudomonas aeruginosa Biofilm, a Programmed Bacterial Life for Fitness.

PubMed

Lee, Keehoon; Yoon, Sang Sun

2017-06-28

A biofilm is a community of microbes that typically inhabit on surfaces and are encased in an extracellular matrix. Biofilms display very dissimilar characteristics to their planktonic counterparts. Biofilms are ubiquitous in the environment and influence our lives tremendously in both positive and negative ways. Pseudomonas aeruginosa is a bacterium known to produce robust biofilms. P. aeruginosa biofilms cause severe problems in immunocompromised patients, including those with cystic fibrosis or wound infection. Moreover, the unique biofilm properties further complicate the eradication of the biofilm infection, leading to the development of chronic infections. In this review, we discuss the history of biofilm research and general characteristics of bacterial biofilms. Then, distinct features pertaining to each stage of P. aeruginosa biofilm development are highlighted. Furthermore, infections caused by biofilms on their own or in association with other bacterial species ( i.e. , multispecies biofilms) are discussed in detail.

Investigation of the Biosynthetic Potential of Endophytes in Traditional Chinese Anticancer Herbs

PubMed Central

Miller, Kristin I.; Qing, Chen; Sze, Daniel Man Yuen; Neilan, Brett A.

2012-01-01

Traditional Chinese medicine encompasses a rich empirical knowledge of the use of plants for the treatment of disease. In addition, the microorganisms associated with medicinal plants are also of interest as the producers of the compounds responsible for the observed plant bioactivity. The present study has pioneered the use of genetic screening to assess the potential of endophytes to synthesize bioactive compounds, as indicated by the presence of non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) genes. The total DNA extracts of 30 traditional Chinese herbs, were screened for functional genes involved in the biosynthesis of bioactive compounds. The four PCR screens were successful in targeting four bacterial PKS, six bacterial NRPS, ten fungal PKS and three fungal NRPS gene fragments. Analysis of the detected endophyte gene fragments afforded consideration of the possible bioactivity of the natural products produced by endophytes in medicinal herbs. This investigation describes a rapid method for the initial screening of medicinal herbs and has highlighted a subset of those plants that host endophytes with biosynthetic potential. These selected plants can be the focus of more comprehensive endophyte isolation and natural product studies. PMID:22629306

Studies on the factors modulating indole-3-acetic acid production in endophytic bacterial isolates from Piper nigrum and molecular analysis of ipdc gene.

PubMed

Jasim, B; Jimtha John, C; Shimil, V; Jyothis, M; Radhakrishnan, E K

2014-09-01

The study mainly aimed quantitative analysis of IAA produced by endophytic bacteria under various conditions including the presence of extract from Piper nigrum. Analysis of genetic basis of IAA production was also conducted by studying the presence and diversity of the ipdc gene among the selected isolates. Five endophytic bacteria isolated previously from P. nigrum were used for the study. The effect of temperature, pH, agitation, tryptophan concentration and plant extract on modulating IAA production of selected isolates was analysed by colorimetric method. Comparative and quantitative analysis of IAA production by colorimetric isolates under optimal culture condition was analysed by HPTLC method. Presence of ipdc gene and thereby biosynthetic basis of IAA production among the selected isolates were studied by PCR-based amplification and subsequent insilico analysis of sequence obtained. Among the selected bacterial isolates from P. nigrum, isolate PnB 8 (Klebsiella pneumoniae) was found to have the maximum yield of IAA under various conditions optimized and was confirmed by colorimetric, HPLC and HPTLC analysis. Very interestingly, the study showed stimulating effect of phytochemicals from P. nigrum on IAA production by endophytic bacteria isolated from same plant. This study is unique because of the selection of endophytes from same source for comparative and quantitative analysis of IAA production under various conditions. Study on stimulatory effect of phytochemicals on bacterial IAA production as explained in the study is a novel approach. Studies on molecular basis of IAA production which was confirmed by sequence analysis of ipdc gene make the study scientifically attractive. Even though microbial production of IAA is well known, current report on detailed optimization, effect of plant extract and molecular confirmation of IAA biosynthesis is comparatively novel in its approach. © 2014 The Society for Applied Microbiology.

Evaluation of the plant-growth-promoting abilities of endophytic bacteria from the psammophyte Ammodendron bifolium.

PubMed

Zhu, Yanlei; She, Xiaoping

2018-04-01

The objective of this study was to assess the plant-growth-promoting abilities of 45 endophytic bacterial isolates from Ammodendron bifolium through physiological characteristics detection and endophytic bacteria-plant interaction. Each of these isolates exhibited 1 or more plant-growth-promoting traits, but only 11 isolates belonging to the genera Bacillus, Staphylococcus, and Kocuria were capable of promoting seed germination and radicle growth. These results together with the results of the correlation analysis revealed that the completion of seed germination may not be due to IAA production, phosphate solubilization, pellicle formation, and ACC deaminase, protease and lipase production by endophytic bacteria, but may be closely related to amylase and cellulase production. Further, endophytic bacterial isolates with plant-growth-promoting traits may also provide beneficial effects to host plants at different growth stages. Thus, these results are of value for understanding the ecological roles of endophytic bacteria in host plant habitats and can serve as a foundation for further studies of their potential in plant regeneration.

Metagenomic insights into communities, functions of endophytes, and their associates with infection by root-knot nematode, Meloidogyne incognita, in tomato roots.

PubMed

Tian, Bao-Yu; Cao, Yi; Zhang, Ke-Qin

2015-11-25

Endophytes are known to play important roles in plant's health and productivity. In this study, we investigated the root microbiome of tomato in association with infection by root knot nematodes. Our objectives were to observe the effects and response of the bacterial endophytes before nematode attacks and to reveal the functional attributes of microbes in plant health and nematode pathogenesis. Community analysis of root-associated microbiomes in healthy and nematode-infected tomatoes indicated that nematode infections were associated with variation and differentiation of the endophyte and rhizosphere bacterial populations in plant roots. The community of the resident endophytes in tomato root was significantly affected by nemato-pathogenesis. Remarkably, some bacterial groups in the nematode feeding structure, the root gall, were specifically enriched, suggesting an association with nematode pathogenesis. Function-based metagenomic analysis indicated that the enriched bacterial populations in root gall harbored abundant genes related to degradation of plant polysaccharides, carbohydrate and protein metabolism, and biological nitrogen fixation. Our data indicated that some of the previously assumed beneficial endophytes or bacterial associates with nematode might be involved in nematode infections of the tomato roots.

Metagenomic insights into communities, functions of endophytes, and their associates with infection by root-knot nematode, Meloidogyne incognita, in tomato roots

PubMed Central

Tian, Bao-Yu; Cao, Yi; Zhang, Ke-Qin

2015-01-01

Endophytes are known to play important roles in plant’s health and productivity. In this study, we investigated the root microbiome of tomato in association with infection by root knot nematodes. Our objectives were to observe the effects and response of the bacterial endophytes before nematode attacks and to reveal the functional attributes of microbes in plant health and nematode pathogenesis. Community analysis of root-associated microbiomes in healthy and nematode-infected tomatoes indicated that nematode infections were associated with variation and differentiation of the endophyte and rhizosphere bacterial populations in plant roots. The community of the resident endophytes in tomato root was significantly affected by nemato-pathogenesis. Remarkably, some bacterial groups in the nematode feeding structure, the root gall, were specifically enriched, suggesting an association with nematode pathogenesis. Function-based metagenomic analysis indicated that the enriched bacterial populations in root gall harbored abundant genes related to degradation of plant polysaccharides, carbohydrate and protein metabolism, and biological nitrogen fixation. Our data indicated that some of the previously assumed beneficial endophytes or bacterial associates with nematode might be involved in nematode infections of the tomato roots. PMID:26603211

Bioaugmentation with engineered endophytic bacteria improves contaminant fate in phytoremediation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weyens, N.; van der Lelie, D.; Artois, T.

Phytoremediation of volatile organic contaminants often proves not ideal because plants and their rhizosphere microbes only partially degrade these compounds. Consequently, plants undergo evapotranspiration that contaminates the ambient air and, thus, undermines the merits of phytoremediation. Under laboratory conditions, endophytic bacteria equipped with the appropriate degradation pathways can improve in plant degradation of volatile organic contaminants. However, several obstacles must be overcome before engineered endophytes will be successful in field-scale phytoremediation projects. Here we report the first in situ inoculation of poplar trees, growing on a TCE-contaminated site, with the TCE-degrading strain Pseudomonas putida W619-TCE. In situ bioaugmentation with strainmore » W619-TCE reduced TCE evapotranspiration by 90% under field conditions. This encouraging result was achieved after the establishment and enrichment of P. putida W619-TCE as a poplar root endophyte and by further horizontal gene transfer of TCE metabolic activity to members of the poplar's endogenous endophytic population. Since P. putida W619-TCE was engineered via horizontal gene transfer, its deliberate release is not restricted under European genetically modified organisms (GMO) regulations.« less

Diversity of cultivable fungal endophytes in Paullinia cupana (Mart.) Ducke and bioactivity of their secondary metabolites.

PubMed

Silva, Fábio de Azevedo; Liotti, Rhavena Graziela; Boleti, Ana Paula de Araújo; Reis, Érica de Melo; Passos, Marilene Borges Silva; Dos Santos, Edson Lucas; Sampaio, Olivia Moreira; Januário, Ana Helena; Branco, Carmen Lucia Bassi; Silva, Gilvan Ferreira da; Mendonça, Elisabeth Aparecida Furtado de; Soares, Marcos Antônio

2018-01-01

Paullinia cupana is associated with a diverse community of pathogenic and endophytic microorganisms. We isolated and identified endophytic fungal communities from the roots and seeds of P. cupana genotypes susceptible and tolerant to anthracnose that grow in two sites of the Brazilian Amazonia forest. We assessed the antibacterial, antitumor and genotoxic activity in vitro of compounds isolated from the strains Trichoderma asperellum (1BDA) and Diaporthe phaseolorum (8S). In concert, we identified eight fungal species not previously reported as endophytes; some fungal species capable of inhibiting pathogen growth; and the production of antibiotics and compounds with bacteriostatic activity against Pseudomonas aeruginosa in both susceptible and multiresistant host strains. The plant genotype, geographic location and specially the organ influenced the composition of P. cupana endophytic fungal community. Together, our findings identify important functional roles of endophytic species found within the microbiome of P. cupana. This hypothesis requires experimental validation to propose management of this microbiome with the objective of promoting plant growth and protection.

Diversity of cultivable fungal endophytes in Paullinia cupana (Mart.) Ducke and bioactivity of their secondary metabolites

PubMed Central

Liotti, Rhavena Graziela; Boleti, Ana Paula de Araújo; Reis, Érica de Melo; Passos, Marilene Borges Silva; dos Santos, Edson Lucas; Sampaio, Olivia Moreira; Januário, Ana Helena; Branco, Carmen Lucia Bassi; da Silva, Gilvan Ferreira; de Mendonça, Elisabeth Aparecida Furtado

2018-01-01

Paullinia cupana is associated with a diverse community of pathogenic and endophytic microorganisms. We isolated and identified endophytic fungal communities from the roots and seeds of P. cupana genotypes susceptible and tolerant to anthracnose that grow in two sites of the Brazilian Amazonia forest. We assessed the antibacterial, antitumor and genotoxic activity in vitro of compounds isolated from the strains Trichoderma asperellum (1BDA) and Diaporthe phaseolorum (8S). In concert, we identified eight fungal species not previously reported as endophytes; some fungal species capable of inhibiting pathogen growth; and the production of antibiotics and compounds with bacteriostatic activity against Pseudomonas aeruginosa in both susceptible and multiresistant host strains. The plant genotype, geographic location and specially the organ influenced the composition of P. cupana endophytic fungal community. Together, our findings identify important functional roles of endophytic species found within the microbiome of P. cupana. This hypothesis requires experimental validation to propose management of this microbiome with the objective of promoting plant growth and protection. PMID:29649297

Growth promotion and colonization of switchgrass (Panicum virgatum) cv. Alamo by bacterial endophyte Burkholderia phytofirmans strain PsJN

PubMed Central

2012-01-01

Background Switchgrass is one of the most promising bioenergy crop candidates for the US. It gives relatively high biomass yield and can grow on marginal lands. However, its yields vary from year to year and from location to location. Thus it is imperative to develop a low input and sustainable switchgrass feedstock production system. One of the most feasible ways to increase biomass yields is to harness benefits of microbial endophytes. Results We demonstrate that one of the most studied plant growth promoting bacterial endophytes, Burkholderia phytofirmans strain PsJN, is able to colonize and significantly promote growth of switchgrass cv. Alamo under in vitro, growth chamber, and greenhouse conditions. In several in vitro experiments, the average fresh weight of PsJN-inoculated plants was approximately 50% higher than non-inoculated plants. When one-month-old seedlings were grown in a growth chamber for 30 days, the PsJN-inoculated Alamo plants had significantly higher shoot and root biomass compared to controls. Biomass yield (dry weight) averaged from five experiments was 54.1% higher in the inoculated treatment compared to non-inoculated control. Similar results were obtained in greenhouse experiments with transplants grown in 4-gallon pots for two months. The inoculated plants exhibited more early tillers and persistent growth vigor with 48.6% higher biomass than controls. We also found that PsJN could significantly promote growth of switchgrass cv. Alamo under sub-optimal conditions. However, PsJN-mediated growth promotion in switchgrass is genotype specific. Conclusions Our results show B. phytofirmans strain PsJN significantly promotes growth of switchgrass cv. Alamo under different conditions, especially in the early growth stages leading to enhanced production of tillers. This phenomenon may benefit switchgrass establishment in the first year. Moreover, PsJN significantly stimulated growth of switchgrass cv. Alamo under sub-optimal conditions

Use of Endophytic and Rhizosphere Bacteria To Improve Phytoremediation of Arsenic-Contaminated Industrial Soils by Autochthonous Betula celtiberica.

PubMed

Mesa, Victoria; Navazas, Alejandro; González-Gil, Ricardo; González, Aida; Weyens, Nele; Lauga, Béatrice; Gallego, Jose Luis R; Sánchez, Jesús; Peláez, Ana Isabel

2017-04-15

The aim of this study was to investigate the potential of indigenous arsenic-tolerant bacteria to enhance arsenic phytoremediation by the autochthonous pseudometallophyte Betula celtiberica The first goal was to perform an initial analysis of the entire rhizosphere and endophytic bacterial communities of the above-named accumulator plant, including the cultivable bacterial species. B. celtiberica 's microbiome was dominated by taxa related to Flavobacteriales , Burkholderiales , and Pseudomonadales , especially the Pseudomonas and Flavobacterium genera. A total of 54 cultivable rhizobacteria and 41 root endophytes, mainly affiliated with the phyla Proteobacteria , Bacteroidetes , Firmicutes , and Actinobacteria , were isolated and characterized with respect to several potentially useful features for metal plant accumulation, such as the ability to promote plant growth, metal chelation, and/or mitigation of heavy-metal stress. Seven bacterial isolates were further selected and tested for in vitro accumulation of arsenic in plants; four of them were finally assayed in field-scale bioaugmentation experiments. The exposure to arsenic in vitro caused an increase in the total nonprotein thiol compound content in roots, suggesting a detoxification mechanism through phytochelatin complexation. In the contaminated field, the siderophore and indole-3-acetic acid producers of the endophytic bacterial consortium enhanced arsenic accumulation in the leaves and roots of Betula celtiberica , whereas the rhizosphere isolate Ensifer adhaerens strain 91R mainly promoted plant growth. Field experimentation showed that additional factors, such as soil arsenic content and pH, influenced arsenic uptake in the plant, attesting to the relevance of field conditions in the success of phytoextraction strategies. IMPORTANCE Microorganisms and plants have developed several ways of dealing with arsenic, allowing them to resist and metabolize this metalloid. These properties form the basis of

Use of Endophytic and Rhizosphere Bacteria To Improve Phytoremediation of Arsenic-Contaminated Industrial Soils by Autochthonous Betula celtiberica

PubMed Central

Navazas, Alejandro; González-Gil, Ricardo; González, Aida; Weyens, Nele; Lauga, Béatrice; Gallego, Jose Luis R.; Sánchez, Jesús; Peláez, Ana Isabel

2017-01-01

ABSTRACT The aim of this study was to investigate the potential of indigenous arsenic-tolerant bacteria to enhance arsenic phytoremediation by the autochthonous pseudometallophyte Betula celtiberica. The first goal was to perform an initial analysis of the entire rhizosphere and endophytic bacterial communities of the above-named accumulator plant, including the cultivable bacterial species. B. celtiberica's microbiome was dominated by taxa related to Flavobacteriales, Burkholderiales, and Pseudomonadales, especially the Pseudomonas and Flavobacterium genera. A total of 54 cultivable rhizobacteria and 41 root endophytes, mainly affiliated with the phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria, were isolated and characterized with respect to several potentially useful features for metal plant accumulation, such as the ability to promote plant growth, metal chelation, and/or mitigation of heavy-metal stress. Seven bacterial isolates were further selected and tested for in vitro accumulation of arsenic in plants; four of them were finally assayed in field-scale bioaugmentation experiments. The exposure to arsenic in vitro caused an increase in the total nonprotein thiol compound content in roots, suggesting a detoxification mechanism through phytochelatin complexation. In the contaminated field, the siderophore and indole-3-acetic acid producers of the endophytic bacterial consortium enhanced arsenic accumulation in the leaves and roots of Betula celtiberica, whereas the rhizosphere isolate Ensifer adhaerens strain 91R mainly promoted plant growth. Field experimentation showed that additional factors, such as soil arsenic content and pH, influenced arsenic uptake in the plant, attesting to the relevance of field conditions in the success of phytoextraction strategies. IMPORTANCE Microorganisms and plants have developed several ways of dealing with arsenic, allowing them to resist and metabolize this metalloid. These properties form the basis of

Whole-Genome Sequence and Classification of 11 Endophytic Bacteria from Poison Ivy (Toxicodendron radicans)

PubMed Central

Tran, Phuong N.; Tan, Nicholas E. H.; Lee, Yin Peng; Gan, Han Ming; Polter, Steven J.; Dailey, Lucas K.; Hudson, André O.

2015-01-01

Here, we report the whole-genome sequences and annotation of 11 endophytic bacteria from poison ivy (Toxicodendron radicans) vine tissue. Five bacteria belong to the genus Pseudomonas, and six single members from other genera were found present in interior vine tissue of poison ivy. PMID:26586879

Endophytic bacteria from Piper tuberculatum Jacq.: isolation, molecular characterization, and in vitro screening for the control of Fusarium solani f. sp piperis, the causal agent of root rot disease in black pepper (Piper nigrum L.).

PubMed

Nascimento, S B; Lima, A M; Borges, B N; de Souza, C R B

2015-07-06

Endophytic bacteria have been found to colonize internal tissues in many different plants, where they can have several beneficial effects, including defense against pathogens. In this study, we aimed to identify endophytic bacteria associated with roots of the tropical piperaceae Piper tuberculatum, which is known for its resistance to infection by Fusarium solani f. sp piperis, the causal agent of black pepper (Piper nigrum) root rot disease in the Amazon region. Based on 16S rRNA gene sequence analysis, we isolated endophytes belonging to 13 genera: Bacillus, Paenibacillus, Pseudomonas, Enterobacter, Rhizobium, Sinorhizobium, Agrobacterium, Ralstonia, Serratia, Cupriavidus, Mitsuaria, Pantoea, and Staphylococcus. The results showed that 56.52% of isolates were associated with the phylum Proteobacteria, which comprised α, β, and γ classes. Other bacteria were related to the phylum Firmicutes, including Bacillus, which was the most abundant genus among all isolates. Antagonistic assays revealed that Pt12 and Pt13 isolates, identified as Pseudomonas putida and Pseudomonas sp, respectively, were able to inhibit F. solani f. sp piperis growth in vitro. We describe, for the first time, the molecular identification of 23 endophytic bacteria from P. tuberculatum, among which two Pseudomonas species have the potential to control the pathogen responsible for root rot disease in black pepper in the Amazon region.

Kinetics of substrate utilization and bacterial growth of crude oil degraded by Pseudomonas aeruginosa.

PubMed

Talaiekhozani, Amirreza; Jafarzadeh, Nematollah; Fulazzaky, Mohamad Ali; Talaie, Mohammad Reza; Beheshti, Masoud

2015-01-01

Pollution associated with crude oil (CO) extraction degrades the quality of waters, threatens drinking water sources and may ham air quality. The systems biology approach aims at learning the kinetics of substrate utilization and bacterial growth for a biological process for which very limited knowledge is available. This study uses the Pseudomonas aeruginosa to degrade CO and determines the kinetic parameters of substrate utilization and bacterial growth modeled from a completely mixed batch reactor. The ability of Pseudomonas aeruginosa can remove 91 % of the total petroleum hydrocarbons and 83 % of the aromatic compounds from oily environment. The value k of 9.31 g of substrate g(-1) of microorganism d(-1) could be far higher than the value k obtained for petrochemical wastewater treatment and that for municipal wastewater treatment. The production of new cells of using CO as the sole carbon and energy source can exceed 2(3) of the existing cells per day. The kinetic parameters are verified to contribute to improving the biological removal of CO from oily environment.

Whole-Genome Sequence and Classification of 11 Endophytic Bacteria from Poison Ivy (Toxicodendron radicans).

PubMed

Tran, Phuong N; Tan, Nicholas E H; Lee, Yin Peng; Gan, Han Ming; Polter, Steven J; Dailey, Lucas K; Hudson, André O; Savka, Michael A

2015-11-19

Here, we report the whole-genome sequences and annotation of 11 endophytic bacteria from poison ivy (Toxicodendron radicans) vine tissue. Five bacteria belong to the genus Pseudomonas, and six single members from other genera were found present in interior vine tissue of poison ivy. Copyright © 2015 Tran et al.

Management of Bacterial Blight of Lilac Caused by Pseudomonas syringae by Growing Plants under Plastic Shelters

USDA-ARS?s Scientific Manuscript database

Pseudomonas syringae pv. syringae causes some of the most economically-important bacterial diseases affecting woody perennials grown by the nursery industry in the Pacific Northwest of the United States. In this study, we evaluated a cultural control practice, placement of plants in plastic shelter...

Antimicrobials from the marine algal endophyte Penicillium sp.

PubMed

Flewelling, Andrew J; Johnson, John A; Gray, Christopher A

2013-03-01

An endophytic fungus identified as Penicillium sp. was isolated from the brown alga Fucus spiralis collected from the Shetland Islands, United Kingdom. Bioassay-guided fractionation of an extract of the fungus led to the isolation of cladosporin, epiepoformin, phyllostine, and patulin, all of which showed antimicrobial activity against either Staphylococcus aureus or Pseudomonas aeruginosa. Cladosporin has not previously been identified from a fungus of the genus Penicillium, and, despite being biosynthetically related, epiepoformin, phyllostine and patulin have not been previously reported from one source.

Salicaceae Endophytes Modulate Stomatal Behavior and Increase Water Use Efficiency in Rice

PubMed Central

Rho, Hyungmin; Van Epps, Victor; Wegley, Nicholas; Doty, Sharon L.; Kim, Soo-Hyung

2018-01-01

Bacterial and yeast endophytes isolated from the Salicaceae family have been shown to promote growth and alleviate stress in plants from different taxa. To determine the physiological pathways through which endophytes affect plant water relations, we investigated leaf water potential, whole-plant water use, and stomatal responses of rice plants to Salicaceae endophyte inoculation under CO2 enrichment and water deficit. Daytime stomatal conductance and stomatal density were lower in inoculated plants compared to controls. Leaf ABA concentrations increased with endophyte inoculation. As a result, transpirational water use decreased significantly with endophyte inoculation while biomass did not change or slightly increased. This response led to a significant increase in cumulative water use efficiency at harvest. Different endophyte strains produced the same results in host plant water relations and stomatal responses. These stomatal responses were also observed under elevated CO2 conditions, and the increase in water use efficiency was more pronounced under water deficit conditions. The effect on water use efficiency was positively correlated with daily light integrals across different experiments. Our results provide insights on the physiological mechanisms of plant-endophyte interactions involving plant water relations and stomatal functions. PMID:29552021

Symbiotic interaction of endophytic bacteria with arbuscular mycorrhizal fungi and its antagonistic effect on Ganoderma boninense.

PubMed

Sundram, Shamala; Meon, Sariah; Seman, Idris Abu; Othman, Radziah

2011-08-01

Endophytic bacteria (Pseudomonas aeruginosa UPMP3 and Burkholderia cepacia UMPB3), isolated from within roots of oil palm (Elaeis guineensis Jacq.) were tested for their presymbiotic effects on two arbuscular mcorrhizal fungi, Glomus intraradices UT126 and Glomus clarum BR152B). These endophytic bacteria were also tested for antagonistic effects on Ganoderma boninense PER 71, a white wood rot fungal pathogen that causes a serious disease in oil palm. Spore germination and hyphal length of each arbuscular mycorrhizal fungal (AMF) pairing with endophytic bacteria was found to be significantly higher than spores plated in the absence of bacteria. Scanning electron microscopy (SEM) showed that the endophytic bacteria were scattered, resting or embedded on the surface hyaline layer or on the degraded walls of AMF spores, possibly feeding on the outer hyaline spore wall. The antagonistic effect of the endophytic bacteria was expressed as severe morphological abnormalities in the hyphal structures of G. boninense PER 71. The effects of the endophytic bacteria on G. boninense PER 71 hyphal structures were observed clearly under SEM. Severe inter-twisting, distortion, lysis and shriveling of the hyphal structures were observed. This study found that the effect of endophytic bacteria on G. intraradices UT126 and G. clarum BR152B resembled that of a mycorrhiza helper bacteria (MHB) association because the association significantly promoted AMF spore germination and hyphal length. However, the endophytic bacteria were extremely damaging to G. boninense PER 71.

Metabolic potential and community structure of endophytic and rhizosphere bacteria associated with the roots of the halophyte Aster tripolium L.

PubMed

Szymańska, Sonia; Płociniczak, Tomasz; Piotrowska-Seget, Zofia; Złoch, Michał; Ruppel, Silke; Hrynkiewicz, Katarzyna

2016-01-01

The submitted work assumes that the abundance and diversity of endophytic and rhizosphere microorganisms co-existing with the halophytic plant Aster tripolium L. growing in a salty meadow in the vicinity of a soda factory (central Poland) represent unique populations of cultivable bacterial strains. Endophytic and rhizosphere bacteria were (i) isolated and identified based on 16S rDNA sequences; (ii) screened for nifH and acdS genes; and (iii) analyzed based on selected metabolic properties. Moreover, total microbial biomass and community structures of the roots (endophytes), rhizosphere and soil were evaluated using a cultivation-independent technique (PLFA) to characterize plant-microbial interactions under natural salt conditions. The identification of the isolated strains showed domination by Gram-positive bacteria (mostly Bacillus spp.) both in the rhizosphere (90.9%) and roots (72.7%) of A. tripolium. Rhizosphere bacterial strains exhibited broader metabolic capacities, while endophytes exhibited higher specificities for metabolic activity. The PLFA analysis showed that the total bacterial biomass decreased in the following order (rhizosphereendophytes) and confirmed the dominance of Gram-positive endophytic bacteria in the roots of the halophyte. The described strain collection provides a valuable basis for a subsequent applications of bacteria in improvement of site adaptation of plants in saline soils. Copyright © 2015 Elsevier GmbH. All rights reserved.

Occurrence of Bacillus amyloliquefaciens as a systemic endophyte of vanilla orchids.

PubMed

White, James F; Torres, Mónica S; Sullivan, Raymond F; Jabbour, Rabih E; Chen, Qiang; Tadych, Mariusz; Irizarry, Ivelisse; Bergen, Marshall S; Havkin-Frenkel, Daphna; Belanger, Faith C

2014-11-01

We report the occurrence of Bacillus amyloliquefaciens in vanilla orchids (Vanilla phaeantha) and cultivated hybrid vanilla (V. planifolia × V. pompona) as a systemic bacterial endophyte. We determined with light microscopy and isolations that tissues of V. phaeantha and the cultivated hybrid were infected by a bacterial endophyte and that shoot meristems and stomatal areas of stems and leaves were densely colonized. We identified the endophyte as B. amyloliquefaciens using DNA sequence data. Since additional endophyte-free plants and seed of this orchid were not available, additional studies were performed on surrogate hosts Amaranthus caudatus, Ipomoea tricolor, and I. purpurea. Plants of A. caudatus inoculated with B. amyloliquefaciens demonstrated intracellular colonization of guard cells and other epidermal cells, confirming the pattern observed in the orchids. Isolations and histological studies suggest that the bacterium may penetrate deeply into developing plant tissues in shoot meristems, forming endospores in maturing tissues. B. amyloliquefaciens produced fungal inhibitors in culture. In controlled experiments using morning glory seedlings we showed that the bacterium promoted seedling growth and reduced seedling necrosis due to pathogens. We detected the gene for phosphopantetheinyl transferase (sfp), an enzyme in the pathway for production of antifungal lipopeptides, and purified the lipopeptide "surfactin" from cultures of the bacterium. We hypothesize that B. amyloliquefaciens is a robust endophyte and defensive mutualist of vanilla orchids. Whether the symbiosis between this bacterium and its hosts can be managed to protect vanilla crops from diseases is a question that should be evaluated in future research. © 2014 Wiley Periodicals, Inc.

Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7

PubMed Central

Maldonado-González, M. Mercedes; Bakker, Peter A. H. M.; Prieto, Pilar; Mercado-Blanco, Jesús

2015-01-01

The effective management of Verticillium wilts (VW), diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control VW of olive caused by the highly virulent, defoliating (D) pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V. dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i) olive D and non-defoliating V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii) strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii) strain PICF7 controls VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. A. thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7. PMID:25904904

Mutations in y-aminobutyric acid (GABA) transaminase genes in plants or Pseudomonas syringae reduce bacterial virulence

USDA-ARS?s Scientific Manuscript database

Pseudomonas syringae pv. tomato DC3000 is a bacterial pathogen of Arabidopsis and tomato that grows in the apoplast. The non-protein amino acid '-amino butyric acid (GABA) is produced by Arabidopsis and tomato and is the most abundant amino acid in the apoplastic fluid of tomato. The DC3000 genome h...

External Bacterial Flora and Antimicrobial Susceptibility Patterns of Staphylococcus spp. and Pseudomonas spp. Isolated from Two Household Cockroaches, Blattella germanica and Blatta orientalis.

PubMed

Menasria, Taha; Tine, Samir; Mahcene, Djaouida; Benammar, Leyla; Megri, Rochdi; Boukoucha, Mourad; Debabza, Manel

2015-04-01

A study was performed to estimate the prevalence of the external bacterial flora of two domestic cockroaches (Blattella germanica and Blatta orientalis) collected from households in Tebessa (northeast Algeria). Three major bacterial groups were cultured (total aerobic, enterobacteria, and staphylococci) from 14 specimens of cockroaches, and antibiotic susceptibility was tested for both Staphylococcus and Pseudomonas isolates. Culturing showed that the total bacterial load of cockroaches from different households were comparable (P<0.001) and enterobacteria were the predominant colonizers of the insect surface, with a bacterial load of (2.1 × 10⁵ CFU/insect), whereas the staphylococci group was the minority. Twenty-eight bacterial species were isolated, and susceptibility patterns showed that most of the staphylococci isolates were highly susceptible to chloramphenicol, gentamycin, pristinamycin, ofloxacin, clindamycin, and vancomycin; however, Pseudomonas strains exhibited resistance to amoxicillin/clavulanic acid, imipenem, and the second-generation antibiotic cephalosporin cefuroxime. Copyright © 2015 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Molecular Characterization and Analysis of Antimicrobial Activity of Endophytic Fungi From Medicinal Plants in Saudi Arabia

PubMed Central

Gashgari, Rukaia; Gherbawy, Youssuf; Ameen, Fuad; Alsharari, Salam

2016-01-01

Background: Endophytic fungi, which have been reported in numerous plant species, are important components of the forest community and contribute significantly to the diversity of natural ecosystems. Objectives: The current study aimed to evaluate and characterize, at the molecular level, the diversity and antimicrobial activities of endophytic fungi from medicinal plants in Saudi Arabia. Materials and Methods: Fungi growing on plant segments were isolated and identified based on morphological and molecular characteristics. The isolates were grouped into 35 distinct operational taxonomic units, based on the sequence of the internal transcribed spacer regions in the rRNA gene. The colonization frequency and the dominant fungi percentage of these endophytic fungi were calculated. A dual culture technique was adopted to investigate the antifungal activity of these endophytes. Results: Tamarix nilotica showed the highest endophytic diversity with a relative frequency of 27.27%, followed by Cressa cretica with a relative frequency of 19.27%. The most frequently isolated species was Penicillium chrysogenum with an overall colonization rate of 98.57%. Seven out of 35 endophytic fungi exhibited strong antifungal activity to all plant fungal pathogens tested. P. chrysogenum, Fusarium oxysporum, and F. nygamai exhibited the highest inhibition against the human pathogenic bacteria Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Aspergillus sydowii, P. chrysogenum, and Eupenicillium crustaceum showed strong antimicrobial activity against Enterococcus faecalis. Conclusions: The antimicrobial activity of these endophytic microorganisms could be exploited in biotechnology, medicine, and agriculture. PMID:27099679

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

PubMed Central

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

Inner Plant Values: Diversity, Colonization and Benefits from Endophytic Bacteria

PubMed Central

Liu, Hongwei; Carvalhais, Lilia C.; Crawford, Mark; Singh, Eugenie; Dennis, Paul G.; Pieterse, Corné M. J.; Schenk, Peer M.

2017-01-01

One of the most exciting scientific advances in recent decades has been the realization that the diverse and immensely active microbial communities are not only ‘passengers’ with plants, but instead play an important role in plant growth, development and resistance to biotic and abiotic stresses. A picture is emerging where plant roots act as ‘gatekeepers’ to screen soil bacteria from the rhizosphere and rhizoplane. This typically results in root endophytic microbiome dominated by Proteobacteria, Actinobacteria and to a lesser extent Bacteroidetes and Firmicutes, but Acidobacteria and Gemmatimonadetes being almost depleted. A synthesis of available data suggest that motility, plant cell-wall degradation ability and reactive oxygen species scavenging seem to be crucial traits for successful endophytic colonization and establishment of bacteria. Recent studies provide solid evidence that these bacteria serve host functions such as improving of plant nutrients through acquisition of nutrients from soil and nitrogen fixation in leaves. Additionally, some endophytes can engage ‘priming’ plants which elicit a faster and stronger plant defense once pathogens attack. Due to these plant growth-promoting effects, endophytic bacteria are being widely explored for their use in the improvement of crop performance. Updating the insights into the mechanism of endophytic bacterial colonization and interactions with plants is an important step in potentially manipulating endophytic bacteria/microbiome for viable strategies to improve agricultural production. PMID:29312235

Enrichment of Root Endophytic Bacteria from Populus deltoides and Single-Cell-Genomics Analysis

DOE PAGES

Utturkar, Sagar M.; Cude, W. Nathan; Robeson, Jr., Michael S.; ...

2016-07-15

Bacterial endophytes that colonize Populus trees contribute to nutrient acquisition, prime immunity responses, and directly or indirectly increase both above- and below-ground biomasses. Endophytes are embedded within plant material, so physical separation and isolation are difficult tasks. Application of culture-independent methods, such as metagenome or bacterial transcriptome sequencing, has been limited due to the predominance of DNA from the plant biomass. In this paper, we present a modified differential and density gradient centrifugation-based protocol for the separation of endophytic bacteria from Populus roots. This protocol achieved substantial reduction in contaminating plant DNA, allowed enrichment of endophytic bacteria away from themore » plant material, and enabled single-cell genomics analysis. Four single-cell genomes were selected for whole-genome amplification based on their rarity in the microbiome (potentially uncultured taxa) as well as their inferred abilities to form associations with plants. Bioinformatics analyses, including assembly, contamination removal, and completeness estimation, were performed to obtain single-amplified genomes (SAGs) of organisms from the phyla Armatimonadetes, Verrucomicrobia, and Planctomycetes, which were unrepresented in our previous cultivation efforts. Finally, comparative genomic analysis revealed unique characteristics of each SAG that could facilitate future cultivation efforts for these bacteria.« less

Non-nodulated bacterial leaf symbiosis promotes the evolutionary success of its host plants in the coffee family (Rubiaceae).

PubMed

Verstraete, Brecht; Janssens, Steven; Rønsted, Nina

2017-08-01

Every plant species on Earth interacts in some way or another with microorganisms and it is well known that certain forms of symbiosis between different organisms can drive evolution. Within some clades of Rubiaceae (coffee family), a specific plant-bacteria interaction exists in which non-pathological endophytes are present in the leaves of their hosts. It is hypothesized that the bacterial endophytes, either alone or by interacting with the host, provide chemical protection against herbivory or pathogens by producing toxic or otherwise advantageous secondary metabolites. If the bacteria indeed have a direct beneficial influence on their hosts, it is reasonable to assume that the endophytes may increase the fitness of their hosts and therefore it is probable that their presence also has an influence on the long-term evolution of the particular plant lineages. In this study, the possible origin in time of non-nodulated bacterial leaf symbiosis in the Vanguerieae tribe of Rubiaceae is elucidated and dissimilarities in evolutionary dynamics between species with endophytes versus species without are investigated. Bacterial leaf symbiosis is shown to have most probably originated in the Late Miocene, a period when the savannah habitat is believed to have expanded on the African continent and herbivore pressure increased. The presence of bacterial leaf endophytes appears to be restricted to Old World lineages so far. Plant lineages with leaf endophytes show a significantly higher speciation rate than plant lineages without endophytes, while there is only a small difference in extinction rate. The transition rate shows that evolving towards having endophytes is twice as fast as evolving towards not having endophytes, suggesting that leaf symbiosis must be beneficial for the host plants. We conclude that the presence of bacterial leaf endophytes may also be an important driver for speciation of host plants. Copyright © 2017 Elsevier Inc. All rights reserved.

An acid-stable bacterial laccase identified from the endophyte Pantoea ananatis Sd-1 genome exhibiting lignin degradation and dye decolorization abilities.

PubMed

Shi, Xiaowei; Liu, Qian; Ma, Jiangshan; Liao, Hongdong; Xiong, Xianqiu; Zhang, Keke; Wang, Tengfei; Liu, Xuanmin; Xu, Ting; Yuan, Shanshan; Zhang, Xin; Zhu, Yonghua

2015-11-01

Isolation and identification of a novel laccase (namely Lac4) with various industrial applications potentials from an endophytical bacterium. Endophyte Sd-1 cultured in rice straw showed intra- and extra-cellular laccase activities. Genomic analysis of Sd-1 identified four putative laccases, Lac1 to Lac4. However, only Lac4 contains the complete signature sequence of laccase and shares at most 64 % sequence identity with other characterized bacterial multi-copper oxidases. Recombinant Lac4 can oxidize non-phenolic and phenolic compounds under acidic conditions and at 30-50 °C; Km values of Lac4 for ABTS at pH 2.5 and for guaiacol at pH 4.5 were 1 ± 0.15 and 6.1 ± 1.7 mM, respectively. The activity of Lac4 was stimulated by 0.8 mM Cu(2+) and 5 mM Fe(2+). In addition, Lac4 could decolorize various synthetic dyes and exhibit the degradation rate of 38 % for lignin. The data suggest that Lac4 possesses promising biotechnological potentials.

Characterization of initial events in bacterial surface colonization by two Pseudomonas species using image analysis.

PubMed

Mueller, R F; Characklis, W G; Jones, W L; Sears, J T

1992-05-01

The processes leading to bacterial colonization on solid-water interfaces are adsorption, desorption, growth, and erosion. These processes have been measured individually in situ in a flowing system in real time using image analysis. Four different substrata (copper, silicon, 316 stainless-steel and glass) and 2 different bacterial species (Pseudomonas aeruginosa and Pseudomonas fluorescens) were used in the experiments. The flow was laminar (Re = 1.4) and the shear stress was kept constant during all experiments at 0.75 N m(-2). The surface roughness varied among the substrata from 0.002 microm (for silicon) to 0.015 microm (for copper). Surface free energies varied from 25.1 dynes cm(-1) for silicon to 31.2 dynes cm(-1) for copper. Cell curface hydrophobicity, reported as hydrocarbon partitioning values, ranged from 0.67 for Ps. fluorescens to 0.97 for Ps. aeruginosa.The adsorption rate coefficient varied by as much as a factor of 10 among the combinations of bacterial strain and substratum material, and was positively correlated with surface free energy, the surface roughness of the substratum, and the hydrophobicity of the cells. The probability of desorption decreased with increasing surface free energy and surface roughness of the substratum. Cell growth was inhibited on copper, but replication of cells overlying an initial cell layer was observed with increased exposure time to the cell-containing bulk water. A mathematical model describing cell accumulation on a substratum is presented.

Plants of the fynbos biome harbour host species-specific bacterial communities.

PubMed

Miyambo, Tsakani; Makhalanyane, Thulani P; Cowan, Don A; Valverde, Angel

2016-08-01

The fynbos biome in South Africa is globally recognised as a plant biodiversity hotspot. However, very little is known about the bacterial communities associated with fynbos plants, despite interactions between primary producers and bacteria having an impact on the physiology of both partners and shaping ecosystem diversity. This study reports on the structure, phylogenetic composition and potential roles of the endophytic bacterial communities located in the stems of three fynbos plants (Erepsia anceps, Phaenocoma prolifera and Leucadendron laureolum). Using Illumina MiSeq 16S rRNA sequencing we found that different subpopulations of Deinococcus-Thermus, Alphaproteobacteria, Acidobacteria and Firmicutes dominated the endophytic bacterial communities. Alphaproteobacteria and Actinobacteria were prevalent in P. prolifera, whereas Deinococcus-Thermus dominated in L. laureolum, revealing species-specific host-bacteria associations. Although a high degree of variability in the endophytic bacterial communities within hosts was observed, we also detected a core microbiome across the stems of the three plant species, which accounted for 72% of the sequences. Altogether, it seems that both deterministic and stochastic processes shaped microbial communities. Endophytic bacterial communities harboured putative plant growth-promoting bacteria, thus having the potential to influence host health and growth. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Combined endophytic inoculants enhance nickel phytoextraction from serpentine soil in the hyperaccumulator Noccaea caerulescens

PubMed Central

Visioli, Giovanna; Vamerali, Teofilo; Mattarozzi, Monica; Dramis, Lucia; Sanangelantoni, Anna M.

2015-01-01

This study assesses the effects of specific bacterial endophytes on the phytoextraction capacity of the Ni-hyperaccumulator Noccaea caerulescens, spontaneously growing in a serpentine soil environment. Five metal-tolerant endophytes had already been selected for their high Ni tolerance (6 mM) and plant growth promoting ability. Here we demonstrate that individual bacterial inoculation is ineffective in enhancing Ni translocation and growth of N. caerulescens in serpentine soil, except for specific strains Ncr-1 and Ncr-8, belonging to the Arthrobacter and Microbacterium genera, which showed the highest indole acetic acid production and 1-aminocyclopropane-1-carboxylic acid-deaminase activity. Ncr-1 and Ncr-8 co-inoculation was even more efficient in promoting plant growth, soil Ni removal, and translocation of Ni, together with that of Fe, Co, and Cu. Bacteria of both strains densely colonized the root surfaces and intercellular spaces of leaf epidermal tissue. These two bacterial strains also turned out to stimulate root length, shoot biomass, and Ni uptake in Arabidopsis thaliana grown in MS agar medium supplemented with Ni. It is concluded that adaptation of N. caerulescens in highly Ni-contaminated serpentine soil can be enhanced by an integrated community of bacterial endophytes rather than by single strains; of the former, Arthrobacter and Microbacterium may be useful candidates for future phytoremediation trials in multiple metal-contaminated sites, with possible extension to non-hyperaccumulator plants. PMID:26322074

Combined endophytic inoculants enhance nickel phytoextraction from serpentine soil in the hyperaccumulator Noccaea caerulescens.

PubMed

Visioli, Giovanna; Vamerali, Teofilo; Mattarozzi, Monica; Dramis, Lucia; Sanangelantoni, Anna M

2015-01-01

This study assesses the effects of specific bacterial endophytes on the phytoextraction capacity of the Ni-hyperaccumulator Noccaea caerulescens, spontaneously growing in a serpentine soil environment. Five metal-tolerant endophytes had already been selected for their high Ni tolerance (6 mM) and plant growth promoting ability. Here we demonstrate that individual bacterial inoculation is ineffective in enhancing Ni translocation and growth of N. caerulescens in serpentine soil, except for specific strains Ncr-1 and Ncr-8, belonging to the Arthrobacter and Microbacterium genera, which showed the highest indole acetic acid production and 1-aminocyclopropane-1-carboxylic acid-deaminase activity. Ncr-1 and Ncr-8 co-inoculation was even more efficient in promoting plant growth, soil Ni removal, and translocation of Ni, together with that of Fe, Co, and Cu. Bacteria of both strains densely colonized the root surfaces and intercellular spaces of leaf epidermal tissue. These two bacterial strains also turned out to stimulate root length, shoot biomass, and Ni uptake in Arabidopsis thaliana grown in MS agar medium supplemented with Ni. It is concluded that adaptation of N. caerulescens in highly Ni-contaminated serpentine soil can be enhanced by an integrated community of bacterial endophytes rather than by single strains; of the former, Arthrobacter and Microbacterium may be useful candidates for future phytoremediation trials in multiple metal-contaminated sites, with possible extension to non-hyperaccumulator plants.

Bacterial and diazotrophic diversities of endophytes in Dendrobium catenatum determined through barcoded pyrosequencing

PubMed Central

Li, Ou; Sun, Lihua; Guan, Chenglin; Kong, Dedong

2017-01-01

As an epiphyte orchid, Dendrobium catenatum relies on microorganisms for requisite nutrients. Metagenome pyrosequencing based on 16S rRNA and nifH genes was used to characterize the bacterial and diazotrophic communities associated with D. catenatum collected from 5 districts in China. Based on Meta-16S rRNA sequencing, 22 bacterial phyla and 699 genera were identified, distributed as 125 genera from 8 phyla and 319 genera from 10 phyla shared by all the planting bases and all the tissues, respectively. The predominant Proteobacteria varied from 71.81% (GZ) to 96.08% (YN), and Delftia (10.39–38.42%), Burkholderia (2.71–15.98%), Escherichia/Shigella (4.90–25.12%), Pseudomonas (2.68–30.72%) and Sphingomonas (1.83–2.05%) dominated in four planting bases. Pseudomonas (17.94–22.06%), Escherichia/Shigella (6.59–11.59%), Delftia (9.65–22.14%) and Burkholderia (3.12–11.05%) dominated in all the tissues. According to Meta-nifH sequencing, 4 phyla and 45 genera were identified, while 17 genera and 24 genera from 4 phyla were shared by all the planting bases and all the tissues, respectively. Burkholderia and Bradyrhizobium were the most popular in the planting bases, followed by Methylovirgula and Mesorhizobium. Mesorhizobium was the most popular in different tissues, followed by Beijerinckia, Xanthobacter, and Burkholderia. Among the genera, 39 were completely overlapped with the results based on the 16S rRNA gene. In conclusion, abundant bacteria and diazotrophs were identified in common in different tissues of D. catenatum from five planting bases, which might play a great role in the supply of nutrients such as nitrogen. The exact abundance of phylum and genus on the different tissues from different planting bases need deeper sequencing with more samples. PMID:28931073

Bacterial and diazotrophic diversities of endophytes in Dendrobium catenatum determined through barcoded pyrosequencing.

PubMed

Li, Ou; Xiao, Rong; Sun, Lihua; Guan, Chenglin; Kong, Dedong; Hu, Xiufang

2017-01-01

As an epiphyte orchid, Dendrobium catenatum relies on microorganisms for requisite nutrients. Metagenome pyrosequencing based on 16S rRNA and nifH genes was used to characterize the bacterial and diazotrophic communities associated with D. catenatum collected from 5 districts in China. Based on Meta-16S rRNA sequencing, 22 bacterial phyla and 699 genera were identified, distributed as 125 genera from 8 phyla and 319 genera from 10 phyla shared by all the planting bases and all the tissues, respectively. The predominant Proteobacteria varied from 71.81% (GZ) to 96.08% (YN), and Delftia (10.39-38.42%), Burkholderia (2.71-15.98%), Escherichia/Shigella (4.90-25.12%), Pseudomonas (2.68-30.72%) and Sphingomonas (1.83-2.05%) dominated in four planting bases. Pseudomonas (17.94-22.06%), Escherichia/Shigella (6.59-11.59%), Delftia (9.65-22.14%) and Burkholderia (3.12-11.05%) dominated in all the tissues. According to Meta-nifH sequencing, 4 phyla and 45 genera were identified, while 17 genera and 24 genera from 4 phyla were shared by all the planting bases and all the tissues, respectively. Burkholderia and Bradyrhizobium were the most popular in the planting bases, followed by Methylovirgula and Mesorhizobium. Mesorhizobium was the most popular in different tissues, followed by Beijerinckia, Xanthobacter, and Burkholderia. Among the genera, 39 were completely overlapped with the results based on the 16S rRNA gene. In conclusion, abundant bacteria and diazotrophs were identified in common in different tissues of D. catenatum from five planting bases, which might play a great role in the supply of nutrients such as nitrogen. The exact abundance of phylum and genus on the different tissues from different planting bases need deeper sequencing with more samples.

Evaluation of bacteria isolated from rice for plant growth promotion and biological control of seedling disease of rice.

PubMed

Adhikari, T B; Joseph, C M; Yang, G; Phillips, D A; Nelson, L M

2001-10-01

Of 102 rhizoplane and endophytic bacteria isolated from rice roots and stems in California, 37% significantly (P < or = 0.05) inhibited the growth in vitro of two pathogens, Achlya klebsiana and Pythium spinosum, causing seedling disease of rice. Four endophytic strains were highly effective against seedling disease in growth pouch assays, and these were identified as Pseudomonas fluorescens (S3), Pseudomonas tolaasii (S20), Pseudomonas veronii (S21), and Sphingomonas trueperi (S12) by sequencing of amplified 16S rRNA genes. Strains S12, S20, and S21 contained the nitrogen fixation gene, nifD, but only S12 was able to reduce acetylene in pure culture. The four strains significantly enhanced plant growth in the absence of pathogens, as evidenced by increases in plant height and dry weight of inoculated rice seedlings relative to noninoculated rice. Three bacterial strains (S3, S20, and S21) were evaluated in pot bioassays and reduced disease incidence by 50%-73%. Strain S3 was as effective at suppressing disease at the lowest inoculum density (106 CFU/mL) as at higher density (10(8) CFU/mL or undiluted suspension). This study indicates that selected endophytic bacterial strains have potential for control of seedling disease of rice and for plant growth promotion.

Brachiaria Grasses (Brachiaria spp.) harbor a diverse bacterial community with multiple attributes beneficial to plant growth and development.

PubMed

Mutai, Collins; Njuguna, Joyce; Ghimire, Sita

2017-10-01

Endophytic and plant-associated bacteria were isolated from plants and rhizoplane soil of naturally grown Brachiaria grasses at International Livestock Research Institute in Nairobi, Kenya. Eighty-four bacterial strains were isolated from leaf tissues, root tissues, and rhizoplane soil on nutrient agar and 869 media. All bacterial strains were identified to the lowest possible taxonomic unit using 16S rDNA primers and were characterized for the production of Indole-3-acetic acid, hydrogen cyanide, and ACC deaminase; phosphate solubilization; siderophore production; antifungal properties; and plant biomass production. The 16S rDNA-based identification grouped these 84 bacterial strains into 3 phyla, 5 classes, 8 orders, 12 families, 16 genera, and 50 unique taxa. The four most frequently isolated genera were Pseudomonas (23), Pantoea (17), Acinetobacter (9), and Enterobacter (8). The functional characterization of these strains revealed that 41 of 84 strains had a minimum of three plant beneficial properties. Inoculation of maize seedlings with Acinetobacter spp., Microbacterium spp., Pectobacterium spp., Pseudomonas spp., and Enterobacter spp. showed positive effects on seedling biomass production. The ability of Brachiaria grasses to host genetically diverse bacteria, many of them with multiple plant growth-promoting attributes, might have contributed to high biomass production and adaptation of Brachiaria grasses to drought and low fertility soils. © 2017 International Livestock Research Institute. MicrobiologyOpen published by John Wiley & Sons Ltd.

Establishing fungal entomopathogens as endophytes: towards endophytic biological control

USDA-ARS?s Scientific Manuscript database

Beauveria basssiana is a fungal entomopathogen with the ability to colonize plants endophytically. As an endophyte, B. bassiana may play a role in protecting plants from herbivory and disease. This protocol demonstrates two inoculation methods to establish B. bassiana endophytically in the common be...

Pseudomonas screening assay

NASA Technical Reports Server (NTRS)

Margalit, Ruth (Inventor)

1993-01-01

A method for the detection of Pseudomonas bacteria is described where an Azurin-specific antibody is employed for detecting the presence of Azurin in a test sample. The detection of the presence of Azurin in the sample is a conclusive indicator of the presence of the Pseudomonas bacteria since the Azurin protein is a specific marker for this bacterial strain.

Relationship between cystic fibrosis respiratory tract bacterial communities and age, genotype, antibiotics and Pseudomonas aeruginosa.

PubMed

Klepac-Ceraj, Vanja; Lemon, Katherine P; Martin, Thomas R; Allgaier, Martin; Kembel, Steven W; Knapp, Alixandra A; Lory, Stephen; Brodie, Eoin L; Lynch, Susan V; Bohannan, Brendan J M; Green, Jessica L; Maurer, Brian A; Kolter, Roberto

2010-05-01

Polymicrobial bronchopulmonary infections in cystic fibrosis (CF) cause progressive lung damage and death. Although the arrival of Pseudomonas aeruginosa often heralds a more rapid rate of pulmonary decline, there is significant inter-individual variation in the rate of decline, the causes of which remain poorly understood. By coupling culture-independent methods with ecological analyses, we discovered correlations between bacterial community profiles and clinical disease markers in respiratory tracts of 45 children with CF. Bacterial community complexity was inversely correlated with patient age, presence of P. aeruginosa and antibiotic exposure, and was related to CF genotype. Strikingly, bacterial communities lacking P. aeruginosa were much more similar to each other than were those containing P. aeruginosa, regardless of antibiotic exposure. This suggests that community composition might be a better predictor of disease progression than the presence of P. aeruginosa alone and deserves further study.

Comparative genome analysis of Burkholderia phytofirmans PsJN reveals a wide spectrum of endophytic lifestyles based on interaction strategies with host plants

PubMed Central

Mitter, Birgit; Petric, Alexandra; Shin, Maria W.; Chain, Patrick S. G.; Hauberg-Lotte, Lena; Reinhold-Hurek, Barbara; Nowak, Jerzy; Sessitsch, Angela

2013-01-01

Burkholderia phytofirmans PsJN is a naturally occurring plant-associated bacterial endophyte that effectively colonizes a wide range of plants and stimulates their growth and vitality. Here we analyze whole genomes, of PsJN and of eight other endophytic bacteria. This study illustrates that a wide spectrum of endophytic life styles exists. Although we postulate the existence of typical endophytic traits, no unique gene cluster could be exclusively linked to the endophytic lifestyle. Furthermore, our study revealed a high genetic diversity among bacterial endophytes as reflected in their genotypic and phenotypic features. B. phytofirmans PsJN is in many aspects outstanding among the selected endophytes. It has the biggest genome consisting of two chromosomes and one plasmid, well-equipped with genes for the degradation of complex organic compounds and detoxification, e.g., 24 glutathione-S-transferase (GST) genes. Furthermore, strain PsJN has a high number of cell surface signaling and secretion systems and harbors the 3-OH-PAME quorum-sensing system that coordinates the switch of free-living to the symbiotic lifestyle in the plant-pathogen R. solanacearum. The ability of B. phytofirmans PsJN to successfully colonize such a wide variety of plant species might be based on its large genome harboring a broad range of physiological functions. PMID:23641251

Anti-Pseudomonas aeruginosa IgY antibodies augment bacterial clearance in a murine pneumonia model.

PubMed

Thomsen, K; Christophersen, L; Bjarnsholt, T; Jensen, P Ø; Moser, C; Høiby, N

2016-03-01

Oral prophylactic therapy by gargling with pathogen-specific egg yolk immunoglobulins (IgY) may reduce the initial airway colonization with Pseudomonas aeruginosa in cystic fibrosis (CF) patients. IgY antibodies impart passive immunization and we investigated the effects of anti-P. aeruginosa IgY antibodies on bacterial eradication in a murine pneumonia model. P. aeruginosa pneumonia was established in Balb/c mice and the effects of prophylactic IgY administration on lung bacteriology, clinical parameters and subsequent inflammation were compared to controls. Prophylactic administration of IgY antibodies targeting P. aeruginosa significantly reduced the bacterial burden by 2-log 24h post-infection compared to controls and was accompanied by significantly reduced clinical symptom scores and successive inflammatory cytokine profile indicative of diminished lung inflammation. Passive immunization by anti-P. aeruginosa IgY therapy facilitates promptly bacterial clearance and moderates inflammation in P. aeruginosa lung infection and may serve as an adjunct to antibiotics in reducing early colonization. Copyright © 2015. Published by Elsevier B.V.

Dynamic laser speckle to detect motile bacterial response of Pseudomonas aeruginosa

NASA Astrophysics Data System (ADS)

Sendra, H.; Murialdo, S.; Passoni, L.

2007-11-01

This proposal deals with the technique for detection of motile response of Pseudomonas aeruginosa using dynamic laser speckle or biospeckle as an alternative method. The study of bacterial displacement plays an essential role in biocatalysts processes and biodegradation. Hence, some biodegrading enzymes are benign catalytic that could be used for the production of industrially useful compounds as well as in wastewater treatments. This work presents an experimental set up and a computational process using frame sequences of dynamic laser speckle as a novel application. The objective was the detection of different levels of motility in bacteria. The encouraging results were achieved through a direct and non invasive observation method of the phenomenon.

Indigenous endophytic seed bacteria promote seedling development and defend against fungal disease in browntop millet (Urochloa ramosa L.).

PubMed

Verma, S K; White, J F

2018-03-01

This study was conducted to investigate indigenous seed endophyte effects on browntop millet seedling development. We report that seed-inhabiting bacterial endophytes are responsible for promoting seedling development, including stimulation of root hair formation, increasing root and shoot length growth and increasing photosynthetic pigment content of seedlings. Bacterial endophytes also improved resistance of seedlings to disease. A total of four endophytic bacteria were isolated from surface-sterilized seeds and identified by 16S rDNA sequencing as Curtobacterium sp. (M1), Microbacterium sp. (M2), Methylobacterium sp. (M3) and Bacillus amyloliquefaciens (M4). Removal of bacteria with streptomycin treatment from the seeds compromised seedling growth and development. When endophytes were reinoculated onto seeds, seedlings recovered normal development. Strains M3 and M4 were found to be most potent in promoting growth of seedlings. Bacteria were found to produce auxin, solubilize phosphate and inhibit fungal pathogens. Significant protection of seedlings from Fusarium infection was found using strain M4 in microcosm assays. The antifungal lipopeptide genes for surfactin and iturin were detected in M4; culture extracts of M4 showed a positive drop collapse result for surfactins. This study demonstrates that browntop millet seeds vector indigenous endophytes that are responsible for modulation of seedling development and protection of seedlings from fungal disease. This study is significant and original in that it is the first report of seed-inhabiting endophytes of browntop millet that influence seedling development and function in defence against soilborne pathogens. This study suggests that conservation and management of seed-vectored endophytes may be important in development of more sustainable agricultural practices. © 2017 The Society for Applied Microbiology.

Resistant and susceptible responses in alfalfa (Medicago sativa) to bacterial stem blight caused by Pseudomonas syringae pv. syringae

USDA-ARS?s Scientific Manuscript database

Bacterial stem blight caused by Pseudomonas syringae pv. syringae is a common disease of alfalfa (Medicago sativa L.) in the central and western U.S. and has been reported in Australia and Europe. The disease is not always recognized because symptoms are often associated with frost damage. Two culti...

Endophytic and rhizospheric bacteria associated with Silene paradoxa grown on metal-contaminated soils are selected and transferred to the next generation of plants as seed endophytes

NASA Astrophysics Data System (ADS)

Mocali, Stefano; Fabiani, Arturo; Chiellini, Carolina; Gori, Giulia; Gonnelli, Cristina

2017-04-01

It is well known that bacteria are commonly associated to the plants, either on the outer surfaces (epiphytes) that inside the plant tissues (endophytes). These bacteria mainly derived from soil and reach the various organs of the plant throughout the root system. Despite recent works have shown that endophytic bacteria can have an important role in the physiology of the plant, little is known of their possible involvement in the resistance and tolerance mechanisms of plants to heavy metals. Furthermore, until now only limited research has been conducted to unravel the exact role and possible applications of seed endophytes. The aim of this work was to characterize the plant-associated bacterial communities present at both the rhizosphere and inside the seeds, roots and aerial parts of plants of Silene paradoxa, a plant highly well-adapted to extreme environments, such as metal-contaminated soils. Thus, soil samples and plants of S. paradoxa were collected from i) the landfill of a Cu mine at Fenice Capanne (Grosseto, Italy); ii) a serpentine soil (with a high Ni content) at Pieve Santo Stefano (Arezzo, Italy); iii) a limestone uncontaminated soil in Colle Val d'Elsa (Siena, Italy). Bacterial communities associated with the three different plant organs have been then characterized by high-throughput sequencing of the 16S rRNA genes (microbiota). Bacteria were also isolated from seeds and soil and the colony forming units (CFU) was determined on plates containing different concentrations of Ni and Cu (5, 10 and 15 mM). The results showed a greater bacterial diversity among the three soils compared to plants. In particular, even though some phyla occurred in all the three soils (Actinobacteria, Proteobacteria, Chlorflexi and Acidobacteria), in general the bacterial community structure of the three soils was quite different from each other. Interestingly, the endophytic composition within each plant compartment was observed to be strongly affected by the soil of

Conservation and Diversity of Seed Associated Endophytes in Zea across Boundaries of Evolution, Ethnography and Ecology

PubMed Central

Johnston-Monje, David; Raizada, Manish N.

2011-01-01

Endophytes are non-pathogenic microbes living inside plants. We asked whether endophytic species were conserved in the agriculturally important plant genus Zea as it became domesticated from its wild ancestors (teosinte) to modern maize (corn) and moved from Mexico to Canada. Kernels from populations of four different teosintes and 10 different maize varieties were screened for endophytic bacteria by culturing, cloning and DNA fingerprinting using terminal restriction fragment length polymorphism (TRFLP) of 16S rDNA. Principle component analysis of TRFLP data showed that seed endophyte community composition varied in relation to plant host phylogeny. However, there was a core microbiota of endophytes that was conserved in Zea seeds across boundaries of evolution, ethnography and ecology. The majority of seed endophytes in the wild ancestor persist today in domesticated maize, though ancient selection against the hard fruitcase surrounding seeds may have altered the abundance of endophytes. Four TRFLP signals including two predicted to represent Clostridium and Paenibacillus species were conserved across all Zea genotypes, while culturing showed that Enterobacter, Methylobacteria, Pantoea and Pseudomonas species were widespread, with γ-proteobacteria being the prevalent class. Twenty-six different genera were cultured, and these were evaluated for their ability to stimulate plant growth, grow on nitrogen-free media, solubilize phosphate, sequester iron, secrete RNAse, antagonize pathogens, catabolize the precursor of ethylene, produce auxin and acetoin/butanediol. Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed. An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass. GFP tagging and maize stem injection confirmed that several seed endophytes could spread systemically through the plant. One seed isolate

Conservation and diversity of seed associated endophytes in Zea across boundaries of evolution, ethnography and ecology.

PubMed

Johnston-Monje, David; Raizada, Manish N

2011-01-01

Endophytes are non-pathogenic microbes living inside plants. We asked whether endophytic species were conserved in the agriculturally important plant genus Zea as it became domesticated from its wild ancestors (teosinte) to modern maize (corn) and moved from Mexico to Canada. Kernels from populations of four different teosintes and 10 different maize varieties were screened for endophytic bacteria by culturing, cloning and DNA fingerprinting using terminal restriction fragment length polymorphism (TRFLP) of 16S rDNA. Principle component analysis of TRFLP data showed that seed endophyte community composition varied in relation to plant host phylogeny. However, there was a core microbiota of endophytes that was conserved in Zea seeds across boundaries of evolution, ethnography and ecology. The majority of seed endophytes in the wild ancestor persist today in domesticated maize, though ancient selection against the hard fruitcase surrounding seeds may have altered the abundance of endophytes. Four TRFLP signals including two predicted to represent Clostridium and Paenibacillus species were conserved across all Zea genotypes, while culturing showed that Enterobacter, Methylobacteria, Pantoea and Pseudomonas species were widespread, with γ-proteobacteria being the prevalent class. Twenty-six different genera were cultured, and these were evaluated for their ability to stimulate plant growth, grow on nitrogen-free media, solubilize phosphate, sequester iron, secrete RNAse, antagonize pathogens, catabolize the precursor of ethylene, produce auxin and acetoin/butanediol. Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed. An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass. GFP tagging and maize stem injection confirmed that several seed endophytes could spread systemically through the plant. One seed isolate

Isolation and enzyme bioprospection of endophytic bacteria associated with plants of Brazilian mangrove ecosystem.

PubMed

Castro, Renata A; Quecine, Maria Carolina; Lacava, Paulo T; Batista, Bruna D; Luvizotto, Danice M; Marcon, Joelma; Ferreira, Anderson; Melo, Itamar S; Azevedo, João L

2014-01-01

The mangrove ecosystem is a coastal tropical biome located in the transition zone between land and sea that is characterized by periodic flooding, which confers unique and specific environmental conditions on this biome. In these ecosystems, the vegetation is dominated by a particular group of plant species that provide a unique environment harboring diverse groups of microorganisms, including the endophytic microorganisms that are the focus of this study. Because of their intimate association with plants, endophytic microorganisms could be explored for biotechnologically significant products, such as enzymes, proteins, antibiotics and others. Here, we isolated endophytic microorganisms from two mangrove species, Rhizophora mangle and Avicennia nitida, that are found in streams in two mangrove systems in Bertioga and Cananéia, Brazil. Bacillus was the most frequently isolated genus, comprising 42% of the species isolated from Cananéia and 28% of the species from Bertioga. However, other common endophytic genera such as Pantoea, Curtobacterium and Enterobacter were also found. After identifying the isolates, the bacterial communities were evaluated for enzyme production. Protease activity was observed in 75% of the isolates, while endoglucanase activity occurred in 62% of the isolates. Bacillus showed the highest activity rates for amylase and esterase and endoglucanase. To our knowledge, this is the first reported diversity analysis performed on endophytic bacteria obtained from the branches of mangrove trees and the first overview of the specific enzymes produced by different bacterial genera. This work contributes to our knowledge of the microorganisms and enzymes present in mangrove ecosystems.

Arsenic transformation and plant growth promotion characteristics of As-resistant endophytic bacteria from As-hyperaccumulator Pteris vittata.

PubMed

Xu, Jia-Yi; Han, Yong-He; Chen, Yanshan; Zhu, Ling-Jia; Ma, Lena Q

2016-02-01

The ability of As-resistant endophytic bacteria in As transformation and plant growth promotion was determined. The endophytes were isolated from As-hyperaccumulator Pteris vittata (PV) after growing for 60 d in a soil containing 200 mg kg(-1) arsenate (AsV). They were isolated in presence of 10 mM AsV from PV roots, stems, and leaflets, representing 4 phyla and 17 genera. All endophytes showed at least one plant growth promoting characteristics including IAA synthesis, siderophore production and P solubilization. The root endophytes had higher P solubilization ability than the leaflet (60.0 vs. 18.3 mg L(-1)). In presence of 10 mM AsV, 6 endophytes had greater growth than the control, suggesting As-stimulated growth. Furthermore, root endophytes were more resistant to AsV while the leaflet endophytes were more tolerant to arsenite (AsIII), which corresponded to the dominant As species in PV tissues. Bacterial As resistance was positively correlated to their ability in AsV reduction but not AsIII oxidation. The roles of those endophytes in promoting plant growth and As resistance in P. vittata warrant further investigation. Published by Elsevier Ltd.

Bacterial Tethering Analysis Reveals a “Run-Reverse-Turn” Mechanism for Pseudomonas Species Motility

PubMed Central

Qian, Chen; Wong, Chui Ching; Swarup, Sanjay

2013-01-01

We have developed a program that can accurately analyze the dynamic properties of tethered bacterial cells. The program works especially well with cells that tend to give rise to unstable rotations, such as polar-flagellated bacteria. The program has two novel components. The first dynamically adjusts the center of the cell's rotational trajectories. The second applies piecewise linear approximation to the accumulated rotation curve to reduce noise and separate the motion of bacteria into phases. Thus, it can separate counterclockwise (CCW) and clockwise (CW) rotations distinctly and measure rotational speed accurately. Using this program, we analyzed the properties of tethered Pseudomonas aeruginosa and Pseudomonas putida cells for the first time. We found that the Pseudomonas flagellar motor spends equal time in both CCW and CW phases and that it rotates with the same speed in both phases. In addition, we discovered that the cell body can remain stationary for short periods of time, leading to the existence of a third phase of the flagellar motor which we call “pause.” In addition, P. aeruginosa cells adopt longer run lengths, fewer pause frequencies, and shorter pause durations as part of their chemotactic response. We propose that one purpose of the pause phase is to allow the cells to turn at a large angle, where we show that pause durations in free-swimming cells positively correlate with turn angle sizes. Taken together, our results suggest a new “run-reverse-turn” paradigm for polar-flagellated Pseudomonas motility that is different from the “run-and-tumble” paradigm established for peritrichous Escherichia coli. PMID:23728820

Bioactive metabolites from an endophytic Cryptosporiopsis sp. inhabiting Clidemia hirta.

PubMed

Zilla, Mahesh K; Qadri, Masroor; Pathania, Anup S; Strobel, Gary A; Nalli, Yedukondalu; Kumar, Sunil; Guru, Santosh K; Bhushan, Shashi; Singh, Sanjay K; Vishwakarma, Ram A; Riyaz-Ul-Hassan, Syed; Ali, Asif

2013-11-01

An endophytic Cryptosporiopsis sp. was isolated from Clidemia hirta and analyzed for its secondary metabolites that lead to the isolation of three bioactive molecules. The compounds were purified from the culture broth of the fungus and their structures were determined by spectroscopic methods as (R)-5-hydroxy-2-methylchroman-4-one (1), 1-(2,6-dihydroxyphenyl)pentan-1-one (2) and (Z)-1-(2-(2-butyryl-3-hydroxyphenoxy)-6-hydroxyphenyl)-3-hydroxybut-2-en-1-one (3). Compound 1 exhibited significant cytotoxic activity against the human leukemia cell line, HL-60 with an IC50 of 4 μg/ml. This compound induced G2 arrest of the HL-60 cell cycle significantly. In addition, out of these compounds, 2 and 3 were active against several bacterial pathogens. Compound 2 was active against Bacillus cereus, Escherichia coli and Staphylococcus aureus with IC50 values varying from 18 to 30 μg/ml, and compound 3 displayed activity against Pseudomonas fluorescens with an IC50 value of 6 μg/ml. Compounds 2 and 3 are novel whereas compound 1 was reported earlier but the stereochemistry of its C-2 methyl is established for the first time. Copyright © 2013 Elsevier Ltd. All rights reserved.

Distinct microbial communities within the endosphere and rhizosphere of Populus deltoides roots across contrasting soil types.

PubMed

Gottel, Neil R; Castro, Hector F; Kerley, Marilyn; Yang, Zamin; Pelletier, Dale A; Podar, Mircea; Karpinets, Tatiana; Uberbacher, Ed; Tuskan, Gerald A; Vilgalys, Rytas; Doktycz, Mitchel J; Schadt, Christopher W

2011-09-01

The root-rhizosphere interface of Populus is the nexus of a variety of associations between bacteria, fungi, and the host plant and an ideal model for studying interactions between plants and microorganisms. However, such studies have generally been confined to greenhouse and plantation systems. Here we analyze microbial communities from the root endophytic and rhizospheric habitats of Populus deltoides in mature natural trees from both upland and bottomland sites in central Tennessee. Community profiling utilized 454 pyrosequencing with separate primers targeting the V4 region for bacterial 16S rRNA and the D1/D2 region for fungal 28S rRNA genes. Rhizosphere bacteria were dominated by Acidobacteria (31%) and Alphaproteobacteria (30%), whereas most endophytes were from the Gammaproteobacteria (54%) as well as Alphaproteobacteria (23%). A single Pseudomonas-like operational taxonomic unit (OTU) accounted for 34% of endophytic bacterial sequences. Endophytic bacterial richness was also highly variable and 10-fold lower than in rhizosphere samples originating from the same roots. Fungal rhizosphere and endophyte samples had approximately equal amounts of the Pezizomycotina (40%), while the Agaricomycotina were more abundant in the rhizosphere (34%) than endosphere (17%). Both fungal and bacterial rhizosphere samples were highly clustered compared to the more variable endophyte samples in a UniFrac principal coordinates analysis, regardless of upland or bottomland site origin. Hierarchical clustering of OTU relative abundance patterns also showed that the most abundant bacterial and fungal OTUs tended to be dominant in either the endophyte or rhizosphere samples but not both. Together, these findings demonstrate that root endophytic communities are distinct assemblages rather than opportunistic subsets of the rhizosphere.

Endophytic Diaporthe sp. LG23 Produces a Potent Antibacterial Tetracyclic Triterpenoid.

PubMed

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

2015-08-28

A new lanostanoid, 19-nor-lanosta-5(10),6,8,24-tetraene-1α,3β,12β,22S-tetraol (1), characterized by the presence of an aromatic B ring and hydroxylated at C-1, C-3, C-12, and C-22, was isolated from an endophytic fungus, Diaporthe sp. LG23, inhabiting leaves of the Chinese medicinal plant Mahonia fortunei. Six biosynthetically related known steroids were also isolated in parallel. Their structures were confirmed on the basis of detailed spectroscopic analysis in conjunction with the published data. Compound 1, an unusual fungus-derived 19-nor-lanostane tetracyclic triterpenoid with an aromatic B-ring system, exhibited pronounced antibacterial efficacy against both Gram-positive and -negative bacteria, especially the clinical isolates of Streptococcus pyogenes and Pseudomonas aeruginosa as well as a human pathogenic strain of Staphylococcus aureus. Our results reveal the potential of endophytes not only in conferring host fitness but also in contributing toward traditional host plant medicines.

The diversity of citrus endophytic bacteria and their interactions with Xylella fastidiosa and host plants.

PubMed

Azevedo, João Lúcio; Araújo, Welington Luiz; Lacava, Paulo Teixeira

2016-01-01

The bacterium Xylella fastidiosa is the causal agent of citrus variegated chlorosis (CVC) and has been associated with important losses in commercial orchards of all sweet orange [Citrus sinensis (L.)] cultivars. The development of this disease depends on the environmental conditions, including the endophytic microbial community associated with the host plant. Previous studies have shown that X. fastidiosa interacts with the endophytic community in xylem vessels as well as in the insect vector, resulting in a lower bacterial population and reduced CVC symptoms. The citrus endophytic bacterium Methylobacterium mesophilicum can trigger X. fastidiosa response in vitro, which results in reduced growth and induction of genes associated with energy production, stress, transport, and motility, indicating that X. fastidiosa has an adaptive response to M. mesophilicum. Although this response may result in reduced CVC symptoms, the colonization rate of the endophytic bacteria should be considered in studies that intend to use this endophyte to suppress CVC disease. Symbiotic control is a new strategy that uses symbiotic endophytes as biological control agents to antagonize or displace pathogens. Candidate endophytes for symbiotic control of CVC must occupy the xylem of host plants and attach to the precibarium of sharpshooter insects to access the pathogen. In the present review, we focus on interactions between endophytic bacteria from sweet orange plants and X. fastidiosa, especially those that may be candidates for control of CVC.

Antimicrobial activity and biodiversity of endophytic fungi in Dendrobium devonianum and Dendrobium thyrsiflorum from Vietnam.

PubMed

Xing, Yong-Mei; Chen, Juan; Cui, Jin-Long; Chen, Xiao-Mei; Guo, Shun-Xing

2011-04-01

Endophytic fungi are rich in orchids and have great impacts on their host plants. 53 endophytes (30 isolates from Dendrobium devonianum and 23 endophytic fungi from D. thyrsiflorum) were isolated, respectively, from roots and stems of Dendrobium species. All the fungi were identified by way of morphological and/or molecular biological methods. 30 endophytic fungi in D. devonianum were categorized into 11 taxa and 23 fungal endophytes in D. thyrsiflorum were grouped into 11 genera, respectively. Fusarium was the dominant species of the two Dendrobium species in common. Antimicrobial activity of ethanol extract of fermentation broth of these fungi was explored using agar diffusion test. 10 endophytic fungi in D. devonianum and 11 in D. thyrsiflorum exhibited antimicrobial activity against at least one pathogenic bacterium or fungus among 6 pathogenic microbes (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus). Out of the fungal endophytes isolated from D. devonianum and D. thyrsiflorum, Phoma displayed strong inhibitory activity (inhibition zones in diameter >20 mm) against pathogens. Epicoccum nigrum from D. thyrsiflorum exhibited antibacterial activity even stronger than ampicillin sodium. Fusarium isolated from the two Dendrobium species was effective against the pathogenic bacterial as well as fungal pathogens. The study reinforced the assumption that endophytic fungi isolated from different Dendrobium species could be of potential antibacterial or antifungal resource.

The diversity of citrus endophytic bacteria and their interactions with Xylella fastidiosa and host plants

PubMed Central

Azevedo, João Lúcio; Araújo, Welington Luiz; Lacava, Paulo Teixeira

2016-01-01

Abstract The bacterium Xylella fastidiosa is the causal agent of citrus variegated chlorosis (CVC) and has been associated with important losses in commercial orchards of all sweet orange [Citrus sinensis (L.)] cultivars. The development of this disease depends on the environmental conditions, including the endophytic microbial community associated with the host plant. Previous studies have shown that X. fastidiosa interacts with the endophytic community in xylem vessels as well as in the insect vector, resulting in a lower bacterial population and reduced CVC symptoms. The citrus endophytic bacterium Methylobacterium mesophilicum can trigger X. fastidiosa response in vitro, which results in reduced growth and induction of genes associated with energy production, stress, transport, and motility, indicating that X. fastidiosa has an adaptive response to M. mesophilicum. Although this response may result in reduced CVC symptoms, the colonization rate of the endophytic bacteria should be considered in studies that intend to use this endophyte to suppress CVC disease. Symbiotic control is a new strategy that uses symbiotic endophytes as biological control agents to antagonize or displace pathogens. Candidate endophytes for symbiotic control of CVC must occupy the xylem of host plants and attach to the precibarium of sharpshooter insects to access the pathogen. In the present review, we focus on interactions between endophytic bacteria from sweet orange plants and X. fastidiosa, especially those that may be candidates for control of CVC. PMID:27727362

Pinus flexilis and Picea engelmannii share a simple and consistent needle endophyte microbiota with a potential role in nitrogen fixation

PubMed Central

Carrell, Alyssa A.; Frank, Anna C.

2014-01-01

Conifers predominantly occur on soils or in climates that are suboptimal for plant growth. This is generally attributed to symbioses with mycorrhizal fungi and to conifer adaptations, but recent experiments suggest that aboveground endophytic bacteria in conifers fix nitrogen (N) and affect host shoot tissue growth. Because most bacteria cannot be grown in the laboratory very little is known about conifer–endophyte associations in the wild. Pinus flexilis (limber pine) and Picea engelmannii (Engelmann spruce) growing in a subalpine, nutrient-limited environment are potential candidates for hosting endophytes with roles in N2 fixation and abiotic stress tolerance. We used 16S rRNA pyrosequencing to ask whether these conifers host a core of bacterial species that are consistently associated with conifer individuals and therefore potential mutualists. We found that while overall the endophyte communities clustered according to host species, both conifers were consistently dominated by the same phylotype, which made up 19–53% and 14–39% of the sequences in P. flexilis and P. engelmannii, respectively. This phylotype is related to Gluconacetobacter diazotrophicus and other N2 fixing acetic acid bacterial endophytes. The pattern observed for the P. flexilis and P. engelmannii needle microbiota—a small number of major species that are consistently associated with the host across individuals and species—is unprecedented for an endophyte community, and suggests a specialized beneficial endophyte function. One possibility is endophytic N fixation, which could help explain how conifers can grow in severely nitrogen-limited soil, and why some forest ecosystems accumulate more N than can be accounted for by known nitrogen input pathways. PMID:25071746

Pseudomonas granadensis sp. nov., a new bacterial species isolated from the Tejeda, Almijara and Alhama Natural Park, Granada, Spain.

PubMed

Pascual, Javier; García-López, Marina; Bills, Gerald F; Genilloud, Olga

2015-02-01

During the course of screening bacterial isolates as sources of as-yet unknown bioactive compounds with pharmaceutical applications, a chemo-organotrophic, Gram-negative bacterium was isolated from a soil sample taken from the Tejeda, Almijara and Alhama Natural Park, Granada, Spain. Strain F-278,770(T) was oxidase- and catalase-positive, aerobic, with a respiratory type of metabolism with oxygen as the terminal electron acceptor, non-spore-forming and motile by one polar flagellum, although some cells had two polar flagella. Phylogenetic analysis of the 16S rRNA, gyrB, rpoB and rpoD genes revealed that strain F-278,770(T) belongs to the Pseudomonas koreensis subgroup (Pseudomonas fluorescens lineage), with Pseudomonas moraviensis, P. koreensis, P. baetica and P. helmanticensis as its closest relatives. Chemotaxonomic traits such as polar lipid and fatty acid compositions and G+C content of genomic DNA corroborated the placement of strain F-278,770(T) in the genus Pseudomonas. DNA-DNA hybridization assays and phenotypic traits confirmed that this strain represents a novel species of the genus Pseudomonas, for which the name Pseudomonas granadensis sp. nov. is proposed. The type strain is F-278,770(T) ( = DSM 28040(T) = LMG 27940(T)). © 2015 Fundacion MEDINA, Centro de Excelencia en Investigacion de Medicamentos Innovadores en Andalucia.

[Pseudomonas folliculitis after spa bath exposure].

PubMed

Uldall Pallesen, Kristine Appel; Andersen, Klaus Ejner; Mørtz, Charlotte Gotthard

2012-06-25

Pseudomonas aeruginosa is a rare cause of folliculitis. Pseudomonas folliculitis can develop after contact with contaminated water from swimming pools, hot tubs and spa baths. Systemic therapy may be indicated in patients with widespread lesions, systemic symptoms or in immunosuppressed patients. We describe a 23-year-old healthy woman who developed a pustular rash and general malaise after using a spa bath contaminated with Pseudomonas aeruginosa. Bacterial culture from a pustule confirmed Pseudomonas folliculitis and the patient was treated with ciprofloxacin with rapid good effect.

Crystal structure analysis reveals Pseudomonas PilY1 as an essential calcium-dependent regulator of bacterial surface motility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orans, Jillian; Johnson, Michael D.L.; Coggan, Kimberly A.

Several bacterial pathogens require the 'twitching' motility produced by filamentous type IV pili (T4P) to establish and maintain human infections. Two cytoplasmic ATPases function as an oscillatory motor that powers twitching motility via cycles of pilus extension and retraction. The regulation of this motor, however, has remained a mystery. We present the 2.1 {angstrom} resolution crystal structure of the Pseudomonas aeruginosa pilus-biogenesis factor PilY1, and identify a single site on this protein required for bacterial translocation. The structure reveals a modified {beta}-propeller fold and a distinct EF-hand-like calcium-binding site conserved in pathogens with retractile T4P. We show that preventing calciummore » binding by PilY1 using either an exogenous calcium chelator or mutation of a single residue disrupts Pseudomonas twitching motility by eliminating surface pili. In contrast, placing a lysine in this site to mimic the charge of a bound calcium interferes with motility in the opposite manner - by producing an abundance of nonfunctional surface pili. Our data indicate that calcium binding and release by the unique loop identified in the PilY1 crystal structure controls the opposing forces of pilus extension and retraction. Thus, PilY1 is an essential, calcium-dependent regulator of bacterial twitching motility.« less

Quorum quenching is an antivirulence strategy employed by endophytic bacteria.

PubMed

Kusari, Parijat; Kusari, Souvik; Lamshöft, Marc; Sezgin, Selahaddin; Spiteller, Michael; Kayser, Oliver

2014-08-01

Bacteria predominantly use quorum sensing to regulate a plethora of physiological activities such as cell-cell crosstalk, mutualism, virulence, competence, biofilm formation, and antibiotic resistance. In this study, we investigated how certain potent endophytic bacteria harbored in Cannabis sativa L. plants use quorum quenching as an antivirulence strategy to disrupt the cell-to-cell quorum sensing signals in the biosensor strain, Chromobacterium violaceum. We used a combination of high-performance liquid chromatography high-resolution mass spectrometry (HPLC-ESI-HRMS(n)) and matrix-assisted laser desorption ionization imaging high-resolution mass spectrometry (MALDI-imaging-HRMS) to first quantify and visualize the spatial distribution of the quorum sensing molecules in the biosensor strain, C. violaceum. We then showed, both quantitatively and visually in high spatial resolution, how selected endophytic bacteria of C. sativa can selectively and differentially quench the quorum sensing molecules of C. violaceum. This study provides fundamental insights into the antivirulence strategies used by endophytes in order to survive in their ecological niches. Such defense mechanisms are evolved in order to thwart the plethora of pathogens invading associated host plants in a manner that prevents the pathogens from developing resistance against the plant/endophyte bioactive secondary metabolites. This work also provides evidence towards utilizing endophytes as tools for biological control of bacterial phytopathogens. In continuation, such insights would even afford new concepts and strategies in the future for combating drug resistant bacteria by quorum-inhibiting clinical therapies.

High taxonomic diversity of cultivation-recalcitrant endophytic bacteria in grapevine field shoots, their in vitro introduction, and unsuspected persistence.

PubMed

Thomas, Pious; Sekhar, Aparna C; Shaik, Sadiq Pasha

2017-11-01

Molecular and microscopic analyses reveal enormous non-cultivable endophytic bacteria in grapevine field shoots with functional significance. Diverse bacteria enter tissue cultures through surface-sterilized tissues and survive surreptitiously with varying taxonomic realignments. The study was envisaged to assess the extent of endophytic bacterial association with field shoot tissues of grapevine and the likelihood of introduction of such internally colonizing bacteria in vitro adopting molecular techniques targeting the non-cultivable bacterial community. PowerFood ® -kit derived DNA from surface-sterilized field shoot tips of grapevine Flame Seedless was employed in a preliminary bacterial class-specific PCR screening proving positive for major prokaryotic taxa including Archaea. Taxonomic and functional diversity were analyzed through whole metagenome profiling (WMG) which revealed predominantly phylum Actinobacteria, Proteobacteria, and minor shares of Firmicutes, Bacteroidetes, and Deinococcus-Thermus with varying functional roles ascribable to the whole bacterial community. Field shoot tip tissues and callus derived from stem segments were further employed in 16S rRNA V3-V4 amplicon taxonomic profiling. This revealed elevated taxonomic diversity in field shoots over WMG, predominantly Proteobacteria succeeded by Actinobacteria, Firmicutes, Bacteroidetes, and 15 other phyla including several candidate phyla (135 families, 179 genera). Callus stocks also displayed broad bacterial diversity (16 phyla; 96 families; 141 genera) bearing resemblance to field tissues with Proteobacterial dominance but a reduction in its share, enrichment of Actinobacteria and Firmicutes, disappearance of some field-associated phyla and detection of a few additional taxonomic groups over field community. Similar results were documented during 16S V3-V4 amplicon taxonomic profiling on Thompson Seedless field shoot tip and callus tissues. Video microscopy on tissue homogenates

Endophytic Bacterium Pseudomonas fluorescens RG11 May Transform Tryptophan to Melatonin and Promote Endogenous Melatonin Levels in the Roots of Four Grape Cultivars

PubMed Central

Ma, Yaner; Jiao, Jian; Fan, Xiucai; Sun, Haisheng; Zhang, Ying; Jiang, Jianfu; Liu, Chonghuai

2017-01-01

Endophytes have been verified to synthesize melatonin in vitro and promote abiotic stress-induced production of endogenous melatonin in grape (Vitis vinifera L.) roots. This study aimed to further characterize the biotransformation of tryptophan to melatonin in the endophytic bacterium Pseudomonas fluorescens RG11 and to investigate its capacity for enhancing endogenous melatonin levels in the roots of different grape cultivars. Using ultra performance liquid chromatography-tandem mass spectrometry combined with 15N double-labeled L-tryptophan as the precursor for melatonin, we detected isotope-labeled 5-hydroxytryptophan, serotonin, N-acetylserotonin, and melatonin, but tryptamine was not detected during the in vitro incubation of P. fluorescens RG11. Furthermore, the production capacity of these four compounds peaked during the exponential growth phase. RG11 colonization increased the endogenous levels of 5-hydroxytryptophan, N-acetylserotonin, and melatonin, but reduced those of tryptamine and serotonin, in the roots of the Red Globe grape cultivar under salt stress conditions. Quantitative real-time PCR revealed that RG11 reduced the transcription of grapevine tryptophan decarboxylase and serotonin N-acetyltransferase genes when compared to the un-inoculated control. These results correlated with decreased reactive oxygen species bursts and cell damage, which were alleviated by RG11 colonization under salt stress conditions. Additionally, RG11 promoted plant growth and enhanced the levels of endogenous melatonin in different grape cultivars. Intraspecific variation in the levels of melatonin precursors was found among four grape cultivars, and the associated root crude extracts appeared to significantly induce RG11 melatonin biosynthesis in vitro. Overall, this study provides useful information that enhances the existing knowledge of a potential melatonin synthesis pathway in rhizobacteria, and it reveals plant–rhizobacterium interactions that affect

Endophytic Bacterium Pseudomonas fluorescens RG11 May Transform Tryptophan to Melatonin and Promote Endogenous Melatonin Levels in the Roots of Four Grape Cultivars.

PubMed

Ma, Yaner; Jiao, Jian; Fan, Xiucai; Sun, Haisheng; Zhang, Ying; Jiang, Jianfu; Liu, Chonghuai

2016-01-01

Endophytes have been verified to synthesize melatonin in vitro and promote abiotic stress-induced production of endogenous melatonin in grape ( Vitis vinifera L.) roots. This study aimed to further characterize the biotransformation of tryptophan to melatonin in the endophytic bacterium Pseudomonas fluorescens RG11 and to investigate its capacity for enhancing endogenous melatonin levels in the roots of different grape cultivars. Using ultra performance liquid chromatography-tandem mass spectrometry combined with 15N double-labeled L -tryptophan as the precursor for melatonin, we detected isotope-labeled 5-hydroxytryptophan, serotonin, N -acetylserotonin, and melatonin, but tryptamine was not detected during the in vitro incubation of P. fluorescens RG11. Furthermore, the production capacity of these four compounds peaked during the exponential growth phase. RG11 colonization increased the endogenous levels of 5-hydroxytryptophan, N -acetylserotonin, and melatonin, but reduced those of tryptamine and serotonin, in the roots of the Red Globe grape cultivar under salt stress conditions. Quantitative real-time PCR revealed that RG11 reduced the transcription of grapevine tryptophan decarboxylase and serotonin N -acetyltransferase genes when compared to the un-inoculated control. These results correlated with decreased reactive oxygen species bursts and cell damage, which were alleviated by RG11 colonization under salt stress conditions. Additionally, RG11 promoted plant growth and enhanced the levels of endogenous melatonin in different grape cultivars. Intraspecific variation in the levels of melatonin precursors was found among four grape cultivars, and the associated root crude extracts appeared to significantly induce RG11 melatonin biosynthesis in vitro . Overall, this study provides useful information that enhances the existing knowledge of a potential melatonin synthesis pathway in rhizobacteria, and it reveals plant-rhizobacterium interactions that affect

Photosynthetic Bradyrhizobia Are Natural Endophytes of the African Wild Rice Oryza breviligulata

PubMed Central

Chaintreuil, Clémence; Giraud, Eric; Prin, Yves; Lorquin, Jean; Bâ, Amadou; Gillis, Monique; de Lajudie, Philippe; Dreyfus, Bernard

2000-01-01

We investigated the presence of endophytic rhizobia within the roots of the wetland wild rice Oryza breviligulata, which is the ancestor of the African cultivated rice Oryza glaberrima. This primitive rice species grows in the same wetland sites as Aeschynomene sensitiva, an aquatic stem-nodulated legume associated with photosynthetic strains of Bradyrhizobium. Twenty endophytic and aquatic isolates were obtained at three different sites in West Africa (Senegal and Guinea) from nodal roots of O. breviligulata and surrounding water by using A. sensitiva as a trap legume. Most endophytic and aquatic isolates were photosynthetic and belonged to the same phylogenetic Bradyrhizobium/Blastobacter subgroup as the typical photosynthetic Bradyrhizobium strains previously isolated from Aeschynomene stem nodules. Nitrogen-fixing activity, measured by acetylene reduction, was detected in rice plants inoculated with endophytic isolates. A 20% increase in the shoot growth and grain yield of O. breviligulata grown in a greenhouse was also observed upon inoculation with one endophytic strain and one Aeschynomene photosynthetic strain. The photosynthetic Bradyrhizobium sp. strain ORS278 extensively colonized the root surface, followed by intercellular, and rarely intracellular, bacterial invasion of the rice roots, which was determined with a lacZ-tagged mutant of ORS278. The discovery that photosynthetic Bradyrhizobium strains, which are usually known to induce nitrogen-fixing nodules on stems of the legume Aeschynomene, are also natural true endophytes of the primitive rice O. breviligulata could significantly enhance cultivated rice production. PMID:11097925

Anti-Pseudomonas aeruginosa IgY Antibodies Induce Specific Bacterial Aggregation and Internalization in Human Polymorphonuclear Neutrophils

PubMed Central

Thomsen, K.; Christophersen, L.; Bjarnsholt, T.; Jensen, P. Ø.; Moser, C.

2015-01-01

Polymorphonuclear neutrophils (PMNs) are essential cellular constituents in the innate host response, and their recruitment to the lungs and subsequent ubiquitous phagocytosis controls primary respiratory infection. Cystic fibrosis pulmonary disease is characterized by progressive pulmonary decline governed by a persistent, exaggerated inflammatory response dominated by PMNs. The principal contributor is chronic Pseudomonas aeruginosa biofilm infection, which attracts and activates PMNs and thereby is responsible for the continuing inflammation. Strategies to prevent initial airway colonization with P. aeruginosa by augmenting the phagocytic competence of PMNs may postpone the deteriorating chronic biofilm infection. Anti-P. aeruginosa IgY antibodies significantly increase the PMN-mediated respiratory burst and subsequent bacterial killing of P. aeruginosa in vitro. The mode of action is attributed to IgY-facilitated formation of immobilized bacteria in aggregates, as visualized by fluorescence microscopy and the induction of increased bacterial hydrophobicity. Thus, the present study demonstrates that avian egg yolk immunoglobulins (IgY) targeting P. aeruginosa modify bacterial fitness, which enhances bacterial killing by PMN-mediated phagocytosis and thereby may facilitate a rapid bacterial clearance in airways of people with cystic fibrosis. PMID:25895968

Influence of Chicken Manure Fertilization on Antibiotic-Resistant Bacteria in Soil and the Endophytic Bacteria of Pakchoi.

PubMed

Yang, Qingxiang; Zhang, Hao; Guo, Yuhui; Tian, Tiantian

2016-06-30

Animal manure is commonly used as fertilizer for agricultural crops worldwide, even though it is believed to contribute to the spread of antibiotic resistance from animal intestines to the soil environment. However, it is unclear whether and how there is any impact of manure fertilization on populations and community structure of antibiotic-resistant endophytic bacteria (AREB) in plant tissues. To investigate the effect of manure and organic fertilizer on endophytic bacterial communities, pot experiments were performed with pakchoi grown with the following treatments: (1) non-treated; (2) chicken manure-treated and (3) organic fertilizer-treated. Manure or organic fertilizer significantly increased the abundances of total cultivable endophytic bacteria (TCEB) and AREB in pakchoi, and the effect of chicken manure was greater than that of organic fertilizer. Further, 16S rDNA sequencing and the phylogenetic analysis indicated that chicken manure or organic fertilizer application increased the populations of multiple antibiotic-resistant bacteria (MARB) in soil and multiple antibiotic-resistant endophytic bacteria (MAREB) in pakchoi. The identical multiple antibiotic-resistant bacterial populations detected in chicken manure, manure- or organic fertilizer-amended soil and the vegetable endophytic system were Brevundimonas diminuta, Brachybacterium sp. and Bordetella sp., suggesting that MARB from manure could enter and colonize the vegetable tissues through manure fertilization. The fact that some human pathogens with multiple antibiotic resistance were detected in harvested vegetables after growing in manure-amended soil demonstrated a potential threat to human health.

Influence of Chicken Manure Fertilization on Antibiotic-Resistant Bacteria in Soil and the Endophytic Bacteria of Pakchoi

PubMed Central

Yang, Qingxiang; Zhang, Hao; Guo, Yuhui; Tian, Tiantian

2016-01-01

Animal manure is commonly used as fertilizer for agricultural crops worldwide, even though it is believed to contribute to the spread of antibiotic resistance from animal intestines to the soil environment. However, it is unclear whether and how there is any impact of manure fertilization on populations and community structure of antibiotic-resistant endophytic bacteria (AREB) in plant tissues. To investigate the effect of manure and organic fertilizer on endophytic bacterial communities, pot experiments were performed with pakchoi grown with the following treatments: (1) non-treated; (2) chicken manure-treated and (3) organic fertilizer-treated. Manure or organic fertilizer significantly increased the abundances of total cultivable endophytic bacteria (TCEB) and AREB in pakchoi, and the effect of chicken manure was greater than that of organic fertilizer. Further, 16S rDNA sequencing and the phylogenetic analysis indicated that chicken manure or organic fertilizer application increased the populations of multiple antibiotic-resistant bacteria (MARB) in soil and multiple antibiotic-resistant endophytic bacteria (MAREB) in pakchoi. The identical multiple antibiotic-resistant bacterial populations detected in chicken manure, manure- or organic fertilizer-amended soil and the vegetable endophytic system were Brevundimonas diminuta, Brachybacterium sp. and Bordetella sp., suggesting that MARB from manure could enter and colonize the vegetable tissues through manure fertilization. The fact that some human pathogens with multiple antibiotic resistance were detected in harvested vegetables after growing in manure-amended soil demonstrated a potential threat to human health. PMID:27376311

Effects of growth stage and fulvic acid on the diversity and dynamics of endophytic bacterial community in Stevia rebaudiana Bertoni leaves

PubMed Central

Yu, Xuejian; Yang, Jinshui; Wang, Entao; Li, Baozhen; Yuan, Hongli

2015-01-01

The aim of this study was to learn the interactions among the endophytic bacteria, the plant growth, the foliar spray of fulvic acid, and the accumulation of steviol glycosides in the leaves of Stevia rebaudiana. Metagenomic DNA was extracted from the Stevia leaves at different growth stages with or without the fulvic acid treatment; and the diversity of endophytic bacteria in Stevia leaves was estimated by pyrosequencing of 16S rRNA genes. As results, Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes were found to be the dominant phyla despite the growth stages and fulvic acid application. Stevia growth stages strongly regulated composition of endophytic community. The genera Agrobacterium (12.3%) and Erwinia (7.2%) dominated in seedling stage were apparently declined in the vegetable and initial flowering stages, while Sphingomonas and Methylobacterium increased in mature leaves at harvest time, which showed that the mature leaves of Stevia preferred to accumulate some certain endophytic bacteria. Sphingomonas and Methylobacterium constituted an important part of the core endophytic community and were positively correlated with the stevioside content and UGT74G1 gene expression, respectively; while Erwinia, Agrobacterium, and Bacillus were negatively correlated with the stevioside accumulation. Fulvic acid treatment accelerated the variation of endophytes along the growth stages and increased the steviol glycosides content. This is the first study to reveal the community composition of endophytic bacteria in the Stevia leaves, to evidence the strong effects of growth stage and fulvic acid application on the endophytes of Stevia, and to demonstrate the correlation between the endophytic bacteria and the steviol glycosides accumulation. PMID:26379644

[Biodiversity of phosphate-dissolving and plant growth--promoting endophytic bacteria of two crops].

PubMed

Huang, Jing; Sheng, Xiafang; He, Linyan

2010-06-01

We isolated and characterized phosphate-dissolving endophytic bacteria from two commonly cultivated crops. Phosphate-dissolving endophytic bacteria were isolated by plating and screening from interior tissues of rape and maize plants on NBRIP medium with tricalcium phosphate as sole phosphate source. Bacteria were characterized regarding characteristics that may be relevant for a beneficial plant-microbe interaction-indoleacetic acid, siderophore and 1-aminocyclopropane-1-carboxylic acid deaminase production,and further classified by restriction analysis of 16S rDNA. Eleven typical strains were identified by 16S rDNA sequence analysis. Thirty-two phosphate-dissolving endophytic bacteria were isolated from maize and rape plants and classified by restriction analysis of 16S rDNA in 8 different taxonomic groups at the similarity level of 76%. All the isolates could release phosphate from tricalcium phosphate and decrease the pH of the medium. The maximum phosphate content (537.6 mg/L) in the solution was obtained with strain M1L5. Thirteen isolates isolated from rape produced indoleacetic acid and siderophore, 68.4% and 63.2% of the strains isolated from maize produced indoleacetic acid and siderophore,respectively. 63.2% of the strains isolated from maize were able to grow on 1-aminocyclopropane-1-carboxylic acid as the sole nitrogen source. The eleven strains belonged to five different genera including Pantoea, Pseudomonas, Burkholderia, Acinetobacter and Ralstonia. Phosphate-dissolving endophytic bacteria isolated from rape and maize plants have abundant characteristics relative to promoting plant growth and genetic diversity.

Interaction between endophytic bacteria from citrus plants and the phytopathogenic bacteria Xylella fastidiosa, causal agent of citrus-variegated chlorosis.

PubMed

Lacava, P T; Araújo, W L; Marcon, J; Maccheroni, W; Azevedo, J L

2004-01-01

To isolate endophytic bacteria and Xylella fastidiosa and also to evaluate whether the bacterial endophyte community contributes to citrus-variegated chlorosis (CVC) status in sweet orange (Citrus sinensis [L.] Osbeck cv. Pera). The presence of Xylella fastidiosa and the population diversity of culturable endophytic bacteria in the leaves and branches of healthy, CVC-asymptomatic and CVC-symptomatic sweet orange plants and in tangerine (Citrus reticulata cv. Blanco) plants were assessed, and the in vitro interaction between endophytic bacteria and X. fastidiosa was investigated. There were significant differences in endophyte incidence between leaves and branches, and among healthy, CVC-asymptomatic and CVC-symptomatic plants. Bacteria identified as belonging to the genus Methylobacterium were isolated only from branches, mainly from those sampled from healthy and diseased plants, from which were also isolated X. fastidiosa. The in vitro interaction experiments indicated that the growth of X. fastidiosa was stimulated by endophytic Methylobacterium extorquens and inhibited by endophytic Curtobacterium flaccumfaciens. This work provides the first evidence of an interaction between citrus endophytic bacteria and X. fastidiosa and suggests a promising approach that can be used to better understand CVC disease.

Biological Evaluation of Endophytic Fungus Chaetomium sp. NF15 of Justicia adhatoda L.: A Potential Candidate for Drug Discovery

PubMed Central

Fatima, Nighat; Mukhtar, Usman; Ihsan-Ul-Haq; Ahmed Qazi, Muneer; Jadoon, Muniba; Ahmed, Safia

2016-01-01

Background The endophytes of medicinal plants, such as Justicia adhatoda L., represent a promising and largely underexplored domain that is considered as a repository of biologically active compounds. Objectives The aim of present study was isolation, identification, and biological evaluation of endophytic fungi associated with the J. adhatoda L. plant for the production of antimicrobial, antioxidant, and cytotoxic compounds Materials and Methods Endophytic fungi associated with the J. adhatoda L. plant were isolated from healthy plant parts and taxonomically characterized through morphological, microscopic, and 18S rDNA sequencing methods. The screening for bioactive metabolite production was achieved using ethyl acetate extracts, followed by the optimization of different parameters for maximum production of bioactive metabolites. Crude and partially purified extracts were used to determine the antimicrobial, antioxidant, and cytotoxic potential Results Out of six endophytic fungal isolates, Chaetomium sp. NF15 showed the most promising biological activity and was selected for detailed study. The crude ethyl acetate extract of NF15 isolate after cultivation under optimized culture conditions showed promising antimicrobial activity, with significant inhibition of the clinical isolates of Staphylococcus aureus (87%, n=42), Pseudomonas aeruginosa (> 85%, n = 41), and Candida albicans (62%, n = 24). Conclusions The present study confirms the notion of selecting endophytic fungi of medicinal plant Justicia for the bioassay-guided isolation of its bioactive compounds, and demonstrates that endophytic fungus Chaetomium sp. NF15 could be a potential source of bioactive metabolites PMID:27635208

Do foliar endophytic bacteria fix nitrogen?

NASA Astrophysics Data System (ADS)

Kueppers, L. M.; Moyes, A. B.; Frank, C.; Pett-Ridge, J.; Carper, D.; Vandehey, N.; O'Neil, J.; Dekas, A.

2015-12-01

Endophytic microorganisms - bacteria and fungi that live inside healthy plant tissue - are a relatively unexplored source of functional diversity in natural ecosystems. Prior to modern sequencing technology, detecting uncultured endophytic bacteria and assessing their putative functions was challenging. However, recent work has revealed a remarkable diversity of as yet non-culturable endophytic taxa and is beginning to identify functional roles within plant microbiomes. We recently examined bacterial communities in the foliage of a long-lived, high-elevation conifer species, limber pine (Pinus flexilis), and discovered a community strongly dominated by acetic acid bacteria (Acetobacteraceae), with several taxa closely related to known nitrogen fixers. Given limber pine's status as a pioneer species that is able to grow in low fertility soils, we hypothesized that this bacterial community has a potential functional role in fixing atmospheric nitrogen, providing a source of this limiting nutrient to the host tree. We used the radioisotope 13N2 to confirm that N2 rapidly diffuses into pine needles, where it could potentially be fixed. With an acetylene reduction assay we confirmed nitrogenase enzyme activity inside excised twigs 4 times over a growing season, and estimate potential rates of N2 fixation at 0.1 nmol N2 g needle-1 hr-1. Scaled to the stand level, this N input could be on the order of ~20 mg N m-2 d-1 over a growing season. While these rates are low, the long lifespan of individual trees (~1000 years) makes them biologically meaningful. Still, measured rates of acetylene reduction and bulk 15N2 incorporation are quite variable in space and time. Much work remains to better characterize the plant-microbial interactions in this system, including the rates of nitrogen fixation and their variability over the growing season, across edaphic conditions, among host species, and through plant development; and to determine which community members are responsible

Identification of the CvsSR regulon in Pseudomonas syringae reveals overlap with the Type-III secretion and AlgU regulons

USDA-ARS?s Scientific Manuscript database

Pseudomonas syringae pv. tomato DC3000 (Pto) lives epiphytically and endophytically during its infection cycle. Two-component systems (TCSs) and extracytoplasmic function (ECF) sigma factors are used by Pto to sense environmental changes within the leaf apoplast during pathogenesis. The TCS, CvsSR i...

Genome-wide analysis of bacterial determinants of plant growth promotion and induced systemic resistance by Pseudomonas fluorescens.

PubMed

Cheng, Xu; Etalo, Desalegn W; van de Mortel, Judith E; Dekkers, Ester; Nguyen, Linh; Medema, Marnix H; Raaijmakers, Jos M

2017-11-01

Pseudomonas fluorescens strain SS101 (Pf.SS101) promotes growth of Arabidopsis thaliana, enhances greening and lateral root formation, and induces systemic resistance (ISR) against the bacterial pathogen Pseudomonas syringae pv. tomato (Pst). Here, targeted and untargeted approaches were adopted to identify bacterial determinants and underlying mechanisms involved in plant growth promotion and ISR by Pf.SS101. Based on targeted analyses, no evidence was found for volatiles, lipopeptides and siderophores in plant growth promotion by Pf.SS101. Untargeted, genome-wide analyses of 7488 random transposon mutants of Pf.SS101 led to the identification of 21 mutants defective in both plant growth promotion and ISR. Many of these mutants, however, were auxotrophic and impaired in root colonization. Genetic analysis of three mutants followed by site-directed mutagenesis, genetic complementation and plant bioassays revealed the involvement of the phosphogluconate dehydratase gene edd, the response regulator gene colR and the adenylsulfate reductase gene cysH in both plant growth promotion and ISR. Subsequent comparative plant transcriptomics analyses strongly suggest that modulation of sulfur assimilation, auxin biosynthesis and transport, steroid biosynthesis and carbohydrate metabolism in Arabidopsis are key mechanisms linked to growth promotion and ISR by Pf.SS101. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Deciphering endophyte behaviour: the link between endophyte biology and efficacious biological control agents.

PubMed

Card, Stuart; Johnson, Linda; Teasdale, Suliana; Caradus, John

2016-08-01

Endophytes associate with the majority of plant species found in natural and managed ecosystems. They are regarded as extremely important plant partners that provide improved stress tolerance to the host compared with plants that lack this symbiosis. Fossil records of endophytes date back more than 400 million years, implicating these microorganisms in host plant adaptation to habitat transitions. However, it is only recently that endophytes, and their bioactive products, have received meaningful attention from the scientific community. The benefits some endophytes can confer on their hosts include plant growth promotion and survival through the inhibition of pathogenic microorganisms and invertebrate pests, the removal of soil contaminants, improved tolerance of low fertility soils, and increased tolerance of extreme temperatures and low water availability. Endophytes are extremely diverse and can exhibit many different biological behaviours. Not all endophyte technologies have been successfully commercialised. Of interest in the development of the next generation of plant protection products is how much of this is due to the biology of the particular endophytic microorganism. In this review, we highlight selected case studies of endophytes and discuss their lifestyles and behavioural traits, and discuss how these factors contribute towards their effectiveness as biological control agents. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Potential of the TCE-degrading endophyte Pseudomonas putida W619-TCE to improve plant growth and reduce TCE phytotoxicity and evapotranspiration in poplar cuttings.

PubMed

Weyens, Nele; Truyens, Sascha; Dupae, Joke; Newman, Lee; Taghavi, Safiyh; van der Lelie, Daniel; Carleer, Robert; Vangronsveld, Jaco

2010-09-01

The TCE-degrading poplar endophyte Pseudomonas putida W619-TCE was inoculated in poplar cuttings, exposed to 0, 200 and 400 mg l(-1) TCE, that were grown in two different experimental setups. During a short-term experiment, plants were grown hydroponically in half strength Hoagland nutrient solution and exposed to TCE for 3 days. Inoculation with P. putida W619-TCE promoted plant growth, reduced TCE phytotoxicity and reduced the amount of TCE present in the leaves. During a mid-term experiment, plants were grown in potting soil and exposed to TCE for 3 weeks. Here, inoculation with P. putida W619-TCE had a less pronounced positive effect on plant growth and TCE phytotoxicity, but resulted in strongly reduced amounts of TCE in leaves and roots of plants exposed to 400 mg l(-1) TCE, accompanied by a lowered evapotranspiration of TCE. Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), which are known intermediates of TCE degradation, were not detected. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Distribution and antimicrobial potential of endophytic fungi associated with ethnomedicinal plant Melastoma malabathricum L.

PubMed

Mishra, Vineet Kumar; Singh, Garima; Passari, Ajit Kumar; Yadav, Mukesh Kumar; Gupta, Vijai Kumar; Singh, Bhim Pratap

2016-03-01

Distributions of endophytic fungi associated with ethnomedicinal plant Melastoma malabathricum L. was studied and 91 isolates belonging to 18 genera were recovered. The isolates were distributed to sordariomycetes (62.63%), dothideomycetes (19.78%), eurotiomycetes (7.69%), zygomycetes (4.19%), agaricomycetes (1.09%), and mycelia sterilia (4.39%). Based on colony morphology and examination of spores, the isolates were classified into 18 taxa, of which Colletotrichum, Phomopsis and Phoma were dominant, their relative frequencies were 23.07%, 17.58% and 12.08% respectively. The colonization rate of endophytic fungi was determined and found to be significantly higher in leaf segments (50.76%), followed by root (41.53%) and stem tissues (27.69%). All the isolates were screened for antimicrobial activity and revealed that 26.37% endophytic fungi were active against one or more pathogens. Twenty four isolates showing significant antimicrobial activity were identified by sequencing the ITS1-5.8S-ITS2 region of rRNA gene. Results indicated that endophytic fungi associated with leaf were functionally versatile as they showed antimicrobial activity against most of the tested pathogens. The endophytic fungi Diaporthe phaseolorum var. meridionalis (KF193982) inhibited all the tested bacterial pathogens, whereas, Penicillium chermesinum (KM405640) displayed most significant antifungal activity. This seems to be the first hand report to understand the distribution and antimicrobial ability of endophytic fungi from ethno-medicinal plant M. malabathricum.

Biocontrol of verticillium wilt and colonization of cotton plants by an endophytic bacterial isolate.

PubMed

Li, C-H; Shi, L; Han, Q; Hu, H-L; Zhao, M-W; Tang, C-M; Li, S-P

2012-09-01

To explore biocontrol potential of 39 DAEB isolates (doubly antagonistic towards both Verticillium dahliae Kleb and Fusarium oxysporum) against verticillium wilt of cotton and to elucidate colonization and category characteristics of an endophytic bacterium with significant biocontrol activity. Thirty-nine antagonistic endophytic bacteria strains were tested for their ability to control verticillium wilt in cotton plants caused by a defoliating pathotype of V. dahliae 107 in cotton under controlled conditions. The biocontrol trial revealed that an endophytic bacterium, designated HA02, showed a significant biocontrol activity to V. dahliae 107. After cotton seedlings were inoculated with a gfp gene-tagged HA02 (HA02-gfp), HA02-gfp populations were higher in the root than in the stem; in addition, the HA02-gfp was distributed in the maturation zone of cotton root. Furthermore, HA02-gfp also colonized seedlings of maize, rape and soybean after the bacteria inoculation. Phylogenetic trees based on 16S rDNA sequences combined with morphological, physiological and identification showed that the bacterium belongs to the Enterobacter genus. Our results showed that only 1 of 39 DAEB isolates demonstrated more efficient biocontrol potential towards V. dahliae 107 in greenhouse and field trials. HA02-gfp mainly colonized cotton in roots. In addition, we quantitatively observed HA02 colonization in other hosts. HA02 belongs to the Enterobacter genus. This is the first study on biocontrol to defoliating pathotype of V. dahliae Kleb by endophytic bacteria. The HA02 showed effective biocontrol to V. dahliae 107 in greenhouse and field trials. Furthermore, we assessed the quantitative and qualitative colonization of HA02 in cotton seedlings. Our study provides basic information to further explore managing strategies to control this critical disease. © 2012 The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

Bacillus subtilis and Enterobacter cloacae endophytes from healthy Theobroma cacao L. trees can systemically colonize seedlings and promote growth.

PubMed

Leite, Hianna Almeida Câmara; Silva, Anderson Barbosa; Gomes, Fábio Pinto; Gramacho, Karina Peres; Faria, José Cláudio; de Souza, Jorge Teodoro; Loguercio, Leandro Lopes

2013-03-01

Clonal genotypes resistant to fungal diseases are an important component of the cocoa production system in southeastern Bahia state (Brazil), so that technologies for faster production of stronger and healthier plantlets are highly desirable. In this study, the effects of inoculated bacterial endophytes isolated from healthy adult cacao plants on seedlings, and aspects related to inoculation methods, colonization patterns, and photosynthesis were investigated. Sequencing of 16S rRNA, hsp-60, and rpo-B genes placed the wild-type isolates within the species Enterobacter cloacae (isolates 341 and 344) and Bacillus subtilis (isolate 629). Spontaneous rifampicin-resistant (rif(R)) variants for 344 were also produced and tested. Endophytic application was either by immersion of surface sterilized seeds in bacterial suspensions or direct inoculation into soil, 20 days after planting non-inoculated seeds into pots. Results from in vitro recovery of inoculated isolates showed that the wild-type endophytes and rif(R) variants systemically colonized the entire cacao seedlings in 15-20 days, regardless of the inoculation method. Some endophytic treatments showed significant increases in seedlings' height, number of leaves, and dry matter. Inoculation methods affected the combined application of endophytes, which maintained the growth-promotion effects, but not in the same manner as in single applications. Interestingly, the 344-3.2 rif(R) variant showed improved performance in relation to both the wild type and another related variant. Photosynthetic rates and stomatal conductance increased significantly for some endophytic treatments, being partially associated with effects on growth and affected by the inoculation method. The results suggest that E. cloacae and B. subtilis endophytes from healthy adult plants (not transmitted by seeds) were able to promote vegetative growth on cacao seedlings. The development of products for large-scale use in seedlings

Cultivation Versus Molecular Analysis of Banana (Musa sp.) Shoot-Tip Tissue Reveals Enormous Diversity of Normally Uncultivable Endophytic Bacteria.

PubMed

Thomas, Pious; Sekhar, Aparna Chandra

2017-05-01

The interior of plants constitutes a unique environment for microorganisms with various organisms inhabiting as endophytes. Unlike subterranean plant parts, aboveground parts are relatively less explored for endophytic microbial diversity. We employed a combination of cultivation and molecular approaches to study the endophytic bacterial diversity in banana shoot-tips. Cultivable bacteria from 20 sucker shoot-tips of cv. Grand Naine included 37 strains under 16 genera and three phyla (Proteobacteria, Actinobacteria, Firmicutes). 16S rRNA gene-ribotyping approach on 799f and 1492r PCR-amplicons to avoid plant organelle sequences was ineffective showing limited bacterial diversity. 16S rRNA metagene profiling targeting the V3-V4 hypervariable region after filtering out the chloroplast (74.2 %), mitochondrial (22.9 %), and unknown sequences (1.1 %) revealed enormous bacterial diversity. Proteobacteria formed the predominant phylum (64 %) succeeded by Firmicutes (12.1 %), Actinobacteria (9.5 %), Bacteroidetes (6.4 %), Planctomycetes, Cyanobacteria, and minor shares (<1 %) of 14 phyla including several candidate phyla besides the domain Euryarchaeota (0.2 %). Microbiome analysis of single shoot-tips through 16S rRNA V3 region profiling showed similar taxonomic richness and diversity and was less affected by plant sequence interferences. DNA extraction kit ominously influenced the phylogenetic diversity. The study has revealed vast diversity of normally uncultivable endophytic bacteria prevailing in banana shoot-tips (20 phyla, 46 classes) with about 2.6 % of the deciphered 269 genera and 1.5 % of the 656 observed species from the same source of shoot-tips attained through cultivation. The predominant genera included several agriculturally important bacteria. The study reveals an immense ecosystem of endophytic bacteria in banana shoot tissues endorsing the earlier documentation of intracellular "Cytobacts" and "Peribacts" with possible roles in plant

Ecosystem services and plant physiological status during endophyte-assisted phytoremediation of metal contaminated soil.

PubMed

Burges, Aritz; Epelde, Lur; Blanco, Fernando; Becerril, José M; Garbisu, Carlos

2017-04-15

Mining sites shelter a characteristic biodiversity with large potential for the phytoremediation of metal contaminated soils. Endophytic plant growth-promoting bacteria were isolated from two metal-(hyper)accumulator plant species growing in a metal contaminated mine soil. After characterizing their plant growth-promoting traits, consortia of putative endophytes were used to carry out an endophyte-assisted phytoextraction experiment using Noccaea caerulescens and Rumex acetosa (singly and in combination) under controlled conditions. We evaluated the influence of endophyte-inoculated plants on soil physicochemical and microbial properties, as well as plant physiological parameters and metal concentrations. Data interpretation through the grouping of soil properties within a set of ecosystem services was also carried out. When grown together, we observed a 41 and 16% increase in the growth of N. caerulescens and R. acetosa plants, respectively, as well as higher values of Zn phytoextraction and soil microbial biomass and functional diversity. Inoculation of the consortia of putative endophytes did not lead to higher values of plant metal uptake, but it improved the plants' physiological status, by increasing the content of chlorophylls and carotenoids by up to 28 and 36%, respectively, indicating a reduction in the stress level of plants. Endophyte-inoculation also stimulated soil microbial communities: higher values of acid phosphatase activity (related to the phosphate solubilising traits of the endophytes), bacterial and fungal abundance, and structural diversity. The positive effects of plant growth and endophyte inoculation on soil properties were reflected in an enhancement of some ecosystem services (biodiversity, nutrient cycling, water flow regulation, water purification and contamination control). Copyright © 2016 Elsevier B.V. All rights reserved.

Selective labelling and eradication of antibiotic-tolerant bacterial populations in Pseudomonas aeruginosa biofilms

PubMed Central

Chua, Song Lin; Yam, Joey Kuok Hoong; Hao, Piliang; Adav, Sunil S.; Salido, May Margarette; Liu, Yang; Givskov, Michael; Sze, Siu Kwan; Tolker-Nielsen, Tim; Yang, Liang

2016-01-01

Drug resistance and tolerance greatly diminish the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. Here we use a proteomics approach, pulsed stable isotope labelling with amino acids (pulsed-SILAC), to quantify newly expressed proteins in colistin-tolerant subpopulations of Pseudomonas aeruginosa biofilms (colistin is a ‘last-resort' antibiotic against multidrug-resistant Gram-negative pathogens). Migration is essential for the formation of colistin-tolerant biofilm subpopulations, with colistin-tolerant cells using type IV pili to migrate onto the top of the colistin-killed biofilm. The colistin-tolerant cells employ quorum sensing (QS) to initiate the formation of new colistin-tolerant subpopulations, highlighting multicellular behaviour in antibiotic tolerance development. The macrolide erythromycin, which has been previously shown to inhibit the motility and QS of P. aeruginosa, boosts biofilm eradication by colistin. Our work provides insights on the mechanisms underlying the formation of antibiotic-tolerant populations in bacterial biofilms and indicates research avenues for designing more efficient treatments against biofilm-associated infections. PMID:26892159

Selective labelling and eradication of antibiotic-tolerant bacterial populations in Pseudomonas aeruginosa biofilms.

PubMed

Chua, Song Lin; Yam, Joey Kuok Hoong; Hao, Piliang; Adav, Sunil S; Salido, May Margarette; Liu, Yang; Givskov, Michael; Sze, Siu Kwan; Tolker-Nielsen, Tim; Yang, Liang

2016-02-19

Drug resistance and tolerance greatly diminish the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. Here we use a proteomics approach, pulsed stable isotope labelling with amino acids (pulsed-SILAC), to quantify newly expressed proteins in colistin-tolerant subpopulations of Pseudomonas aeruginosa biofilms (colistin is a 'last-resort' antibiotic against multidrug-resistant Gram-negative pathogens). Migration is essential for the formation of colistin-tolerant biofilm subpopulations, with colistin-tolerant cells using type IV pili to migrate onto the top of the colistin-killed biofilm. The colistin-tolerant cells employ quorum sensing (QS) to initiate the formation of new colistin-tolerant subpopulations, highlighting multicellular behaviour in antibiotic tolerance development. The macrolide erythromycin, which has been previously shown to inhibit the motility and QS of P. aeruginosa, boosts biofilm eradication by colistin. Our work provides insights on the mechanisms underlying the formation of antibiotic-tolerant populations in bacterial biofilms and indicates research avenues for designing more efficient treatments against biofilm-associated infections.

Pseudomonas folliculitis in Arabian baths.

PubMed

Molina-Leyva, Alejandro; Ruiz-Ruigomez, Maria

2013-07-14

A 35-year-old man presented with a painful cutaneous skin eruption that was localized on the upper trunk. He stated that the previous weekend he had attended an Arabian bath. The physical examination revealed multiple hair follicle-centered papulopustules surrounded by an erythematous halo. A clinical diagnosis of pseudomonas folliculitis was made and treatment was prescribed. Afterwards Pseudomonas aeruginosa was isolated from a pustule culture. Pseudomonas folliculitis is a bacterial infection of the hair follicles. The most common reservoirs include facilities with hot water and complex piping systems that are difficult to clean, such as hot tubs and bathtubs. Despite adequate or high chlorine levels, Pseudomonas aeruginosa can grow within a biofilm.

Purification and characterization of a highly active chromate reductase from endophytic Bacillus sp. DGV19 of Albizzia lebbeck (L.) Benth. actively involved in phytoremediation of tannery effluent-contaminated sites.

PubMed

Manikandan, Muthu; Gopal, Judy; Kumaran, Rangarajulu Senthil; Kannan, Vijayaraghavan; Chun, Sechul

2016-01-01

Phytoremediation using timber-yielding tree species is considered to be the most efficient method for chromium/tannery effluent-contaminated sites. In this study, we have chosen Albizzia lebbeck, a chromium hyperaccumulator plant, and studied one of its chromium detoxification processes operated by its endophytic bacterial assemblage. Out of the four different groups of endophytic bacteria comprising Pseudomonas, Rhizobium, Bacillus, and Salinicoccus identified from A. lebbeck employed in phytoremediation of tannery effluent-contaminated soil, Bacillus predominated with three species, which exhibited not only remarkable chromium accumulation ability but also high chromium reductase activity. A chromate reductase was purified to homogeneity from the most efficient chromium accumulator, Bacillus sp. DGV 019, and the purified 34.2-kD enzyme was observed to be stable at temperatures from 20°C to 60°C. The enzyme was active over a wide range of pH values (4.0-9.0). Furthermore, the enzyme activity was enhanced with the electron donors NADH, followed by NADPH, not affected by glutathione and ascorbic acid. Cu(2+) enhanced the activity of the purified enzyme but was inhibited by Zn(2+) and etheylenediamine tetraacetic acid (EDTA). In conclusion, due to its versatile adaptability the chromate reductase can be used for chromium remediation.

Identification of an Endophytic Antifungal Bacterial Strain Isolated from the Rubber Tree and Its Application in the Biological Control of Banana Fusarium Wilt

PubMed Central

Sun, Xuepiao; Zheng, Peng; Zhang, Jiaming

2015-01-01

Banana Fusarium wilt (also known as Panama disease) is one of the most disastrous plant diseases. Effective control methods are still under exploring. The endophytic bacterial strain ITBB B5-1 was isolated from the rubber tree, and identified as Serratia marcescens by morphological, biochemical, and phylogenetic analyses. This strain exhibited a high potential for biological control against the banana Fusarium disease. Visual agar plate assay showed that ITBB B5-1 restricted the mycelial growth of the pathogenic fungus Fusarium oxysporum f. sp. cubense race 4 (FOC4). Microscopic observation revealed that the cell wall of the FOC4 mycelium close to the co-cultured bacterium was partially decomposed, and the conidial formation was prohibited. The inhibition ratio of the culture fluid of ITBB B5-1 against the pathogenic fungus was 95.4% as estimated by tip culture assay. Chitinase and glucanase activity was detected in the culture fluid, and the highest activity was obtained at Day 2 and Day 3 of incubation for chitinase and glucanase, respectively. The filtrated cell-free culture fluid degraded the cell wall of FOC4 mycelium. These results indicated that chitinase and glucanase were involved in the antifungal mechanism of ITBB B5-1. The potted banana plants that were inoculated with ITBB B5-1 before infection with FOC4 showed 78.7% reduction in the disease severity index in the green house experiments. In the field trials, ITBB B5-1 showed a control effect of approximately 70.0% against the disease. Therefore, the endophytic bacterial strain ITBB B5-1 could be applied in the biological control of banana Fusarium wilt. PMID:26133557

Optimization of isolation and cultivation of bacterial endophytes through addition of plant extract to nutrient media

PubMed Central

Eevers, N; Gielen, M; Sánchez-López, A; Jaspers, S; White, J C; Vangronsveld, J; Weyens, N

2015-01-01

Many endophytes have beneficial effects on plants and can be exploited in biotechnological applications. Studies hypothesize that only 0.001–1% of all plant-associated bacteria are cultivable. Moreover, even after successful isolations, many endophytic bacteria often show reduced regrowth capacity. This research aimed to optimize isolation processes and culturing these bacteria afterwards. We compared several minimal and complex media in a screening. Beside the media themselves, two gelling agents and adding plant extract to media were investigated to enhance the number and diversity of endophytes as well as the growth capacity when regrown after isolation. In this work, 869 medium delivered the highest numbers of cultivable bacteria, as well as the highest diversity. When comparing gelling agents, no differences were observed in the numbers of bacteria. Adding plant extract to the media lead to a slight increase in diversity. However, when adding plant extract to improve the regrowth capacity, sharp increases of viable bacteria occurred in both rich and minimal media. PMID:25997013

The hyperaccumulator Sedum plumbizincicola harbors metal-resistant endophytic bacteria that improve its phytoextraction capacity in multi-metal contaminated soil.

PubMed

Ma, Ying; Oliveira, Rui S; Nai, Fengjiao; Rajkumar, Mani; Luo, Yongming; Rocha, Inês; Freitas, Helena

2015-06-01

Endophyte-assisted phytoremediation has recently been suggested as a successful approach for ecological restoration of metal contaminated soils, however little information is available on the influence of endophytic bacteria on the phytoextraction capacity of metal hyperaccumulating plants in multi-metal polluted soils. The aims of our study were to isolate and characterize metal-resistant and 1-aminocyclopropane-1-carboxylate (ACC) utilizing endophytic bacteria from tissues of the newly discovered Zn/Cd hyperaccumulator Sedum plumbizincicola and to examine if these endophytic bacterial strains could improve the efficiency of phytoextraction of multi-metal contaminated soils. Among a collection of 42 metal resistant bacterial strains isolated from the tissues of S. plumbizincicola grown on Pb/Zn mine tailings, five plant growth promoting endophytic bacterial strains (PGPE) were selected due to their ability to promote plant growth and to utilize ACC as the sole nitrogen source. The five isolates were identified as Bacillus pumilus E2S2, Bacillus sp. E1S2, Bacillus sp. E4S1, Achromobacter sp. E4L5 and Stenotrophomonas sp. E1L and subsequent testing revealed that they all exhibited traits associated with plant growth promotion, such as production of indole-3-acetic acid and siderophores and solubilization of phosphorus. These five strains showed high resistance to heavy metals (Cd, Zn and Pb) and various antibiotics. Further, inoculation of these ACC utilizing strains significantly increased the concentrations of water extractable Cd and Zn in soil. Moreover, a pot experiment was conducted to elucidate the effects of inoculating metal-resistant ACC utilizing strains on the growth of S. plumbizincicola and its uptake of Cd, Zn and Pb in multi-metal contaminated soils. Out of the five strains, B. pumilus E2S2 significantly increased root (146%) and shoot (17%) length, fresh (37%) and dry biomass (32%) of S. plumbizincicola as well as plant Cd uptake (43%), whereas

Inhibition of bacterial quorum sensing by extracts from aquatic fungi: first report from marine endophytes.

PubMed

Martín-Rodríguez, Alberto J; Reyes, Fernando; Martín, Jesús; Pérez-Yépez, Juan; León-Barrios, Milagros; Couttolenc, Alan; Espinoza, César; Trigos, Angel; Martín, Víctor S; Norte, Manuel; Fernández, José J

2014-11-19

In our search for quorum-sensing (QS) disrupting molecules, 75 fungal isolates were recovered from reef organisms (endophytes), saline lakes and mangrove rhizosphere. Their QS inhibitory activity was evaluated in Chromobacterium violaceum CVO26. Four strains of endophytic fungi stood out for their potent activity at concentrations from 500 to 50 μg mL-1. The molecular characterization, based on the internal transcribed spacer (ITS) region sequences (ITS1, 5.8S and ITS2) between the rRNA of 18S and 28S, identified these strains as belonging to four genera: Sarocladium (LAEE06), Fusarium (LAEE13), Epicoccum (LAEE14), and Khuskia (LAEE21). Interestingly, three came from coral species and two of them came from the same organism, the coral Diploria strigosa. Metabolic profiles obtained by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) suggest that a combination of fungal secondary metabolites and fatty acids could be the responsible for the observed activities. The LC-HRMS analysis also revealed the presence of potentially new secondary metabolites. This is, to the best of our knowledge, the first report of QS inhibition by marine endophytic fungi.

Inhibition of Bacterial Quorum Sensing by Extracts from Aquatic Fungi: First Report from Marine Endophytes

PubMed Central

Martín-Rodríguez, Alberto J.; Reyes, Fernando; Martín, Jesús; Pérez-Yépez, Juan; León-Barrios, Milagros; Couttolenc, Alan; Espinoza, César; Trigos, Ángel; Martín, Víctor S.; Norte, Manuel; Fernández, José J.

2014-01-01

In our search for quorum-sensing (QS) disrupting molecules, 75 fungal isolates were recovered from reef organisms (endophytes), saline lakes and mangrove rhizosphere. Their QS inhibitory activity was evaluated in Chromobacterium violaceum CVO26. Four strains of endophytic fungi stood out for their potent activity at concentrations from 500 to 50 μg mL−1. The molecular characterization, based on the internal transcribed spacer (ITS) region sequences (ITS1, 5.8S and ITS2) between the rRNA of 18S and 28S, identified these strains as belonging to four genera: Sarocladium (LAEE06), Fusarium (LAEE13), Epicoccum (LAEE14), and Khuskia (LAEE21). Interestingly, three came from coral species and two of them came from the same organism, the coral Diploria strigosa. Metabolic profiles obtained by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) suggest that a combination of fungal secondary metabolites and fatty acids could be the responsible for the observed activities. The LC-HRMS analysis also revealed the presence of potentially new secondary metabolites. This is, to the best of our knowledge, the first report of QS inhibition by marine endophytic fungi. PMID:25415350

Functional bacterial amyloid increases Pseudomonas biofilm hydrophobicity and stiffness

PubMed Central

Zeng, Guanghong; Vad, Brian S.; Dueholm, Morten S.; Christiansen, Gunna; Nilsson, Martin; Tolker-Nielsen, Tim; Nielsen, Per H.; Meyer, Rikke L.; Otzen, Daniel E.

2015-01-01

The success of Pseudomonas species as opportunistic pathogens derives in great part from their ability to form stable biofilms that offer protection against chemical and mechanical attack. The extracellular matrix of biofilms contains numerous biomolecules, and it has recently been discovered that in Pseudomonas one of the components includes β-sheet rich amyloid fibrils (functional amyloid) produced by the fap operon. However, the role of the functional amyloid within the biofilm has not yet been investigated in detail. Here we investigate how the fap-based amyloid produced by Pseudomonas affects biofilm hydrophobicity and mechanical properties. Using atomic force microscopy imaging and force spectroscopy, we show that the amyloid renders individual cells more resistant to drying and alters their interactions with hydrophobic probes. Importantly, amyloid makes Pseudomonas more hydrophobic and increases biofilm stiffness 20-fold. Deletion of any one of the individual members of in the fap operon (except the putative chaperone FapA) abolishes this ability to increase biofilm stiffness and correlates with the loss of amyloid. We conclude that amyloid makes major contributions to biofilm mechanical robustness. PMID:26500638

Functional bacterial amyloid increases Pseudomonas biofilm hydrophobicity and stiffness.

PubMed

Zeng, Guanghong; Vad, Brian S; Dueholm, Morten S; Christiansen, Gunna; Nilsson, Martin; Tolker-Nielsen, Tim; Nielsen, Per H; Meyer, Rikke L; Otzen, Daniel E

2015-01-01

The success of Pseudomonas species as opportunistic pathogens derives in great part from their ability to form stable biofilms that offer protection against chemical and mechanical attack. The extracellular matrix of biofilms contains numerous biomolecules, and it has recently been discovered that in Pseudomonas one of the components includes β-sheet rich amyloid fibrils (functional amyloid) produced by the fap operon. However, the role of the functional amyloid within the biofilm has not yet been investigated in detail. Here we investigate how the fap-based amyloid produced by Pseudomonas affects biofilm hydrophobicity and mechanical properties. Using atomic force microscopy imaging and force spectroscopy, we show that the amyloid renders individual cells more resistant to drying and alters their interactions with hydrophobic probes. Importantly, amyloid makes Pseudomonas more hydrophobic and increases biofilm stiffness 20-fold. Deletion of any one of the individual members of in the fap operon (except the putative chaperone FapA) abolishes this ability to increase biofilm stiffness and correlates with the loss of amyloid. We conclude that amyloid makes major contributions to biofilm mechanical robustness.

Isolation, Characterization, and Insecticidal Activity of an Endophyte of Drunken Horse Grass, Achnatherum inebrians

PubMed Central

Shi, YingWu; Zhang, Xuebing; Lou, Kai

2013-01-01

Endophytic microorganisms reside within plant tissues and have often been found to promote plant growth. In this study, endophytic microorganisms were isolated from the roots, stems, leaves, and seeds of healthy drunken horse grass, Achnatherum inebrians (Hance) Keng (Poales: Poaceae), through the use of a grinding separation method and identified by a dual approach of morphological and physiological observation and 16S rRNA gene-based (for bacteria) and internal transcribed sequence-based (for fungi) molecular identification. The endophytes were then inoculated into liquid media for fermentation, and their crude extracts were employed for insecticidal activity tests using slide disc immersion and nebulization methods. A total of 89 bacteria species, which were classified into eight genera, Bacillus, Pseudomonas, Actinomyces, Corynebacterium, Acinetobacter, Sphingomonas, Paenibacillus, and Phyllobacterium, and two fungi, Claviceps and Chaetomium, were isolated. Of these species, isolates Streptomyces albus (Rossi-Doria) Waksman and Henrici (Actinomycetales: Streptomycetaceae) (GA) and Claviceps purpurea (Fr.) Tul. (Hypocreales: Clavicipitaceae) (PF-2) were shown to produce mortality rates of more than 90% in the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), after first and second screenings. The isolates PF-2 and GA associated with A. inebrians had significant insecticidal activities towards A. gossypii Glover (Hemiptera: Aphididae) and may provide a new biological resource for exploring a new microbial insecticide. PMID:24784492

Endophytic fungi and soil microbial community characteristics over different years of phytoremediation in a copper tailings dam of Shanxi, China.

PubMed

Tong, Jia; Miaowen, Cao; Juhui, Jing; Jinxian, Liu; Baofeng, Chai

2017-01-01

We conducted a survey of native grass species infected by endophytic fungi in a copper tailings dam over progressive years of phytoremediation. We investigated how endophytic fungi, soil microbial community structure and soil physiochemical properties and enzymatic activity varied in responses to heavy metal pollution over different stages of phytoremediation. endophyte infection frequency increased with years of phytoremediation. Rates of endophyte infection varied among different natural grass species in each sub-dam. Soil carbon content and soil enzymatic activity gradually increased through the years of phytoremediation. endophyte infection rates of Bothriochloa ischaemum and Festuca rubra were positively related to levels of cadmium (Cd) pollution levels, and fungal endophytes associated with Imperata cylindrical and Elymus dahuricus developed tolerance to lead (Pb). The structure and relative abundance of bacterial communities varied little over years of phytoremediation, but there was a pronounced variation in soil fungi types. Leotiomycetes were the dominant class of resident fungi during the initial phytoremediation period, but Pezizomycetes gradually became dominant as the phytoremediation period progressed. Fungal endophytes in native grasses as well as soil fungi and soil bacteria play different ecological roles during phytoremediation processes. Copyright © 2016 Elsevier B.V. All rights reserved.

Endophytic Bacteria Associated with Hieracium piloselloides: Their Potential for Hydrocarbon-Utilizing and Plant Growth-Promotion.

PubMed

Pawlik, Małgorzata; Piotrowska-Seget, Zofia

2015-01-01

The aim of this study was to assess the potential of 18 crude-oil-degrading endophytic bacteria for removal of hydrocarbons and promotion of plant growth. Strains were isolated from Hieracium piloselloides (tall hawkweed), which grows in soil heavily polluted with petroleum hydrocarbons. Bacteria from the genus Pseudomonas were abundant among the isolates. The potential for hydrocarbon degradation was evaluated by polymerase chain reaction (PCR) analyses of the genes alkB, alkH, C23O, P450, and pah. It was found that 88.89% of the endophytic bacteria contained gene-encoding polycyclic aromatic hydrocarbon (PAH) initial dioxygenase, 61% possessed the 2,3-catechol dioxygenase gene, and 39% of strains that were tested had the cytochrome P-450 hydroxylase gene. All isolates were capable of producing indole-3-acetic acid (1.8-76.4 μg/ml). Only 17% of them were able to produce siderophores, excrete cellulase, and solubilize phosphate. Hydrogen cyanide synthesis occurred in 33% of endophytic bacteria. The 1-aminocyclopropane-1-carboxylate deaminase activity in isolates that were screened was in the range of 2.6 to 74.1 μmol α-ketobutyrate/mg/h. This feature of the bacteria indicated that isolates may enhance the phytoremediation process. Data suggest that crude-oil-degrading endophytic bacteria possess potential to be promising candidates for enhancement of phytoremediation of hydrocarbon-contaminated soil. Further evaluation of these bacteria is needed in order to assess the role played in the degradation of petroleum hydrocarbons.

The genome of the endophytic bacterium H. frisingense GSF30(T) identifies diverse strategies in the Herbaspirillum genus to interact with plants.

PubMed

Straub, Daniel; Rothballer, Michael; Hartmann, Anton; Ludewig, Uwe

2013-01-01

The diazotrophic, bacterial endophyte Herbaspirillum frisingense GSF30(T) has been identified in biomass grasses grown in temperate climate, including the highly nitrogen-efficient grass Miscanthus. Its genome was annotated and compared with related Herbaspirillum species from diverse habitats, including H. seropedicae, and further well-characterized endophytes. The analysis revealed that Herbaspirillum frisingense lacks a type III secretion system that is present in some related Herbaspirillum grass endophytes. Together with the lack of components of the type II secretion system, the genomic inventory indicates distinct interaction scenarios of endophytic Herbaspirillum strains with plants. Differences in respiration, carbon, nitrogen and cell wall metabolism among Herbaspirillum isolates partially correlate with their different habitats. Herbaspirillum frisingense is closely related to strains isolated from the rhizosphere of phragmites and from well water, but these lack nitrogen fixation and metabolism genes. Within grass endophytes, the high diversity in their genomic inventory suggests that even individual plant species provide distinct, highly diverse metabolic niches for successful endophyte-plant associations.

The genome of the endophytic bacterium H. frisingense GSF30T identifies diverse strategies in the Herbaspirillum genus to interact with plants

PubMed Central

Straub, Daniel; Rothballer, Michael; Hartmann, Anton; Ludewig, Uwe

2013-01-01

The diazotrophic, bacterial endophyte Herbaspirillum frisingense GSF30T has been identified in biomass grasses grown in temperate climate, including the highly nitrogen-efficient grass Miscanthus. Its genome was annotated and compared with related Herbaspirillum species from diverse habitats, including H. seropedicae, and further well-characterized endophytes. The analysis revealed that Herbaspirillum frisingense lacks a type III secretion system that is present in some related Herbaspirillum grass endophytes. Together with the lack of components of the type II secretion system, the genomic inventory indicates distinct interaction scenarios of endophytic Herbaspirillum strains with plants. Differences in respiration, carbon, nitrogen and cell wall metabolism among Herbaspirillum isolates partially correlate with their different habitats. Herbaspirillum frisingense is closely related to strains isolated from the rhizosphere of phragmites and from well water, but these lack nitrogen fixation and metabolism genes. Within grass endophytes, the high diversity in their genomic inventory suggests that even individual plant species provide distinct, highly diverse metabolic niches for successful endophyte-plant associations. PMID:23825472

Grass fungal endophytes and uses thereof

DOEpatents

Craven, Kelly

2015-03-10

The invention provides isolated fungal endophytes and synthetic combinations thereof with host grass plants. Methods for inoculating grass plant with the endophytes, for propagating the grass-endophyte combinations, and for producing feeds and biofuels from grass-endophyte combinations are also provided.

Endophytic fungi associated with Sudanese medicinal plants show cytotoxic and antibiotic potential.

PubMed

Khiralla, Afra; Mohamed, Ietidal E; Tzanova, Tzvetomira; Schohn, Hervé; Slezack-Deschaumes, Sophie; Hehn, Alain; André, Philippe; Carre, Gaëlle; Spina, Rosella; Lobstein, Annelise; Yagi, Sakina; Laurain-Mattar, Dominique

2016-06-01

In this study, we isolated 15 endophytic fungi from five Sudanese medicinal plants. Each fungal endophytic strain was identified by sequencing of internal transcribed spacer (ITS) regions of rDNA. Ethyl acetate extracts were prepared from each endophyte cultivated in vitro and tested for their respective antibacterial activities and antiproliferative activities against human cancer cells. Antibacterial screening was carried out against two bacterial strains: Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus, by the broth dilution method. Cell viability was evaluated by the MTT procedure after exposure of MCF7 breast cancer cells and HT29 or HCT116 human colon adenocarcinoma cells to each endophytic extract. Of interest, Byssochlamys spectabilis isolated from Euphorbia prostata showed cytotoxicity (IC50 = 1.51 ± 0.2 μg mL(-1)) against MCF7 cells, but had a low effect against HT29 or HCT116 cells (IC50 > 20 μg mL(-1)). Cladosporium cladosporioides 2, isolated from Vernonia amygdalina leaves, showed antiproliferative activities against MCF7 cells (IC50 = 10.5 ± 1.5 μg mL(-1)) only. On the other hand, B. spectabilis and Alternaria sp. extract had antibacterial activities against the S. aureus strain. The findings of this work revealed that endophytic fungi associated with medicinal plants from Sudan could be considered as an attractive source of new therapeutic compounds. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Isolation of Antagonistic Endophytes from Banana Roots against Meloidogyne javanica and Their Effects on Soil Nematode Community

PubMed Central

Su, Lanxi; Shen, Zongzhuan; Ruan, Yunze; Tao, Chengyuan; Chao, Yifan; Li, Rong; Shen, Qirong

2017-01-01

Banana production is seriously hindered by Meloidogyne spp. all over the world. Endophytes are ideal candidates compared to pesticides as an environmentally benign agent. In the present study, endophytes isolated from banana roots infected by Meloidogyne spp. with different disease levels were tested in vitro, and in sterile and nature banana monoculture soils against Meloidogyne javanica. The proportion of antagonistic endophytes were higher in the roots of middle and high disease levels. Among those, bacteria were dominant, and Pseudomonas spp., Bacillus spp. and Streptomyces spp. showed more abundant populations. One strain, named as SA, with definite root inner-colonization ability was isolated and identified as Streptomyces sp. This strain showed an inhibiting rate of >50% in vitro and biocontrol efficiency of 70.7% in sterile soil against Meloidogyne javanica, compared to the control. Greenhouse experiment results showed that the strain SA exhibits excellent biological control ability for plant-parasites both in roots and in root-knot nematode infested soil. SA treatment showed a higher number of bacterivores, especially Mesorhabditis and Cephalobus. The maturity index was significantly lower, while enrichment index (EI) was significantly higher in the SA treatment. In conclusion, this study presents an important potential application of the endophytic strain Streptomyces sp. for the control of plant-parasitic nematodes, especially Meloidogyne javanica, and presents the effects on the associated variation of the nematode community. PMID:29123509

Antimicrobial Potential of Endophytic Fungi Derived from Three Seagrass Species: Cymodocea serrulata, Halophila ovalis and Thalassia hemprichii

PubMed Central

Supaphon, Preuttiporn; Phongpaichit, Souwalak; Rukachaisirikul, Vatcharin; Sakayaroj, Jariya

2013-01-01

Endophytic fungi from three commonly found seagrasses in southern Thailand were explored for their ability to produce antimicrobial metabolites. One hundred and sixty endophytic fungi derived from Cymodocea serrulata (Family Cymodoceaceae), Halophila ovalis and Thalassia hemprichii (Family Hydrocharitaceae) were screened for production of antimicrobial compounds by a colorimetric broth microdilution test against ten human pathogenic microorganisms including Staphylococcus aureus ATCC 25923, a clinical isolate of methicillin-resistant S. aureus, Escherichia coli ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 90028 and NCPF 3153, Cryptococcus neoformans ATCC 90112 and ATCC 90113 and clinical isolates of Microsporum gypseum and Penicillium marneffei . Sixty-nine percent of the isolates exhibited antimicrobial activity against at least one test strain. Antifungal activity was more pronounced than antibacterial activity. Among the active fungi, seven isolates including Hypocreales sp. PSU-ES26 from C . serrulata , Trichoderma spp. PSU-ES8 and PSU-ES38 from H . ovalis , and Penicillium sp. PSU-ES43, Fusarium sp. PSU-ES73, Stephanonectria sp. PSU-ES172 and an unidentified endophyte PSU-ES190 from T . hemprichii exhibited strong antimicrobial activity against human pathogens with minimum inhibitory concentrations (MIC) of less than 10 µg/ml. The inhibitory extracts at concentrations of 4 times their MIC destroyed the targeted cells as observed by scanning electron microscopy. These results showed the antimicrobial potential of extracts from endophytic fungi from seagrasses. PMID:23977310

Antimicrobial potential of endophytic fungi derived from three seagrass species: Cymodocea serrulata, Halophila ovalis and Thalassia hemprichii.

PubMed

Supaphon, Preuttiporn; Phongpaichit, Souwalak; Rukachaisirikul, Vatcharin; Sakayaroj, Jariya

2013-01-01

Endophytic fungi from three commonly found seagrasses in southern Thailand were explored for their ability to produce antimicrobial metabolites. One hundred and sixty endophytic fungi derived from Cymodoceaserrulata (Family Cymodoceaceae), Halophilaovalis and Thalassiahemprichii (Family Hydrocharitaceae) were screened for production of antimicrobial compounds by a colorimetric broth microdilution test against ten human pathogenic microorganisms including Staphylococcus aureus ATCC 25923, a clinical isolate of methicillin-resistant S. aureus, Escherichia coli ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 90028 and NCPF 3153, Cryptococcus neoformans ATCC 90112 and ATCC 90113 and clinical isolates of Microsporumgypseum and Penicilliummarneffei. Sixty-nine percent of the isolates exhibited antimicrobial activity against at least one test strain. Antifungal activity was more pronounced than antibacterial activity. Among the active fungi, seven isolates including Hypocreales sp. PSU-ES26 from C. serrulata, Trichoderma spp. PSU-ES8 and PSU-ES38 from H. ovalis, and Penicillium sp. PSU-ES43, Fusarium sp. PSU-ES73, Stephanonectria sp. PSU-ES172 and an unidentified endophyte PSU-ES190 from T. hemprichii exhibited strong antimicrobial activity against human pathogens with minimum inhibitory concentrations (MIC) of less than 10 µg/ml. The inhibitory extracts at concentrations of 4 times their MIC destroyed the targeted cells as observed by scanning electron microscopy. These results showed the antimicrobial potential of extracts from endophytic fungi from seagrasses.

Tannerella forsythia and Pseudomonas aeruginosa in subgingival bacterial samples from parous women.

PubMed

Persson, G Rutger; Hitti, Jane; Paul, Katie; Hirschi, Regula; Weibel, Marianne; Rothen, Marilynn; Persson, Rigmor E

2008-03-01

Information on the subgingival microbiota in parous women is limited. The present study assessed 74 bacterial species at periodontal sites. Subgingival bacterial plaque was collected from women > or =6 months after delivery. Bacteria were assessed by the checkerboard DNA-DNA hybridization method. Gingivitis was defined as > or =20% of sites with bleeding on probing (BOP), and periodontitis was defined as radiographic evidence of bone loss and probing depths > or =5.0 mm. A total of 197 women (mean age: 29.4 +/- 6.8 years; range: 18 to 46 years) were included in the study. Gingivitis was identified in 82 of 138 subjects without evidence of periodontitis (59.4%). Periodontitis was found in 59 women (32%). Higher bacterial levels in subjects with gingivitis compared to those without evidence of gingivitis were observed for Actinomyces neuii, Bifidobacterium bifidum, Corynebacterium pseudogenitalis, Porphyromonas endodontalis, Prevotella bivia, and Pseudomonas aeruginosa (P <0.001 for each). Higher bacterial levels in subjects with periodontitis compared to those without periodontitis (BOP not accounted for) were found for 32 of 79 species (P <0.001) including Lactobacillus iners, Haemophilus influenzae, Porphyromonas gingivalis, Tannerella forsythia (previously T. forsythensis), Prevotella bivia, P. aeruginosa, and Staphylococcus aureus. Binary univariate logistic regression analysis identified that P. aeruginosa (P <0.001) and T. forsythia (P <0.05) were independently predictive of periodontal status. The odds ratio of having P. aeruginosa at levels > or =1 x 10(5) in the sample and periodontitis was 3.1 (95% confidence interval: 1.6 to 5.9; P <0.001). In addition to P. gingivalis and T. forsythia, a diverse microbiota, including P. aeruginosa, P. endodontalis, P. bivia, and S. aureus, can be found in subgingival plaque samples from women of child-bearing age with periodontitis.

Endophytic bacteria in plant tissue culture: differences between easy- and difficult-to-propagate Prunus avium genotypes.

PubMed

Quambusch, Mona; Pirttilä, Anna Maria; Tejesvi, Mysore V; Winkelmann, Traud; Bartsch, Melanie

2014-05-01

The endophytic bacterial communities of six Prunus avium L. genotypes differing in their growth patterns during in vitro propagation were identified by culture-dependent and culture-independent methods. Five morphologically distinct isolates from tissue culture material were identified by 16S rDNA sequence analysis. To detect and analyze the uncultivable fraction of endophytic bacteria, a clone library was established from the amplified 16S rDNA of total plant extract. Bacterial diversity within the clone libraries was analyzed by amplified ribosomal rDNA restriction analysis and by sequencing a clone for each identified operational taxonomic unit. The most abundant bacterial group was Mycobacterium sp., which was identified in the clone libraries of all analyzed Prunus genotypes. Other dominant bacterial genera identified in the easy-to-propagate genotypes were Rhodopseudomonas sp. and Microbacterium sp. Thus, the community structures in the easy- and difficult-to-propagate cherry genotypes differed significantly. The bacterial genera, which were previously reported to have plant growth-promoting effects, were detected only in genotypes with high propagation success, indicating a possible positive impact of these bacteria on in vitro propagation of P. avium, which was proven in an inoculation experiment. © The Author 2014. Published by Oxford University Press. All rights reserved.

Plant-endophyte symbiosis, an ecological perspective.

PubMed

Wani, Zahoor Ahmed; Ashraf, Nasheeman; Mohiuddin, Tabasum; Riyaz-Ul-Hassan, Syed

2015-04-01

Endophytism is the phenomenon of mutualistic association of a plant with a microorganism wherein the microbe lives within the tissues of the plant without causing any symptoms of disease. In addition to being a treasured biological resource, endophytes play diverse indispensable functions in nature for plant growth, development, stress tolerance, and adaptation. Our understanding of endophytism and its ecological aspects are overtly limited, and we have only recently started to appreciate its essence. Endophytes may impact plant biology through the production of diverse chemical entities including, but not limited to, plant growth hormones and by modulating the gene expression of defense and other secondary metabolic pathways of the host. Studies have shown differential recruitment of endophytes in endophytic populations of plants growing in the same locations, indicating host specificity and that endophytes evolve in a coordinated fashion with the host plants. Endophytic technology can be employed for the efficient production of agricultural and economically important plants and plant products. The rational application of endophytes to manipulate the microbiota, intimately associated with plants, can help in enhancement of production of agricultural produce, increased production of key metabolites in medicinal and aromatic plants, as well as adaption to new bio-geographic regions through tolerance to various biotic and abiotic conditions. However, the potential of endophytic biology can be judiciously harnessed only when we obtain insight into the molecular mechanism of this unique mutualistic relationship. In this paper, we present a discussion on endophytes, endophytism, their significance, and diverse functions in nature as unraveled by the latest research to understand this universal natural phenomenon.

Discovery of anti-microbial and anti-tubercular molecules from Fusarium solani: an endophyte of Glycyrrhiza glabra.

PubMed

Shah, A; Rather, M A; Hassan, Q P; Aga, M A; Mushtaq, S; Shah, A M; Hussain, A; Baba, S A; Ahmad, Z

2017-05-01

Glycyrrhiza glabra is a high-value medicinal plant thriving in biodiversity rich Kashmir Himalaya. The present study was designed to explore the fungal endophytes from G. glabra as a source of bioactive molecules. The extracts prepared from the isolated endophytes were evaluated for anti-microbial activities using broth micro-dilution assay. The endophytic strain coded as A2 exhibiting promising anti-bacterial as well as anti-tuberculosis activity was identified as Fusarium solani by ITS-5.8S ribosomal gene sequencing technique. This strain was subjected to large-scale fermentation followed by isolation of its bioactive compounds using column chromatography. From the results of spectral data analysis and comparison with literature, the molecules were identified as 3,6,9-trihydroxy-7-methoxy-4,4-dimethyl-3,4-dihydro-1H-benzo[g]isochromene-5,10-dione (1), fusarubin (2), 3-O-methylfusarubin (3) and javanicin (4). Compound 1 is reported for the first time from this strain. All the four compounds inhibited the growth of various tested bacterial strains with MIC values in the range of <1 to 256 μg ml -1 . Fusarubin showed good activity against Mycobacterium tuberculosis strain H37Rv with MIC value of 8 μg ml -1 , whereas compounds 1, 3 and 4 exhibited moderate activity with MIC values of 256, 64, 32 μg ml -1 , respectively. To the best of our knowledge, this is the first study that reports significant anti-tuberculosis potential of bioactive molecules from endophytic F. solani evaluated against the virulent strain of M. tuberculosis. This study sets background towards their synthetic intervention for activity enhancement experiments in anti-microbial drug discovery programme. Due to the chemoprofile variation of same endophyte with respect to source plant and ecoregions, further studies are required to explore endophytes of medicinal plants of all unusual biodiversity rich ecoregions for important and or novel bioactive molecules. © 2017 The Society for Applied

Fungal endophytes: modifiers of plant disease.

PubMed

Busby, Posy E; Ridout, Mary; Newcombe, George

2016-04-01

Many recent studies have demonstrated that non-pathogenic fungi within plant microbiomes, i.e., endophytes ("endo" = within, "phyte" = plant), can significantly modify the expression of host plant disease. The rapid pace of advancement in endophyte ecology warrants a pause to synthesize our understanding of endophyte disease modification and to discuss future research directions. We reviewed recent literature on fungal endophyte disease modification, and here report on several emergent themes: (1) Fungal endophyte effects on plant disease span the full spectrum from pathogen antagonism to pathogen facilitation, with pathogen antagonism most commonly reported. (2) Agricultural plant pathosystems are the focus of research on endophyte disease modification. (3) A taxonomically diverse group of fungal endophytes can influence plant disease severity. And (4) Fungal endophyte effects on plant disease severity are context-dependent. Our review highlights the importance of fungal endophytes for plant disease across a broad range of plant pathosystems, yet simultaneously reveals that complexity within plant microbiomes presents a significant challenge to disentangling the biotic environmental factors affecting plant disease severity. Manipulative studies integrating eco-evolutionary approaches with emerging molecular tools will be poised to elucidate the functional importance of endophytes in natural plant pathosystems that are fundamental to biodiversity and conservation.

Root ethylene signalling is involved in Miscanthus sinensis growth promotion by the bacterial endophyte Herbaspirillum frisingense GSF30T

PubMed Central

Ludewig, Uwe

2013-01-01

The bacterial endophyte Herbaspirillum frisingense GSF30T is a colonizer of several grasses grown in temperate climates, including the highly nitrogen-efficient perennial energy grass Miscanthus. Inoculation of Miscanthus sinensis seedlings with H. frisingense promoted root and shoot growth but had only a minor impact on nutrient concentrations. The bacterium affected the root architecture and increased fine-root structures. Although H. frisingense has the genetic requirements to fix nitrogen, only minor changes in nitrogen concentrations were observed. Herbaspirillum agglomerates were identified primarily in the root apoplast but also in the shoots. The short-term (3h) and long-term (3 weeks) transcriptomic responses of the plant to bacterial inoculation revealed that H. frisingense induced rapid changes in plant hormone signalling, most prominent in jasmonate signalling. Ethylene signalling pathways were also affected and persisted after 3 weeks in the root. Growth stimulation of the root by the ethylene precursor 1-aminocyclopropane 1-carboxylic acid was dose dependent and was affected by H. frisingense inoculation. Minor changes in the proteome were identified after 3 weeks. This study suggests that H. frisingense improves plant growth by modulating plant hormone signalling pathways and provides a framework to understand the beneficial effects of diazotrophic plant-growth-promoting bacteria, such as H. frisingense, on the biomass grass Miscanthus. PMID:24043849

Strong shift in the diazotrophic endophytic bacterial community inhabiting rice (Oryza sativa) plants after flooding.

PubMed

Ferrando, Lucía; Fernández Scavino, Ana

2015-09-01

Flooding impacts soil microbial communities, but its effect on endophytic communities has rarely been explored. This work addresses the effect of flooding on the abundance and diversity of endophytic diazotrophic communities on rice plants established in a greenhouse experiment. The nifH gene was significantly more abundant in roots after flooding, whereas the nifH gene copy numbers in leaves were unaffected and remained low. The PCA (principal component analysis) of T-RFLP (terminal restriction fragment length polymorphism) profiles indicated that root communities of replicate plots were more similar and diverse after flooding than before flooding. The nifH libraries obtained by cloning and 454 pyrosequencing consistently showed a remarkable shift in the diazotrophic community composition after flooding. Gammaproteobacteria (66-98%), mainly of the genus Stenotrophomonas, prevailed in roots before flooding, whereas Betaproteobacteria was the dominant class (26-34%) after flooding. A wide variety of aerotolerant and anaerobic diazotrophic bacteria (e.g. Dechloromonas, Rhodopseudomonas, Desulfovibrio, Geobacter, Chlorobium, Spirochaeta, Selenomonas and Dehalobacter) with diverse metabolic traits were retrieved from flooded rice roots. These findings suggest that endophytic communities could be significantly impacted by changes in plant-soil conditions derived from flooding during rice cropping. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Isolation, taxonomic analysis, and phenotypic characterization of bacterial endophytes present in alfalfa (Medicago sativa) seeds.

PubMed

López, José Luis; Alvarez, Florencia; Príncipe, Analía; Salas, María Eugenia; Lozano, Mauricio Javier; Draghi, Walter Omar; Jofré, Edgardo; Lagares, Antonio

2018-02-10

A growing body of evidence has reinforced the central role of microbiomes in the life of sound multicellular eukaryotes, thus more properly described as true holobionts. Though soil was considered a main source of plant microbiomes, seeds have been shown to be endophytically colonized by microorganisms thus representing natural carriers of a selected microbial inoculum to the young seedlings. In this work we have investigated the type of culturable endophytic bacteria that are carried within surface-sterilized alfalfa seeds. MALDI-TOF analysis revealed the presence of bacteria that belonged to 40 separate genera, distributed within four taxa (Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes). Nonsymbiotic members of the Rhizobiaceae family were also found. The evaluation of nine different in-vitro biochemical activities demonstrated isolates with complex combinations of traits that, upon a Principal-Component-Analysis, could be classified into four phenotypic groups. That isolates from nearly half of the genera identified had been able to colonize alfalfa plants grown under axenic conditions was remarkable. Further analyses should be addressed to investigating the colonization mechanisms of the alfalfa seeds, the evolutionary significance of the alfalfa-seed endophytes, and also how after germination the seed microbiome competes with spermospheric and rhizospheric soil bacteria to colonize newly emerging seedlings. Copyright © 2018 Elsevier B.V. All rights reserved.

Highly diverse endophytes in roots of Cycas bifida (Cycadaceae), an ancient but endangered gymnosperm.

PubMed

Zheng, Ying; Chiang, Tzen-Yuh; Huang, Chao-Li; Gong, Xun

2018-05-01

As an ancient seed plant, cycads are one of the few gymnosperms that develop a root symbiosis with cyanobacteria, which has allowed cycads to cope with harsh geologic and climatic conditions during the evolutionary process. However, the endophytic microbes in cycad roots remain poorly identified. In this study, using next-generation sequencing techniques, we investigated the microbial diversity and composition of both the coralloid and regular roots of Cycas bifida (Dyer) K.D. Hill. Highly diverse endophytic communities were observed in both the coralloid and regular roots. Of the associated bacteria, the top five families were the Nostocaceae, Sinobacteraceae, Bradyrhizobiaceae, Bacillaceae, and Hyphomicrobiaceae. The Nectriaceae, Trichocomaceae, and Incertae sedis were the predominant fungal families in all root samples. A significant difference in the endophytic bacterial community was detected between coralloid roots and regular roots, but no difference was observed between the fungal communities in the two root types. Cyanobacteria were more dominant in coralloid roots than in regular roots. The divergence of cycad root structures and the modified physiological processes may have contributed to the abundance of cyanobionts in coralloid roots. Consequently, the colonization of cyanobacteria inhibits the assemblage of other endophytes. Our results contribute to an understanding of the species diversity and composition of the cycad-endophyte microbiome and provide an abbreviated list of potential ecological roles of the core microbes present.

Host-Parasite-Bacteria Triangle: The Microbiome of the Parasitic Weed Phelipanche aegyptiaca and Tomato-Solanum lycopersicum (Mill.) as a Host

PubMed Central

Iasur Kruh, Lilach; Lahav, Tamar; Abu-Nassar, Jacline; Achdari, Guy; Salami, Raghda; Freilich, Shiri; Aly, Radi

2017-01-01

Broomrapes (Phelipanche/Orobanche spp.) are holoparasitic plants that subsist on the roots of a variety of agricultural crops, establishing direct connections with the host vascular system. This connection allows for the exchange of various substances and a possible exchange of endophytic microorganisms that inhabit the internal tissues of both plants. To shed some light on bacterial interactions occurring between the parasitic Phelipanche aegyptiaca and its host tomato, we characterized the endophytic composition in the parasite during the parasitization process and ascertained if these changes were accompanied by changes to endophytes in the host root. Endophyte communities of the parasitic weed were significantly different from that of the non-parasitized tomato root but no significant differences were observed between the parasite and its host after parasitization, suggesting the occurrence of bacterial exchange between these two plants. Moreover, the P. aegyptiaca endophytic community composition showed a clear shift from gram negative to gram-positive bacteria at different developmental stages of the parasite life cycle. To examine possible functions of the endophytic bacteria in both the host and the parasite plants, a number of unique bacterial candidates were isolated and characterized. Results showed that a Pseudomonas strain PhelS10, originating from the tomato roots, suppressed approximately 80% of P. aegyptiaca seed germination and significantly reduced P. aegyptiaca parasitism. The information gleaned in the present study regarding the endophytic microbial communities in this unique ecological system of two plants connected by their vascular system, highlights the potential of exploiting alternative environmentally friendly approaches for parasitic weed control. PMID:28298918

Reactive oxygen species and hormone signaling cascades in endophytic bacterium induced essential oil accumulation in Atractylodes lancea.

PubMed

Zhou, Jia-Yu; Li, Xia; Zhao, Dan; Deng-Wang, Meng-Yao; Dai, Chuan-Chao

2016-09-01

Pseudomonas fluorescens induces gibberellin and ethylene signaling via hydrogen peroxide in planta . Ethylene activates abscisic acid signaling. Hormones increase sesquiterpenoid biosynthesis gene expression and enzyme activity, inducing essential oil accumulation. Atractylodes lancea is a famous Chinese medicinal plant, whose main active components are essential oils. Wild A. lancea has become endangered due to habitat destruction and over-exploitation. Although cultivation can ensure production of the medicinal material, the essential oil content in cultivated A. lancea is significantly lower than that in the wild herb. The application of microbes as elicitors has become an effective strategy to increase essential oil accumulation in cultivated A. lancea. Our previous study identified an endophytic bacterium, Pseudomonas fluorescens ALEB7B, which can increase essential oil accumulation in A. lancea more efficiently than other endophytes; however, the underlying mechanisms remain unknown (Physiol Plantarum 153:30-42, 2015; Appl Environ Microb 82:1577-1585, 2016). This study demonstrates that P. fluorescens ALEB7B firstly induces hydrogen peroxide (H2O2) signaling in A. lancea, which then simultaneously activates gibberellin (GA) and ethylene (ET) signaling. Subsequently, ET activates abscisic acid (ABA) signaling. GA and ABA signaling increase expression of HMGR and DXR, which encode key enzymes involved in sesquiterpenoid biosynthesis, leading to increased levels of the corresponding enzymes and then an accumulation of essential oils. Specific reactive oxygen species and hormone signaling cascades induced by P. fluorescens ALEB7B may contribute to high-efficiency essential oil accumulation in A. lancea. Illustrating the regulation mechanisms underlying P. fluorescens ALEB7B-induced essential oil accumulation not only provides the theoretical basis for the inducible synthesis of terpenoids in many medicinal plants, but also further reveals the complex and diverse

An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes.

PubMed

Kandel, Shyam L; Firrincieli, Andrea; Joubert, Pierre M; Okubara, Patricia A; Leston, Natalie D; McGeorge, Kendra M; Mugnozza, Giuseppe S; Harfouche, Antoine; Kim, Soo-Hyung; Doty, Sharon L

2017-01-01

Microbial communities in the endosphere of Salicaceae plants, poplar ( Populus trichocarpa ) and willow ( Salix sitchensis ), have been demonstrated to be important for plant growth promotion, protection from biotic and abiotic stresses, and degradation of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae endophytes against various soil borne plant pathogens including Rhizoctonia solani AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici , and Pythium ultimum . Additionally, different plant growth promoting traits such as biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore production were assessed in all bio-control positive strains. Burkholderia, Rahnella, Pseudomonas , and Curtobacterium were major endophyte genera that showed bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia strains were stronger across all tested plant pathogens as compared to other stains. Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify the putative genes involved in the bio-control activities. The ocf and hcnABC gene clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Moreover, some strains reduced acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF. Salicaceae endophytes could be useful for bio-control of various plant pathogens, and plant growth promotion possibly through the mechanisms of BNF, IAA production, and nutrient acquisition.

Characterization of N2-fixing plant growth promoting endophytic and epiphytic bacterial community of Indian cultivated and wild rice (Oryza spp.) genotypes.

PubMed

Banik, Avishek; Mukhopadhaya, Subhra Kanti; Dangar, Tushar Kanti

2016-03-01

The diversity of endophytic and epiphytic diazotrophs in different parts of rice plants has specificity to the niche (i.e. leaf, stem and root) of different genotypes and nutrient availability of the organ. Inoculation of the indigenous, polyvalent diazotrophs can facilitate and sustain production of non-leguminous crops like rice. Therefore, N2-fixing plant growth promoting bacteria (PGPB) were isolated from different parts of three Indian cultivated [Oryza sativa L. var. Sabita (semi deep/deep water)/Swarna (rain fed shallow lowland)/Swarna-Sub1(submergence tolerant)] and a wild (O. eichingeri) rice genotypes which respond differentially to nitrogenous fertilizers. Thirty-five isolates from four rice genotypes were categorized based on acetylene reduction assay on nitrogenase activity, biochemical tests, BIOLOG and 16S rRNA gene sequencing. The bacteria produced 9.36-155.83 nmole C2H4 mg(-1) dry bacteria h(-1) and among them nitrogenase activity of 11 potent isolates was complemented by nifH-sequence analysis. Phylogenetic analysis based on 16S rDNA sequencing divided them into five groups (shared 95-100 % sequence homology with type strains) belonging to five classes-alpha (Ancylobacter, Azorhizobium, Azospirillum, Rhizobium, Bradyrhizobium, Sinorhizobium, Novosphingobium, spp.), beta (Burkholderia sp.), gamma (Acinetobacter, Aeromonas, Azotobacter, Enterobacter, Klebsiella, Pantoea, Pseudomonas, Stenotrophomonas spp.) Proteobacteria, Bacilli (Bacillus, Paenibacillus spp.) and Actinobacteria (Microbacterium sp.). Besides, all bacterial strains possessed the intrinsic PGP traits of like indole (0.44-7.4 µg ml(-1)), ammonia (0.18-6 mmol ml(-1)), nitrite (0.01-3.4 mol ml(-1)), and siderophore (from 0.16-0.57 μmol ml(-1)) production. Inoculation of rice (cv. Swarna) seedlings with selected isolates had a positive impact on plant growth parameters like shoot and root elongation which was correlated with in vitro PGP attributes. The results indicated that the

Contrasting colonization and plant growth promoting capacity between wild type and gfp-derative of the endophyte Pseudomonas putida W619 in hybrid poplar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weyens N.; van der Lelie D.; Boulet, J.

2011-06-09

This study aims to investigate the colonization of poplar by the endophyte Pseudomonas putida W619 and its capacity to promote plant growth. Poplar cuttings were inoculated with P. putida W619 (wild-type or gfp-labelled). The colonization of both strains was investigated and morphological, physiological and biochemical parameters were analyzed to evaluate plant growth promotion. Inoculation with P. putida W619 (wild-type) resulted in remarkable growth promotion, decreased activities of antioxidative defence related enzymes, and reduced stomatal resistance, all indicative of improved plant health and growth in comparison with the non-inoculated cuttings. In contrast, inoculation with gfp-labelled P. putida W619 did not promotemore » growth; it even had a negative effect on plant health and growth. Furthermore, compared to the wildtype strain, colonization by the gfp-labelled P. putida W619::gfp1 was much lower; it only colonized the rhizosphere and root cortex while the wild-type strain also colonized the root xylem vessels. Despite the strong plant growth promoting capacity of P. putida W619 (wild-type), after gfp labelling its growth promoting characteristics disappeared and its colonization capacity was strongly influenced; for these reasons gfp labelling should be applied with sufficient caution.« less

Chemical constituents of Aspergillus sp EJC08 isolated as endophyte from Bauhinia guianensis and their antimicrobial activity.

PubMed

Pinheiro, Eduardo A A; Carvalho, Josiwander M; Santos, Diellem C P dos; Feitosa, André O; Marinho, Patrícia S B; Guilhon, Giselle Maria S P; Santos, Lourivaldo S; Souza, Afonso L D de; Marinho, Andrey M R

2013-01-01

The present work reports the isolation of five compounds from Aspergillus sp EJC08 isolated as endophytic from Bauhinia guianensis, a tipical plant of the Amazon. The compounds ergosterol (1), ergosterol peroxide (2), mevalolactone (3), monomethylsulochrin (4) and trypacidin A (5) were isolated by chromatographic procedures and identified by spectral methods of 1D and 2D NMR and MS. Compounds 3, 4 and 5 were tested against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus and showed good activity.

Soil mixture composition alters Arabidopsis susceptibility to Pseudomonas syringae infection

USDA-ARS?s Scientific Manuscript database

Pseudomonas syringae is a Gram-negative bacterial pathogen that causes disease on more than 100 different plant species, including the model plant Arabidopsis thaliana. Dissection of the Arabidopsis thaliana-Pseudomonas syringae pathosystem has identified many factors that contribute to successful ...

Diversity of endophytic and rhizoplane bacterial communities associated with exotic Spartina alterniflora and native mangrove using Illumina amplicon sequencing.

PubMed

Hong, Youwei; Liao, Dan; Hu, Anyi; Wang, Han; Chen, Jinsheng; Khan, Sardar; Su, Jianqiang; Li, Hu

2015-10-01

Root-associated microbial communities are very important for biogeochemical cycles in wetland ecosystems and help to elaborate the mechanisms of plant invasions. In the estuary of Jiulong River (China), Spartina alterniflora has widely invaded Kandelia obovata-dominated habitats, offering an opportunity to study the influence of root-associated bacteria. The community structures of endophytic and rhizosphere bacteria associated with selected plant species were investigated using the barcoded Illumina paired-end sequencing technique. The diversity indices of bacteria associated with the roots of S. alterniflora were higher than those of the transition stands and K. obovata monoculture. Using principal coordinate analysis with UniFrac metrics, the comparison of β-diversity showed that all samples could be significantly clustered into 3 major groups, according to the bacteria communities of origin. Four phyla, namely Proteobacteria, Bacteroidetes, Chloroflexi, and Firmicutes, were enriched in the rhizoplane of both salt marsh plants, while they shared higher abundances of Cyanobacteria and Proteobacteria among endophytic bacteria. Members of the phyla Spirochaetes and Chloroflexi were found among the endophytic bacteria of S. alterniflora and K. obovata, respectively. One of the interesting findings was that endophytes were more sensitive in response to plant invasion than were rhizosphere bacteria. With linear discriminate analysis, we found some predominant rhizoplane and endophytic bacteria, including Methylococcales, Pseudoalteromonadacea, Clostridium, Vibrio, and Desulfovibrio, which have the potential to affect the carbon, nitrogen, and sulfur cycles. Thus, the results provide clues to the isolation of functional bacteria and the effects of root-associated microbial groups on S. alterniflora invasions.

The ACC deaminase expressing endophyte Pseudomonas spp. Enhances NaCl stress tolerance by reducing stress-related ethylene production, resulting in improved growth, photosynthetic performance, and ionic balance in tomato plants.

PubMed

Win, Khin Thuzar; Fukuyo, Tanaka; Keiki, Okazaki; Ohwaki, Yoshinari

2018-06-01

Plant growth promoting bacteria (PGPB) endophytes that express 1-aminocyclopropane-1-carboxylate (ACC) deaminase reportedly confer plant tolerance to abiotic stresses such as salinity by lowering stress-related ethylene levels. Two preselected ACC deaminase expressing endophytic Pseudomonas spp. strains, OFT2 and OFT5, were compared in terms of their potential to promote plant growth, leaf water contents, photosynthetic performance, and ionic balance of tomato plants under conditions of moderate NaCl stress (75 mM). Salinity stress strongly affected growth, leaf water contents, and photosynthetic performance of tomato seedlings, and inoculation with either OFT2 or OFT5 ameliorated these adverse effects. Decreases in plant biomass due to salinity stress were significant in both uninoculated control plants and in plants inoculated with OFT2 compared with plants without NaCl stress. However, no reductions in total biomass were observed in plants that were inoculated with the OFT5 strain. Strain OFT5 influenced growth, physiological status, and ionic balance of tomato plants more efficiently than strain OFT2 under NaCl stress. In particular, inoculated OFT5 reduced salt-induced ethylene production by tomato seedlings, and although it did not reduce shoot uptake of Na, it promoted shoot uptake of other macronutrients (P, K, and Mg) and micronutrients (Mn, Fe, Cu, and Zn). These nutrients may activate processes that alleviate the effects of salt, suggesting that OFT5 can be used to improve nutrient uptake and plant growth under moderate salt-affected conditions by reducing stress-related ethylene levels. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Bacteriome from Pinus arizonica and P. durangensis: Diversity, Comparison of Assemblages, and Overlapping Degree with the Gut Bacterial Community of a Bark Beetle That Kills Pines.

PubMed

Gonzalez-Escobedo, Roman; Briones-Roblero, Carlos I; Pineda-Mendoza, Rosa M; Rivera-Orduña, Flor N; Zúñiga, Gerardo

2018-01-01

Symbioses between plants and microorganims have been fundamental in the evolution of both groups. The endophytic bacteria associated with conifers have been poorly studied in terms of diversity, ecology, and function. Coniferous trees of the genera Larix , Pseudotsugae , Picea and mainly Pinus , are hosts of many insects, including bark beetles and especially the Dendroctonus species. These insects colonize and kill these trees during their life cycle. Several bacteria detected in the gut and cuticle of these insects have been identified as endophytes in conifers. In this study, we characterized and compared the endophytic bacterial diversity in roots, phloem and bark of non-attacked saplings of Pinus arizonica and P. durangensis using 16S rRNA gene pyrosequencing. In addition, we evaluated the degree of taxonomic relatedness, and the association of metabolic function profiles of communities of endophytic bacteria and previously reported gut bacterial communities of D. rhizophagus ; a specialized bark beetle that colonizes and kills saplings of these pine species. Our results showed that both pine species share a similar endophytic community. A total of seven bacterial phyla, 14 classes, 26 orders, 43 families, and 51 genera were identified. Enterobacteriaceae was the most abundant family across all samples, followed by Acetobacteraceae and Acidobacteriaceae, which agree with previous studies performed in other pines and conifers. Endophytic communities and that of the insect gut were significantly different, however, the taxonomic relatedness of certain bacterial genera of pines and insect assemblages suggested that some bacteria from pine tissues might be the same as those in the insect gut. Lastly, the metabolic profile using PICRUSt showed there to be a positive association between communities of both pines and insect gut. This study represents the baseline into the knowledge of the endophytic bacterial communities of two of the major hosts affected by D

Histological Examination of Horse Chestnut Infection by Pseudomonas syringae pv. aesculi and Non-Destructive Heat Treatment to Stop Disease Progression

PubMed Central

de Keijzer, Jeroen; van den Broek, Lambertus A. M.; Ketelaar, Tijs; van Lammeren, André A. M.

2012-01-01

Since its emergence in Northwest Europe as a pathogen that infects trunks and branches of Aesculus spp. (the horse chestnuts) approximately one decade ago, Pseudomonas syringae pv. aesculi has rapidly established itself as major threat to these trees. Infected trees exhibit extensive necrosis of phloem and cambium, which can ultimately lead to dieback. The events after host entry leading to extensive necrosis are not well documented. In this work, the histopathology of this interaction is investigated and heat-treatment is explored as method to eradicate bacteria associated with established infections. The early wound-repair responses of A. hippocastanum, both in absence and presence of P. s. pv. aesculi, included cell wall lignification by a distinct layer of phloem and cortex parenchyma cells. The same cells also deposited suberin lamellae later on, suggesting this layer functions in compartmentalizing healthy from disrupted tissues. However, monitoring bacterial ingress, its construction appeared inadequate to constrain pathogen spread. Microscopic evaluation of bacterial dispersal in situ using immunolabelling and GFP-tagging of P. s. pv. aesculi, revealed two discriminative types of bacterial colonization. The forefront of lesions was found to contain densely packed bacteria, while necrotic areas housed bacterial aggregates with scattered individuals embedded in an extracellular matrix of bacterial origin containing alginate. The endophytic localization and ability of P. s. pv aesculi to create a protective matrix render it poorly accessible for control agents. To circumvent this, a method based on selective bacterial lethality at 39°C was conceived and successfully tested on A. hippocastanum saplings, providing proof of concept for controlling this disease by heat-treatment. This may be applicable for curing other tree cankers, caused by related phytopathogens. PMID:22808044

Histological examination of horse chestnut infection by Pseudomonas syringae pv. aesculi and non-destructive heat treatment to stop disease progression.

PubMed

de Keijzer, Jeroen; van den Broek, Lambertus A M; Ketelaar, Tijs; van Lammeren, André A M

2012-01-01

Since its emergence in Northwest Europe as a pathogen that infects trunks and branches of Aesculus spp. (the horse chestnuts) approximately one decade ago, Pseudomonas syringae pv. aesculi has rapidly established itself as major threat to these trees. Infected trees exhibit extensive necrosis of phloem and cambium, which can ultimately lead to dieback. The events after host entry leading to extensive necrosis are not well documented. In this work, the histopathology of this interaction is investigated and heat-treatment is explored as method to eradicate bacteria associated with established infections. The early wound-repair responses of A. hippocastanum, both in absence and presence of P. s. pv. aesculi, included cell wall lignification by a distinct layer of phloem and cortex parenchyma cells. The same cells also deposited suberin lamellae later on, suggesting this layer functions in compartmentalizing healthy from disrupted tissues. However, monitoring bacterial ingress, its construction appeared inadequate to constrain pathogen spread. Microscopic evaluation of bacterial dispersal in situ using immunolabelling and GFP-tagging of P. s. pv. aesculi, revealed two discriminative types of bacterial colonization. The forefront of lesions was found to contain densely packed bacteria, while necrotic areas housed bacterial aggregates with scattered individuals embedded in an extracellular matrix of bacterial origin containing alginate. The endophytic localization and ability of P. s. pv aesculi to create a protective matrix render it poorly accessible for control agents. To circumvent this, a method based on selective bacterial lethality at 39 °C was conceived and successfully tested on A. hippocastanum saplings, providing proof of concept for controlling this disease by heat-treatment. This may be applicable for curing other tree cankers, caused by related phytopathogens.

Uptake of carbamazepine by rhizomes and endophytic bacteria of Phragmites australis

PubMed Central

Sauvêtre, Andrés; Schröder, Peter

2015-01-01

Carbamazepine is an antiepileptic and mood-stabilizing drug which is used widely in Europe and North America. In the environment, it is found as a persistent and recalcitrant contaminant, being one of the most prominent hazardous pharmaceuticals and personal care products in effluents of wastewater treatment plants. Phragmites australis is one of the species with both, the highest potential of detoxification and phytoremediation. It has been used successfully in the treatment of industrial and municipal wastewater. Recently, the identification of endophytic microorganisms from different plant species growing in contaminated sites has provided a list of candidates which could be used as bio-inoculants for bioremediation of difficult compounds. In this study, Phragmites australis plants were exposed to 5 mg/L of carbamazepine. After 9 days the plants had removed 90% of the initial concentration. Endophytic bacteria were isolated from these plants and further characterized. Phylogenetic analysis based on 16S rDNA sequencing revealed that the majority of these isolates belong to three groups: Proteobacteria, Actinobacteria, and Bacteroidetes. Carbamazepine uptake and plant growth promoting (PGP) traits were analyzed among the isolates. Ninety percent of the isolates produce indole acetic acid (IAA) and all of them possess at least one of the PGP traits tested. One isolate identified as Chryseobacterium taeanense combines good carbamazepine uptake and all of the PGP traits. Rhizobium daejeonense can remove carbamazepine and produces 23 μg/mL of IAA. Diaphorobacter nitroreducens and Achromobacter mucicolens are suitable for carbamazepine removal while both, Pseudomonas veronii and Pseudomonas lini show high siderophore production and phosphate solubilization. Alone or in combination, these isolates might be applied as inoculates in constructed wetlands in order to enhance the phytoremediation of carbamazepine during wastewater treatment. PMID:25750647

Illumina-based analysis of endophytic bacterial diversity and space-time dynamics in sugar beet on the north slope of Tianshan mountain.

PubMed

Shi, YingWu; Yang, Hongmei; Zhang, Tao; Sun, Jian; Lou, Kai

2014-01-01

Plants harbors complex and variable microbial communities. Endophytic bacteria play an important function and potential role more effectively in developing sustainable systems of crop production. To examine how endophytic bacteria in sugar beet (Beta vulgaris L.) vary across both host growth period and location, PCR-based Illumina was applied to revealed the diversity and stability of endophytic bacteria in sugar beet on the north slope of Tianshan mountain, China. A total of 60.84 M effective sequences of 16S rRNA gene V3 region were obtained from sugar beet samples. These sequences revealed huge amount of operational taxonomic units (OTUs) in sugar beet, that is, 19-121 OTUs in a beet sample, at 3 % cutoff level and sequencing depth of 30,000 sequences. We identified 13 classes from the resulting 449,585 sequences. Alphaproteobacteria were the dominant class in all sugar beets, followed by Acidobacteria, Gemmatimonadetes and Actinobacteria. A marked difference in the diversity of endophytic bacteria in sugar beet for different growth periods was evident. The greatest number of OTUs was detected during rossette formation (109 OTUs) and tuber growth (146 OTUs). Endophytic bacteria diversity was reduced during seedling growth (66 OTUs) and sucrose accumulation (95 OTUs). Forty-three OTUs were common to all four periods. There were more tags of Alphaproteobacteria and Gammaproteobacteria in Shihezi than in Changji. The dynamics of endophytic bacteria communities were influenced by plant genotype and plant growth stage. To the best of our knowledge, this study is the first application of PCR-based Illumina pyrosequencing to characterize and compare multiple sugar beet samples.

Biotransformation of Tributyltin chloride by Pseudomonas stutzeri strain DN2

PubMed Central

Khanolkar, Dnyanada S.; Naik, Milind Mohan; Dubey, Santosh Kumar

2014-01-01

A bacterial isolate capable of utilizing tributyltin chloride (TBTCl) as sole carbon source was isolated from estuarine sediments of west coast of India and identified as Pseudomonas stutzeri based on biochemical tests and Fatty acid methyl ester (FAME) analysis. This isolate was designated as strain DN2. Although this bacterial isolate could resist up to 3 mM TBTCl level, it showed maximum growth at 2 mM TBTCl in mineral salt medium (MSM). Pseudomonas stutzeri DN2 exposed to 2 mM TBTCl revealed significant alteration in cell morphology as elongation and shrinkage in cell size along with roughness of cell surface. FTIR and NMR analysis of TBTCl degradation product extracted using chloroform and purified using column chromatography clearly revealed biotransformation of TBTCl into Dibutyltin dichloride (DBTCl2) through debutylation process. Therefore, Pseudomonas stutzeri strain DN2 may be used as a potential bacterial strain for bioremediation of TBTCl contaminated aquatic environmental sites. PMID:25763027

Antimicrobial metabolites from the plant endophytic fungus Penicillium sp.

PubMed

Yang, Ming-Hua; Li, Tian-Xiao; Wang, Ying; Liu, Rui-Huan; Luo, Jun; Kong, Ling-Yi

2017-01-01

Five rare dichloro aromatic polyketides (1-5) were obtained from an endophytic fungus Penicillium sp., along with five known metabolites (6-10). Their structures were elucidated by extensive spectroscopic analysis, Mosher methods, as well as [Rh 2 (OCOCF 3 ) 4 ]-induced electronic circular dichroism (ECD) experiments. Compounds 2-4 and 6 structurally involved acyclic 1.3-diols, the uneasy configuration determinations of which were well carried out by double-derivation NMR methods. Compounds 1-10 were evaluated for their antibacterial and antifungal activities against five strains of human pathogenic microorganisms. Helvolic acid (7) showed potent inhibitory effects against Staphylococcus aureus and Pseudomonas aeruginosa with MIC (minimum inhibitory concentration) values of 5.8 and 4.6μg/mL, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Revealing structure and assembly cues for Arabidopsis root-inhabiting bacterial microbiota.

PubMed

Bulgarelli, Davide; Rott, Matthias; Schlaeppi, Klaus; Ver Loren van Themaat, Emiel; Ahmadinejad, Nahal; Assenza, Federica; Rauf, Philipp; Huettel, Bruno; Reinhardt, Richard; Schmelzer, Elmon; Peplies, Joerg; Gloeckner, Frank Oliver; Amann, Rudolf; Eickhorst, Thilo; Schulze-Lefert, Paul

2012-08-02

The plant root defines the interface between a multicellular eukaryote and soil, one of the richest microbial ecosystems on Earth. Notably, soil bacteria are able to multiply inside roots as benign endophytes and modulate plant growth and development, with implications ranging from enhanced crop productivity to phytoremediation. Endophytic colonization represents an apparent paradox of plant innate immunity because plant cells can detect an array of microbe-associated molecular patterns (also known as MAMPs) to initiate immune responses to terminate microbial multiplication. Several studies attempted to describe the structure of bacterial root endophytes; however, different sampling protocols and low-resolution profiling methods make it difficult to infer general principles. Here we describe methodology to characterize and compare soil- and root-inhabiting bacterial communities, which reveals not only a function for metabolically active plant cells but also for inert cell-wall features in the selection of soil bacteria for host colonization. We show that the roots of Arabidopsis thaliana, grown in different natural soils under controlled environmental conditions, are preferentially colonized by Proteobacteria, Bacteroidetes and Actinobacteria, and each bacterial phylum is represented by a dominating class or family. Soil type defines the composition of root-inhabiting bacterial communities and host genotype determines their ribotype profiles to a limited extent. The identification of soil-type-specific members within the root-inhabiting assemblies supports our conclusion that these represent soil-derived root endophytes. Surprisingly, plant cell-wall features of other tested plant species seem to provide a sufficient cue for the assembly of approximately 40% of the Arabidopsis bacterial root-inhabiting microbiota, with a bias for Betaproteobacteria. Thus, this root sub-community may not be Arabidopsis-specific but saprophytic bacteria that would naturally be found

Plant-endophytes interaction influences the secondary metabolism in Echinacea purpurea (L.) Moench: an in vitro model.

PubMed

Maggini, Valentina; De Leo, Marinella; Mengoni, Alessio; Gallo, Eugenia Rosaria; Miceli, Elisangela; Reidel, Rose Vanessa Bandeira; Biffi, Sauro; Pistelli, Luisa; Fani, Renato; Firenzuoli, Fabio; Bogani, Patrizia

2017-12-05

The influence of the interaction(s) between the medicinal plant Echinacea purpurea (L.) Moench and its endophytic communities on the production of alkamides is investigated. To mimic the in vivo conditions, we have set up an infection model of axenic in vitro E. purpurea plants inoculated with a pool of bacterial strains isolated from the E. purpurea stems and leaves. Here we show different alkamide levels between control (not-inoculated) and inoculated plants, suggesting that the alkamide biosynthesis may be modulated by the bacterial infection. Then, we have analysed the branched-chain amino acids (BCCA) decarboxylase gene (GenBank Accession #LT593930; the enzymatic source for the amine moiety formation of the alkamides) expression patterns. The expression profile shows a higher expression level in the inoculated E. purpurea tissues than in the control ones. These results suggest that the plant-endophyte interaction can influence plant secondary metabolism affecting the therapeutic properties of E. purpurea.

Combined genetic and bioactivity-based prioritization leads to the isolation of an endophyte-derived antimycobacterial compound.

PubMed

Alvin, A; Kalaitzis, J A; Sasia, B; Neilan, B A

2016-05-01

To initiate a genetic and bioactivity-based screening programme of culturable endophytes to identify micro-organisms capable of producing bioactive polyketides and peptides. Fungal endophytes were isolated from flowers, leaves and roots of Rhoeo spathacea, revealing a community consisting of Colletotrichum sp., Fusarium sp., Guignardia sp., Phomopsis sp., Phoma sp. and Microdochium sp. Genetic screening showed that all isolates had polyketide synthase (PKS) genes and most had nonribosomal peptide synthetase (NRPS) genes. Ethyl acetate extracts of the fungal isolates exhibited antiproliferative activity against at least one of the seven bacterial and mycobacterial test strains. Nuclear Magnetic Resonance -guided fractionation of the crude extract from a Fusarium sp. strain which exhibited strong antiproliferative activity against Mycobacterium tuberculosis resulted in the isolation of the polyketide javanicin. This compound was active against Myco. tuberculosis (MIC = 25 μg ml(-1)) and Mycobacterium phlei (MIC = 50 μg ml(-1)). The medicinal plant R. spathacea hosts a variety of fungal endophytes capable of producing antibacterial and antimycobacterial compounds. There is a positive correlation between the presence of PKS and/or NRPS encoding genes in endophytes and the bioactivity of their respective organic extracts. This is the first report on the fungal endophytic diversity of R. spathacea, and the isolation of an antimycobacterial compound from the plant which has been traditionally used for the treatment of tuberculosis symptoms. © 2016 The Society for Applied Microbiology.

Study on the diversity of endophytic communities from rice (Oryza sativa L.) and their antagonistic activities in vitro.

PubMed

Naik, B Shankar; Shashikala, J; Krishnamurthy, Y L

2009-01-01

Endophytic populations were isolated from 2400 segments of Oryza sativa collected from Bhadra River Project Area, Southern India during December 2005 (Winter) and April 2006 (Summer). Overall colonization rates from surface sterilized tissues were 40.3% in roots and 25.83% in leaves during winter season, 20.15% in roots and 8.66% in leaves during summer season. Nineteen different fungal taxa, a Streptomyces sp. and bacterial species were isolated. Streptomyces sp., Chaetomium globosum, Penicillium chrysogenum, Fusarium oxysporum and Cladosporium cladosporioides were dominant endophytes in this study. Frequency of colonization between the sites, seasons and rice varieties were found to differ significantly. Dual culture studies revealed that C. globosum, P. chrysogenum and Streptomyces sp. are suitable candidates for extraction of biologically active compounds. Rice harbors many endophytic organisms and some of them have antagonistic properties against fungal pathogens.

Interactions between Co-Habitating fungi Elicit Synthesis of Taxol from an Endophytic Fungus in Host Taxus Plants

PubMed Central

Soliman, Sameh S. M.; Raizada, Manish N.

2012-01-01

Within a plant, there can exist an ecosystem of pathogens and endophytes, the latter described as bacterial and fungal inhabitants that thrive without causing disease to the host. Interactions between microbial inhabitants represent a novel area of study for natural products research. Here we analyzed the interactions between the fungal endophytes of Taxus (yew) trees. Fungal endophytes of Taxus have been proposed to produce the terpenoid secondary metabolite, Taxol, an anti-cancer drug. It is widely reported that plant extracts stimulate endophytic fungal Taxol production, but the underlying mechanism is not understood. Here, Taxus bark extracts stimulated fungal Taxol production 30-fold compared to a 10-fold induction with wood extracts. However, candidate plant-derived defense compounds (i.e., salicylic acid, benzoic acid) were found to act only as modest elicitors of fungal Taxol production from the endophytic fungus Paraconiothyrium SSM001, consistent with previous studies. We hypothesized the Taxus plant extracts may contain elicitors derived from other microbes inhabiting these tissues. We investigated the effects of co-culturing SSM001 with other fungi observed to inhabit Taxus bark, but not wood. Surprisingly, co-culture of SSM001 with a bark fungus (Alternaria) caused a ∼threefold increase in Taxol production. When SSM001 was pyramided with both the Alternaria endophyte along with another fungus (Phomopsis) observed to inhabit Taxus, there was an ∼eightfold increase in fungal Taxol production from SSM001. These results suggest that resident fungi within a host plant interact with one another to stimulate Taxol biosynthesis, either directly or through their metabolites. More generally, our results suggest that endophyte secondary metabolism should be studied in the context of its native ecosystem. PMID:23346084

Antiangiogenic activity of the lipophilic antimicrobial peptides from an endophytic bacterial strain isolated from red pepper leaf.

PubMed

Jung, Hye Jin; Kim, Yonghyo; Lee, Hyang Burm; Kwon, Ho Jeong

2015-03-01

The induction of angiogenesis is a crucial step in tumor progression, and therefore, efficient inhibition of angiogenesis is considered a powerful strategy for the treatment of cancer. In the present study, we report that the lipophilic antimicrobial peptides from EML-CAP3, a new endophytic bacterial strain isolated from red pepper leaf (Capsicum annuum L.), exhibit potent antiangiogenic activity both in vitro and in vivo. The newly obtained antimicrobial peptides effectively inhibited the proliferation of human umbilical vein endothelial cells at subtoxic doses. Furthermore, the peptides suppressed the in vitro characteristics of angiogenesis such as endothelial cell invasion and tube formation stimulated by vascular endothelial growth factor, as well as neovascularization of the chorioallantoic membrane of growing chick embryos in vivo without showing cytotoxicity. Notably, the angiostatic peptides blocked tumor cell-induced angiogenesis by suppressing the expression levels of hypoxia-inducible factor-1α and its target gene, vascular endothelial growth factor (VEGF). To our knowledge, our findings demonstrate for the first time that the antimicrobial peptides from EML-CAP3 possess antiangiogenic potential and may thus be used for the treatment of hypervascularized tumors.

Root endophytic bacteria of a (137)Cs and Mn accumulator plant, Eleutherococcus sciadophylloides, increase (137)Cs and Mn desorption in the soil.

PubMed

Yamaji, Keiko; Nagata, Satoshi; Haruma, Toshikatsu; Ohnuki, Toshihiko; Kozaki, Tamotsu; Watanabe, Naoko; Nanba, Kenji

2016-03-01

We found that root endophytes of (137)Cs accumulator plant produce siderophores, resulting in the desorption of (137)Cs from the contaminated soil collected at Fukushima, Japan. We selected an endemic Japanese deciduous tree, Eleutherococcus sciadophylloides (Franch. et Sav), that accumulates high concentrations of (137)Cs and Mn. Root endophytic bacteria were isolated from E. sciadophylloides and microbial siderophore production was evaluated via chrome azurol S (CAS) Fe and CAS Al assays. Of the 463 strains that we isolated, 107 (23.1%) produced the siderophores. Using eight strains that showed high siderophore production in our assays, we examined desorption of (137)Cs, Mn, Fe and Al by the bacterial culture filtrates from (137)Cs-contaminated soil after decomposing the soil organic matter using hydrogen peroxide. We found (137)Cs and Mn desorption concomitant with Al and Fe desorption, as well as a decrease of pH. We also detected succinic acid, a well-known siderophore, in the bacterial culture filtrates of our two root endophytic bacteria. Our results strongly suggest that the root endophytic bacteria of E. sciadophylloides produce the siderophores that enhance (137)Cs and Mn desorption in the rhizosphere, making the resulting (137)Cs and Mn ions easier for E. sciadophylloides to absorb from the rhizosphere. Copyright © 2015 Elsevier Ltd. All rights reserved.

High pressure inactivation of Pseudomonas in black truffle - comparison with Pseudomonas fluorescens in tryptone soya broth

NASA Astrophysics Data System (ADS)

Ballestra, Patricia; Verret, Catherine; Cruz, Christian; Largeteau, Alain; Demazeau, Gerard; El Moueffak, Abdelhamid

2010-03-01

Pseudomonas is one of the most common genera in black Perigord truffle. Its inactivation by high pressure (100-500 MPa/10 min) applied on truffles at sub-zero or low temperatures was studied and compared with those of Pseudomonas fluorescens in tryptone soya broth. Pressurization of truffles at 300 MPa/4 °C reduced the bacterial count of Pseudomonas by 5.3 log cycles. Higher pressures of 400 or 500 MPa, at 4 °C or 20 °C, allowed us to slightly increase the level of destruction to the value of ca. 6.5 log cycles but did not permit us to completely inactivate Pseudomonas. The results showed a residual charge of about 10 CFU/g. Pressure-shift freezing of truffles, which consists in applying a pressure of 200 MPa/-18 °C for 10 min and then quickly releasing this pressure to induce freezing, reduced the population of Pseudomonas by 3.3 log cycles. The level of inactivation was higher than those obtained with conventional freezing. Endogenous Pseudomonas in truffle was shown to be more resistant to high pressure treatments than P. fluorescens used for inoculation of broths.

Fungal Disease Prevention in Seedlings of Rice (Oryza sativa) and Other Grasses by Growth-Promoting Seed-Associated Endophytic Bacteria from Invasive Phragmites australis

PubMed Central

Verma, Satish K.; Kingsley, Kathryn L.; Bergen, Marshall S.; White, James F.

2018-01-01

Non-cultivated plants carry microbial endophytes that may be used to enhance development and disease resistance of crop species where growth-promoting and protective microbes may have been lost. During seedling establishment, seedlings may be infected by several fungal pathogens that are seed or soil borne. Several species of Fusarium, Pythium and other water moulds cause seed rots during germination. Fusarium blights of seedlings are also very common and significantly affect seedling development. In the present study we screened nine endophytic bacteria isolated from the seeds of invasive Phragmites australis by inoculating onto rice, Bermuda grass (Cynodon dactylon), or annual bluegrass (Poa annua) seeds to evaluate plant growth promotion and protection from disease caused by Fusarium oxysporum. We found that three bacteria belonging to genus Pseudomonas spp. (SLB4-P. fluorescens, SLB6-Pseudomonas sp. and SY1-Pseudomonas sp.) promoted seedling development, including enhancement of root and shoot growth, and stimulation of root hair formation. These bacteria were also found to increase phosphate solubilization in in vitro experiments. Pseudomonas sp. (SY1) significantly protected grass seedlings from Fusarium infection. In co-culture experiments, strain SY1 strongly inhibited fungal pathogens with 85.71% growth inhibition of F. oxysporum, 86.33% growth inhibition of Curvularia sp. and 82.14% growth inhibition of Alternaria sp. Seedlings previously treated with bacteria were found much less infected by F. oxysporum in comparison to non-treated controls. On microscopic observation we found that bacteria appeared to degrade fungal mycelia actively. Metabolite products of strain SY1 in agar were also found to inhibit fungal growth on nutrient media. Pseudomonas sp. (SY1) was found to produce antifungal volatiles. Polymerase chain reaction (PCR) amplification using specific primers for pyrrolnitirin synthesis and HCN (hydrogen cyanide) production suggested presence of

Fungal Disease Prevention in Seedlings of Rice (Oryza sativa) and Other Grasses by Growth-Promoting Seed-Associated Endophytic Bacteria from Invasive Phragmites australis.

PubMed

Verma, Satish K; Kingsley, Kathryn L; Bergen, Marshall S; Kowalski, Kurt P; White, James F

2018-03-08

Non-cultivated plants carry microbial endophytes that may be used to enhance development and disease resistance of crop species where growth-promoting and protective microbes may have been lost. During seedling establishment, seedlings may be infected by several fungal pathogens that are seed or soil borne. Several species of Fusarium , Pythium and other water moulds cause seed rots during germination. Fusarium blights of seedlings are also very common and significantly affect seedling development. In the present study we screened nine endophytic bacteria isolated from the seeds of invasive Phragmites australis by inoculating onto rice, Bermuda grass ( Cynodon dactylon ), or annual bluegrass ( Poa annua ) seeds to evaluate plant growth promotion and protection from disease caused by Fusarium oxysporum . We found that three bacteria belonging to genus Pseudomonas spp. (SLB4- P. fluorescens , SLB6- Pseudomonas sp. and SY1- Pseudomonas sp.) promoted seedling development, including enhancement of root and shoot growth, and stimulation of root hair formation. These bacteria were also found to increase phosphate solubilization in in vitro experiments. Pseudomonas sp. (SY1) significantly protected grass seedlings from Fusarium infection. In co-culture experiments, strain SY1 strongly inhibited fungal pathogens with 85.71% growth inhibition of F. oxysporum , 86.33% growth inhibition of Curvularia sp. and 82.14% growth inhibition of Alternaria sp. Seedlings previously treated with bacteria were found much less infected by F. oxysporum in comparison to non-treated controls. On microscopic observation we found that bacteria appeared to degrade fungal mycelia actively. Metabolite products of strain SY1 in agar were also found to inhibit fungal growth on nutrient media. Pseudomonas sp. (SY1) was found to produce antifungal volatiles. Polymerase chain reaction (PCR) amplification using specific primers for pyrrolnitirin synthesis and HCN (hydrogen cyanide) production suggested

Isolation, Purification, and Characterization of Five Active Diketopiperazine Derivatives from Endophytic Streptomyces SUK 25 with Antimicrobial and Cytotoxic Activities.

PubMed

Alshaibani, Muhanna; Zin, Noraziah; Jalil, Juriyati; Sidik, Nik; Ahmad, Siti Junaidah; Kamal, Nurkhalida; Edrada-Ebel, Ruangelie

2017-07-28

In our search for new sources of bioactive secondary metabolites from Streptomyces sp., the ethyl acetate extracts from endophytic Streptomyces SUK 25 afforded five active diketopiperazine (DKP) compounds. The aim of this study was to characterize the bioactive compounds isolated from endophytic Streptomyces SUK 25 and evaluate their bioactivity against multiple drug resistance (MDR) bacteria such as Enterococcus raffinosus, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacter spp., and their cytotoxic activities against the human hepatoma (HepaRG) cell line. The production of secondary metabolites by this strain was optimized through Thornton's medium. Isolation, purification, and identification of the bioactive compounds were carried out using high-performance liquid chromatography, high-resolution mass liquid chromatography-mass spectrometry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance, and cryopreserved HepaRG cells were selected to test the cytotoxicity. The results showed that endophytic Streptomyces SUK 25 produces four active DKP compounds and an acetamide derivative, which were elucidated as cyclo -( L -Val- L -Pro), cyclo -( L -Leu- L -Pro), cyclo -( L -Phe- L -Pro), cyclo -( L -Val- L -Phe), and N -(7-hydroxy-6-methyl-octyl)-acetamide. These active compounds exhibited activity against methicillin-resistant S. aureus ATCC 43300 and Enterococcus raffinosus , with low toxicity against human hepatoma HepaRG cells. Endophytic Streptomyces SUK 25 has the ability to produce DKP derivatives biologically active against some MDR bacteria with relatively low toxicity against HepaRG cells line.

Endophytic Fungi in Species of Artemisia.

PubMed

Cosoveanu, Andreea; Cabrera, Raimundo

2018-05-01

The genus Artemisia , a collection of ~400 hardy herbaceous plant and shrub species, is an important resource contributing to chemistry, medicine, agriculture, industry, and ecology. Its communities of endophytic fungi have only recently begun to be explored. Summarized from studies conducted on the fungal endophytes in Artemisia species, both fungal phylogenetic diversity and the associated bioactivity was examined. Isolations from 14 species of Artemisia have led to 51 genera of fungal endophytes, 28 families, and 18 orders. Endophytes belonged mainly to Ascomycota , except for two taxa of Cantharellales and Sporidiobolales , one taxon of Mucoromycota , and one species of Oomycota . The mostly common families were Pleosporaceae , Trichocomaceae , Leptosphaeriaceae , and Botryosphaeriaceae (relative abundance = 14.89, 8.51, 7.14 and 6.38, respectively). In the search for bioactive metabolites, 27 novel compounds were characterized and 22 metabolites were isolated between 2006 and 2017. The first study on endophytic fungi isolated from species of Artemisia was published but 18 years ago. This summary of recently acquired data illustrates the considerable diversity of biological purposes addressed by fungal endophytes of Artemisia spp.

Fungal Endophytes: Beyond Herbivore Management

PubMed Central

Bamisile, Bamisope S.; Dash, Chandra K.; Akutse, Komivi S.; Keppanan, Ravindran; Wang, Liande

2018-01-01

The incorporation of entomopathogenic fungi as biocontrol agents into Integrated Pest Management (IPM) programs without doubt, has been highly effective. The ability of these fungal pathogens such as Beauveria bassiana and Metarhizium anisopliae to exist as endophytes in plants and protect their colonized host plants against the primary herbivore pests has widely been reported. Aside this sole role of pest management that has been traditionally ascribed to fungal endophytes, recent findings provided evidence of other possible functions as plant yield promoter, soil nutrient distributor, abiotic stress and drought tolerance enhancer in plants. However, reports on these additional important effects of fungal endophytes on the colonized plants remain scanty. In this review, we discussed the various beneficial effects of endophytic fungi on the host plants and their primary herbivore pests; as well as some negative effects that are relatively unknown. We also highlighted the prospects of our findings in further increasing the acceptance of fungal endophytes as an integral part of pest management programs for optimized crop production. PMID:29628919

Bacterial Sialidase

NASA Technical Reports Server (NTRS)

2004-01-01

Data shows that elevated sialidase in bacterial vaginosis patients correlates to premature births in women. Bacterial sialidase also plays a significant role in the unusual colonization of Pseudomonas aeruginosa in cystic fibrosis patients. Crystals of Salmonella sialidase have been reproduced and are used for studying the inhibitor-enzyme complexes. These inhibitors may also be used to inhibit a trans-sialidase of Trypanosome cruzi, a very similar enzyme to bacterial sialidase, therefore preventing T. cruzi infection, the causitive agent of Chagas' disease. The Center for Macromolecular Crystallography suggests that inhibitors of bacterial sialidases can be used as prophylactic drugs to prevent bacterial infections in these critical cases.

Habitat filters in fungal endophyte community assembly

USDA-ARS?s Scientific Manuscript database

Fungal endophytes can influence host health, and more broadly, can instigate trophic cascades with effects scaling to the ecosystem level. Despite this, biotic mechanisms of endophyte community assembly are largely unknown. We used maize to investigate three potential habitat filters in endophyte co...

Fungal endophytes: diversity and functional roles

USGS Publications Warehouse

Rodriguez, R.J.; White, J.F.; Arnold, A.E.; Redman, R.S.

2009-01-01

All plants in natural ecosystems appear to be symbiotic with fungal endophytes. This highly diverse group of fungi can have profound impacts on plant communities through increasing fitness by conferring abiotic and biotic stress tolerance, increasing biomass and decreasing water consumption, or decreasing fitness by altering resource allocation. Despite more than 100 yr of research resulting in thousands of journal articles, the ecological significance of these fungi remains poorly characterized. Historically, two endophytic groups (clavicipitaceous (C) and nonclavicipitaceous (NC)) have been discriminated based on phylogeny and life history traits. Here, we show that NC-endophytes represent three distinct functional groups based on host colonization and transmission, in planta biodiversity and fitness benefits conferred to hosts. Using this framework, we contrast the life histories, interactions with hosts and potential roles in plant ecophysiology of C- and NC-endophytes, and highlight several key questions for future work in endophyte biology.

Does the essential oil of Lippia sidoides Cham. (pepper-rosmarin) affect its endophytic microbial community?

PubMed

da Silva, Thais Freitas; Vollú, Renata Estebanez; Jurelevicius, Diogo; Alviano, Daniela Sales; Alviano, Celuta Sales; Blank, Arie Fitzgerald; Seldin, Lucy

2013-02-07

Lippia sidoides Cham., also known as pepper-rosmarin, produces an essential oil in its leaves that is currently used by the pharmaceutical, perfumery and cosmetic industries for its antimicrobial and aromatic properties. Because of the antimicrobial compounds (mainly thymol and carvacrol) found in the essential oil, we believe that the endophytic microorganisms found in L. sidoides are selected to live in different parts of the plant. In this study, the endophytic microbial communities from the stems and leaves of four L. sidoides genotypes were determined using cultivation-dependent and cultivation-independent approaches. In total, 145 endophytic bacterial strains were isolated and further grouped using either ERIC-PCR or BOX-PCR, resulting in 76 groups composed of different genera predominantly belonging to the Gammaproteobacteria. The endophytic microbial diversity was also analyzed by PCR-DGGE using 16S rRNA-based universal and group-specific primers for total bacteria, Alphaproteobacteria, Betaproteobacteria and Actinobacteria and 18S rRNA-based primers for fungi. PCR-DGGE profile analysis and principal component analysis showed that the total bacteria, Alphaproteobacteria, Betaproteobacteria and fungi were influenced not only by the location within the plant (leaf vs. stem) but also by the presence of the main components of the L. sidoides essential oil (thymol and/or carvacrol) in the leaves. However, the same could not be observed within the Actinobacteria. The data presented here are the first step to begin shedding light on the impact of the essential oil in the endophytic microorganisms in pepper-rosmarin.

Surfactin, Iturin, and Fengycin Biosynthesis by Endophytic Bacillus sp. from Bacopa monnieri.

PubMed

Jasim, B; Sreelakshmi, K S; Mathew, Jyothis; Radhakrishnan, E K

2016-07-01

Endophytic microorganisms which are ubiquitously present in plants may colonize intracellularly or intercellularly without causing any diseases. By living within the unique chemical environment of a host plant, they produce a vast array of compounds with a wide range of biological activities. Because of this, natural products of endophytic origin have been exploited for antimicrobial, antiviral, anticancer, and antioxidant properties. Also, they can be considered to function as an efficient microbial barrier to protect plants from various pathogens. In the present study, endophytic bacterium BmB 9 with antifungal and antibacterial activity isolated from the stem tissue of Bacopa monnieri was studied for the molecular and chemical basis of its activity. PCR-based genome mining for various biosynthetic gene clusters proved the presence of surfactin, iturin, and type I polyketide synthase (PKS) genes in the isolate. The LC-MS/MS based analysis of the extract further confirmed the production of surfactin derivatives (M + H(+)-1008.6602, 1022.6755), iturin (M + H(+)-1043.5697), and fengycin (M + H(+)-1491.8195, 1477.8055) by the selected bacterial isolate. The 16S rDNA sequence similarity based analysis identified the isolate BmB 9 as Bacillus sp. with 100 % identity to Bacillus sp. LCF1 (KP257289).

The use of high throughput DNA sequence analysis to assess the endophytic microbiome of date palm roots grown under different levels of salt stress.

PubMed

Yaish, Mahmoud W; Al-Harrasi, Ibtisam; Alansari, Aliya S; Al-Yahyai, Rashid; Glick, Bernard R

2016-09-01

Date palms are able to grow under diverse abiotic stress conditions including in saline soils, where microbial communities may be help in the plant's salinity tolerance. These communities able to produce specific growth promoting substances can enhance date palm growth in a saline environment. However, these communities are poorly defined. In the work reported here, the date palm endophytic bacterial and fungal communities were identified using the pyrosequencing method, and the microbial differential abundance in the root upon exposure to salinity stress was estimated. Approximately 150,061 reads were produced from the analysis of six ribosomal DNA libraries, which were prepared from endophytic microorganisms colonizing date palm root tissues. DNA sequence analysis of these libraries predicted the presence of a variety of bacterial and fungal endophytic species, some known and others unknown. The microbial community compositions of 30% and 8% of the bacterial and fungal species, respectively, were significantly (p ≤ 0.05) altered in response to salinity stress. Differential enrichment analysis showed that microbe diversity indicated by the Chao, Shannon and Simpson indices were slightly reduced, however, the overall microbial community structures were not significantly affected as a consequence of salinity. This may reflect a buffering effect by the host plant on the internal environments that these communities are colonizing. Some of the endophytes identified in this study were strains that were previously isolated from saline and marine environments. This suggests possible interactions with the plant that are favorable to salinity tolerance in date palm. [Int Microbiol 19(3):143-155 (2016)]. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

Endophytic Fungi in a Hordeum Germplasm Collection

Treesearch

A. Dan Wilson; S.L. Clement; W.J. Kaiser

1991-01-01

The incidence of clavicipitaceous anamorphic endophytes in a Hordeum spp. germplasm collection is reported. The potential application of endophytes as biocontrol agents against pests of cereal crops is recognized. Suggestions are proposed to modify existing germplasm maintenance procedures to ensure that both seed viability and endophyte viability...

A community of unknown, endophytic fungi in western white pine.

PubMed

Ganley, Rebecca J; Brunsfeld, Steven J; Newcombe, George

2004-07-06

The endophytic fungi of woody plants may be diverse as often claimed, and likewise, they may be functionally novel as demonstrated in a few studies. However, the endophyte taxa that are most frequently reported tend to belong to fungal groups composed of morphologically similar endophytes and parasites. Thus, it is plausible that endophytes are known (i.e., described) parasites in a latent phase within the host. If this null hypothesis were true, endophytes would represent neither additional fungal diversity distinct from parasite diversity nor a symbiont community likely to be novel ecologically. To be synonymous with parasites of the host, endophytes should at least be most closely related to those same parasites. Here we report that seven distinct parasites of Pinus monticola do not occur as endophytes. The majority of endophytes of P. monticola (90% of 2,019 cultures) belonged to one fungal family, the Rhytismataceae. However, not a single rhytismataceous endophyte was found to be most closely related by sequence homology to the three known rhytismataceous parasites of P. monticola. Similarly, neither endophytic Mycosphaerella nor endophytic Rhizosphaera isolates were most closely related to known parasites of P. monticola. Morphologically, the endophytes of P. monticola can be confounded with the parasites of the same host. However, they are actually most closely related to, but distinct from, parasites of other species of Pinus. If endophytes are generally unknown species, then estimates of 1 million endophytes (i.e., approximately 1 in 14 of all species of life) seem reasonable.

Effects of bacterial pollution caused by a strong typhoon event and the restoration of a recreational beach: Transitions of fecal bacterial counts and bacterial flora in beach sand.

PubMed

Suzuki, Yoshihiro; Teranishi, Kotaro; Matsuwaki, Tomonori; Nukazawa, Kei; Ogura, Yoshitoshi

2018-05-28

To determine the effects of bacteria pollution associated with a strong typhoon event and to assess the restoration of the normal bacterial flora, we used conventional filtration methods and nextgeneration sequencing of 16S rRNA genes to analyze the transition of fecal and total bacterial counts in water and core sand samples collected from a recreational beach. Immediately after the typhoon event, Escherichia coli counts increased to 82 CFU/100 g in the surface beach sand. E. coli was detected through the surface to sand 85-cm deep at the land side point (10-m land side from the high-water line). However, E. coli disappeared within a month from the land side point. The composition of the bacterial flora in the beach sand at the land point was directly influenced by the typhoon event. Pseudomonas was the most prevalent genus throughout the sand layers (0-102-cm deep) during the typhoon event. After 3 months, the population of Pseudomonas significantly decreased, and the predominant genus in the surface layer was Kaistobacter, although Pseudomonas was the major genus in the 17- to 85-cm layer. When the beach conditions stabilized, the number of pollutant Pseudomonas among the 10 most abundant genera decreased to lower than the limit of detection. The bacterial population of the sand was subsequently restored to the most populous pre-event orders at the land point. A land-side beach, where users directly contact the sand, was significantly affected by bacterial pollution caused by a strong typhoon event. We show here that the normal bacterial flora of the surface sand was restored within 1 month. Copyright © 2018 Elsevier B.V. All rights reserved.

Seed-borne endophytic Bacillus amyloliquefaciens RWL-1 produces gibberellins and regulates endogenous phytohormones of Oryza sativa.

PubMed

Shahzad, Raheem; Waqas, Muhammad; Khan, Abdul Latif; Asaf, Sajjad; Khan, Muhammad Aaqil; Kang, Sang-Mo; Yun, Byung-Wook; Lee, In-Jung

2016-09-01

Some microorganisms are adapted to an endophytic mode, living symbiotically with plants through vertical transmission in seeds. The role of plant growth-promoting endophytes has been well studied, but those of seed-associated endophytic bacteria are less understood. The current study aimed to isolate and identify bacterial endophytes associated with rice (Oryza sativa L. 'Jin so mi') seeds, their potential to produce gibberellins (GAs), and role in improving host-plant physiology. The isolated bacterial endophyte RWL-1 was identified as Bacillus amyloliquefaciens by using 16S rRNA sequencing and phylogenetic analysis. The pure culture of B. amyloliquefaciens RWL-1, supplied with deuterated internal standards, was subjected to gas chromatography and mass spectrometric selected ion monitoring (GC-MS/SIM) for quantification of GAs. Results showed the presence of GAs in various quantities (ng/mL) viz., GA20 (17.88 ± 4.04), GA36 (5.75 ± 2.36), GA24 (5.64 ± 2.46), GA4 (1.02 ± 0.16), GA53 (0.772 ± 0.20), GA9 (0.12 ± 0.09), GA19 (0.093 ± 0.13), GA5 (0.08 ± 0.04), GA12 (0.014 ± 0.34), and GA8 (0.013 ± 0.01). Since endogenous seed GAs are essential for prolonged seed growth and subsequent plant development, we used exogenous GA3 as a positive control and water as a negative control for comparative analysis of the application of B. amyloliquefaciens RWL-1 to rice plants. The growth parameters of rice plants treated with endophytic bacterial cell application was significantly increased compared to the plants treated with exogenous GA3 and water. This was also revealed by the significant up-regulation of endogenous GA1 (17.54 ± 2.40 ng), GA4 (310 ± 5.41 ng), GA7 (192.60 ± 3.32 ng), and GA9 (19.04 ± 2.49 ng) as compared to results of the positive and negative control treatments. Rice plants inoculated with B. amyloliquefaciens RWL-1 exhibited significantly higher endogenous salicylic acid (1615.06 ± 10.81 μg), whereas

Antibiotic Conditioned Growth Medium of Pseudomonas Aeruginosa

ERIC Educational Resources Information Center

Benathen, Isaiah A.; Cazeau, Barbara; Joseph, Njeri

2004-01-01

A simple method to study the consequences of bacterial antibiosis after interspecific competition between microorganisms is presented. Common microorganisms are used as the test organisms and Pseudomonas aeruginosa are used as the source of the inhibitor agents.

Molecular phylogenetics and anti-Pythium activity of endophytes from rhizomes of wild ginger congener, Zingiber zerumbet Smith.

PubMed

Keerthi, D; Aswati Nair, R; Prasath, D

2016-03-01

Zingiber zerumbet, a perennial rhizomatous herb exhibits remarkable disease resistance as well as a wide range of pharmacological activities. Towards characterizing the endophytic population of Z. zerumbet rhizomes, experiments were carried out during two different growing seasons viz., early-June of 2013 and late-July of 2014. A total of 34 endophytes were isolated and categorized into 11 morphologically distinct groups. Fungi were observed to predominate bacterial species with colonization frequency values ranging from 12.5 to 50%. Among the 11 endophyte groups isolated, molecular analyses based on ITS/16S rRNA gene sequences identified seven isolate groups as Fusarium solani, two as F. oxysporum and one as the bacterium Rhizobium spp. Phylogenetic tree clustered the ITS sequences from Z. zerumbet endophytes into distinct clades consistent with morphological and sequence analysis. Dual culture assays were carried out to determine antagonistic activity of the isolated endophytes against Pythium myriotylum, an economically significant soil-borne phytopathogen of cultivated ginger. Experiments revealed significant P. myriotylum growth inhibition by F. solani and F. oxysporum isolates with percentage of inhibition (PoI) ranging from 45.17 ± 0.29 to 62.2 ± 2.58 with F. oxysporum exhibiting higher PoI values against P. myriotylum. Using ZzEF8 metabolite extract, concentration-dependent P. myriotylum hyphal growth inhibition was observed following radial diffusion assays. These observations were confirmed by scanning electron microscopy analysis wherein exposure to ZzEF8 metabolite extract induced hyphal deformities. Results indicate Z. zerumbet endophytes as promising resources for biologically active compounds and as biocontrol agents for soft rot disease management caused by Pythium spp.

Methylobacterium sp. resides in unculturable state in potato tissues in vitro and becomes culturable after induction by Pseudomonas fluorescens IMGB163.

PubMed

Podolich, O; Laschevskyy, V; Ovcharenko, L; Kozyrovska, N; Pirttilä, A M

2009-03-01

To induce growth of endophytic bacteria residing in an unculturable state in tissues of in vitro-grown potato plantlets. To isolate and identify the induced bacteria and to localize the strains in tissues of in vitro-grown potato plantlets. The inoculation of in vitro-grown potato plants with Pseudomonas fluorescens IMBG163 led to induction of another bacterium, a pink-pigmented facultative methylotroph that was identified as Methylobacterium sp. using phylogenetic 16S rDNA approach. Two molecular methods were used for localizing methylobacteria in potato plantlets: PCR and in situ hybridization (ISH/FISH). A PCR product specific for the Methylobacterium genus was found in DNA isolated from the surface-sterilized plantlet leaves. Presence of Methylobacterium rRNA was detected by ISH/FISH in leaves and stems of inoculated as well as axenic potato plantlets although the bacterium cannot be isolated from the axenic plants. Methylobacterium sp. resides in unculturable state within tissues of in vitro-grown potato plants and becomes culturable after inoculation with P. fluorescens IMBG163. In order to develop endophytic biofertilizers and biocontrol agents, a detailed knowledge of the life-style of endophytes is essential. To our knowledge, this is the first report on increase of the culturability of endophytes in response to inoculation by nonpathogenic bacteria.

The interaction between Pseudomonas aeruginosa cells and cationic PC:Chol:DOTAP liposomal vesicles versus outer-membrane structure and envelope properties of bacterial cell.

PubMed

Drulis-Kawa, Zuzanna; Dorotkiewicz-Jach, Agata; Gubernator, Jerzy; Gula, Grzegorz; Bocer, Tomasz; Doroszkiewicz, Wlodzimierz

2009-02-09

The interactions between cationic liposomal formulations (PC:Chol:DOTAP 3:4:3) and 23 Pseudomonas aeruginosa strains were tested. The study was undertaken because different antimicrobial results had been obtained by the authors for Pseudomonas aeruginosa strains and liposomal antibiotics (Drulis-Kawa, Z., Gubernator, J., Dorotkiewicz-Jach, A., Doroszkiewicz, W., Kozubek, A., 2006. The comparison of in vitro antimicrobial activity of liposomes containing meropenem and gentamicin. Cell. Mol. Biol. Lett., 11, 360-375; Drulis-Kawa, Z., Gubernator, J., Dorotkiewicz-Jach, A., Doroszkiewicz W., Kozubek, A., 2006. In vitro antimicrobial activity of liposomal meropenem against Pseudomonas aeruginosa strains. Int. J. Pharm., 315, 59-66). The experiments evaluate the roles of the bacterial outer-membrane structure, especially outer-membrane proteins and LPS, and envelope properties (hydrophobicity and electrostatic potential) in the interactions/fusion process between cells and lipid vesicles. The interactions were examined by fluorescent microscopy using PE-rhodamine-labelled liposomes. Some of the strains exhibited red-light emission (fusion with vesicles or vesicles surrounding the cell) and some showed negative reaction (no red-light emission). The main aim of the study was to determine what kinds of bacterial structure or envelope properties have a major influence on the fusion process. Negatively charged cells and hydrophobic properties promote interaction with cationic lipid vesicles, but no specific correlation was noted for the tested strains. A similar situation concerned LPS structure, where parent strains and their mutants possessing identical ladder-like band patterns in SDS-PAGE analysis exhibited totally different results with fluorescent microscopy. Outer-membrane protein analysis showed that an 18-kDA protein occurred in the isolates showing fusion with rhodamine-labelled vesicles and, conversely, strains lacking the 18-kDA protein exhibited no positive

Endophytic root bacteria associated with the natural vegetation growing at the hydrocarbon-contaminated Bitumount Provincial Historic site.

PubMed

Blain, Natalie P; Helgason, Bobbi L; Germida, James J

2017-06-01

The Bitumount Provincial Historic site is the location of 2 of the world's first oil-extracting and -refining operations. Despite hydrocarbon levels ranging from 330 to 24 700 mg·(kg soil) -1 , plants have been able to recolonize the site through means of natural revegetation. This study was designed to achieve a better understanding of the plant-root-associated bacterial partnerships occurring within naturally revegetated hydrocarbon-contaminated soils. Root endophytic bacterial communities were characterized from representative plant species throughout the site by both high-throughput sequencing and culturing techniques. Population abundance of rhizosphere and root endosphere bacteria was significantly influenced (p < 0.05) by plant species and sampling location. In general, members of the Actinomycetales, Rhizobiales, Pseudomonadales, Burkholderiales, and Sphingomonadales orders were the most commonly identified orders. Community structure of root-associated bacteria was influenced by both plant species and sampling location. Quantitative real-time polymerase chain reaction was used to determine the potential functional diversity of the root endophytic bacteria. The gene copy numbers of 16S rRNA and 2 hydrocarbon-degrading genes (CYP153 and alkB) were significantly affected (p < 0.05) by the interaction of plant species and sampling location. Our findings suggest that some of the bacterial communities detected are known to exhibit plant growth promotion characteristics.

Phytoremediation: plant-endophyte partnerships take the challenge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weyens, N.; van der Lelie, D.; Taghavi, S.

A promising field to exploit plant-endophyte partnerships is the remediation of contaminated soils and (ground) water. Many plant growth promoting endophytes can assist their host plant to overcome contaminant-induced stress responses, thus providing improved plant growth. During phytoremediation of organic contaminants, plants can further benefit from endophytes possessing appropriate degradation pathways and metabolic capabilities, leading to more efficient contaminant degradation and reduction of both phytotoxicity and evapotranspiration of volatile contaminants. For phytoremediation of toxic metals, endophytes possessing a metal-resistance/sequestration system can lower metal phytotoxicity and affect metal translocation to the above-ground plant parts. Furthermore, endophytes that can degrade organic contaminantsmore » and deal with or, even better, improve extraction of the metals offer promising ways to improve phytoremediation of mixed pollution.« less

Porins of Pseudomonas fluorescens MFO as fibronectin-binding proteins.

PubMed

Rebière-Huët, J; Guérillon, J; Pimenta, A L; Di Martino, P; Orange, N; Hulen, C

2002-09-24

Bacterial adherence is a complex phenomenon involving specific interactions between receptors, including matricial fibronectin, and bacterial ligands. We show here that fibronectin and outer membrane proteins of Pseudomonas fluorescens were able to inhibit adherence of P. fluorescens to fibronectin-coated wells. We identified at least six fibronectin-binding proteins with molecular masses of 70, 55, 44, 37, 32 and 28 kDa. The presence of native (32 kDa) and heat-modified forms (37 kDa) of OprF was revealed by immuno-analysis and the 44-kDa band was composed of three proteins, their N-terminal sequences showing homologies with Pseudomonas aeruginosa porins (OprD, OprE1 and OprE3).

Symptoms of Fern Distortion Syndrome Resulting from Inoculation with Opportunistic Endophytic Fluorescent Pseudomonas spp.

PubMed Central

Kloepper, Joseph W.; McInroy, John A.; Liu, Ke; Hu, Chia-Hui

2013-01-01

Background Fern Distortion Syndrome (FDS) is a serious disease of Leatherleaf fern (Rumohra adiantiformis). The main symptom of FDS is distortion of fronds, making them unmarketable. Additional symptoms include stunting, irregular sporulation, decreased rhizome diameter, and internal discoloration of rhizomes. We previously reported an association of symptoms with increased endophytic rhizome populations of fluorescent pseudomonads (FPs). The aim of the current study was to determine if FPs from ferns in Costa Rica with typical FDS symptoms would recreate symptoms of FDS. Methodology and Findings Greenhouse tests were conducted over a 29-month period. Micro-propagated ferns derived from tissue culture were first grown one year to produce rhizomes. Then, using an 8×9 randomized complete block experimental design, 8 replicate rhizomes were inoculated by dipping into 9 different treatments before planting. Treatments included water without bacteria (control), and four different groups of FPs, each at a two concentrations. The four groups of FPs included one group from healthy ferns without symptoms (another control treatment), two groups isolated from inside rhizomes of symptomatic ferns, and one group isolated from inside roots of symptomatic ferns. Symptoms were assessed 12 and 17 months later, and populations of FPs inside newly formed rhizomes were determined after 17 months. Results showed that inoculation with mixtures of FPs from ferns with FDS symptoms, but not from healthy ferns, recreated the primary symptom of frond deformities and also the secondary symptoms of irregular sporulation, decreased rhizome diameter, and internal discoloration of rhizomes. Conclusions These results suggest a model of causation of FDS in which symptoms result from latent infections by multiple species of opportunistic endophytic bacteria containing virulence genes that are expressed when populations inside the plant reach a minimum level. PMID:23516499

Influence of Culturing Conditions on Bioprospecting and the Antimicrobial Potential of Endophytic Fungi from Schinus terebinthifolius.

PubMed

Tonial, Fabiana; Maia, Beatriz H L N S; Gomes-Figueiredo, Josiane A; Sobottka, Andrea M; Bertol, Charise D; Nepel, Angelita; Savi, Daiani C; Vicente, Vânia A; Gomes, Renata R; Glienke, Chirlei

2016-02-01

In this study, we analyzed the antimicrobial activity of extracts harvested from 17 endophytic fungi isolated from the medicinal plant Schinus terebinthifolius. Morphological and molecular analyses indicated that these fungal species belonged to the genera Alternaria, Bjerkandera, Colletotrichum, Diaporthe, Penicillium, and Xylaria. Of the endophytes analyzed, 64.7 % produced antimicrobial compounds under at least one of the fermentation conditions tested. Nine isolates produced compounds that inhibited growth of Staphylococcus aureus, four produced compounds that inhibited Candida albicans, and two that inhibited Pseudomonas aeruginosa. The fermentation conditions of the following endophytes were optimized: Alternaria sp. Sect. Alternata-LGMF626, Xylaria sp.-LGMF673, and Bjerkandera sp.-LGMF713. Specifically, the carbon and nitrogen sources, initial pH, temperature, and length of incubation were varied. In general, production of antimicrobial compounds was greatest when galactose was used as a carbon source, and acidification of the growth medium enhanced the production of compounds that inhibited C. albicans. Upon large-scale fermentation, Alternaria sp. Sect. Alternata-LGMF626 produced an extract containing two fractions that were active against methicillin-resistant S. aureus. One of the extracts exhibited high activity (minimum inhibitory concentration of 18.52 µg/mL), and the other exhibited moderate activity (minimum inhibitory concentration of 55.55 µg/mL). The compounds E-2-hexyl-cinnamaldehyde and two compounds of the pyrrolopyrazine alkaloids class were identified in the active fractions by gas chromatography-mass spectrometry.

Properties of an R Factor from Pseudomonas aeruginosa

PubMed Central

Datta, Naomi; Hedges, R. W.; Shaw, Elizabeth J.; Sykes, R. B.; Richmond, M. H.

1971-01-01

An R factor from Pseudomonas aeruginosa, which confers resistance to penicillins, kanamycin, and tetracycline, was studied in Escherichia coli K-12. The R factor could coexist with F-like or I-like plasmids and therefore constituted a novel compatibility group. The R factor was transferable from E. coli to bacterial genera outside the Enterobacteriaceae (Pseudomonas and members of the Rhizobiaceae) to which transfer of F-like and I-like plasmids could not be demonstrated. PMID:4945193

Management of Meloidogyne incognita on tomato with endophytic bacteria and fresh residue of Wasabia japonica.

PubMed

Li, G J; Dong, Q E; Ma, L; Huang, Y; Zhu, M L; Ji, Y P; Wang, Q H; Mo, M H; Zhang, K Q

2014-10-01

To characterize the nematicidal endophytic bacteria (NEB) of Wasabia japonica (wasabi) and evaluated the control efficacies of promising NEB as well as fresh wasabi residue (FWR) against Meloidogyne incognita on tomato. By in vitro bioassay, 53 NEB strains showing nematicidal efficacies of >50% against J2 of M. incognita were isolated from wasabi. Basing on 16S rRNA gene sequences, these NEB were identified into 18 species of 11 genera. In greenhouse, incorporation of selected NEB culture or FWR into potted soil significantly reduced infection of M. incognita on tomato. Treating tomatoes with either FWR or NEB of Raoultella terrigena RN16 and Pseudomonas reinekei SN21 in the field yielded excellent control efficacies against M. incognita, especially the combinations of FWR with either R. terrigena RN16 or Ps. reinekei SN21 at doses of 50 g plus 100 ml per plant or more. The results established that R. terrigena RN16 and Ps. reinekei SN21 applied separately or combined with FWR have the potential to provide bioprotection agents against M. incognita. This study provides novel way for disease management using combination of endophyte and host residue. © 2014 The Society for Applied Microbiology.

Characterization of bacterial knot disease caused by Pseudomonas savastanoi pv. savastanoi on pomegranate (Punica granatum L.) trees: a new host of the pathogen.

PubMed

Bozkurt, I A; Soylu, S; Mirik, M; Ulubas Serce, C; Baysal, Ö

2014-11-01

This study aimed to isolate and identify the causal organism causing hyperplastic outgrowths (knots) on stems and branches of pomegranate trees in the Eastern Mediterranean region of Turkey. Bacterial colonies were isolated from young knots on plates containing selective nutrient media. Biochemical tests, fatty acid analysis and PCR were performed to identify possible causal disease agent. Representative isolates were identified as Pseudomonas.pv.savastanoi (Psv) using biochemical tests, fatty acid profiling and PCR. Following inoculation of pomegranate plants (cv. hicaz) with bacterial suspensions, 25 of 54 bacterial isolates caused typical knots at the site of inoculation. PCR analysis, using specific primer for Psv, generated a single amplicon from all isolates. The similarity of the sequence of Turkish pomegranate isolate was 99% similar to the corresponding gene sequences of Psv in the databases. Based on symptoms, biochemical, molecular, pathogenicity tests and sequence analyses, the disease agent of knots observed on the pomegranate trees is Psv. To the best of our knowledge, this research has revealed pomegranate as a natural host of Psv, which extends the list of host plant species affected by the pathogen in the world and Turkey. Pomegranate trees were affected by the disease with outgrowths (galls or knot) disease. Currently, there is no published study on disease agent(s) causing the galls or knots on pomegranate trees in worldwide. Bacterial colonies were isolated from young knots. The causal agent of the knot Pseudomonas savastanoi pv.savastanoi (Psv) was identified based on symptoms, biochemical, molecular methods, pathogenicity tests and sequence analysis. To the best of our knowledge, this is the first report of Psv on pomegranate as a natural host, which extends the growing list of plant species affected by this bacterium in the world and Turkey. © 2014 The Society for Applied Microbiology.

An ability of endophytic bacteria from nutgrass (cyperus rotundus) from lafau beach of north nias in producing indole acetic acid and in solubilizing phosphate

NASA Astrophysics Data System (ADS)

Zega, Atriani; Suryanto, Dwi; Yurnaliza

2018-03-01

Endophytic bacteria have taken much attention for their potency to promote plant growth. This study was aimed to isolate endophytic bacteria from nutgrass (Cyperus rotundus) and to examine their potency in producing indole acetic acid (IAA) and in solubilizing phosphate. Isolation of endophytic bacteria was done by slicing and sterilizing root, stem, and leaf sample surface with alcohol 70% and sodium hypochlorite 2%, followed by incubation of the sliced samples in nutrient agar medium. Morphological characterization and simple biochemical tests were performed on bacterial isolates. All bacterial isolates were examined for their ability to produce indole acetic acid and to solubilize phosphate. Three isolates (AZ5, AZ12 and AZ6) out of fifteen indicated the ability to produce indole acetic acid and to solubilize phosphate. IAA producing test using spectrophotometry method showed that AZ5, AZ12,and AZ6 produce more IAA with concentration of 49,91, 48,18, and 44,45 ppm, respectively. Phosphate solubilizing test using Pikovskaya agar medium showed that the three isolates were able to solubilize phosphate with index of 6.27, 3,31, and 3.41 respectively.

Mechanisms Involved in Nematode Control by Endophytic Fungi.

PubMed

Schouten, Alexander

2016-08-04

Colonization of plants by particular endophytic fungi can provide plants with improved defenses toward nematodes. Evidently, such endophytes can be important in developing more sustainable agricultural practices. The mechanisms playing a role in this quantitative antagonism are poorly understood but most likely multifactorial. This knowledge gap obstructs the progress regarding the development of endophytes or endophyte-derived constituents into biocontrol agents. In part, this may be caused by the fact that endophytic fungi form a rather heterogeneous group. By combining the knowledge of the currently characterized antagonistic endophytic fungi and their effects on nematode behavior and biology with the knowledge of microbial competition and induced plant defenses, the various mechanisms by which this nematode antagonism operates or may operate are discussed. Now that new technologies are becoming available and more accessible, the currently unresolved mechanisms can be studied in greater detail than ever before.

Disease protection and allelopathic interactions of seed-transmitted endophytic pseudomonads of invasive reed grass (Phragmites australis)

USGS Publications Warehouse

White, James F.; Kingsley, Katheryn I; Kowalski, Kurt P.; Irizarry, Ivelisse; Micci, April; Soares, Marcos Antonio; Bergen, Marshall S.

2018-01-01

Background and aimsNon-native Phragmites australis (haplotype M) is an invasive grass that decreases biodiversity and produces dense stands. We hypothesized that seeds of Phragmites carry microbes that improve seedling growth, defend against pathogens and maximize capacity of seedlings to compete with other plants.MethodsWe isolated bacteria from seeds of Phragmites, then evaluated representatives for their capacities to become intracellular in root cells, and their effects on: 1.) germination rates and seedling growth, 2.) susceptibility to damping-off disease, and 3.) mortality and growth of competitor plant seedlings (dandelion (Taraxacum officionale F. H. Wigg) and curly dock (Rumex crispus L.)).ResultsTen strains (of 23 total) were identified and characterized; seven were identified as Pseudomonas spp. Strains Sandy LB4 (Pseudomonas fluorescens) and West 9 (Pseudomonas sp.) entered root meristems and became intracellular. These bacteria improved seed germination in Phragmites and increased seedling root branching in Poa annua. They increased plant growth and protected plants from damping off disease. Sandy LB4 increased mortality and reduced growth rates in seedlings of dandelion and curly dock.ConclusionsPhragmites plants associate with endophytes to increase growth and disease resistance, and release bacteria into the soil to create an environment that is favorable to their seedlings and less favorable to competitor plants.

Antibacterial Activity of Cinnamaldehyde and Estragole Extracted from Plant Essential Oils against Pseudomonas syringae pv. actinidiae Causing Bacterial Canker Disease in Kiwifruit

PubMed Central

Song, Yu-Rim; Choi, Min-Seon; Choi, Geun-Won; Park, Il-Kwon; Oh, Chang-Sik

2016-01-01

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker disease in kiwifruit. Antibacterial activity of plant essential oils (PEOs) originating from 49 plant species were tested against Psa by a vapor diffusion and a liquid culture assays. The five PEOs from Pimenta racemosa, P. dioica, Melaleuca linariifolia, M. cajuputii, and Cinnamomum cassia efficiently inhibited Psa growth by either assays. Among their major components, estragole, eugenol, and methyl eugenol showed significant antibacterial activity by only the liquid culture assay, while cinnamaldehyde exhibited antibacterial activity by both assays. The minimum inhibitory concentrations (MICs) of estragole and cinnamaldehyde by the liquid culture assay were 1,250 and 2,500 ppm, respectively. The MIC of cinnamaldehyde by the vapor diffusion assay was 5,000 ppm. Based on the formation of clear zones or the decrease of optical density caused by these compounds, they might kill the bacterial cells and this feature might be useful for managing the bacterial canker disease in kiwifruit. PMID:27493612

Transcriptional Responses to Sucrose Mimic the Plant-Associated Life Style of the Plant Growth Promoting Endophyte Enterobacter sp. 638

DOE PAGES

Taghavi, Safiyh; Wu, Xiao; Ouyang, Liming; ...

2015-01-21

Growth in sucrose medium was previously found to trigger the expression of functions involved in the plant associated life style of the endophytic bacterium Enterobacter sp. 638. Therefore, comparative transcriptome analysis between cultures grown in sucrose or lactate medium was used to gain insights in the expression levels of bacterial functions involved in the endophytic life style of strain 638. Growth on sucrose as a carbon source resulted in major changes in cell physiology, including a shift from a planktonic life style to the formation of bacterial aggregates. This shift was accompanied by a decrease in transcription of genes involvedmore » in motility (e.g. flagella biosynthesis) and an increase in the transcription of genes involved in colonization, adhesion and biofilm formation. The transcription levels of functions previously suggested as being involved in endophytic behavior and functions responsible for plant growth promoting properties, including the synthesis of indole-acetic acid, acetoin and 2,3-butanediol, also increased significantly for cultures grown in sucrose medium. Interestingly, despite an abundance of essential nutrients transcription levels of functions related to uptake and processing of nitrogen and iron became increased for cultures grown on sucrose as sole carbon source. Transcriptome data were also used to analyze putative regulatory relationships. In addition to the small RNA csrABCD regulon, which seems to play a role in the physiological adaptation and possibly the shift between free-living and plant-associated endophytic life style of Enterobacter sp. 638, our results also pointed to the involvement of rcsAB in controlling responses by Enterobacter sp. 638 to a plant-associated life style. Lastly, targeted mutagenesis was used to confirm this role and showed that compared to wild-type Enterobacter sp. 638 a ΔrcsB mutant was affected in its plant growth promoting ability.« less

Transcriptional Responses to Sucrose Mimic the Plant-Associated Life Style of the Plant Growth Promoting Endophyte Enterobacter sp. 638

PubMed Central

Taghavi, Safiyh; Wu, Xiao; Ouyang, Liming; Stadler, Andrea; McCorkle, Sean; Zhu, Wei; Maslov, Sergei; van der Lelie, Daniel

2015-01-01

Growth in sucrose medium was previously found to trigger the expression of functions involved in the plant associated life style of the endophytic bacterium Enterobacter sp. 638. Therefore, comparative transcriptome analysis between cultures grown in sucrose or lactate medium was used to gain insights in the expression levels of bacterial functions involved in the endophytic life style of strain 638. Growth on sucrose as a carbon source resulted in major changes in cell physiology, including a shift from a planktonic life style to the formation of bacterial aggregates. This shift was accompanied by a decrease in transcription of genes involved in motility (e.g. flagella biosynthesis) and an increase in the transcription of genes involved in colonization, adhesion and biofilm formation. The transcription levels of functions previously suggested as being involved in endophytic behavior and functions responsible for plant growth promoting properties, including the synthesis of indole-acetic acid, acetoin and 2,3-butanediol, also increased significantly for cultures grown in sucrose medium. Interestingly, despite an abundance of essential nutrients transcription levels of functions related to uptake and processing of nitrogen and iron became increased for cultures grown on sucrose as sole carbon source. Transcriptome data were also used to analyze putative regulatory relationships. In addition to the small RNA csrABCD regulon, which seems to play a role in the physiological adaptation and possibly the shift between free-living and plant-associated endophytic life style of Enterobacter sp. 638, our results also pointed to the involvement of rcsAB in controlling responses by Enterobacter sp. 638 to a plant-associated life style. Targeted mutagenesis was used to confirm this role and showed that compared to wild-type Enterobacter sp. 638 a ΔrcsB mutant was affected in its plant growth promoting ability. PMID:25607953

Transcriptional responses to sucrose mimic the plant-associated life style of the plant growth promoting endophyte Enterobacter sp. 638.

PubMed

Taghavi, Safiyh; Wu, Xiao; Ouyang, Liming; Zhang, Yian Biao; Stadler, Andrea; McCorkle, Sean; Zhu, Wei; Maslov, Sergei; van der Lelie, Daniel

2015-01-01

Growth in sucrose medium was previously found to trigger the expression of functions involved in the plant associated life style of the endophytic bacterium Enterobacter sp. 638. Therefore, comparative transcriptome analysis between cultures grown in sucrose or lactate medium was used to gain insights in the expression levels of bacterial functions involved in the endophytic life style of strain 638. Growth on sucrose as a carbon source resulted in major changes in cell physiology, including a shift from a planktonic life style to the formation of bacterial aggregates. This shift was accompanied by a decrease in transcription of genes involved in motility (e.g., flagella biosynthesis) and an increase in the transcription of genes involved in colonization, adhesion and biofilm formation. The transcription levels of functions previously suggested as being involved in endophytic behavior and functions responsible for plant growth promoting properties, including the synthesis of indole-acetic acid, acetoin and 2,3-butanediol, also increased significantly for cultures grown in sucrose medium. Interestingly, despite an abundance of essential nutrients transcription levels of functions related to uptake and processing of nitrogen and iron became increased for cultures grown on sucrose as sole carbon source. Transcriptome data were also used to analyze putative regulatory relationships. In addition to the small RNA csrABCD regulon, which seems to play a role in the physiological adaptation and possibly the shift between free-living and plant-associated endophytic life style of Enterobacter sp. 638, our results also pointed to the involvement of rcsAB in controlling responses by Enterobacter sp. 638 to a plant-associated life style. Targeted mutagenesis was used to confirm this role and showed that compared to wild-type Enterobacter sp. 638 a ΔrcsB mutant was affected in its plant growth promoting ability.

Transcriptional Responses to Sucrose Mimic the Plant-Associated Life Style of the Plant Growth Promoting Endophyte Enterobacter sp. 638

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taghavi, Safiyh; Wu, Xiao; Ouyang, Liming

Growth in sucrose medium was previously found to trigger the expression of functions involved in the plant associated life style of the endophytic bacterium Enterobacter sp. 638. Therefore, comparative transcriptome analysis between cultures grown in sucrose or lactate medium was used to gain insights in the expression levels of bacterial functions involved in the endophytic life style of strain 638. Growth on sucrose as a carbon source resulted in major changes in cell physiology, including a shift from a planktonic life style to the formation of bacterial aggregates. This shift was accompanied by a decrease in transcription of genes involvedmore » in motility (e.g. flagella biosynthesis) and an increase in the transcription of genes involved in colonization, adhesion and biofilm formation. The transcription levels of functions previously suggested as being involved in endophytic behavior and functions responsible for plant growth promoting properties, including the synthesis of indole-acetic acid, acetoin and 2,3-butanediol, also increased significantly for cultures grown in sucrose medium. Interestingly, despite an abundance of essential nutrients transcription levels of functions related to uptake and processing of nitrogen and iron became increased for cultures grown on sucrose as sole carbon source. Transcriptome data were also used to analyze putative regulatory relationships. In addition to the small RNA csrABCD regulon, which seems to play a role in the physiological adaptation and possibly the shift between free-living and plant-associated endophytic life style of Enterobacter sp. 638, our results also pointed to the involvement of rcsAB in controlling responses by Enterobacter sp. 638 to a plant-associated life style. Lastly, targeted mutagenesis was used to confirm this role and showed that compared to wild-type Enterobacter sp. 638 a ΔrcsB mutant was affected in its plant growth promoting ability.« less

Characterization of Pseudomonas pathovars isolated from rosaceous fruit trees in East Algeria.

PubMed

Harzallah, D; Sadallah, S; Larous, L

2004-01-01

A survey of bacterial diseases due to Pseudomonas on rosaceous fruit trees was conducted. In forty two orchards located in the Constantine region ( East Algeria). Pseudomonas isolates were identified on the bases of their cultural and biochemical characteristics . A total of fifty nine phytopathogenic bacteria were isolated from diseased pome and stone fruit trees. Thirty one strains comparable to Pseudomonas syringae pv. syringae were isolated from cherry (Prunus avium L.), plum (P. domestica L.), apricot (P. armeniaca L.), almond (P. dulcis L.) and pear trees (Pirus communis L.); sixteen strains comparable to Pseudomonas syringae pv. morsprunorum were obtained from samples of cherry and plum. Twelve strains of Pseudomonas viridiflava were isolated from cherry, apricot and peach (Prunus persica L.).

Arbuscular mycorrhizal fungus inoculation reduces the drought-resistance advantage of endophyte-infected versus endophyte-free Leymus chinensis.

PubMed

Liu, Hui; Chen, Wei; Wu, Man; Wu, Rihan; Zhou, Yong; Gao, Yubao; Ren, Anzhi

2017-11-01

Grasses can be infected simultaneously by endophytic fungi and arbuscular mycorrhizal (AM) fungi. In this study, we tested the hypothesis that endophyte-associated drought resistance of a native grass was affected by an AM fungus. In a greenhouse experiment, we compared the performance of endophyte-infected (EI) and endophyte-free (EF) Leymus chinensis, a dominant species native to the Inner Mongolia steppe, under altered water and AM fungus availability. The results showed that endophyte infection significantly increased drought resistance of the host grass, but the beneficial effects were reduced by AM fungus inoculation. In the mycorrhizal-non-inoculated (MF) treatment, EI plants accumulated significantly more biomass, had greater proline and total phenolic concentration, and lower malondialdehyde concentration than EF plants. In the mycorrhizal-inoculation (MI) treatment, however, no significant difference occurred in either growth or physiological characters measured between EI and EF plants. AM fungus inoculation enhanced drought resistance of EF plants but had no significant effect on drought resistance of EI plants, thus AM fungus inoculation reduced the difference between EI and EF plants. Our findings highlight the importance of interactions among multiple microorganisms for plant performance under drought stress.

N2 Gas Flushing Alleviates the Loss of Bacterial Diversity and Inhibits Psychrotrophic Pseudomonas during the Cold Storage of Bovine Raw Milk.

PubMed

Gschwendtner, Silvia; Alatossava, Tapani; Kublik, Susanne; Fuka, Mirna Mrkonjić; Schloter, Michael; Munsch-Alatossava, Patricia

2016-01-01

The quality and safety of raw milk still remains a worldwide challenge. Culture-dependent methods indicated that the continuous N2 gas-flushing of raw milk reduced the bacterial growth during cold storage by up to four orders of magnitude, compared to cold storage alone. This study investigated the influence of N2 gas-flushing on bacterial diversity in bovine raw-milk samples, that were either cold stored at 6°C or additionally flushed with pure N2 for up to one week. Next-generation sequencing (NGS) of the V1-V2 hypervariable regions of 16S rRNA genes, derived from amplified cDNA, which was obtained from RNA directly isolated from raw-milk samples, was performed. The reads, which were clustered into 2448 operational taxonomic units (OTUs), were phylogenetically classified. Our data revealed a drastic reduction in the diversity of OTUs in raw milk during cold storage at 6°C at 97% similarity level; but, the N2-flushing treatment alleviated this reduction and substantially limited the loss of bacterial diversity during the same cold-storage period. Compared to cold-stored milk, the initial raw-milk samples contained less Proteobacteria (mainly Pseudomonadaceae, Moraxellaceae and Enterobacteriaceae) but more Firmicutes (mainly Ruminococcaceaea, Lachnospiraceae and Oscillospiraceaea) and Bacteroidetes (mainly Bacteroidales). Significant differences between cold-stored and additionally N2-flushed milk were mainly related to higher levels of Pseudomononadaceae (including the genera Pseudomonas and Acinetobacter) in cold-stored milk samples; furthermore, rare taxa were better preserved by the N2 gas flushing compared to the cold storage alone. No major changes in bacterial composition with time were found regarding the distribution of the major 9 OTUs, that dominated the Pseudomonas genus in N2-flushed or non-flushed milk samples, other than an intriguing predominance of bacteria related to P. veronii. Overall, this study established that neither bacteria causing milk

N2 Gas Flushing Alleviates the Loss of Bacterial Diversity and Inhibits Psychrotrophic Pseudomonas during the Cold Storage of Bovine Raw Milk

PubMed Central

Kublik, Susanne; Fuka, Mirna Mrkonjić; Schloter, Michael; Munsch-Alatossava, Patricia

2016-01-01

The quality and safety of raw milk still remains a worldwide challenge. Culture-dependent methods indicated that the continuous N2 gas-flushing of raw milk reduced the bacterial growth during cold storage by up to four orders of magnitude, compared to cold storage alone. This study investigated the influence of N2 gas-flushing on bacterial diversity in bovine raw-milk samples, that were either cold stored at 6°C or additionally flushed with pure N2 for up to one week. Next-generation sequencing (NGS) of the V1-V2 hypervariable regions of 16S rRNA genes, derived from amplified cDNA, which was obtained from RNA directly isolated from raw-milk samples, was performed. The reads, which were clustered into 2448 operational taxonomic units (OTUs), were phylogenetically classified. Our data revealed a drastic reduction in the diversity of OTUs in raw milk during cold storage at 6°C at 97% similarity level; but, the N2-flushing treatment alleviated this reduction and substantially limited the loss of bacterial diversity during the same cold-storage period. Compared to cold-stored milk, the initial raw-milk samples contained less Proteobacteria (mainly Pseudomonadaceae, Moraxellaceae and Enterobacteriaceae) but more Firmicutes (mainly Ruminococcaceaea, Lachnospiraceae and Oscillospiraceaea) and Bacteroidetes (mainly Bacteroidales). Significant differences between cold-stored and additionally N2-flushed milk were mainly related to higher levels of Pseudomononadaceae (including the genera Pseudomonas and Acinetobacter) in cold-stored milk samples; furthermore, rare taxa were better preserved by the N2 gas flushing compared to the cold storage alone. No major changes in bacterial composition with time were found regarding the distribution of the major 9 OTUs, that dominated the Pseudomonas genus in N2-flushed or non-flushed milk samples, other than an intriguing predominance of bacteria related to P. veronii. Overall, this study established that neither bacteria causing milk

Bioactive endophytes warrant intensified exploration and conservation.

PubMed

Smith, Stephen A; Tank, David C; Boulanger, Lori-Ann; Bascom-Slack, Carol A; Eisenman, Kaury; Kingery, David; Babbs, Beatrice; Fenn, Kathleen; Greene, Joshua S; Hann, Bradley D; Keehner, Jocelyn; Kelley-Swift, Elizabeth G; Kembaiyan, Vivek; Lee, Sun Jin; Li, Puyao; Light, David Y; Lin, Emily H; Ma, Cong; Moore, Emily; Schorn, Michelle A; Vekhter, Daniel; Nunez, Percy V; Strobel, Gary A; Donoghue, Michael J; Strobel, Scott A

2008-08-25

A key argument in favor of conserving biodiversity is that as yet undiscovered biodiversity will yield products of great use to humans. However, the link between undiscovered biodiversity and useful products is largely conjectural. Here we provide direct evidence from bioassays of endophytes isolated from tropical plants and bioinformatic analyses that novel biology will indeed yield novel chemistry of potential value. We isolated and cultured 135 endophytic fungi and bacteria from plants collected in Peru. nrDNAs were compared to samples deposited in GenBank to ascertain the genetic novelty of cultured specimens. Ten endophytes were found to be as much as 15-30% different than any sequence in GenBank. Phylogenetic trees, using the most similar sequences in GenBank, were constructed for each endophyte to measure phylogenetic distance. Assays were also conducted on each cultured endophyte to record bioactivity, of which 65 were found to be bioactive. The novelty of our contribution is that we have combined bioinformatic analyses that document the diversity found in environmental samples with culturing and bioassays. These results highlight the hidden hyperdiversity of endophytic fungi and the urgent need to explore and conserve hidden microbial diversity. This study also showcases how undergraduate students can obtain data of great scientific significance.

Endophytic actinobacteria of medicinal plants: diversity and bioactivity.

PubMed

Golinska, Patrycja; Wypij, Magdalena; Agarkar, Gauravi; Rathod, Dnyaneshwar; Dahm, Hanna; Rai, Mahendra

2015-08-01

Endophytes are the microorganisms that exist inside the plant tissues without having any negative impact on the host plant. Medicinal plants constitute the huge diversity of endophytic actinobacteria of economical importance. These microbes have huge potential to synthesis of numerous novel compounds that can be exploited in pharmaceutical, agricultural and other industries. It is of prime importance to focus the present research on practical utilization of this microbial group in order to find out the solutions to the problems related to health, environment and agriculture. An extensive characterization of diverse population of endophytic actinobacteria associated with medicinal plants can provide a greater insight into the plant-endophyte interactions and evolution of mutualism. In the present review, we have discussed the diversity of endophytic actinobacteria of from medicinal plants their multiple bioactivities.

Identification and structural characterization of serobactins, a suite of lipopeptide siderophores produced by the grass endophyte Herbaspirillum seropedicae.

PubMed

Rosconi, Federico; Davyt, Danilo; Martínez, Verónica; Martínez, Marcela; Abin-Carriquiry, Juan Andrés; Zane, Hannah; Butler, Alison; de Souza, Emanuel M; Fabiano, Elena

2013-03-01

Herbaspirillum seropedicae Z67 is a diazotrophic endophyte able to colonize the interior of many economically relevant crops such as rice, wheat, corn and sorghum. Structures of siderophores produced by bacterial endophytes have not yet been elucidated. The aim of this work was to identify and characterize the siderophores produced by this bacterium. In a screening for mutants unable to produce siderophores we found a mutant that had a transposon insertion in a non-ribosomal peptide synthase (NRPS) gene coding for a putative siderophore biosynthetic enzyme. The chemical structure of the siderophore was predicted using computational genomic tools. The predicted structure was confirmed by chemical analysis. We found that siderophores produced by H. seropedicae Z67 are a suite of amphiphilic lipopeptides, named serobactin A, B and C, which vary by the length of the fatty acid chain. We also demonstrated the biological activity of serobactins as nutritional iron sources for H. seropedicae. These are the first structurally described siderophores produced by endophytic bacteria. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Metabolic pathways of Pseudomonas aeruginosa involved in competition with respiratory bacterial pathogens

PubMed Central

Beaume, Marie; Köhler, Thilo; Fontana, Thierry; Tognon, Mikael; Renzoni, Adriana; van Delden, Christian

2015-01-01

Background: Chronic airway infection by Pseudomonas aeruginosa considerably contributes to lung tissue destruction and impairment of pulmonary function in cystic-fibrosis (CF) patients. Complex interplays between P. aeruginosa and other co-colonizing pathogens including Staphylococcus aureus, Burkholderia sp., and Klebsiella pneumoniae may be crucial for pathogenesis and disease progression. Methods: We generated a library of PA14 transposon insertion mutants to identify P. aeruginosa genes required for exploitative and direct competitions with S. aureus, Burkholderia cenocepacia, and K. pneumoniae. Results: Whereas wild-type PA14 inhibited S. aureus growth, two transposon insertions located in pqsC and carB, resulted in reduced growth inhibition. PqsC is involved in the synthesis of 4-hydroxy-2-alkylquinolines (HAQs), a family of molecules having antibacterial properties, while carB is a key gene in pyrimidine biosynthesis. The carB mutant was also unable to grow in the presence of B. cepacia and K. pneumoniae but not Escherichia coli and S. epidermidis. We further identified a transposon insertion in purF, encoding a key enzyme of purine metabolism. This mutant displayed a severe growth deficiency in the presence of Gram-negative but not of Gram-positive bacteria. We identified a beneficial interaction in a bioA transposon mutant, unable to grow on rich medium. This growth defect could be restored either by addition of biotin or by co-culturing the mutant in the presence of K. pneumoniae or E. coli. Conclusion: Complex interactions take place between the various bacterial species colonizing CF-lungs. This work identified both detrimental and beneficial interactions occurring between P. aeruginosa and three other respiratory pathogens involving several major metabolic pathways. Manipulating these pathways could be used to interfere with bacterial interactions and influence the colonization by respiratory pathogens. PMID:25954256

Fungal Endophyte Diversity in Sarracenia

PubMed Central

Glenn, Anthony; Bodri, Michael S.

2012-01-01

Fungal endophytes were isolated from 4 species of the carnivorous pitcher plant genus Sarracenia: S. minor, S. oreophila, S. purpurea, and S. psittacina. Twelve taxa of fungi, 8 within the Ascomycota and 4 within the Basidiomycota, were identified based on PCR amplification and sequencing of the internal transcribed spacer sequences of nuclear ribosomal DNA (ITS rDNA) with taxonomic identity assigned using the NCBI nucleotide megablast search tool. Endophytes are known to produce a large number of metabolites, some of which may contribute to the protection and survival of the host. We speculate that endophyte-infected Sarracenia may benefit from their fungal associates by their influence on nutrient availability from within pitchers and, possibly, by directly influencing the biota within pitchers. PMID:22427921

Fungal endophyte diversity in Sarracenia.

PubMed

Glenn, Anthony; Bodri, Michael S

2012-01-01

Fungal endophytes were isolated from 4 species of the carnivorous pitcher plant genus Sarracenia: S. minor, S. oreophila, S. purpurea, and S. psittacina. Twelve taxa of fungi, 8 within the Ascomycota and 4 within the Basidiomycota, were identified based on PCR amplification and sequencing of the internal transcribed spacer sequences of nuclear ribosomal DNA (ITS rDNA) with taxonomic identity assigned using the NCBI nucleotide megablast search tool. Endophytes are known to produce a large number of metabolites, some of which may contribute to the protection and survival of the host. We speculate that endophyte-infected Sarracenia may benefit from their fungal associates by their influence on nutrient availability from within pitchers and, possibly, by directly influencing the biota within pitchers.

Enhanced resistance to Spodoptera litura in endophyte infected cauliflower plants.

PubMed

Thakur, Abhinay; Kaur, Sanehdeep; Kaur, Amarjeet; Singh, Varinder

2013-04-01

Endophytic fungi, which live within host plant tissues without causing any visible symptom of disease, are important mediators of plant-herbivore interactions. These endophytes enhance resistance of host plant against insect herbivores mainly by productions of various alkaloid based defensive compounds in the plant tissue or through alterations of plant nutritional quality. Two endophytic fungi, i.e., Nigrospora sp. and Cladosporium sp., were isolated from Tinospora cordifolia (Thunb.) Miers, a traditional indian medicinal plant. Cauliflower (Brassica oleracea L.) plants were inoculated with these two endophytic fungi. The effect of endophyte infected and uninfected cauliflower plants were measured on the survival and development of Spodoptera litura (Fab.), a polyphagous pest. Endophyte infected cauliflower plants showed resistance to S. litura in the form of significant increase in larval and pupal mortality in both the fungi. Inhibitory effects of endophytic fungi also were observed on adult emergence, longevity, reproductive potential, as well as hatchability of eggs. Thus, it is concluded that antibiosis to S. litura could be imparted by artificial inoculation of endophytes and this could be used to develop alternative ecologically safe control strategies.

Influence of simulated acidic rain on bacterial speck of tomato. [Lycopersicon esculentum Mill var. 'Chico III', Pseudomonas tomato

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bisessar, S.; Palmer, K.T.; Kuja, A.L.

Ambient rain in southern Ontario has a volume-weighted average pH of approximately 4.2. Tomato (Lycopersicon esculentum Mill var. 'Chico III') seedlings were exposed to simulated acidic rain in specially designed chambers. The inoculum of Pseudomonas tomato (Okabe) Alstatt, causal agent of bacterial speck, was sprayed on plants before or after exposure to acidic rain of pH 2.5, 3.5, and 4.5, as well as on plants not exposed to the simulated acidic rain. Speck symptoms (small, dark, brown spots with yellow halos) were found on all inoculated plants. Exposure of plants to simulted acidic rain inhibited speck development, but the inhibitionmore » was greater on plants exposed to acidic rain after inoculation. Spot necrosis, a typical response to acid rain, occurred on up to 15 to 20% of the leaf area on all tomato plants treated with acidic rain at pH 2.5. Plants alos showed a decrease in growth (height and fresh and dry weights) with an increase in rain acidity. Leaves injured by simulated acidic rain and examined histopathologically displayed cellular malformations including hyperplasia and hypertrophy. Pseudomonas tomato failed to grow on acidified King B medium or Difco nutrient broth adjusted to pH 3.5 or lower.« less

Endophytic fungi reduce leaf-cutting ant damage to seedlings

PubMed Central

Bittleston, L. S.; Brockmann, F.; Wcislo, W.; Van Bael, S. A.

2011-01-01

Our study examines how the mutualism between Atta colombica leaf-cutting ants and their cultivated fungus is influenced by the presence of diverse foliar endophytic fungi (endophytes) at high densities in tropical leaf tissues. We conducted laboratory choice trials in which ant colonies chose between Cordia alliodora seedlings with high (Ehigh) or low (Elow) densities of endophytes. The Ehigh seedlings contained 5.5 times higher endophyte content and a greater diversity of fungal morphospecies than the Elow treatment, and endophyte content was not correlated with leaf toughness or thickness. Leaf-cutting ants cut over 2.5 times the leaf area from Elow relative to Ehigh seedlings and had a tendency to recruit more ants to Elow plants. Our findings suggest that leaf-cutting ants may incur costs from cutting and processing leaves with high endophyte loads, which could impact Neotropical forests by causing variable damage rates within plant communities. PMID:20610420

Pseudomonas spp. diversity is negatively associated with suppression of the wheat take-all pathogen

PubMed Central

Mehrabi, Zia; McMillan, Vanessa E.; Clark, Ian M.; Canning, Gail; Hammond-Kosack, Kim E.; Preston, Gail; Hirsch, Penny R.; Mauchline, Tim H.

2016-01-01

Biodiversity and ecosystem functioning research typically shows positive diversity- productivity relationships. However, local increases in species richness can increase competition within trophic levels, reducing the efficacy of intertrophic level population control. Pseudomonas spp. are a dominant group of soil bacteria that play key roles in plant growth promotion and control of crop fungal pathogens. Here we show that Pseudomonas spp. richness is positively correlated with take-all disease in wheat and with yield losses of ~3 t/ha in the field. We modeled the interactions between Pseudomonas and the take-all pathogen in abstract experimental microcosms, and show that increased bacterial genotypic richness escalates bacterial antagonism and decreases the ability of the bacterial community to inhibit growth of the take-all pathogen. Future work is required to determine the generality of these negative biodiversity effects on different media and directly at infection zones on root surfaces. However, the increase in competition between bacteria at high genotypic richness and the potential loss of fungal biocontrol activity highlights an important mechanism to explain the negative Pseudomonas diversity-wheat yield relationship we observed in the field. Together our results suggest that the effect of biodiversity on ecosystem functioning can depend on both the function and trophic level of interest. PMID:27549739

Symbiotic lifestyle expression by fungal endophytes and the adaptation of plants to stress: unraveling the complexities of intimacy

USGS Publications Warehouse

Redman, Regina S.; Henson, Joan M.; Rodriguez, Russell J.

2005-01-01

The fossil record indicates that fungal symbionts have been associated with plants since the Ordovician period (approximately 400 million years ago), when plants first became established on land (Pirozynski and Malloch, 1975; Redecker et al., 2000; Remy et al., 1994; Simon et al., 1993). Transitioning from aquatic to terrestrial habitats likely presented plants with new stresses, including periods of desiccation. Since symbiotic fungi are known to confer drought tolerance to plants (Bacon, 1993; Read and Camp, 1986), it has been suggested that fungal symbiosis was involved with or responsible for the establishment of land plants (Pirozynski and Malloch, 1975). Symbiosis was first defined by De Bary in 1879, and since that time, all plants in natural ecosystems have been found to be colonized with fungal and bacterial symbionts. It is clear that individual plants represent symbiotic communities with microorganisms associated in or on tissues below- and aboveground.There are two major classes of fungal symbionts associated with internal plant tissues: fungal endophytes that reside entirely within plants and may be associated with roots, stems leaves, or flowers; and mycorrhizal fungi that reside only in roots but extend out into the rhizosphere. In addition, fungal endophytes may be divided into two classes: (1) a relatively small number of fastidious species that are limited to a few monocot hosts (Clay and Schardl, 2002), and (2) a large number of tractable species with broad host ranges, including both monocots and eudicots (Stone et al., 2000). While significant resources and research have been invested in mycorrhizae and class 1 endophytes, comparatively little is known about class 2 endophytes, which may represent the largest group of fungal symbionts. This is partially because the symbiotic functionalities of class 2 endophytes have only recently been elucidated and shown to be responsible for the adaptation of some plants to high-stress environments (Redman

Isolation and Characterization of an Endophytic Fungal Strain with Potent Antimicrobial and Termiticidal Activities From Port-Orford-Cedar.

PubMed

Sun, Liqing; Hse, Chung-Yun; Shupe, Todd; Sun, Mingjing; Wang, Xiaohua; Zhao, Kai

2015-06-01

Termites are responsible for an estimated US$1 billion annually in property damage, repairs, pest control, and prevention. There is an urgent need of finding a better alternative way to control and prevent termites. Port-Orford-Cedar (POC) has been known to have significant levels of natural durability and termiticidal activities due to its extractive contents. In this study, 25 endophytes including 22 fungal and 3 bacterial strains were isolated from the POC. Four strains, namely, HDZK-BYF21, HDZK-BYF1, HDZK-BYF2, and HDZK-BYB11, were chosen to test their termiticidal activities. The fermentation broth of strain HDZK-BYF21 displayed the potent antimicrobial and termiticidal activities. Morphological examination and 18 S rDNA sequence analysis demonstrated that strain HDZK-BYF21 belonged to the genus Aspergillus. This finding indicates the existence of an interesting chemical symbiosis between an endophytic fungus and its host. This is also the first report on endophytes isolated from the POC that may have potential termiticidal activities. Endophytes with termiticidal activities can be grown in bioreactor to provide an inexhaustible supply of bioactive compounds and thus can be exploited commercially. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Short communication: Pseudomonas azotoformans causes gray discoloration in HTST fluid milk.

PubMed

Evanowski, Rachel L; Reichler, Samuel J; Kent, David J; Martin, Nicole H; Boor, Kathryn J; Wiedmann, Martin

2017-10-01

Pseudomonas species are well recognized as dairy product spoilage organisms, particularly due to their ability to grow at refrigeration temperatures. Although Pseudomonas-related spoilage usually manifests itself in flavor, odor, and texture defects, which are typically due to production of bacterial enzymes, Pseudomonas is also reported to cause color defects. Because of consumer complaints, a commercial dairy company shipped 4 samples of high temperature, short time (HTST)-pasteurized milk with distinctly gray colors to our laboratory. Bacterial isolates from all 4 samples were identified as Pseudomonas azotoformans. All isolates shared the same partial 16S rDNA sequence and showed black pigmentation on Dichloran Rose Bengal Chloramphenicol agar. Inoculation of one pigment-producing P. azotoformans isolate into HTST-pasteurized fluid milk led to development of gray milk after 14 d of storage at 6°C, but only in containers that had half of the total volume filled with milk (∼500 mL of milk in ∼1,000-mL bottles). We conclusively demonstrate that Pseudomonas can cause a color defect in fluid milk that manifests in gray discoloration, adding to the palette of color defects known to be caused by Pseudomonas. This information is of considerable interest to the dairy industry, because dairy processors and others may not typically associate black or gray colors in fluid milk with the presence of microbial contaminants but rather with product tampering (e.g., addition of ink) or other inadvertent chemical contamination. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Endophytic Cultivable Bacteria of the Metal Bioaccumulator Spartina maritima Improve Plant Growth but Not Metal Uptake in Polluted Marshes Soils

PubMed Central

Mesa, Jennifer; Mateos-Naranjo, Enrique; Caviedes, Miguel A.; Redondo-Gómez, Susana; Pajuelo, Eloisa; Rodríguez-Llorente, Ignacio D.

2015-01-01

Endophytic bacterial population was isolated from Spartina maritima tissues, a heavy metal bioaccumulator cordgrass growing in the estuaries of Tinto, Odiel, and Piedras River (south west Spain), one of the most polluted areas in the world. Strains were identified and ability to tolerate salt and heavy metals along with plant growth promoting and enzymatic properties were analyzed. A high proportion of these bacteria were resistant toward one or several heavy metals and metalloids including As, Cu, and Zn, the most abundant in plant tissues and soil. These strains also exhibited multiple enzymatic properties as amylase, cellulase, chitinase, protease and lipase, as well as plant growth promoting properties, including nitrogen fixation, phosphates solubilization, and production of indole-3-acetic acid (IAA), siderophores and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. The best performing strains (Micrococcus yunnanensis SMJ12, Vibrio sagamiensis SMJ18, and Salinicola peritrichatus SMJ30) were selected and tested as a consortium by inoculating S. maritima wild plantlets in greenhouse conditions along with wild polluted soil. After 30 days, bacterial inoculation improved plant photosynthetic traits and favored intrinsic water use efficiency. However, far from stimulating plant metal uptake, endophytic inoculation lessened metal accumulation in above and belowground tissues. These results suggest that inoculation of S. maritima with indigenous metal-resistant endophytes could mean a useful approach in order to accelerate both adaption and growth of this indigenous cordgrass in polluted estuaries in restorative operations, but may not be suitable for rhizoaccumulation purposes. PMID:26733985

Dark septate endophyte decreases stress on rice plants.

PubMed

Santos, Silvana Gomes Dos; Silva, Paula Renata Alves da; Garcia, Andres Calderin; Zilli, Jerri Édson; Berbara, Ricardo Luis Louro

Abiotic stress is one of the major limiting factors for plant development and productivity, which makes it important to identify microorganisms capable of increasing plant tolerance to stress. Dark septate endophytes can be symbionts of plants. In the present study, we evaluated the ability of dark septate endophytes isolates to reduce the effects of water stress in the rice varieties Nipponbare and Piauí. The experiments were performed under gnotobiotic conditions, and the water stress was induced with PEG. Four dark septate endophytes were isolated from the roots of wild rice (Oryza glumaepatula) collected from the Brazilian Amazon. Plant height as well as shoot and root fresh and dry matter were measured. Leaf protein concentrations and antioxidant enzyme activity were also estimated. The dark septate endophytes were grown in vitro in Petri dishes containing culture medium; they exhibited different levels of tolerance to salinity and water stress. The two rice varieties tested responded differently to inoculation with dark septate endophytes. Endophytes promoted rice plant growth both in the presence and in the absence of a water deficit. Decreased oxidative stress in plants in response to inoculation was observed in nearly all inoculated treatments, as indicated by the decrease in antioxidant enzyme activity. Dark septate endophytes fungi were shown to increase the tolerance of rice plants to stress caused by water deficiency. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

How Does Salinity Shape Bacterial and Fungal Microbiomes of Alnus glutinosa Roots?

PubMed Central

Thiem, Dominika; Gołębiewski, Marcin; Hulisz, Piotr; Piernik, Agnieszka; Hrynkiewicz, Katarzyna

2018-01-01

Black alder (Alnus glutinosa Gaertn.) belongs to dual mycorrhizal trees, forming ectomycorrhizal (EM) and arbuscular (AM) root structures, as well as represents actinorrhizal plants that associate with nitrogen-fixing actinomycete Frankia sp. We hypothesized that the unique ternary structure of symbionts can influence community structure of other plant-associated microorganisms (bacterial and fungal endophytes), particularly under seasonally changing salinity in A. glutinosa roots. In our study we analyzed black alder root bacterial and fungal microbiome present at two forest test sites (saline and non-saline) in two different seasons (spring and fall). The dominant type of root microsymbionts of alder were ectomycorrhizal fungi, whose distribution depended on site (salinity): Tomentella, Lactarius, and Phialocephala were more abundant at the saline site. Mortierella and Naucoria (representatives of saprotrophs or endophytes) displayed the opposite tendency. Arbuscular mycorrhizal fungi belonged to Glomeromycota (orders Paraglomales and Glomales), however, they represented less than 1% of all identified fungi. Bacterial community structure depended on test site but not on season. Sequences affiliated with Rhodanobacter, Granulicella, and Sphingomonas dominated at the saline site, while Bradyrhizobium and Rhizobium were more abundant at the non-saline site. Moreover, genus Frankia was observed only at the saline site. In conclusion, bacterial and fungal community structure of alder root microsymbionts and endophytes depends on five soil chemical parameters: salinity, phosphorus, pH, saturation percentage (SP) as well as total organic carbon (TOC), and seasonality does not appear to be an important factor shaping microbial communities. Ectomycorrhizal fungi are the most abundant symbionts of mature alders growing in saline soils. However, specific distribution of nitrogen-fixing Frankia (forming root nodules) and association of arbuscular fungi at early stages of

How Does Salinity Shape Bacterial and Fungal Microbiomes of Alnus glutinosa Roots?

PubMed

Thiem, Dominika; Gołębiewski, Marcin; Hulisz, Piotr; Piernik, Agnieszka; Hrynkiewicz, Katarzyna

2018-01-01

Black alder ( Alnus glutinosa Gaertn.) belongs to dual mycorrhizal trees, forming ectomycorrhizal (EM) and arbuscular (AM) root structures, as well as represents actinorrhizal plants that associate with nitrogen-fixing actinomycete Frankia sp. We hypothesized that the unique ternary structure of symbionts can influence community structure of other plant-associated microorganisms (bacterial and fungal endophytes), particularly under seasonally changing salinity in A. glutinosa roots. In our study we analyzed black alder root bacterial and fungal microbiome present at two forest test sites (saline and non-saline) in two different seasons (spring and fall). The dominant type of root microsymbionts of alder were ectomycorrhizal fungi, whose distribution depended on site (salinity): Tomentella , Lactarius , and Phialocephala were more abundant at the saline site. Mortierella and Naucoria (representatives of saprotrophs or endophytes) displayed the opposite tendency. Arbuscular mycorrhizal fungi belonged to Glomeromycota (orders Paraglomales and Glomales), however, they represented less than 1% of all identified fungi. Bacterial community structure depended on test site but not on season. Sequences affiliated with Rhodanobacter , Granulicella , and Sphingomonas dominated at the saline site, while Bradyrhizobium and Rhizobium were more abundant at the non-saline site. Moreover, genus Frankia was observed only at the saline site. In conclusion, bacterial and fungal community structure of alder root microsymbionts and endophytes depends on five soil chemical parameters: salinity, phosphorus, pH, saturation percentage (SP) as well as total organic carbon (TOC), and seasonality does not appear to be an important factor shaping microbial communities. Ectomycorrhizal fungi are the most abundant symbionts of mature alders growing in saline soils. However, specific distribution of nitrogen-fixing Frankia (forming root nodules) and association of arbuscular fungi at early stages

Corneal surface glycosylation is modulated by IL-1R and Pseudomonas aeruginosa challenge but is insufficient for inhibiting bacterial binding.

PubMed

Jolly, Amber L; Agarwal, Paresh; Metruccio, Matteo M E; Spiciarich, David R; Evans, David J; Bertozzi, Carolyn R; Fleiszig, Suzanne M J

2017-06-01

Cell surface glycosylation is thought to be involved in barrier function against microbes at mucosal surfaces. Previously we showed that the epithelium of healthy mouse corneas becomes vulnerable to Pseudomonas aeruginosa adhesion if it lacks the innate defense protein MyD88 (myeloid differentiation primary response gene 88), or after superficial injury by blotting with tissue paper. Here we explored their effect on corneal surface glycosylation using a metabolic label, tetra-acetylated N -azidoacetylgalactosamine (Ac 4 GalNAz). Ac 4 GalNAz treatment labeled the surface of healthy mouse corneas, leaving most cells viable, and bacteria preferentially associated with GalNAz-labeled regions. Surprisingly, corneas from MyD88 -/- mice displayed similar GalNAz labeling to wild-type corneas, but labeling was reduced and patchy on IL-1 receptor (IL-1R)-knockout mouse corneas ( P < 0.05, ANOVA). Tissue paper blotting removed GalNAz-labeled surface cells, causing DAPI labeling (permeabilization) of underlying cells. MS of material collected on the tissue paper blots revealed 67 GalNAz-labeled proteins, including intracellular proteins. These data show that the normal distribution of surface glycosylation requires IL-1R, but not MyD88, and is not sufficient to prevent bacterial binding. They also suggest increased P. aeruginosa adhesion to MyD88 -/- and blotted corneas is not due to reduction in total surface glycosylation, and for tissue paper blotting is likely due to cell permeabilization.-Jolly, A. L., Agarwal, P., Metruccio, M. M. E., Spiciarich, D. R., Evans, D. J., Bertozzi, C. R., Fleiszig, S. M. J. Corneal surface glycosylation is modulated by IL-1R and Pseudomonas aeruginosa challenge but is insufficient for inhibiting bacterial binding. © FASEB.

Pathovars of Pseudomonas syringae Causing Bacterial Brown Spot and Halo Blight in Phaseolus vulgaris L. Are Distinguishable by Ribotyping

PubMed Central

González, Ana J.; Landeras, Elena; Mendoza, M. Carmen

2000-01-01

Ribotyping was evaluated as a method to differentiate between Pseudomonas syringae pv. phaseolicola and pv. syringae strains causing bacterial brown spot and halo blight diseases in Phaseolus vulgaris L. Ribotyping, with restriction enzymes BglI and SalI and using the Escherichia coli rrnB operon as the probe, differentiated 11 and 14 ribotypes, respectively, and a combination of data from both procedures yielded 19 combined ribotypes. Cluster analysis of the combined ribotypes differentiated the pathovars phaseolicola and syringae, as well as different clonal lineages within these pathovars. The potential of ribotyping to screen for correlations between lineages and factors such as geographical region and/or bean varieties is also reported. PMID:10653764

Endophytic bacteria: prospects and applications for the phytoremediation of organic pollutants.

PubMed

Afzal, Muhammad; Khan, Qaiser M; Sessitsch, Angela

2014-12-01

Recently, there has been an increased effort to enhance the efficacy of phytoremediation of contaminated environments by exploiting plant-microbe interactions. The combined use of plants and endophytic bacteria is an emerging approach for the clean-up of soil and water polluted with organic compounds. In plant-endophyte partnerships, plants provide the habitat as well as nutrients to their associated endophytic bacteria. In response, endophytic bacteria with appropriate degradation pathways and metabolic activities enhance degradation of organic pollutants, and diminish phytotoxicity and evapotranspiration of organic pollutants. Moreover, endophytic bacteria possessing plant growth-promoting activities enhance the plant's adaptation and growth in soil and water contaminated with organic pollutants. Overall, the application of endophytic bacteria gives new insights into novel protocols to improve phytoremediation efficiency. However, successful application of plant-endophyte partnerships for the clean-up of an environment contaminated with organic compounds depends on the abundance and activity of the degrading endophyte in different plant compartments. Although many endophytic bacteria have the potential to degrade organic pollutants and improve plant growth, their contribution to enhance phytoremediation efficiency is still underestimated. A better knowledge of plant-endophyte interactions could be utilized to increase the remediation of polluted soil environments and to protect the foodstuff by decreasing agrochemical residues in food crops. Copyright © 2014 Elsevier Ltd. All rights reserved.

New strategies for genetic engineering Pseudomonas syringae using recombination

USDA-ARS?s Scientific Manuscript database

Here we report that DNA oligonucleotides (oligos) introduced directly into bacteria by electroporation can recombine with the bacterial chromosome. This phenomenon was identified in Pseudomonas syringae and we subsequently found that Escherichia coli, Salmonella typhimurium and Shigella flexneri are...

Induction of abiotic stress tolerance in plants by endophytic microbes.

PubMed

Lata, R; Chowdhury, S; Gond, S K; White, J F

2018-04-01

Endophytes are micro-organisms including bacteria and fungi that survive within healthy plant tissues and promote plant growth under stress. This review focuses on the potential of endophytic microbes that induce abiotic stress tolerance in plants. How endophytes promote plant growth under stressful conditions, like drought and heat, high salinity and poor nutrient availability will be discussed. The molecular mechanisms for increasing stress tolerance in plants by endophytes include induction of plant stress genes as well as biomolecules like reactive oxygen species scavengers. This review may help in the development of biotechnological applications of endophytic microbes in plant growth promotion and crop improvement under abiotic stress conditions. Increasing human populations demand more crop yield for food security while crop production is adversely affected by abiotic stresses like drought, salinity and high temperature. Development of stress tolerance in plants is a strategy to cope with the negative effects of adverse environmental conditions. Endophytes are well recognized for plant growth promotion and production of natural compounds. The property of endophytes to induce stress tolerance in plants can be applied to increase crop yields. With this review, we intend to promote application of endophytes in biotechnology and genetic engineering for the development of stress-tolerant plants. © 2018 The Society for Applied Microbiology.

Variation in endophytic fungi from roots and leaves of Lepanthes (Orchidaceae)

Treesearch

PAUL BAYMAN; LIGIA L. LEBRO; RAYMOND L. TREMBLAY; JEAN D. LODGE

1997-01-01

Little is known about non-mycorrhizal endophytic fungi in tropical orchids; still less is known about how endophytes vary within and between individual orchid plants. Fungal endophytes were isolated from roots and leaves of epiphytic and lithophytic orchids in the genus Lepanthes; seven species, from rainforests in Puerto Rico, were sampled. The endophytes observed...

[Production of inhibiting plant growth and development hormones by pathogenic for legumes Pseudomonas genus bacteria].

PubMed

Dankevich, L A

2013-01-01

It has been studied the ability of pathogenic for legumes pathovars of Pseudomonas genus to produce ethylene and abscisic acid in vitro. A direct correlation between the level of ethylene production by agent of bacterial pea burn--Pseudomonas syringae pv. pisi and level of its aggressiveness for plants has been found. It is shown that the amount of abscisic acid synthesized by pathogenic for legumes Pseudomonas genus bacteria correlates with their aggressiveness for plants.

Adding Selectivity to Antimicrobial Peptides: Rational Design of a Multidomain Peptide against Pseudomonas spp.

PubMed Central

Eckert, Randal; Qi, Fengxia; Yarbrough, Daniel K.; He, Jian; Anderson, Maxwell H.; Shi, Wenyuan

2006-01-01

Currently available antimicrobials exhibit broad killing with regard to bacterial genera and species. Indiscriminate killing of microbes by these conventional antibiotics can disrupt the ecological balance of the indigenous microbial flora, often resulting in negative clinical consequences. Species-specific antimicrobials capable of precisely targeting pathogenic bacteria without damaging benign microorganisms provide a means of avoiding this problem. In this communication, we report the successful creation of the first synthetic, target-specific antimicrobial peptide, G10KHc, via addition of a rationally designed Pseudomonas-specific targeting moiety (KH) to a generally killing peptide (novispirin G10). The resulting chimeric peptide showed enhanced bactericidal activity and faster killing kinetics against Pseudomonas spp. than G10 alone. The enhanced killing activities are due to increased binding and penetration of the outer membrane of Pseudomonas sp. cells. These properties were not observed in tests of untargeted bacterial species, and this specificity allowed G10KHc to selectively eliminate Pseudomonas spp. from mixed cultures. This work lays a foundation for generating target-specific “smart” antimicrobials to complement currently available conventional antibiotics. PMID:16569868

Rethinking production of Taxol® (paclitaxel) using endophyte biotechnology.

PubMed

Kusari, Souvik; Singh, Satpal; Jayabaskaran, Chelliah

2014-06-01

Taxol® (generic name paclitaxel) represents one of the most clinically valuable natural products known to mankind in the recent past. More than two decades have elapsed since the notable discovery of the first Taxol®-producing endophytic fungus, which was followed by a plethora of reports on other endophytes possessing similar biosynthetic potential. However, industrial-scale Taxol® production using fungal endophytes, although seemingly promising, has not seen the light of the day. In this opinion article, we embark on the current state of knowledge on Taxol® biosynthesis focusing on the chemical ecology of its producers, and ask whether it is actually possible to produce Taxol® using endophyte biotechnology. The key problems that have prevented the exploitation of potent endophytic fungi by industrial bioprocesses for sustained production of Taxol® are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fungal disease prevention in seedlings of rice (Oryza sativa) and other grasses by growth-promoting seed-associated endophytic bacteria from invasive Phragmites australis

USGS Publications Warehouse

Verma, Satish K.; Kingsley, Kathryn L.; Bergen, Marshall S.; Kowalski, Kurt P.; White, James F.

2018-01-01

Non-cultivated plants carry microbial endophytes that may be used to enhance development and disease resistance of crop species where growth-promoting and protective microbes may have been lost. During seedling establishment, seedlings may be infected by several fungal pathogens that are seed or soil borne. Several species of Fusarium, Pythium and other water moulds cause seed rots during germination. Fusariumblights of seedlings are also very common and significantly affect seedling development. In the present study we screened nine endophytic bacteria isolated from the seeds of invasive Phragmites australis by inoculating onto rice, Bermuda grass (Cynodon dactylon), or annual bluegrass (Poa annua) seeds to evaluate plant growth promotion and protection from disease caused by Fusarium oxysporum. We found that three bacteria belonging to genus Pseudomonas spp. (SLB4-P. fluorescens, SLB6-Pseudomonas sp. and SY1-Pseudomonassp.) promoted seedling development, including enhancement of root and shoot growth, and stimulation of root hair formation. These bacteria were also found to increase phosphate solubilization in in vitro experiments. Pseudomonas sp. (SY1) significantly protected grass seedlings from Fusarium infection. In co-culture experiments, strain SY1 strongly inhibited fungal pathogens with 85.71% growth inhibition of F. oxysporum, 86.33% growth inhibition of Curvularia sp. and 82.14% growth inhibition of Alternaria sp. Seedlings previously treated with bacteria were found much less infected by F. oxysporum in comparison to non-treated controls. On microscopic observation we found that bacteria appeared to degrade fungal mycelia actively. Metabolite products of strain SY1 in agar were also found to inhibit fungal growth on nutrient media. Pseudomonas sp. (SY1) was found to produce antifungal volatiles. Polymerase chain reaction (PCR) amplification using specific primers for pyrrolnitirin synthesis and HCN (hydrogen cyanide) production

[Isolation and physiological characteristics of endophytic actinobacteria from medicinal plants].

PubMed

Du, Huijing; Su, Jing; Yu, Liyan; Zhang, Yuqin

2013-01-04

To isolate, incubate and characterize cultivable endophytic antinobacteria from medicinal plants, and analyze the diversity of the endophytic antinobacteria, then explore the novel microbial resources. Ten media were used to isolate endophytic antinobacteria from 37 fresh medicinal plant tissue samples. The optimal cultivation conditions for endophytic antinobacteria were determined by comparison. Based on the morphology of the colonies and cells of the new isolates, we chose 174 isolates to analyze their 16S rRNA gene sequences and the diversity of the medicinal plant endophytic antinobacteria. The physiological characteristics of 27 representative strains were studied using Biolog GEN III MicroPlates, API 50CH and API ZYM kits. In total 940 endophytics affiliated to 47 genera of 30 families were isolated, among which more than 600 actinobacteria belonged to 34 genera and 7 unknown taxa. Good growth of the endophytic antinobacteria on PYG (peptone-yeast-glycerol) medium with pH 7.2 at 28-32 degrees C was observed. Physiological characteristics differences of these isolates related to their phylogenetic relationships. Greater differences were shown among the strains from the same host plants than those from differ,ent plants grown in the same area. There are great diverse endophytic actinobacteria inside the medicinal plants. No direct relationship of the endophytic actinobacteria from medicinal plants with the host plants in the sole carbon source utilization, fermentation of carbon sources to produce acid and the enzyme activities was found, while it seemed that the physiological characteristics of the isolates related to the geographical distribution of their host.

Endophyte Microbiome Diversity in Micropropagated Atriplex canescens and Atriplex torreyi var griffithsii

PubMed Central

Lucero, Mary E.; Unc, Adrian; Cooke, Peter; Dowd, Scot; Sun, Shulei

2011-01-01

Microbial diversity associated with micropropagated Atriplex species was assessed using microscopy, isolate culturing, and sequencing. Light, electron, and confocal microscopy revealed microbial cells in aseptically regenerated leaves and roots. Clone libraries and tag-encoded FLX amplicon pyrosequencing (TEFAP) analysis amplified sequences from callus homologous to diverse fungal and bacterial taxa. Culturing isolated some seed borne endophyte taxa which could be readily propagated apart from the host. Microbial cells were observed within biofilm-like residues associated with plant cell surfaces and intercellular spaces. Various universal primers amplified both plant and microbial sequences, with different primers revealing different patterns of fungal diversity. Bacterial and fungal TEFAP followed by alignment with sequences from curated databases revealed 7 bacterial and 17 ascomycete taxa in A. canescens, and 5 bacterial taxa in A. torreyi. Additional diversity was observed among isolates and clone libraries. Micropropagated Atriplex retains a complex, intimately associated microbiome which includes diverse strains well poised to interact in manners that influence host physiology. Microbiome analysis was facilitated by high throughput sequencing methods, but primer biases continue to limit recovery of diverse sequences from even moderately complex communities. PMID:21437280

Root-hair endophyte stacking in finger millet creates a physicochemical barrier to trap the fungal pathogen Fusarium graminearum.

PubMed

Mousa, Walaa K; Shearer, Charles; Limay-Rios, Victor; Ettinger, Cassie L; Eisen, Jonathan A; Raizada, Manish N

2016-09-26

The ancient African crop, finger millet, has broad resistance to pathogens including the toxigenic fungus Fusarium graminearum. Here, we report the discovery of a novel plant defence mechanism resulting from an unusual symbiosis between finger millet and a root-inhabiting bacterial endophyte, M6 (Enterobacter sp.). Seed-coated M6 swarms towards root-invading Fusarium and is associated with the growth of root hairs, which then bend parallel to the root axis, subsequently forming biofilm-mediated microcolonies, resulting in a remarkable, multilayer root-hair endophyte stack (RHESt). The RHESt results in a physical barrier that prevents entry and/or traps F. graminearum, which is then killed. M6 thus creates its own specialized killing microhabitat. Tn5-mutagenesis shows that M6 killing requires c-di-GMP-dependent signalling, diverse fungicides and resistance to a Fusarium-derived antibiotic. Further molecular evidence suggests long-term host-endophyte-pathogen co-evolution. The end result of this remarkable symbiosis is reduced deoxynivalenol mycotoxin, potentially benefiting millions of subsistence farmers and livestock. Further results suggest that the anti-Fusarium activity of M6 may be transferable to maize and wheat. RHESt demonstrates the value of exploring ancient, orphan crop microbiomes.

Genome Sequence of the Plant Growth Promoting Endophytic Bacterium Enterobacter sp. 638

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taghavi, S.; van der Lelie, D.; Hoffman, A.

2010-05-13

Enterobacter sp. 638 is an endophytic plant growth promoting gamma-proteobacterium that was isolated from the stem of poplar (Populus trichocarpa x deltoides cv. H11-11), a potentially important biofuel feed stock plant. The Enterobacter sp. 638 genome sequence reveals the presence of a 4,518,712 bp chromosome and a 157,749 bp plasmid (pENT638-1). Genome annotation and comparative genomics allowed the identification of an extended set of genes specific to the plant niche adaptation of this bacterium. This includes genes that code for putative proteins involved in survival in the rhizosphere (to cope with oxidative stress or uptake of nutrients released by plantmore » roots), root adhesion (pili, adhesion, hemagglutinin, cellulose biosynthesis), colonization/establishment inside the plant (chemiotaxis, flagella, cellobiose phosphorylase), plant protection against fungal and bacterial infections (siderophore production and synthesis of the antimicrobial compounds 4-hydroxybenzoate and 2-phenylethanol), and improved poplar growth and development through the production of the phytohormones indole acetic acid, acetoin, and 2,3-butanediol. Metabolite analysis confirmed by quantitative RT-PCR showed that, the production of acetoin and 2,3-butanediol is induced by the presence of sucrose in the growth medium. Interestingly, both the genetic determinants required for sucrose metabolism and the synthesis of acetoin and 2,3-butanediol are clustered on a genomic island. These findings point to a close interaction between Enterobacter sp. 638 and its poplar host, where the availability of sucrose, a major plant sugar, affects the synthesis of plant growth promoting phytohormones by the endophytic bacterium. The availability of the genome sequence, combined with metabolome and transcriptome analysis, will provide a better understanding of the synergistic interactions between poplar and its growth promoting endophyte Enterobacter sp. 638. This information can be further

Influence of endophytic root bacteria on the growth, cadmium tolerance and uptake of switchgrass (Panicum virgatum L.).

PubMed

Afzal, S; Begum, N; Zhao, H; Fang, Z; Lou, L; Cai, Q

2017-08-01

This study aimed to evaluate the effect of five cadmium-tolerant endophytic plant growth-promoting bacteria (PGPB) strains on the biomass and cadmium tolerance, and accumulation of the bioenergy plant switchgrass (Panicum virgatum L.) under cadmium (Cd)-contaminated conditions. Five bacterial strains (Bj05, Le14, Ps14, So02 and Bo03) that could tolerate up to 2000 μmol l -1 CdCl 2 with a high Cd-binding capacity were isolated from plants grown in Cd-contaminated soil. These strains could promote the growth of switchgrass in the presence of 20 μmol l -1 CdCl 2 . Under Cd stress, both the root and shoot length and biomass in two switchgrass cultivars, Alamo and Cave-in-Rock (CIR), increased significantly after treatment with PGPB (P ˂ 0·05). Of the five PGPB strains, Bj05 and Le14 most effectively alleviated the Cd-induced growth inhibition of Alamo plants. Interestingly, the five PGPB strains increased Cd tolerance and decreased the accumulation and translocation factor (TF) of Cd in switchgrass when grown in the presence of 20 μmol l -1 CdCl 2 . The Cd concentrations in roots and shoots of Alamo and CIR plants were significantly reduced (P ˂ 0·05) compared with noninoculated plants. By 16S rRNA sequencing, these PGPB strains were classified as Pseudomonas putida Bj05, Pseudomonas fluorescens Ps14, and Enterobacter spp. Le14, So02 and Bo03. Inoculation with PGPB protects plants from the inhibitory effects of Cd, improves plant growth and decreases Cd concentration. These observations suggest that these strains could be used to promote growth and lower the bioavailability of Cd in switchgrass. These strains are potential candidates for the development of low Cd-accumulating switchgrass, particularly in areas of Cd contamination and pollution, and could be used efficiently for the bioremediation of contaminated soil. © 2017 The Society for Applied Microbiology.

Bacterial surface adaptation

NASA Astrophysics Data System (ADS)

Utada, Andrew

2014-03-01

Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

Influence of chelation strength and bacterial uptake of gallium salicylidene acylhydrazide on biofilm formation and virulence of Pseudomonas aeruginosa.

PubMed

Hakobyan, Shoghik; Rzhepishevska, Olena; Björn, Erik; Boily, Jean-François; Ramstedt, Madeleine

2016-07-01

Development of antibiotic resistance in bacteria causes major challenges for our society and has prompted a great need for new and alternative treatment methods for infection. One promising approach is to target bacterial virulence using for example salicylidene acylhydrazides (hydrazones). Hydrazones coordinate metal ions such as Fe(III) and Ga(III) through a five-membered and a six-membered chelation ring. One suggested mode of action is via restricting bacterial Fe uptake. Thus, it was hypothesized that the chelating strength of these substances could be used to predict their biological activity on bacterial cells. This was investigated by comparing Ga chelation strength of two hydrazone complexes, as well as bacterial Ga uptake, biofilm formation, and virulence in the form of production and secretion of a toxin (ExoS) by Pseudomonas aeruginosa. Equilibrium constants for deprotonation and Ga(III) binding of the hydrazone N'-(5-chloro-2-hydroxy-3-methylbenzylidene)-2,4-dihydroxybenzhydrazide (ME0329), with anti-virulence effect against P. aeruginosa, were determined and compared to bacterial siderophores and the previously described Ga(III) 2-oxo-2-[N-(2,4,6-trihydroxy-benzylidene)-hydrazino]-acetamide (Ga-ME0163) and Ga-citrate complexes. In comparison with these two complexes, it was shown that the uptake of Ga(III) was higher from the Ga-ME0329 complex. The results further show that the Ga-ME0329 complex reduced ExoS expression and secretion to a higher extent than Ga-citrate, Ga-ME0163 or the non-coordinated hydrazone. However, the effect against biofilm formation by P. aeruginosa, by the ME0329 complex, was similar to Ga-citrate and lower than what has been reported for Ga-ME0163. Copyright © 2016. Published by Elsevier Inc.

Endophytic fungi associated with Macrosolen tricolor and its host Camellia oleifera.

PubMed

Sheng-Liang, Zhou; Shu-Zhen, Yan; Zhen-Ying, Wu; Shuang-Lin, Chen

2014-06-01

Endophytic fungi play an important role in terrestrial ecosystem, while little is known about those in hemi-parasitic plants, a group of special plants which absorb nutrients from its hosts by haustoria. The relationship of the endophytes in the two parts of the bipartite systems (hemiparasites together with their hosts) is also poorly understood. Endophytic fungi of a hemi-parasitic plant Macrosolen tricolor, and its host plant Camellia oleifera were investigated and compared in this study. M. tricolor contained rich and diversified endophytic fungi (H' = 2.829), which consisted mainly of ascomycetes, distributed in more than ten orders of four classes (Sordariomycetes, Dothideomycetes, Leotiomycetes and Eurotiomycetes) besides Incertae sedis strains (23.2 % of total). In addition, 2.2 % of isolates were identified to be Basidiomycota, all of which belonged to Agaricomycetes. Obvious differences were observed between the endophytic fungal assembles in the leaves and those in the branches of M. tricolor. The endophytic fungi isolated from C. oleifera distributed in nearly same orders of the four classes of Ascomycota and one class (Agaricomycetes) of Basidiomycota as those from M. tricolor with similar proportion. For both M. tricolor and C. oleifera, Valsa sp. was the dominant endophyte species in the leaves, Torula sp. 1 and Fusarium sp. 1 were the dominant endophytic fungi in the branches. The similarity coefficient of the endophyte assembles in the two host was 64.4 %. Canonical correspondence analysis showed that the endophyte assembles of M. tricolor and C. oleifera were significantly different (p < 0.01).

Chemical ecology of endophytic fungi: origins of secondary metabolites.

PubMed

Kusari, Souvik; Hertweck, Christian; Spiteller, Michael

2012-07-27

Endophytes constitute a remarkably multifarious group of microorganisms ubiquitous in plants and maintain an imperceptible association with their hosts for at least a part of their life cycle. Their enormous biological diversity coupled with their capability to biosynthesize bioactive secondary metabolites has provided the impetus for a number of investigations on endophytes. Here, we highlight the possible current and future strategies of understanding the chemical communication of endophytic fungi with other endophytes (fungi and bacteria) and with their host plants, which might not only allow the discovery and sustainable production of desirable natural products but also other mostly overlooked bioactive secondary metabolites. Copyright © 2012 Elsevier Ltd. All rights reserved.

Colonization strategy of the endophytic plant growth-promoting strains of Pseudomonas fluorescens and Klebsiella oxytoca on the seeds, seedlings and roots of the epiphytic orchid, Dendrobium nobile Lindl.

PubMed

Pavlova, A S; Leontieva, M R; Smirnova, T A; Kolomeitseva, G L; Netrusov, A I; Tsavkelova, E A

2017-04-29

Orchids form strong mycorrhizal associations, but their interactions with bacteria are poorly understood. We aimed to investigate the distribution of plant growth promoting rhizobacteria (PGPR) at different stages of orchid development and to study if there is any selective specificity in choosing PGPR partners. Colonization patterns of gfp-tagged Pseudomonas fluorescens and Klebsiella oxytoca were studied on roots, seeds, and seedlings of Dendrobium nobile. Endophytic rhizobacteria rapidly colonized velamen and core parenchyma entering through exodermis and the passage cells, whereas at the early stages, they stayed restricted to the surface and the outer layers of the protocorms and rhizoids. The highest amounts of auxin (indole-3-acetic acid) were produced by K. oxytoca and P. fluorescens in the nitrogen-limiting and NO 3 -containing media respectively. Bacterization of D. nobile seeds resulted in promotion of their in vitro germination. The plant showed no selective specificity to the tested strains. Klebsiella oxytoca demonstrated more intense colonization activity and more efficient growth promoting impact under tryptophan supplementation, while P. fluorescens revealed its growth-promoting capacity without tryptophan. Both strategies are regarded as complementary, improving adaptive potentials of the orchid when different microbial populations colonize the plant. This study enlarges our knowledge on orchid-microbial interactions, and provides new features on application of the nonorchid PGPR in orchid seed germination and conservation. © 2017 The Society for Applied Microbiology.

Genome Sequence of the Plant Growth Promoting Endophytic Bacterium Enterobacter sp. 638

PubMed Central

Taghavi, Safiyh; van der Lelie, Daniel; Hoffman, Adam; Zhang, Yian-Biao; Walla, Michael D.; Vangronsveld, Jaco; Newman, Lee; Monchy, Sébastien

2010-01-01

Enterobacter sp. 638 is an endophytic plant growth promoting gamma-proteobacterium that was isolated from the stem of poplar (Populus trichocarpa×deltoides cv. H11-11), a potentially important biofuel feed stock plant. The Enterobacter sp. 638 genome sequence reveals the presence of a 4,518,712 bp chromosome and a 157,749 bp plasmid (pENT638-1). Genome annotation and comparative genomics allowed the identification of an extended set of genes specific to the plant niche adaptation of this bacterium. This includes genes that code for putative proteins involved in survival in the rhizosphere (to cope with oxidative stress or uptake of nutrients released by plant roots), root adhesion (pili, adhesion, hemagglutinin, cellulose biosynthesis), colonization/establishment inside the plant (chemiotaxis, flagella, cellobiose phosphorylase), plant protection against fungal and bacterial infections (siderophore production and synthesis of the antimicrobial compounds 4-hydroxybenzoate and 2-phenylethanol), and improved poplar growth and development through the production of the phytohormones indole acetic acid, acetoin, and 2,3-butanediol. Metabolite analysis confirmed by quantitative RT–PCR showed that, the production of acetoin and 2,3-butanediol is induced by the presence of sucrose in the growth medium. Interestingly, both the genetic determinants required for sucrose metabolism and the synthesis of acetoin and 2,3-butanediol are clustered on a genomic island. These findings point to a close interaction between Enterobacter sp. 638 and its poplar host, where the availability of sucrose, a major plant sugar, affects the synthesis of plant growth promoting phytohormones by the endophytic bacterium. The availability of the genome sequence, combined with metabolome and transcriptome analysis, will provide a better understanding of the synergistic interactions between poplar and its growth promoting endophyte Enterobacter sp. 638. This information can be further exploited to

Pervasive Effects of Wildfire on Foliar Endophyte Communities in Montane Forest Trees.

PubMed

Huang, Yu-Ling; Devan, M M Nandi; U'Ren, Jana M; Furr, Susan H; Arnold, A Elizabeth

2016-02-01

Plants in all terrestrial ecosystems form symbioses with endophytic fungi that inhabit their healthy tissues. How these foliar endophytes respond to wildfires has not been studied previously, but is important given the increasing frequency and intensity of severe wildfires in many ecosystems, and because endophytes can influence plant growth and responses to stress. The goal of this study was to examine effects of severe wildfires on endophyte communities in forest trees, with a focus on traditionally fire-dominated, montane ecosystems in the southwestern USA. We evaluated the abundance, diversity, and composition of endophytes in foliage of Juniperus deppeana (Cupressaceae) and Quercus spp. (Fagaceae) collected contemporaneously from areas affected by recent wildfire and paired areas not affected by recent fire. Study sites spanned four mountain ranges in central and southern Arizona. Our results revealed significant effects of fires on endophyte communities, including decreases in isolation frequency, increases in diversity, and shifts in community structure and taxonomic composition among endophytes of trees affected by recent fires. Responses to fire were similar in endophytes of each host in these fire-dominated ecosystems and reflect regional fire-return intervals, with endophytes after fire representing subsets of the regional mycoflora. Together, these findings contribute to an emerging perspective on the responses of diverse communities to severe fire, and highlight the importance of considering fire history when estimating endophyte diversity and community structure for focal biomes.

Bacterial attack on phenolic ethers. Purification and characterization of the components of the meta O-dealkylase of Pseudomonas fluorescens Tp.

PubMed

Pietrowski, R A; Cartwright, N J

1977-01-01

The meta O-dealkylase of Pseudomonas fluorescens Tp has been resolved into two protein components, neither of which is a cytochrome. The substrate binding terminal oxidase has been purified and shown to be a non-haem iron protein of approximate molecular weight 118,000, consisting of two seemingly identical subunits, each of molecular weight 55,000. Binding of substrate by the terminal oxidase has been established by difference spectroscopy. The amino acid composition of the protein has also been determined. The NADH-dependent reductase of the system has been partly purified and appears to have a molecular weight of 80,000. The similarity between this and other bacterial O-dealkylases is discussed.

Thienopyrimidine-type compounds protect Arabidopsis plants against the hemibiotrophic fungal pathogen Colletotrichum higginsianum and bacterial pathogen Pseudomonas syringae pv. maculicola.

PubMed

Narusaka, Mari; Narusaka, Yoshihiro

2017-03-04

Plant activators activate systemic acquired resistance-like defense responses or induced systemic resistance, and thus protect plants from pathogens. We screened a chemical library composed of structurally diverse small molecules. We isolated six plant immune-inducing thienopyrimidine-type compounds and their analogous compounds. It was observed that the core structure of thienopyrimidine plays a role in induced resistance in plants. Furthermore, we highlight the protective effect of thienopyrimidine-type compounds against both hemibiotrophic fungal pathogen, Colletotrichum higginsianum, and bacterial pathogen, Pseudomonas syringae pv. maculicola, in Arabidopsis thaliana. We suggest that thienopyrimidine-type compounds could be potential lead compounds as novel plant activators, and can be useful and effective agrochemicals against various plant diseases.

Increased growth and root Cu accumulation of Sorghum sudanense by endophytic Enterobacter sp. K3-2: Implications for Sorghum sudanense biomass production and phytostabilization.

PubMed

Li, Ya; Wang, Qi; Wang, Lu; He, Lin-Yan; Sheng, Xia-Fang

2016-02-01

Endophytic bacterial strain K3-2 was isolated from the roots of Sorghum sudanense (an bioenergy plant) grown in a Cu mine wasteland soils and characterized. Strain K3-2 was identified as Enterobacter sp. based on 16S rRNA gene sequence analysis. Strain K3-2 exhibited Cu resistance and produced 1-aminocyclopropane-1-carboxylate (ACC) deaminase, indole-3-acetic acid (IAA), siderophores, and arginine decarboxylase. Pot experiments showed that strain K3-2 significantly increased the dry weight and root Cu accumulation of Sorghum sudanense grown in the Cu mine wasteland soils. Furthermore, increase in total Cu uptake (ranging from 49% to 95%) of the bacterial inoculated-Sorghum sudanense was observed compared to the control. Notably, most of Cu (83-86%) was accumulated in the roots of Sorghum sudanense. Furthermore, inoculation with strain K3-2 was found to significantly increase Cu bioconcentration factors and the proportions of IAA- and siderophore-producing bacteria in the root interiors and rhizosphere soils of Sorghum sudanense compared with the control. Significant decrease in the available Cu content was also observed in the rhizosphere soils of the bacterial-inoculated Sorghum sudanense. The results suggest that the endophytic bacterial strain K3-2 may be exploited for promoting Sorghum sudanense biomass production and Cu phytostabilization in the Cu mining wasteland soils. Copyright © 2015 Elsevier Inc. All rights reserved.

Nitrogen acquisition in Agave tequilana from degradation of endophytic bacteria

PubMed Central

Beltran-Garcia, Miguel J.; White, Jr., James F.; Prado, Fernanda M.; Prieto, Katia R.; Yamaguchi, Lydia F.; Torres, Monica S.; Kato, Massuo J.; Medeiros, Marisa H. G.; Di Mascio, Paolo

2014-01-01

Plants form symbiotic associations with endophytic bacteria within tissues of leaves, stems, and roots. It is unclear whether or how plants obtain nitrogen from these endophytic bacteria. Here we present evidence showing nitrogen flow from endophytic bacteria to plants in a process that appears to involve oxidative degradation of bacteria. In our experiments we employed Agave tequilana and its seed-transmitted endophyte Bacillus tequilensis to elucidate organic nitrogen transfer from 15N-labeled bacteria to plants. Bacillus tequilensis cells grown in a minimal medium with 15NH4Cl as the nitrogen source were watered onto plants growing in sand. We traced incorporation of 15N into tryptophan, deoxynucleosides and pheophytin derived from chlorophyll a. Probes for hydrogen peroxide show its presence during degradation of bacteria in plant tissues, supporting involvement of reactive oxygen in the degradation process. In another experiment to assess nitrogen absorbed as a result of endophytic colonization of plants we demonstrated that endophytic bacteria potentially transfer more nitrogen to plants and stimulate greater biomass in plants than heat-killed bacteria that do not colonize plants but instead degrade in the soil. Findings presented here support the hypothesis that some plants under nutrient limitation may degrade and obtain nitrogen from endophytic microbes. PMID:25374146

Nitrogen acquisition in Agave tequilana from degradation of endophytic bacteria.

PubMed

Beltran-Garcia, Miguel J; White, James F; Prado, Fernanda M; Prieto, Katia R; Yamaguchi, Lydia F; Torres, Monica S; Kato, Massuo J; Medeiros, Marisa H G; Di Mascio, Paolo

2014-11-06

Plants form symbiotic associations with endophytic bacteria within tissues of leaves, stems, and roots. It is unclear whether or how plants obtain nitrogen from these endophytic bacteria. Here we present evidence showing nitrogen flow from endophytic bacteria to plants in a process that appears to involve oxidative degradation of bacteria. In our experiments we employed Agave tequilana and its seed-transmitted endophyte Bacillus tequilensis to elucidate organic nitrogen transfer from (15)N-labeled bacteria to plants. Bacillus tequilensis cells grown in a minimal medium with (15)NH4Cl as the nitrogen source were watered onto plants growing in sand. We traced incorporation of (15)N into tryptophan, deoxynucleosides and pheophytin derived from chlorophyll a. Probes for hydrogen peroxide show its presence during degradation of bacteria in plant tissues, supporting involvement of reactive oxygen in the degradation process. In another experiment to assess nitrogen absorbed as a result of endophytic colonization of plants we demonstrated that endophytic bacteria potentially transfer more nitrogen to plants and stimulate greater biomass in plants than heat-killed bacteria that do not colonize plants but instead degrade in the soil. Findings presented here support the hypothesis that some plants under nutrient limitation may degrade and obtain nitrogen from endophytic microbes.

Effects of the fungal endophyte, Neotyphodium lolii, on net photosynthesis and growth rates of perennial ryegrass (Lolium perenne) are independent of In Planta endophyte concentration.

PubMed

Spiering, Martin J; Greer, Dennis H; Schmid, Jan

2006-08-01

Neotyphodium lolii is a fungal endophyte of perennial ryegrass (Lolium perenne), improving grass fitness through production of bioactive alkaloids. Neotyphodium species can also affect growth and physiology of their host grasses (family Poaceae, sub-family Pooideae), but little is known about the mechanisms. This study examined the effect of N. lolii on net photosynthesis (P(n)) and growth rates in ryegrass genotypes differing in endophyte concentration in all leaf tissues. Plants from two ryegrass genotypes, Nui D and Nui UIV, infected with N. lolii (E+) differing approx. 2-fold in endophyte concentration or uninfected clones thereof (E-) were grown in a controlled environment. For each genotype x endophyte treatment, plant growth rates were assessed as tillering and leaf extension rates, and the light response of P(n), dark respiration and transpiration measured in leaves of young (30-45 d old) and old (>90 d old) plants with a single-chamber open infrared gas-exchange system. Neotyphodium lolii affected CO(2)-limited rates of P(n), which were approx. 17 % lower in E+ than E- plants (P < 0.05) in the young plants. Apparent photon yield and dark respiration were unaffected by the endophyte (P > 0.05). Neotyphodium lolii also decreased transpiration (P < 0.05), but only in complete darkness. There were no endophyte effects on P(n) in the old plants (P > 0.05). E+ plants grew faster immediately after replanting (P < 0.05), but had approx. 10 % lower growth rates during mid-log growth (P < 0.05) than E- plants, but there was no effect on final plant biomass (P > 0.05). The endophyte effects on P(n) and growth tended to be more pronounced in Nui UIV, despite having a lower endophyte concentration than Nui D. Neotyphodium lolii affects CO(2) fixation, but not light interception and photochemistry of P(n). The impact of N. lolii on plant growth and photosynthesis is independent of endophyte concentration in the plant, suggesting that the endophyte mycelium is not simply

Diversity and distribution of 16S rRNA and phenol monooxygenase genes in the rhizosphere and endophytic bacteria isolated from PAH-contaminated sites

NASA Astrophysics Data System (ADS)

Peng, Anping; Liu, Juan; Ling, Wanting; Chen, Zeyou; Gao, Yanzheng

2015-07-01

This is the first investigation of the diversity and distribution of 16S rRNA and phenol monooxygenase (PHE) genes in endophytic and rhizosphere bacteria of plants at sites contaminated with different levels of PAHs. Ten PAHs at concentrations from 34.22 to 55.29 and 45.79 to 97.81 mg·kg-1 were measured in rhizosphere soils of Alopecurus aequalis Sobol and Oxalis corniculata L., respectively. The diversity of 16S rRNA and PHE genes in rhizosphere soils or plants changed with varying PAH pollution levels, as shown based on PCR-DGGE data. Generally, higher Shannon-Weiner indexes were found in mild or moderate contaminated areas. A total of 82 different bacterial 16S rRNA gene sequences belonging to five phyla; namely, Acfinobacteria, Proteobacteria, Chloroflexi, Cyanophyta, and Bacteroidetes, were obtained from rhizosphere soils. For the 57 identified PHE gene sequences, 18 were excised from rhizosphere bacteria and 39 from endophytic bacteria. The copy numbers of 16S rRNA and PHE genes in rhizosphere and endophytic bacteria varied from 3.83 × 103 to 2.28 × 106 and 4.17 × 102 to 1.99 × 105, respectively. The copy numbers of PHE genes in rhizosphere bacteria were significantly higher than in endophytic bacteria. Results increase our understanding of the diversity of rhizosphere and endophytic bacteria from plants grown in PAH-contaminated sites.

Molecular Characterisation of Endophytic Fungi from Roots of Wild Banana (Musa acuminata)

PubMed Central

Zakaria, Latiffah; Jamil, Muhamad Izham Muhamad; Anuar, Intan Sakinah Mohd

2016-01-01

Endophytic fungi inhabit apparently healthy plant tissues and are prevalent in terrestrial plants, especially root tissues, which harbour a wide assemblage of fungal endophytes. Therefore, this study focused on the isolation and characterisation of endophytic fungi from the roots of wild banana (Musa acuminata). A total of 31 isolates of endophytic fungi were isolated from 80 root fragments. The endophytic fungi were initially sorted according to morphological characteristics and identified using the sequences of the translation elongation factor-1α (TEF-1α) gene of Fusarium spp. and the Internal Transcribed Spacer (ITS) regions of other fungi. The most common fungal isolates were species of the genus Fusarium, which were identified as F. proliferatum, Fusarium sp., F. solani species complex, and F. oxysporum. Other isolated endophytic fungi included Curvularia lunata, Trichoderma atroviride, Calonectria gracilis, Rhizoctonia solani, Bionectria ochroleuca, and Stromatoneurospora phoenix (Xylariceae). Several of the fungal genera, such as Fusarium, Trichoderma, Rhizoctonia, and Xylariceae, are among the common fungal endophytes reported in plants. This study showed that the roots of wild banana harbour a diverse group of endophytic fungi. PMID:27019688

Fungi with multifunctional lifestyles: endophytic insect pathogenic fungi.

PubMed

Barelli, Larissa; Moonjely, Soumya; Behie, Scott W; Bidochka, Michael J

2016-04-01

This review examines the symbiotic, evolutionary, proteomic and genetic basis for a group of fungi that occupy a specialized niche as insect pathogens as well as endophytes. We focus primarily on species in the genera Metarhizium and Beauveria, traditionally recognized as insect pathogenic fungi but are also found as plant symbionts. Phylogenetic evidence suggests that these fungi are more closely related to grass endophytes and diverged from that lineage ca. 100 MYA. We explore how the dual life cycles of these fungi as insect pathogens and endophytes are coupled. We discuss the evolution of insect pathogenesis while maintaining an endophytic lifestyle and provide examples of genes that may be involved in the transition toward insect pathogenicity. That is, some genes for insect pathogenesis may have been co-opted from genes involved in endophytic colonization. Other genes may be multifunctional and serve in both lifestyle capacities. We suggest that their evolution as insect pathogens allowed them to effectively barter a specialized nitrogen source (i.e. insects) with host plants for photosynthate. These ubiquitous fungi may play an important role as plant growth promoters and have a potential reservoir of secondary metabolites.

Gamma-irradiated bacterial preparation having anti-tumor activity

DOEpatents

Vass, Arpad A.; Tyndall, Richard L.; Terzaghi-Howe, Peggy

1999-01-01

A bacterial preparation from Pseudomonas species isolated #15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

Biosynthesis of Gold Nanoparticles Using Pseudomonas Aeruginosa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abd El-Aziz, M.; Badr, Y.; Mahmoud, M. A.

2007-02-14

Pseudomonas aeruginosa were used for extracellular biosynthesis of gold nanoparticles (Au NPs). Consequently, Au NPs were formed due to reduction of gold ion by bacterial cell supernatant of P. aeruginos ATCC 90271, P. aeruginos (2) and P. aeruginos (1). The UV-Vis. and fluorescence spectra of the bacterial as well as chemical prepared Au NPs were recorded. Transmission electron microscopy (TEM) micrograph showed the formation of well-dispersed gold nanoparticles in the range of 15-30 nm. The process of reduction being extracellular and may lead to the development of an easy bioprocess for synthesis of Au NPs.

Influence of nanophase titania topography on bacterial attachment and metabolism

PubMed Central

Park, Margaret R; Banks, Michelle K; Applegate, Bruce; Webster, Thomas J

2008-01-01

Surfaces with nanophase compared to conventional (or nanometer smooth) topographies are known to have different properties of area, charge, and reactivity. Previously published research indicates that the attachment of certain bacteria (such as Pseudomonas fluorescens 5RL) is higher on surfaces with nanophase compared to conventional topographies, however, their effect on bacterial metabolism is unclear. Results presented here show that the adhesion of Pseudomonas fluorescens 5RL and Pseudomonas putida TVA8 was higher on nanophase than conventional titania. Importantly, in terms of metabolism, bacteria attached to the nanophase surfaces had higher bioluminescence rates than on the conventional surfaces under all nutrient conditions. Thus, the results from this study show greater select bacterial metabolism on nanometer than conventional topographies, critical results with strong consequences for the design of improved biosensors for bacteria detection. PMID:19337418

Pervasive effects of wildfire on foliar endophyte communities in montane forest trees

PubMed Central

Huang, Yu-Ling; Devan, MM Nandi; U'Ren, Jana M.; Furr, Susan H.; Arnold, A. Elizabeth

2015-01-01

Plants in all terrestrial ecosystems form symbioses with endophytic fungi that inhabit their healthy tissues. How these foliar endophytes respond to wildfires has not been studied previously, but is important given the increasing frequency and intensity of severe wildfires in many ecosystems, and because endophytes can influence plant growth and responses to stress. The goal of this study was to examine effects of severe wildfires on endophyte communities in forest trees, with a focus on traditionally fire-dominated, montane ecosystems in the southwestern USA. We evaluated the abundance, diversity, and composition of endophytes in foliage of Juniperus deppeana (Cupressaceae) and Quercus spp. (Fagaceae) collected contemporaneously from areas affected by recent wildfire and paired areas not affected by recent fire. Study sites spanned four mountain ranges in central and southern Arizona. Our results revealed significant effects of fires on endophyte communities, including decreases in isolation frequency, increases in diversity, and shifts in community structure and taxonomic composition among endophytes of trees affected by recent fires. Responses to fire were similar in endophytes of each host in these fire-dominated ecosystems and reflect regional fire-return intervals, with endophytes after fire representing subsets of the regional mycoflora. Together these findings contribute to an emerging perspective on the responses of diverse communities to severe fire, and highlight the importance of considering fire history when estimating endophyte diversity and community structure for focal biomes. PMID:26370111

Host status of endophyte-infected and noninfected tall fescue grass to Meloidogyne spp.

USDA-ARS?s Scientific Manuscript database

Tall fescue grass cultivars with or without endophytes were evaluated for their susceptibility to Meloidogyne incognita in the greenhouse. Tall fescue cultivars evaluated included, i) wild-type Jesup (E+, ergot-producing endophyte present), ii) endophyte-free Jesup (E-, no endophyte present), iii) ...

Properties of Polyhydroxyalkanoate Granules and Bioemulsifiers from Pseudomonas sp. and Burkholderia sp. Isolates Growing on Glucose.

PubMed

Sacco, Laís Postai; Castellane, Tereza Cristina Luque; Lopes, Erica Mendes; de Macedo Lemos, Eliana Gertrudes; Alves, Lúcia Maria Carareto

2016-03-01

A Burkholderia and Pseudomonas species designated as AB4 and AS1, respectively, were isolated from soil containing decomposing straw or sugar cane bagasse collected from Brazil. This study sought to evaluate the capacities of culture media, cell-free medium, and crude lysate preparations (containing PHB inclusion bodies) from bacterial cell cultures to stabilize emulsions with several hydrophobic compounds. Four conditions showed good production of bioemulsifiers (E24 ≥ 50 %), headed by substantially cell-free media from bacterial cell cultures in which bacterial isolates from Burkholderia sp. strain AB4 and Pseudomonas sp. strain AS1 were grown. Our results revealed that the both isolates (AB4 and AS1 strains) exhibited high emulsification indices (indicating usefulness in bioremediation) and good stabilities.

The plant pathogenic fungus Gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain Pseudomonas fluorescens Pf29Arp.

PubMed

Barret, M; Frey-Klett, P; Boutin, M; Guillerm-Erckelboudt, A-Y; Martin, F; Guillot, L; Sarniguet, A

2009-01-01

In soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. Direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. An in vitro confrontation bioassay between the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) and the biocontrol bacterial strain Pseudomonas fluorescens Pf29Arp was set up to analyse bacterial transcriptional changes induced by the fungal mycelium at three time-points of the interaction before cell contact and up until contact. For this, a Pf29Arp shotgun DNA microarray was constructed. Specifity of Ggt effect was assessed in comparison with one of two other filamentous fungi, Laccaria bicolor and Magnaporthe grisea. During a commensal interaction, Ggt increased the growth rate of Pf29Arp. Before contact, Ggt induced bacterial genes involved in mycelium colonization. At contact, genes encoding protein of stress response and a patatin-like protein were up-regulated. Among all the bacterial genes identified, xseB was specifically up-regulated at contact by Ggt but down-regulated by the other fungi. Data showed that the bacterium sensed the presence of the fungus early, but the main gene alteration occurred during bacterial-fungal cell contact.

[Screening endophytic bacteria against plant-parasitic nematodes].

PubMed

Peng, Shuang; Yan, Shuzhen; Chen, Shuanglin

2011-03-01

Plant-parasite nematode is one of the most important pathogens in plant. Our objective is to screen endophytic bacteria against plant-parasitic nematodes from plant. Endophytic bacteria were isolated and screened by testing their metabolite against Bursaphelenchus xylophilus in vitro. Those strains inhibiting B. xylophilus were selected to culture in liquid medium and fermentation conditions were optimized by orthogonal test. The stability of the antinematode substances was evaluated by various. In addition, four strains were identified by 16SrDNA sequence analysis. In total 13 strains of endophytic bacteria secreting antinematode metabolite were isolated from 6 species of plant. The supernatant of the fermentation broth of these endophytic bacteria gave 100% mortality of nematodes after treated as the follows: 1 ml each was mixed with 0.2 ml of the suspension of nematodes (2000 nematodes/ml) then incubated at 250C for 24 h, some of which could led to leakage or dissolution of nematodes. Among them, four strains, BCM2, SZ5, CCM7 and DP1, showed stronger activity than others. The supernatants diluted three times also gave not less than 95% mortality after 24 h treatment, and those from DP1 and SZ5 even gave 100% mortality. The fermentation conditions of the four strains were optimized and the antinematode activity grew up four times after optimization. The antinematode substances of these strains were found stable when treated with protease or heating or stored at 4 degrees C after 100 days, while instable when treated with acid or alkali. DP1 and CCM7 were identified to be Bacillus subtilis, while SZ5 and BCM2 to be Bacillus cereus. Endophytic bacteria secreting antinematode metabolite were found in economic crops. The metabolite of some strains showed strong and stable antinematode activity. Our results indicate the real potential of biocontrol by endophytic bacteria.

Anti-MRSA activity of oxysporone and xylitol from the endophytic fungus Pestalotia sp. growing on the Sundarbans mangrove plant Heritiera fomes.

PubMed

Nurunnabi, Tauhidur Rahman; Nahar, Lutfun; Al-Majmaie, Shaymaa; Rahman, S M Mahbubur; Sohrab, Md Hossain; Billah, Md Morsaline; Ismail, Fyaz M D; Rahman, M Mukhlesur; Sharples, George P; Sarker, Satyajit D

2018-02-01

Heritiera fomes Buch.-Ham., a mangrove plant from the Sundarbans, has adapted to a unique habitat, muddy saline water, anaerobic soil, brackish tidal activities, and high microbial competition. Endophytic fungal association protects this plant from adverse environmental conditions. This plant is used in Bangladeshi folk medicine, but it has not been extensively studied phytochemically, and there is hardly any report on investigation on endophytic fungi growing on this plant. In this study, endophytic fungi were isolated from the surface sterilized cladodes and leaves of H. fomes. The antimicrobial activities were evaluated against two Gram-positive and two Gram-negative bacteria and the fungal strain, Candida albicans. Extracts of Pestalotia sp. showed activities against all test bacterial strains, except that the ethyl acetate extract was inactive against Escherichia coli. The structures of the purified compounds, oxysporone and xylitol, were elucidated by spectroscopic means. The anti-MRSA potential of the isolated compounds were determined against various MRSA strains, that is, ATCC 25923, SA-1199B, RN4220, XU212, EMRSA-15, and EMRSA-16, with minimum inhibitory concentration values ranging from 32 to 128 μg/ml. This paper, for the first time, reports on the anti-MRSA property of oxysporone and xylitol, isolation of the endophyte Pestalotia sp. from H. fomes, and isolation of xylitol from a Pestalotia sp. Copyright © 2017 John Wiley & Sons, Ltd.

Isolation of a rice endophytic bacterium, Pantoea sp. Sd-1, with ligninolytic activity and characterization of its rice straw degradation ability.

PubMed

Xiong, X Q; Liao, H D; Ma, J S; Liu, X M; Zhang, L Y; Shi, X W; Yang, X L; Lu, X N; Zhu, Y H

2014-02-01

This study focused on an endophytic bacterial strain, Pantoea sp. Sd-1, which can be used to degrade lignin and rice straw. This strain was isolated from rice seeds by an optimized surface sterilization method. Pantoea sp. Sd-1 showed exceptional ability to degrade rice straw and lignin. In rice straw or kraft lignin-containing medium supplemented with 1% glucose and 0.5% peptone, Pantoea sp. Sd-1 effectively reduced the rice straw mass weight by 54.5% after 6 days of treatment. The strain was also capable of reducing the lignin colour (52.4%) and content (69.1%) after 4 days of incubation. The findings suggested that the rice endophytic bacterium Pantoea sp. Sd-1 could be applied for the degradation of lignocellulose biomass, such as rice straw. Rice straw, an abundant agricultural by-product in China, is very difficult to degrade because of its high lignin content. Due to the immense environmental adaptability and biochemical versatility of bacteria, endophytic bacteria are useful resources for biodegradation. In this study, we screened for endophytic bacteria capable of biodegrading rice straw and lignin and obtained one strain, Pantoea sp. Sd-1, with suitable characteristics. Sd-1 could be used for degradation of rice straw and lignin, and may play an important role in biodegradation of this agricultural by-product. © 2013 The Society for Applied Microbiology.

Effect of bacterial components of mixed culture supernatants of planktonic and biofilm Pseudomonas aeruginosa with commensal Escherichia coli on the neutrophil response in vitro.

PubMed

Maslennikova, Irina L; Kuznetsova, Marina V; Nekrasova, Irina V; Shirshev, Sergei V

2017-11-30

Pseudomonas aeruginosa (PA) responsible for acute and chronic infections often forms a well-organized bacterial population with different microbial species including commensal strains of Escherichia coli. Bacterial extracellular components of mixed culture can modulate the influence of bacteria on the neutrophil functions. The objective of this study was to compare the effect of pyocyanin, pyoverdine, LPS, exopolysaccharide of single species and mixed culture supernatants of PA strains and E. coli K12 on microbicidal, secretory activity of human neutrophils in vitro. Bacterial components of E. coli K12 in mixed supernatants with 'biofilm' PA strains (PA ATCC, PA BALG) enhanced short-term microbicidal mechanisms and inhibited neutrophil secretion delayed in time. The influence of 'planktonic' PA (PA 9-3) exometabolites in mixed culture is almost mimicked by E. coli K12 effect on functional neutrophil changes. This investigation may help to understand some of the mechanisms of neutrophil response to mixed infections of different PA with other bacteria species. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Live cell imaging reveals extensive intracellular cytoplasmic colonization of banana by normally non-cultivable endophytic bacteria.

PubMed

Thomas, Pious; Sekhar, Aparna Chandra

2014-01-01

It is generally believed that endophytic microorganisms are intercellular inhabitants present in either cultivable or non-cultivable form primarily as root colonizers. The objective of this study was to determine whether the actively mobile micro-particles observed in the intracellular matrix of fresh tissue sections of banana included endophytic bacteria. Tissue sections (50-100 µm) from apical leaf sheaths of surface-disinfected suckers (cv. Grand Naine) displayed 'Brownian motion'-reminiscent abundant motile micro-particles under bright-field and phase-contrast (×1000), which appeared similar in size and motility to the pure cultures of endophytes previously isolated from banana. Observations on callus, embryonic cells and protoplasts with intact cell wall/plasma membrane confirmed their cytoplasmic nature. The motility of these entities reduced or ceased upon tissue fixation or staining with safranin/crystal violet (0.5 % w/v), but continued uninterrupted following treatment with actin-disrupting drugs, ruling out the possibility of micro-organelles like peroxisomes. Staining with 2,3,5-triphenyl tetrazolium chloride (TTC) confirmed them to be live bacteria with similar observations after dilute safranin (0.005 %) treatment. Tissue staining with SYTO-9 coupled with epi-fluorescence or confocal laser scanning microscopy showed bacterial colonization along the peri-space between cell wall and plasma membrane initially. SYTO-9 counterstaining on TTC- or safranin-treated tissue and those subjected to enzymatic permeabilization revealed the cytoplasmic bacteria. These included organisms moving freely in the cytoplasm and those adhering to the nuclear envelope or vacuoles and the intravacuolar colonizers. The observations appeared ubiquitous to different genomes and genotypes of banana. Plating the tissue homogenate on nutrient media seldom yielded colony growth. This study, supported largely by live cell video-imaging, demonstrates enormous intracellular

Live cell imaging reveals extensive intracellular cytoplasmic colonization of banana by normally non-cultivable endophytic bacteria

PubMed Central

Thomas, Pious; Sekhar, Aparna Chandra

2014-01-01

It is generally believed that endophytic microorganisms are intercellular inhabitants present in either cultivable or non-cultivable form primarily as root colonizers. The objective of this study was to determine whether the actively mobile micro-particles observed in the intracellular matrix of fresh tissue sections of banana included endophytic bacteria. Tissue sections (50–100 µm) from apical leaf sheaths of surface-disinfected suckers (cv. Grand Naine) displayed ‘Brownian motion’-reminiscent abundant motile micro-particles under bright-field and phase-contrast (×1000), which appeared similar in size and motility to the pure cultures of endophytes previously isolated from banana. Observations on callus, embryonic cells and protoplasts with intact cell wall/plasma membrane confirmed their cytoplasmic nature. The motility of these entities reduced or ceased upon tissue fixation or staining with safranin/crystal violet (0.5 % w/v), but continued uninterrupted following treatment with actin-disrupting drugs, ruling out the possibility of micro-organelles like peroxisomes. Staining with 2,3,5-triphenyl tetrazolium chloride (TTC) confirmed them to be live bacteria with similar observations after dilute safranin (0.005 %) treatment. Tissue staining with SYTO-9 coupled with epi-fluorescence or confocal laser scanning microscopy showed bacterial colonization along the peri-space between cell wall and plasma membrane initially. SYTO-9 counterstaining on TTC- or safranin-treated tissue and those subjected to enzymatic permeabilization revealed the cytoplasmic bacteria. These included organisms moving freely in the cytoplasm and those adhering to the nuclear envelope or vacuoles and the intravacuolar colonizers. The observations appeared ubiquitous to different genomes and genotypes of banana. Plating the tissue homogenate on nutrient media seldom yielded colony growth. This study, supported largely by live cell video-imaging, demonstrates enormous intracellular

Cultured bacterial diversity and human impact on alpine glacier cryoconite.

PubMed

Lee, Yung Mi; Kim, So-Yeon; Jung, Jia; Kim, Eun Hye; Cho, Kyeung Hee; Schinner, Franz; Margesin, Rosa; Hong, Soon Gyu; Lee, Hong Kum

2011-06-01

The anthropogenic effect on the microbial communities in alpine glacier cryoconites was investigated by cultivation and physiological characterization of bacteria from six cryoconite samples taken at sites with different amounts of human impact. Two hundred and forty seven bacterial isolates were included in Actinobacteria (9%, particularly Arthrobacter), Bacteroidetes (14%, particularly Olleya), Firmicutes (0.8%), Alphaproteobacteria (2%), Betaproteobacteria (16%, particularly Janthinobacterium), and Gammaproteobacteria (59%, particularly Pseudomonas). Among them, isolates of Arthrobacter were detected only in samples from sites with no human impact, while isolates affiliated with Enterobacteriaceae were detected only in samples from sites with strong human impact. Bacterial isolates included in Actinobacteria and Bacteroidetes were frequently isolated from pristine sites and showed low maximum growth temperature and enzyme secretion. Bacterial isolates included in Gammaproteobacteria were more frequently isolated from sites with stronger human impact and showed high maximum growth temperature and enzyme secretion. Ecotypic differences were not evident among isolates of Janthinobacterium lividum, Pseudomonas fluorescens, and Pseudomonas veronii, which were frequently isolated from sites with different degrees of anthropogenic effect.

Antioxidant, antihypertensive, and antibacterial properties of endophytic Pestalotiopsis species from medicinal plants.

PubMed

Tejesvi, Mysore V; Kini, Kukkundoor R; Prakash, Harishchandra S; Subbiah, Ven; Shetty, Hunthrike S

2008-09-01

Pestalotiopsis species were most dominant endophytic species isolated from four medicinal plants including Terminalia arjuna, Terminalia chebula, Azadirachta indica, and Holarrhena antidysenterica. Thirty Pestalotiopsis species isolated from different parts of the medicinal plants were selected for the study. The antioxidant and antihypertensive properties of Pestalotiopsis isolates were determined by measuring 1,1-diphenyl-2-picrylhydrazyl inhibitory activity, lipid peroxidation, and angiotensin-converting enzyme inhibition activity. Pestalotiopsis isolates of T. arjuna origin exhibited maximum radical scavenging activity compared with the others. The IC50 values of Pestalotiopsis extracts for 1,1-diphenyl-2-picrylhydrazyl scavenging activity ranged from 14 to 27 microg/mL compared with 15 and 6 microg/mL for butylated hydroxytoluene and ascorbic acid, respectively. The DNA damage study was also done for three isolates, TC-315, TA-37, and TA-60; TA-37 gave 80% protection. The IC50 values of Pestalotiopsis extracts for lipid peroxidation ranged between 30 and 35.5 microg/mL, while for the positive control butylated hydroxytoluene, it was 26 microg/mL. Out of 32 fungal extracts screened for antihypertensive assay, five (TA-37, TA-60, TA-102, TA-103, and TC-320) showed >60% inhibition of angiotensin-converting enzyme. The IC50 values for five extracts ranged from 21 to 37 microg/mL and was 20 microg/mL for captopril used as a positive control. The antibacterial activity was measured by the microplate-based turbidity measurement method. Four Pestalotiopsis extracts (TA-04, TA-37, TA-60, and TA-102) showed >75% inhibition against five bacterial strains including Bacillus subtilis, Escherichia coli, Pseudomonas fluorescens, Xanthomonas axonopodis pv. malvacearum, and Staphylococcus aureus. The antioxidant, antibacterial, and antihypertensive activities demonstrated the potential of Pestalotiopsis extracts as therapeutic targets.

Geographic Variation in Festuca rubra L. Ploidy Levels and Systemic Fungal Endophyte Frequencies.

PubMed

Dirihan, Serdar; Helander, Marjo; Väre, Henry; Gundel, Pedro E; Garibaldi, Lucas A; Irisarri, J Gonzalo N; Saloniemi, Irma; Saikkonen, Kari

2016-01-01

Polyploidy and symbiotic Epichloë fungal endophytes are common and heritable characteristics that can facilitate environmental range expansion in grasses. Here we examined geographic patterns of polyploidy and the frequency of fungal endophyte colonized plants in 29 Festuca rubra L. populations from eight geographic sites across latitudes from Spain to northernmost Finland and Greenland. Ploidy seemed to be positively and negatively correlated with latitude and productivity, respectively. However, the correlations were nonlinear; 84% of the plants were hexaploids (2n = 6x = 42), and the positive correlation between ploidy level and latitude is the result of only four populations skewing the data. In the southernmost end of the gradient 86% of the plants were tetraploids (2n = 4x = 28), whereas in the northernmost end of the gradient one population had only octoploid plants (2n = 8x = 56). Endophytes were detected in 22 out of the 29 populations. Endophyte frequencies varied among geographic sites, and populations and habitats within geographic sites irrespective of ploidy, latitude or productivity. The highest overall endophyte frequencies were found in the southernmost end of the gradient, Spain, where 69% of plants harbored endophytes. In northern Finland, endophytes were detected in 30% of grasses but endophyte frequencies varied among populations from 0% to 75%, being higher in meadows compared to riverbanks. The endophytes were detected in 36%, 30% and 27% of the plants in Faroe Islands, Iceland and Switzerland, respectively. Practically all examined plants collected from southern Finland and Greenland were endophyte-free, whereas in other geographic sites endophyte frequencies were highly variable among populations. Common to all populations with high endophyte frequencies is heavy vertebrate grazing. We propose that the detected endophyte frequencies and ploidy levels mirror past distribution history of F. rubra after the last glaciation period, and local

Geographic Variation in Festuca rubra L. Ploidy Levels and Systemic Fungal Endophyte Frequencies

PubMed Central

Dirihan, Serdar; Helander, Marjo; Väre, Henry; Gundel, Pedro E.; Garibaldi, Lucas A.; Irisarri, J. Gonzalo N.; Saloniemi, Irma; Saikkonen, Kari

2016-01-01

Polyploidy and symbiotic Epichloë fungal endophytes are common and heritable characteristics that can facilitate environmental range expansion in grasses. Here we examined geographic patterns of polyploidy and the frequency of fungal endophyte colonized plants in 29 Festuca rubra L. populations from eight geographic sites across latitudes from Spain to northernmost Finland and Greenland. Ploidy seemed to be positively and negatively correlated with latitude and productivity, respectively. However, the correlations were nonlinear; 84% of the plants were hexaploids (2n = 6x = 42), and the positive correlation between ploidy level and latitude is the result of only four populations skewing the data. In the southernmost end of the gradient 86% of the plants were tetraploids (2n = 4x = 28), whereas in the northernmost end of the gradient one population had only octoploid plants (2n = 8x = 56). Endophytes were detected in 22 out of the 29 populations. Endophyte frequencies varied among geographic sites, and populations and habitats within geographic sites irrespective of ploidy, latitude or productivity. The highest overall endophyte frequencies were found in the southernmost end of the gradient, Spain, where 69% of plants harbored endophytes. In northern Finland, endophytes were detected in 30% of grasses but endophyte frequencies varied among populations from 0% to 75%, being higher in meadows compared to riverbanks. The endophytes were detected in 36%, 30% and 27% of the plants in Faroe Islands, Iceland and Switzerland, respectively. Practically all examined plants collected from southern Finland and Greenland were endophyte-free, whereas in other geographic sites endophyte frequencies were highly variable among populations. Common to all populations with high endophyte frequencies is heavy vertebrate grazing. We propose that the detected endophyte frequencies and ploidy levels mirror past distribution history of F. rubra after the last glaciation period, and local

Tall fescue management: Pasture and cattle responses to endophyte and fertilization

USDA-ARS?s Scientific Manuscript database

Yearling heifers grazing tall fescue pastures had greatest performance in winter and spring on endophyte-free and novel endophyte associations, because of high forage quality and lack of ergot alkaloids produced by a common “wild” tall fescue-endophyte association. Pasture and cattle responses were...

[Isolation and diversity analyses of endophytic fungi from Paris polyphylla var. yunnanensis].

PubMed

Wang, Qian; Shen, Shi-Kang; Zhang, Ai-Li; Wu, Chun-Yan; Wu, Fu-Qin; Zhang, Xin-Jun; Wang, Yue-Hua

2013-11-01

The paper is aimed at studying the diversity of endophytic fungi community from Paris polyphylla var. yunnanensis, and to provide a scientific basis for the utilization value of the endophytic fungi as bioactive material resources. In the present study, endophytic fungi were isolated from roots, rhizomes and leaves of wild P. polyphylla var. yunnanensis collected from Baoshan, Heqing county and Songming city of Yunnan province, and identified and classified by morphological methods together with its ITS sequence analysis. Seven and forty-nine strains of endophytic fungi were isolated from P. polyphylla var. yunnanensis. They were identified belonging to 41 genus. In these 41 genus, 3 genus exist in root only, 12 genus only exist in rhizome and 8 genus only exist in leaf. There was difference in endophytic fungi isolated from different sample sites. Endophytic fungi diversity from rhizomes of Heqing site was the highest. Endophytic fungi similarity coefficient was low among different sites and tissues. Based on these results, it is reasonable to propose that endophytic fungi of P. polyphylla var. yannanensis from different tissue and different sample sites has a certain difference which is possibly relate to their different habitats, different structure and composition of each tissue.

The defensive role of foliar endophytic fungi for a South American tree

PubMed Central

González-Teuber, Marcia

2016-01-01

Fungal endophytes colonize living internal plant tissues without causing any visible symptoms of disease. Endophytic fungi associated with healthy leaves may play an important role in the protection of hosts against herbivores and pathogens. In this study, the diversity of foliar endophytic fungi (FEF) of the southern temperate tree Embothrium coccineum (Proteaceae), as well as their role in plant protection in nature was determined. Fungal endophytes were isolated from 40 asymptomatic leaves by the culture method for molecular identification of the 18S rRNA gene. A relationship between FEF frequency and plant protection was evaluated in juveniles of E. coccineum. Fungal endophyte frequency was estimated using real-time PCR analyses to determine endophyte DNA content per plant. A total of 178 fungal isolates were identified, with sequence data revealing 34 different operational taxonomic units (OTUs). A few common taxa dominated the fungal endophyte community, whereas most taxa qualified as rare. A significant positive correlation between plant protection (evaluated in terms of percentage of leaf damage) and FEF frequency was found. Furthermore, in vitro confrontation assays indicated that FEF were able to inhibit the growth of fungal pathogens. The data showed a relatively high diversity of fungal endophytes associated with leaves of E. coccineum, and suggest a positive relationship between fungal endophyte frequencies in leaves and host protection in nature. PMID:27339046

[Diversity and community structure of endophytic fungi from Taxus chinensis var. mairei].

PubMed

2014-07-01

A total of 628 endophytic fungi were isolated from 480 tissue segments of needles and branches of Taxus chinensis var. mairei. According to morphological characteristics and ITS sequences, they represented 43 taxa in 28 genera, of which 10 Hyphomycetes, 20 Coelomycetes, 12 Ascomycetes and 1 unknown fungus. Phomopsis mali was confirmed as the dominant species. In accordance with relative frequency, Alternaria alternata, Aureobasidium pullulans, Colletotrichum boninense, C. gloeosporioides, Epicoccum nigrum , Fungal sp., Fusarium lateritium, Glomerella cingulata, Magnaporthales sp. , Nigrospora oryzae, Pestalotiopsis maculiformans, P. microspora, Peyronellaea glomerata and Xylaria sp. 1 were more common in T. chinensis var. mairei. T. chinensis var. mairei were severely infected by endophytic fungi. Endophytic fungi were found in 81 percent of plant tissues with a high diversity. Distribution ranges of endophytic fungi were influenced by tissue properties. The colonization rate, richness, diversity of endophytic fungi in needles were obviously lower than in branches, and kinds of endophytic fungi between branches were more similar than those in needles, thus endophytic fungi had tissue preference. In addition, tissue age influenced the community structure of endophytic fungi. The elder branch tissues were, the higher colonization rate, richness, diversity of endophytic fungi were. Systematic studying the diversity and community structure of endophytic fungi in T. chinensis var. mairei and clarifying their distribution regularity in plant tissues would offer basic data and scientific basis for their development and utilization. Discussing the presence of fungal pathogens in healthy plant tissues would be of positive significance for source protection of T. chinensis var. mairei.

Antimicrobial activities of endophytic fungi obtained from the arid zone invasive plant Opuntia dillenii and the isolation of equisetin, from endophytic Fusarium sp.

PubMed

Ratnaweera, Pamoda B; de Silva, E Dilip; Williams, David E; Andersen, Raymond J

2015-07-10

Opuntia dillenii is an invasive plant well established in the harsh South-Eastern arid zone of Sri Lanka. Evidence suggests it is likely that the endophytic fungal populations of O. dillenii assist the host in overcoming biotic and abiotic stress by producing biologically active metabolites. With this in mind there is potential to discover novel natural products with useful biological activities from this hitherto poorly investigated source. Consequently, an investigation of the antimicrobial activities of the endophytes of O. dillenii, that occupies a unique ecological niche, may well provide useful leads in the discovery of new pharmaceuticals. Endophytic fungi were isolated from the surface sterilized cladodes and flowers of O. dillenii using several nutrient media and the antimicrobial activities were evaluated against three Gram-positive and two Gram-negative bacteria and Candida albicans. The two most bioactive fungi were identified by colony morphology and DNA sequencing. The secondary metabolite of the endophyte Fusarium sp. exhibiting the best activity was isolated via bioassay guided chromatography. The chemical structure was elucidated from the ESIMS and NMR spectroscopic data obtained for the active metabolite. The minimum inhibitory concentrations (MICs) of the active compound were determined. Eight endophytic fungi were isolated from O. dillenii and all except one showed antibacterial activities against at least one of the test bacteria. All extracts were inactive against C. albicans. The most bioactive fungus was identified as Fusarium sp. and the second most active as Aspergillus niger. The structure of the major antibacterial compound of the Fusarium sp. was shown to be the tetramic acid derivative, equisetin. The MIC's for equisetin were 8 μg mL(-1) against Bacillus subtilis, 16 μg mL(-1) against Staphylococcus aureus and Methicillin Resistant Staphylococcus aureus (MRSA). O. dillenii, harbors several endophytic fungi capable of producing

Biofilm formation and cellulose expression among diverse environmental Pseudomonas isolates.

PubMed

Ude, Susanne; Arnold, Dawn L; Moon, Christina D; Timms-Wilson, Tracey; Spiers, Andrew J

2006-11-01

The ability to form biofilms is seen as an increasingly important colonization strategy among both pathogenic and environmental bacteria. A survey of 185 plant-associated, phytopathogenic, soil and river Pseudomonas isolates resulted in 76% producing biofilms at the air-liquid (A-L) interface after selection in static microcosms. Considerable variation in biofilm phenotype was observed, including waxy aggregations, viscous and floccular masses, and physically cohesive biofilms with continuously varying strengths over 1500-fold. Calcofluor epifluorescent microscopy identified cellulose as the matrix component in biofilms produced by Pseudomonas asplenii, Pseudomonas corrugata, Pseudomonas fluorescens, Pseudomonas marginalis, Pseudomonas putida, Pseudomonas savastanoi and Pseudomonas syringae isolates. Cellulose expression and biofilm formation could be induced by the constitutively active WspR19 mutant of the cyclic-di-GMP-associated, GGDEF domain-containing response regulator involved in the P. fluorescens SBW25 wrinkly spreader phenotype and cellular aggregation in Pseudomonas aeruginosa PA01. WspR19 could also induce P. putida KT2440, which otherwise did not produce a biofilm or express cellulose, as well as Escherichia coli K12 and Salmonella typhimurium LT2, both of which express cellulose yet lack WspR homologues. Statistical analysis of biofilm parameters suggest that biofilm development is a more complex process than that simply described by the production of attachment and matrix components and bacterial growth. This complexity was also seen in multivariate analysis as a species-ecological habitat effect, underscoring the fact that in vitro biofilms are abstractions of those surface and volume colonization processes used by bacteria in their natural environments.

Anaerobic oxidation of 2-chloroethanol under denitrifying conditions by Pseudomonas stutzeri strain JJ.

PubMed

Dijk, J A; Stams, A J M; Schraa, G; Ballerstedt, H; de Bont, J A M; Gerritse, J

2003-11-01

A bacterium that uses 2-chloroethanol as sole energy and carbon source coupled to denitrification was isolated from 1,2-dichloroethane-contaminated soil. Its 16 S rDNA sequence showed 98% similarity with the type strain of Pseudomonas stutzeri (DSM 5190) and the isolate was tentatively identified as Pseudomonas stutzeri strain JJ. Strain JJ oxidized 2-chloroethanol completely to CO(2) with NO(3)(- )or O(2) as electron acceptor, with a preference for O(2) if supplied in combination. Optimum growth on 2-chloroethanol with nitrate occurred at 30 degrees C with a mu(max) of 0.14 h(-1) and a yield of 4.4 g protein per mol 2-chloroethanol metabolized. Under aerobic conditions, the mu(max) was 0.31 h(-1). NO(2)(-) also served as electron acceptor, but reduction of Fe(OH)(3), MnO(2), SO(4)(2-), fumarate or ClO(3)(-) was not observed. Another chlorinated compound used as sole energy and carbon source under aerobic and denitrifying conditions was chloroacetate. Various different bacterial strains, including some closely related Pseudomonas stutzeri strains, were tested for their ability to grow on 2-chloroethanol as sole energy and carbon source under aerobic and denitrifying conditions, respectively. Only three strains, Pseudomonas stutzeri strain LMD 76.42, Pseudomonas putida US2 and Xanthobacter autotrophicus GJ10, grew aerobically on 2-chloroethanol. This is the first report of oxidation of 2-chloroethanol under denitrifying conditions by a pure bacterial culture.

Nitrogen signalling in plant interactions with associative and endophytic diazotrophic bacteria.

PubMed

Carvalho, T L G; Balsemão-Pires, E; Saraiva, R M; Ferreira, P C G; Hemerly, A S

2014-10-01

Some beneficial plant-interacting bacteria can biologically fix N2 to plant-available ammonium. Biological nitrogen fixation (BNF) is an important source of nitrogen (N) input in agriculture and represents a promising substitute for chemical N fertilizers. Diazotrophic bacteria have the ability to develop different types of root associations with different plant species. Among the highest rates of BNF are those measured in legumes nodulated by endosymbionts, an already very well documented model of plant-diazotrophic bacterial association. However, it has also been shown that economically important crops, especially monocots, can obtain a substantial part of their N needs from BNF by interacting with associative and endophytic diazotrophic bacteria, that either live near the root surface or endophytically colonize intercellular spaces and vascular tissues of host plants. One of the best reported outcomes of this association is the promotion of plant growth by direct and indirect mechanisms. Besides fixing N, these bacteria can also produce plant growth hormones, and some species are reported to improve nutrient uptake and increase plant tolerance against biotic and abiotic stresses. Thus, this particular type of plant-bacteria association consists of a natural beneficial system to be explored; however, the regulatory mechanisms involved are still not clear. Plant N status might act as a key signal, regulating and integrating various metabolic processes that occur during association with diazotrophic bacteria. This review will focus on the recent progress in understanding plant association with associative and endophytic diazotrophic bacteria, particularly on the knowledge of the N networks involved in BNF and in the promotion of plant growth. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Endophytic Fusarium spp. from Roots of Lawn Grass (Axonopus compressus)

PubMed Central

Zakaria, Latiffah; Ning, Chua Harn

2013-01-01

Fungal endophytes are found inside host plants but do not produce any noticeable disease symptoms in their host. In the present study, endophytic Fusarium species were isolated from roots of lawn grass (Axonopus compressus). A total of 51 isolates were recovered from 100 root segments. Two Fusarium species, F. oxysporum (53%) and F. solani (47%), were identified based on macroconidia and conidiogenous cell morphology. The detection of endophytic F. oxysporum and F. solani in the roots of lawn grass contributes to the knowledge of both the distribution of the two Fusarium species and the importance of roots as endophytic niches for Fusarium species. PMID:24575251

Indigenous Pseudomonas spp. Strains from the Olive (Olea europaea L.) Rhizosphere as Effective Biocontrol Agents against Verticillium dahliae: From the Host Roots to the Bacterial Genomes

PubMed Central

Gómez-Lama Cabanás, Carmen; Legarda, Garikoitz; Ruano-Rosa, David; Pizarro-Tobías, Paloma; Valverde-Corredor, Antonio; Niqui, José L.; Triviño, Juan C.; Roca, Amalia; Mercado-Blanco, Jesús

2018-01-01

The use of biological control agents (BCA), alone or in combination with other management measures, has gained attention over the past decades, driven by the need to seek for sustainable and eco-friendly alternatives to confront plant pathogens. The rhizosphere of olive (Olea europaea L.) plants is a source of bacteria with potential as biocontrol tools against Verticillium wilt of olive (VWO) caused by Verticillium dahliae Kleb. A collection of bacterial isolates from healthy nursery-produced olive (cultivar Picual, susceptible to VWO) plants was generated based on morphological, biochemical and metabolic characteristics, chemical sensitivities, and on their in vitro antagonistic activity against several olive pathogens. Three strains (PIC25, PIC105, and PICF141) showing high in vitro inhibition ability of pathogens' growth, particularly against V. dahliae, were eventually selected. Their effectiveness against VWO caused by the defoliating pathotype of V. dahliae was also demonstrated, strain PICF141 being the rhizobacteria showing the best performance as BCA. Genotypic and phenotypic traits traditionally associated with plant growth promotion and/or biocontrol abilities were evaluated as well (e.g., phytase, xylanase, catalase, cellulase, chitinase, glucanase activities, and siderophore and HCN production). Multi-locus sequence analyses of conserved genes enabled the identification of these strains as Pseudomonas spp. Strain PICF141 was affiliated to the “Pseudomonas mandelii subgroup,” within the “Pseudomonas fluorescens group,” Pseudomonas lini being the closest species. Strains PIC25 and PIC105 were affiliated to the “Pseudomonas aeruginosa group,” Pseudomonas indica being the closest relative. Moreover, we identified P. indica (PIC105) for the first time as a BCA. Genome sequencing and in silico analyses allowed the identification of traits commonly associated with plant-bacteria interactions. Finally, the root colonization ability of these olive

Indigenous Pseudomonas spp. Strains from the Olive (Olea europaea L.) Rhizosphere as Effective Biocontrol Agents against Verticillium dahliae: From the Host Roots to the Bacterial Genomes.

PubMed

Gómez-Lama Cabanás, Carmen; Legarda, Garikoitz; Ruano-Rosa, David; Pizarro-Tobías, Paloma; Valverde-Corredor, Antonio; Niqui, José L; Triviño, Juan C; Roca, Amalia; Mercado-Blanco, Jesús

2018-01-01

The use of biological control agents (BCA), alone or in combination with other management measures, has gained attention over the past decades, driven by the need to seek for sustainable and eco-friendly alternatives to confront plant pathogens. The rhizosphere of olive ( Olea europaea L.) plants is a source of bacteria with potential as biocontrol tools against Verticillium wilt of olive (VWO) caused by Verticillium dahliae Kleb. A collection of bacterial isolates from healthy nursery-produced olive (cultivar Picual, susceptible to VWO) plants was generated based on morphological, biochemical and metabolic characteristics, chemical sensitivities, and on their in vitro antagonistic activity against several olive pathogens. Three strains (PIC25, PIC105, and PICF141) showing high in vitro inhibition ability of pathogens' growth, particularly against V. dahliae , were eventually selected. Their effectiveness against VWO caused by the defoliating pathotype of V. dahliae was also demonstrated, strain PICF141 being the rhizobacteria showing the best performance as BCA. Genotypic and phenotypic traits traditionally associated with plant growth promotion and/or biocontrol abilities were evaluated as well (e.g., phytase, xylanase, catalase, cellulase, chitinase, glucanase activities, and siderophore and HCN production). Multi-locus sequence analyses of conserved genes enabled the identification of these strains as Pseudomonas spp. Strain PICF141 was affiliated to the " Pseudomonas mandelii subgroup," within the " Pseudomonas fluorescens group," Pseudomonas lini being the closest species. Strains PIC25 and PIC105 were affiliated to the " Pseudomonas aeruginosa group," Pseudomonas indica being the closest relative. Moreover, we identified P. indica (PIC105) for the first time as a BCA. Genome sequencing and in silico analyses allowed the identification of traits commonly associated with plant-bacteria interactions. Finally, the root colonization ability of these olive

Successful phytoremediation of crude-oil contaminated soil at an oil exploration and production company by plants-bacterial synergism.

PubMed

Fatima, Kaneez; Imran, Asma; Amin, Imran; Khan, Qaiser M; Afzal, Muhammad

2018-06-07

Phytoremediation is a promising approach for the cleanup of soil contaminated with petroleum hydrocarbons. This study aimed to develop plant-bacterial synergism for the successful remediation of crude oil-contaminated soil. A consortia of three endophytic bacteria was augmented to two grasses, Leptochloa fusca and Brachiaria mutica, grown in oil-contaminated soil (46.8 g oil kg -1 soil) in the vicinity of an oil exploration and production company. Endophytes augmentation improved plant growth, crude oil degradation, and soil health. Maximum oil degradation (80%) was achieved with B. mutica plants augmented with the endophytes and it was significantly (P < 0.05) higher than the use of plants or bacteria individually. Moreover, endophytes showed more persistence, the abundance and expression of alkB gene in the rhizosphere as well as in the endosphere of the tested plants than in unvegetated soil. A positive relationship (r = 0.70) observed between gene expression and crude oil reduction indicates that catabolic gene expression is important for hydrocarbon mineralization. This investigation showed that the use of endophytes with appropriate plant is an effective strategy for the cleanup of oil-contaminated soil under field conditions.

The Biology and Biological Activity of Pseudomonas syringae pv. tagetis

USDA-ARS?s Scientific Manuscript database

Pseudomonas syringae pv. tagetis (Pst) is a disease of plants in the family Asteraceae. A distinctive characteristic of this bacterial pathogen is the symptom of apical chlorosis in infected plants, caused by the phytotoxin tagetitoxin. Strains of Pst have been isolated from several plant species ...

Recent Insights into the Diversity, Frequency and Ecological Roles of Phenazines in Fluorescent Pseudomonas spp.

USDA-ARS?s Scientific Manuscript database

Phenazine compounds represent a large class of bacterial metabolites that are produced by some fluorescent Pseudomonas spp. and a few other bacterial genera. Phenazines were first noted in the scientific literature over 100 years ago, but for a long time were considered to be pigments of uncertain f...

Antibiofilm and Anti-Infection of a Marine Bacterial Exopolysaccharide Against Pseudomonas aeruginosa

PubMed Central

Wu, Shimei; Liu, Ge; Jin, Weihua; Xiu, Pengyuan; Sun, Chaomin

2016-01-01

Pseudomonas aeruginosa is a well-known pathogenic bacterium that forms biofilms and produces virulence factors, thus leading to major problems in many fields, such as clinical infection, food contamination, and marine biofouling. In this study, we report the purification and characterization of an exopolysaccharide EPS273 from the culture supernatant of marine bacterium P. stutzeri 273. The exopolysaccharide EPS273 not only effectively inhibits biofilm formation but also disperses preformed biofilm of P. aeruginosa PAO1. High performance liquid chromatography traces of the hydrolyzed polysaccharides shows that EPS273 primarily consists of glucosamine, rhamnose, glucose and mannose. Further investigation demonstrates that EPS273 reduces the production of the virulence factors pyocyanin, exoprotease, and rhamnolipid, and the virulence of P. aeruginosa PAO1 to human lung cells A549 and zebrafish embryos is also obviously attenuated by EPS273. In addition, EPS273 also greatly reduces the production of hydrogen peroxide (H2O2) and extracellular DNA (eDNA), which are important factors for biofilm formation. Furthermore, EPS273 exhibits strong antioxidant potential by quenching hydroxyl and superoxide anion radicals. Notably, the antibiofouling activity of EPS273 is observed in the marine environment up to 2 weeks according to the amounts of bacteria and diatoms in the glass slides submerged in the ocean. Taken together, the properties of EPS273 indicate that it has a promising prospect in combating bacterial biofilm-associated infection, food-processing contamination and marine biofouling. PMID:26903981

Gamma-irradiated bacterial preparation having anti-tumor activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vass, A.A.; Tyndall, R.L.; Terzaghi-Howe, P.

1999-11-16

This application describes a bacterial preparation from Pseudomonas species isolated {number{underscore}sign}15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

Biodiversity, Phylogeny, and Antifungal Functions of Endophytic Fungi Associated with Zanthoxylum bungeanum.

PubMed

Li, Peiqin; Wu, Zhou; Liu, Tao; Wang, Yanan

2016-09-13

This study investigated the biodiversity, phylogeny, and antifungal activity of endophytic fungi isolated from Zanthoxylum bungeanum. A total of 940 isolates obtained were grouped into 93 morphotypes, 43 species, and 23 genera, which were authenticated by molecular identification based on rDNA internal transcribed spacer (ITS) sequence analysis. A high diversity of endophytic fungi from Z. bungeanum are observed with high species richness S (43), Margalef index D' (6.1351), Shannon-Wiener index H' (3.2743), Simpson diversity index Ds (0.9476), PIE index (0.9486), and evenness Pielou index J (0.8705) but a low dominant index λ (0.0524). Significant tissue specificity of the endophytic fungi was observed in Z. bungeanum, and the highest species richness and diversity indexes were obtained in the stem. Phylogenetic analyses of the 93 endophytic isolates were carried out by the neighbor-joining (NJ) method to demonstrate their evolutionary processes. Antifungal activities of endophytic fungi were assayed and eight endophytic isolates showed strong and long-lasting inhibition against host pathogenic fungi Fusarium sambucinum and Pseudocercospora zanthoxyli. Here, for the first time, we systematically demonstrate the biodiversity, phylogeny, and antifungal activity of endophytic fungi associated with Z. bungeanum and reveal the value of sampling different tissues of a given plant to obtain the greatest endophyte species diversity, which might offer a framework for further investigation and utilization of endophytic fungi as aunique source of interesting and useful bioactive compounds.

Biodiversity, Phylogeny, and Antifungal Functions of Endophytic Fungi Associated with Zanthoxylum bungeanum

PubMed Central

Li, Peiqin; Wu, Zhou; Liu, Tao; Wang, Yanan

2016-01-01

This study investigated the biodiversity, phylogeny, and antifungal activity of endophytic fungi isolated from Zanthoxylum bungeanum. A total of 940 isolates obtained were grouped into 93 morphotypes, 43 species, and 23 genera, which were authenticated by molecular identification based on rDNA internal transcribed spacer (ITS) sequence analysis. A high diversity of endophytic fungi from Z. bungeanum are observed with high species richness S (43), Margalef index D′ (6.1351), Shannon–Wiener index H′ (3.2743), Simpson diversity index Ds (0.9476), PIE index (0.9486), and evenness Pielou index J (0.8705) but a low dominant index λ (0.0524). Significant tissue specificity of the endophytic fungi was observed in Z. bungeanum, and the highest species richness and diversity indexes were obtained in the stem. Phylogenetic analyses of the 93 endophytic isolates were carried out by the neighbor-joining (NJ) method to demonstrate their evolutionary processes. Antifungal activities of endophytic fungi were assayed and eight endophytic isolates showed strong and long-lasting inhibition against host pathogenic fungi Fusarium sambucinum and Pseudocercospora zanthoxyli. Here, for the first time, we systematically demonstrate the biodiversity, phylogeny, and antifungal activity of endophytic fungi associated with Z. bungeanum and reveal the value of sampling different tissues of a given plant to obtain the greatest endophyte species diversity, which might offer a framework for further investigation and utilization of endophytic fungi as aunique source of interesting and useful bioactive compounds. PMID:27649145

Endohyphal Bacterium Enhances Production of Indole-3-Acetic Acid by a Foliar Fungal Endophyte

PubMed Central

Hoffman, Michele T.; Gunatilaka, Malkanthi K.; Wijeratne, Kithsiri; Gunatilaka, Leslie; Arnold, A. Elizabeth

2013-01-01

Numerous plant pathogens, rhizosphere symbionts, and endophytic bacteria and yeasts produce the important phytohormone indole-3-acetic acid (IAA), often with profound effects on host plants. However, to date IAA production has not been documented among foliar endophytes -- the diverse guild of primarily filamentous Ascomycota that live within healthy, above-ground tissues of all plant species studied thus far. Recently bacteria that live within hyphae of endophytes (endohyphal bacteria) have been detected, but their effects have not been studied previously. Here we show not only that IAA is produced in vitro by a foliar endophyte (here identified as Pestalotiopsis aff. neglecta, Xylariales), but that IAA production is enhanced significantly when the endophyte hosts an endohyphal bacterium (here identified as Luteibacter sp., Xanthomonadales). Both the endophyte and the endophyte/bacterium complex appear to rely on an L-tryptophan dependent pathway for IAA synthesis. The bacterium can be isolated from the fungus when the symbiotic complex is cultivated at 36°C. In pure culture the bacterium does not produce IAA. Culture filtrate from the endophyte-bacterium complex significantly enhances growth of tomato in vitro relative to controls and to filtrate from the endophyte alone. Together these results speak to a facultative symbiosis between an endophyte and endohyphal bacterium that strongly influences IAA production, providing a new framework in which to explore endophyte-plant interactions. PMID:24086270

Plant-Associated Bacterial Degradation of Toxic Organic Compounds in Soil

PubMed Central

McGuinness, Martina; Dowling, David

2009-01-01

A number of toxic synthetic organic compounds can contaminate environmental soil through either local (e.g., industrial) or diffuse (e.g., agricultural) contamination. Increased levels of these toxic organic compounds in the environment have been associated with human health risks including cancer. Plant-associated bacteria, such as endophytic bacteria (non-pathogenic bacteria that occur naturally in plants) and rhizospheric bacteria (bacteria that live on and near the roots of plants), have been shown to contribute to biodegradation of toxic organic compounds in contaminated soil and could have potential for improving phytoremediation. Endophytic and rhizospheric bacterial degradation of toxic organic compounds (either naturally occurring or genetically enhanced) in contaminated soil in the environment could have positive implications for human health worldwide and is the subject of this review. PMID:19742157

The role of the Oregon State University Endophyte Service Laboratory in diagnosing clinical cases of endophyte toxicoses.

PubMed

Craig, A Morrie; Blythe, Linda L; Duringer, Jennifer M

2014-07-30

The Oregon State University Colleges of Veterinary Medicine and Agricultural Sciences instituted the Endophyte Service Laboratory to aid in diagnosing toxicity problems associated with cool-season grasses in livestock. The endophyte (Neotyphodium coenophalum) present in tall fescue (Festuca arundinacea) produces ergopeptine alkaloids, of which ergovaline is the molecule used to determine exposure and toxicity thresholds for the vasoconstrictive conditions "fescue foot" and "summer slump". Another vasoconstrictive syndrome, "ergotism," is caused by a parasitic fungus, Claviceps purpurea, and its primary toxin, ergotamine. "Ryegrass staggers" is a neurological condition that affects livestock consuming endophyte (Neotyphodium lolii)-infected perennial ryegrass (Lolium perenne) with high levels of lolitrem B. HPLC-fluorescent analytical methods for these mycotoxins are described and were used to determine threshold levels of toxicity for ergovaline and lolitrem B in cattle, sheep, horses, and camels. In addition, six clinical cases in cattle are presented to illustrate diagnosis of these three diseases.

Transcriptome response in different tissues of Lolium arundinaceum to the fungal endophyte Epichloe coenophiala

USDA-ARS?s Scientific Manuscript database

Tall fescue (Lolium arundinaceum) plants symbiotic with the endophytic fungus, Epichloe coenophiala , (E+), have been shown to have better survivability and persistence than plants lacking the endophyte (E-). To understand more about the grass-endophyte interactions and how endophyte affects the ho...

Bacterial avirulence genes.

PubMed

Leach, J E; White, F F

1996-01-01

Although more than 30 bacterial avirulence genes have been cloned and characterized, the function of the gene products in the elictitation of resistance is unknown in all cases but one. The product of avrD from Pseudomonas syringae pv. glycinea likely functions indirectly to elicit resistance in soybean, that is, evidence suggests the gene product is an enzyme involved in elicitor production. In most if not all cases, bacterial avirulence gene function is dependent on interactions with the hypersensitive response and pathogenicity (hrp) genes. Many hrp genes are similar to genes involved in delivery of pathogenicity factors in mammalian bacterial pathogens. Thus, analogies between mammalian and plant pathogens may provide needed clues to elucidate how virulence gene products control induction of resistance.

Diversity of indigenous endophytic bacteria associated with the roots of Chinese cabbage (Brassica campestris L.) cultivars and their antagonism towards pathogens.

PubMed

Haque, Md Azizul; Yun, Han Dae; Cho, Kye Man

2016-05-01

The study aimed to reveal the diversity of endophytic bacteria in the roots of Chinese cabbage (CC) cultivated in two areas in Korea, namely, Seosang-gun (SS) and Haenam-gun (HN), and also in a transgenic plant (TP) from the laboratory. A total of 653 colonies were isolated from the interior of CC roots, comprising 118, 302, and 233 isolates from SS, HN, and TP samples, respectively. Based on 16S rRNA gene sequence analysis, the isolates belonged to four major phylogenetic groups: high-G+C Gram-positive bacteria (HGC-GPB), low-G+C Gram-positive bacteria (LGC-GPB), Proteobacteria, and Bacteriodetes. The most dominant groups in the roots of the SS, HN, and TP cultivars were LGC-GPB (48.3%), Proteobacteria (50.2%), and HGC-GPB (38.2%), respectively. Importantly, most of the isolates that produced cell-walldegrading enzymes belonged to the genus Bacillus. Bacillus sp. (HNR03, TPR06), Bacillus pumilus (SSR07, HNR11, TPR07), and Bacillus subtilis (TPR03) showed high antagonism against the tested food-borne pathogenic bacteria. In addition, Bacillus sp. (HNR03, TPR06), Bacillus pumilus (SSR07, HNR11, HNR17, TPR11), Microbacterium oxidans (SSR09, TPR04), Bacillus cereus HNR10, Pseudomonas sp. HNR13, and Bacillus subtilis (TPR02, TPR03) showed strong antagonistic activity against the fungi Phythium ultimum, Phytophthora capsici, Fusarium oxysporum, and Rhizoctonia solani. The endophytes isolated from the TP cultivar showed the strongest antagonistic reactions against pathogens. This study is the first report on endophytic bacteria from Chinese cabbage roots.

Marine Algicolous Endophytic Fungi - A Promising Drug Resource of the Era.

PubMed

Sarasan, Manomi; Puthumana, Jayesh; Job, Neema; Han, Jeonghoon; Lee, Jae-Seong; Philip, Rosamma

2017-06-28

Endophytic fungi have currently been acknowledged as the most promising source of bioactive compounds for drug discovery, and considerable progress has been made in exploring their diversity, species richness, and bioprospecting. Fungal endophytes from unique environmental settings offer a pool of potentially useful medicinal entities. Owing to the constant stresses imposed on macroalgae by marine environments, it is believed that algae and their associated endophytic symbionts represent a good source of structurally diverse bioactive secondary metabolites. Despite the proven significance of active metabolites of algal endophytes, little have been exploited. This review highlights the latest discoveries in algicolous endophytic research, with particular focus on the bioactive metabolites from algal endophytes. Compounds are classified according to their reported biological activities, like anticancer, antibacterial, antifungal, and antioxidant properties. Present experimental evidence suggests that a majority of the bioactive metabolites were reported from Phaeophyceae followed by Rhodophyceae and Chlorophyceae. An intensive search for newer and more effective bioactive metabolites has generated a treasure trove of publications, and this review partially covers the literature published up to 2016.

Exploring Arabidopsis thaliana Root Endophytes via Single-Cell Genomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lundberg, Derek; Woyke, Tanja; Tringe, Susannah

2014-03-19

Land plants grow in association with microbial communities both on their surfaces and inside the plant (endophytes). The relationships between microbes and their host can vary from pathogenic to mutualistic. Colonization of the endophyte compartment occurs in the presence of a sophisticated plant immune system, implying finely tuned discrimination of pathogens from mutualists and commensals. Despite the importance of the microbiome to the plant, relatively little is known about the specific interactions between plants and microbes, especially in the case of endophytes. The vast majority of microbes have not been grown in the lab, and thus one of the fewmore » ways of studying them is by examining their DNA. Although metagenomics is a powerful tool for examining microbial communities, its application to endophyte samples is technically difficult due to the presence of large amounts of host plant DNA in the sample. One method to address these difficulties is single-cell genomics where a single microbial cell is isolated from a sample, lysed, and its genome amplified by multiple displacement amplification (MDA) to produce enough DNA for genome sequencing. This produces a single-cell amplified genome (SAG). We have applied this technology to study the endophytic microbes in Arabidopsis thaliana roots. Extensive 16S gene profiling of the microbial communities in the roots of multiple inbred A. thaliana strains has identified 164 OTUs as being significantly enriched in all the root endophyte samples compared to their presence in bulk soil.« less

Diversity of endophytic fungi in Glycine max.

PubMed

Fernandes, Elio Gomes; Pereira, Olinto Liparini; da Silva, Cynthia Cânedo; Bento, Claudia Braga Pereira; de Queiroz, Marisa Vieira

2015-12-01

Endophytic fungi are microorganisms that live within plant tissues without causing disease during part of their life cycle. With the isolation and identification of these fungi, new species are being discovered, and ecological relationships with their hosts have also been studied. In Glycine max, limited studies have investigated the isolation and distribution of endophytic fungi throughout leaves and roots. The distribution of these fungi in various plant organs differs in diversity and abundance, even when analyzed using molecular techniques that can evaluate fungal communities in different parts of the plants, such as denaturing gradient gel electrophoresis (DGGE). Our results show there is greater species richness of culturable endophytic filamentous fungi in the leaves G. max as compared to roots. Additionally, the leaves had high values for diversity indices, i.e. Simpsons, Shannon and Equitability. Conversely, dominance index was higher in roots as compared to leaves. The fungi Ampelomyces sp., Cladosporium cladosporioides, Colletotrichum gloeosporioides, Diaporthe helianthi, Guignardia mangiferae and Phoma sp. were more frequently isolated from the leaves, whereas the fungi Fusarium oxysporum, Fusarium solani and Fusarium sp. were prevalent in the roots. However, by evaluating the two communities by DGGE, we concluded that the species richness was higher in the roots than in the leaves. UPGMA analysis showed consistent clustering of isolates; however, the fungus Leptospora rubella, which belongs to the order Dothideales, was grouped among species of the order Pleosporales. The presence of endophytic Fusarium species in G. max roots is unsurprising, since Fusarium spp. isolates have been previously described as endophyte in other reports. However, it remains to be determined whether the G. max Fusarium endophytes are latent pathogens or non-pathogenic forms that benefit the plant. This study provides a broader knowledge of the distribution of the fungal

Endophytic Bacteria Improve Plant Growth, Symbiotic Performance of Chickpea (Cicer arietinum L.) and Induce Suppression of Root Rot Caused by Fusarium solani under Salt Stress.

PubMed

Egamberdieva, Dilfuza; Wirth, Stephan J; Shurigin, Vyacheslav V; Hashem, Abeer; Abd Allah, Elsayed F

2017-01-01

Salinity causes disturbance in symbiotic performance of plants, and increases susceptibility of plants to soil-borne pathogens. Endophytic bacteria are an essential determinant of cross-tolerance to biotic and abiotic stresses in plants. The aim of this study was to isolate non-rhizobial endophytic bacteria from the root nodules of chickpea ( Cicer arietinum L.), and to assess their ability to improve plant growth and symbiotic performance, and to control root rot in chickpea under saline soil conditions. A total of 40 bacterial isolates from internal root tissues of chickpea grown in salinated soil were isolated. Four bacterial isolates, namely Bacillus cereus NUU1 , Achromobacter xylosoxidans NUU2, Bacillus thuringiensis NUU3, and Bacillus subtilis NUU4 colonizing root tissue demonstrated plant beneficial traits and/or antagonistic activity against F. solani and thus were characterized in more detail. The strain B. subtilis NUU4 proved significant plant growth promotion capabilities, improved symbiotic performance of host plant with rhizobia, and promoted yield under saline soil as compared to untreated control plants under field conditions. A combined inoculation of chickpea with M. ciceri IC53 and B. subtilis NUU4 decreased H 2 O 2 concentrations and increased proline contents compared to the un-inoculated plants indicating an alleviation of adverse effects of salt stress. Furthermore, the bacterial isolate was capable to reduce the infection rate of root rot in chickpea caused by F. solani . This is the first report of F. solani causing root rot of chickpea in a salinated soil of Uzbekistan. Our findings demonstrated that the endophytic B. subtilis strain NUU4 provides high potentials as a stimulator for plant growth and as biological control agent of chickpea root rot under saline soil conditions. These multiple relationships could provide promising practical approaches to increase the productivity of legumes under salt stress.

Endophytic Bacteria Improve Plant Growth, Symbiotic Performance of Chickpea (Cicer arietinum L.) and Induce Suppression of Root Rot Caused by Fusarium solani under Salt Stress

PubMed Central

Egamberdieva, Dilfuza; Wirth, Stephan J.; Shurigin, Vyacheslav V.; Hashem, Abeer; Abd_Allah, Elsayed F.

2017-01-01

Salinity causes disturbance in symbiotic performance of plants, and increases susceptibility of plants to soil-borne pathogens. Endophytic bacteria are an essential determinant of cross-tolerance to biotic and abiotic stresses in plants. The aim of this study was to isolate non–rhizobial endophytic bacteria from the root nodules of chickpea (Cicer arietinum L.), and to assess their ability to improve plant growth and symbiotic performance, and to control root rot in chickpea under saline soil conditions. A total of 40 bacterial isolates from internal root tissues of chickpea grown in salinated soil were isolated. Four bacterial isolates, namely Bacillus cereus NUU1, Achromobacter xylosoxidans NUU2, Bacillus thuringiensis NUU3, and Bacillus subtilis NUU4 colonizing root tissue demonstrated plant beneficial traits and/or antagonistic activity against F. solani and thus were characterized in more detail. The strain B. subtilis NUU4 proved significant plant growth promotion capabilities, improved symbiotic performance of host plant with rhizobia, and promoted yield under saline soil as compared to untreated control plants under field conditions. A combined inoculation of chickpea with M. ciceri IC53 and B. subtilis NUU4 decreased H2O2 concentrations and increased proline contents compared to the un-inoculated plants indicating an alleviation of adverse effects of salt stress. Furthermore, the bacterial isolate was capable to reduce the infection rate of root rot in chickpea caused by F. solani. This is the first report of F. solani causing root rot of chickpea in a salinated soil of Uzbekistan. Our findings demonstrated that the endophytic B. subtilis strain NUU4 provides high potentials as a stimulator for plant growth and as biological control agent of chickpea root rot under saline soil conditions. These multiple relationships could provide promising practical approaches to increase the productivity of legumes under salt stress. PMID:29033922

Influence of plant species and environmental conditions on epiphytic and endophytic pink-pigmented facultative methylotrophic bacterial populations associated with field-grown rice cultivars.

PubMed

Madhaiyan, Munusamy; Poonguzhali, Selvaraj; Sa, Tongmin

2007-10-01

The total methylotrophic population associated with rice plants from different cultivars was enumerated at three different stages: vegetative, flowering, and harvesting. The bacterial population in the leaf, rhizosphere soil, endophytic in the stem and roots, and epiphytic in the florets and grains were determined from four rice cultivars, Il-mi, Nam-pyeoung, O-dae, and Dong-jin, sampled from three different field sites. The methylotrophic bacteria isolated on AMS media containing 0.5% methanol as the sole carbon source uniformly showed three distinct morphologies, which were recorded as separate groups and their distribution among the various samples was determined using the ecophysiological index. The growth stage at the time of sampling had a more significant effect on the methylotrophic population and their distribution than the field site or cultivar. A similar effect was also observed for the PPFMs, where their population in different plant parts increased from V10 to R4 and then decreased towards stage R9. A canonical discriminant analysis of the PPFM population from different parts of rice showed clear variations among the cultivars, sampled sites, and growth stages, although the variations were more prominent among the growth stages.

Genetically modified luminescent bacteria Ralostonia solanacerum, Pseudomonas syringae, Pseudomonas savastanoi, and wild type bacterium Vibrio fischeri in biosynthesis of gold nanoparticles from gold chloride trihydrate.

PubMed

Attaran, Neda; Eshghi, Hossein; Rahimizadeh, Mohammad; Mashreghi, Mansour; Bakavoli, Mehdi

2014-08-04

The effect of different genetically engineered bacteria, Pseudomonas syringae, Pseudomonas savastanoi, and Ralostonia solanacerum and also a natural marine bacterial species, Vibrio fischeri NRRL B-11177, is studied in producing gold nanoparticles. This is the first report about the biosynthesis of gold nanoparticles by natural and genetically engineered luminescent bacteria. These microorganisms reduced gold ions and produced fairly monodisperse nanoparticles. TEM analysis indicated that spherical nano gold particles in the different diameters and shapes were obtained at pH values of 6.64. In this biosynthesis protocol, the gold nanoparticles with desired shape and size can be prepared.

Application of Chemical Genomics to Plant-Bacteria Communication: A High-Throughput System to Identify Novel Molecules Modulating the Induction of Bacterial Virulence Genes by Plant Signals.

PubMed

Vandelle, Elodie; Puttilli, Maria Rita; Chini, Andrea; Devescovi, Giulia; Venturi, Vittorio; Polverari, Annalisa

2017-01-01

The life cycle of bacterial phytopathogens consists of a benign epiphytic phase, during which the bacteria grow in the soil or on the plant surface, and a virulent endophytic phase involving the penetration of host defenses and the colonization of plant tissues. Innovative strategies are urgently required to integrate copper treatments that control the epiphytic phase with complementary tools that control the virulent endophytic phase, thus reducing the quantity of chemicals applied to economically and ecologically acceptable levels. Such strategies include targeted treatments that weaken bacterial pathogens, particularly those inhibiting early infection steps rather than tackling established infections. This chapter describes a reporter gene-based chemical genomic high-throughput screen for the induction of bacterial virulence by plant molecules. Specifically, we describe a chemical genomic screening method to identify agonist and antagonist molecules for the induction of targeted bacterial virulence genes by plant extracts, focusing on the experimental controls required to avoid false positives and thus ensuring the results are reliable and reproducible.

7 CFR 201.58d - Fungal endophyte test.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Method of preparation of aniline blue stain for use in testing grass seed and plant material for the presence of fungal endophyte: (1) Prepare a 1 percent aqueous aniline blue solution by dissolving 1 gram aniline blue in 100 ml distilled water. (2) Prepare the endophyte staining solution of one part of 1...

7 CFR 201.58d - Fungal endophyte test.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Method of preparation of aniline blue stain for use in testing grass seed and plant material for the presence of fungal endophyte: (1) Prepare a 1 percent aqueous aniline blue solution by dissolving 1 gram aniline blue in 100 ml distilled water. (2) Prepare the endophyte staining solution of one part of 1...

7 CFR 201.58d - Fungal endophyte test.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Method of preparation of aniline blue stain for use in testing grass seed and plant material for the presence of fungal endophyte: (1) Prepare a 1 percent aqueous aniline blue solution by dissolving 1 gram aniline blue in 100 ml distilled water. (2) Prepare the endophyte staining solution of one part of 1...

A novel method to scale up fungal endophyte isolations

USDA-ARS?s Scientific Manuscript database

Estimations of species diversity are influenced by sampling intensity which in turn is influenced by methodology. For fungal endophyte diversity studies, the methodology includes surface-sterilization prior to isolation of endophytes. Surface-sterilization is an essential component of fungal endophy...

Diversity and host range of foliar fungal endophytes: are tropical leaves biodiversity hotspots?

PubMed

Arnold, A Elizabeth; Lutzoni, F

2007-03-01

Fungal endophytes are found in asymptomatic photosynthetic tissues of all major lineages of land plants. The ubiquity of these cryptic symbionts is clear, but the scale of their diversity, host range, and geographic distributions are unknown. To explore the putative hyperdiversity of tropical leaf endophytes, we compared endophyte communities along a broad latitudinal gradient from the Canadian arctic to the lowland tropical forest of central Panama. Here, we use molecular sequence data from 1403 endophyte strains to show that endophytes increase in incidence, diversity, and host breadth from arctic to tropical sites. Endophyte communities from higher latitudes are characterized by relatively few species from many different classes of Ascomycota, whereas tropical endophyte assemblages are dominated by a small number of classes with a very large number of endophytic species. The most easily cultivated endophytes from tropical plants have wide host ranges, but communities are dominated by a large number of rare species whose host range is unclear. Even when only the most easily cultured species are considered, leaves of tropical trees represent hotspots of fungal species diversity, containing numerous species not yet recovered from other biomes. The challenge remains to recover and identify those elusive and rarely cultured taxa with narrower host ranges, and to elucidate the ecological roles of these little-known symbionts in tropical forests.

Endophyte-mediated interactions between cauliflower, the herbivore Spodoptera litura, and the ectoparasitoid Bracon hebetor.

PubMed

Kaur, Tamanreet; Singh, Bahaderjeet; Kaur, Amarjeet; Kaur, Sanehdeep

2015-10-01

Fungal endosymbionts in plants may influence interactions among plants, herbivores and their parasitoids through the production of secondary metabolites. We used a lepidopteran pest and its generalist parasitoid to test the effect of endophyte-infected plants on a third trophic level. Endophytic fungi, Aspergillus flavus and Aspergillus niger, isolated from Acacia arabica, were used to infect cauliflower plants. We found that the presence of the endophyte in the plants significantly extended the development period of Spodoptera litura (Fab.) larvae. Feeding of the host on endophyte-infected plants further adversely affected the development and performance of its parasitoid, Bracon hebetor (Say). A negative impact was also recorded for longevity and fecundity of endophyte-naive parasitoid females due to the parasitization of host larvae fed on endophyte-infected plants. The presence of endophytes in the diet of the host larvae significantly prolonged the development of the parasitoid. A strong detrimental effect was also recorded for larval survival and emergence of parasitoid adults. The longevity and parasitism rate of female wasps were reduced significantly due to the ingestion of endophyte-infected cauliflower plants by S. litura larvae. Overall, we found that both endophytic fungi had a negative impact on the parasitoid.

Enhanced Degradation of TCE on a Superfund Site Using Endophyte-Assisted Poplar Tree Phytoremediation.

PubMed

Doty, Sharon L; Freeman, John L; Cohu, Christopher M; Burken, Joel G; Firrincieli, Andrea; Simon, Andrew; Khan, Zareen; Isebrands, J G; Lukas, Joseph; Blaylock, Michael J

2017-09-05

Trichloroethylene (TCE) is a widespread environmental pollutant common in groundwater plumes associated with industrial manufacturing areas. We had previously isolated and characterized a natural bacterial endophyte, Enterobacter sp. strain PDN3, of poplar trees, that rapidly metabolizes TCE, releasing chloride ion. We now report findings from a successful three-year field trial of endophyte-assisted phytoremediation on the Middlefield-Ellis-Whisman Superfund Study Area TCE plume in the Silicon Valley of California. The inoculated poplar trees exhibited increased growth and reduced TCE phytotoxic effects with a 32% increase in trunk diameter compared to mock-inoculated control poplar trees. The inoculated trees excreted 50% more chloride ion into the rhizosphere, indicative of increased TCE metabolism in planta. Data from tree core analysis of the tree tissues provided further supporting evidence of the enhanced rate of degradation of the chlorinated solvents in the inoculated trees. Test well groundwater analyses demonstrated a marked decrease in concentration of TCE and its derivatives from the tree-associated groundwater plume. The concentration of TCE decreased from 300 μg/L upstream of the planted area to less than 5 μg/L downstream of the planted area. TCE derivatives were similarly removed with cis-1,2-dichloroethene decreasing from 160 μg/L to less than 5 μg/L and trans-1,2-dichloroethene decreasing from 3.1 μg/L to less than 0.5 μg/L downstream of the planted trees. 1,1-dichloroethene and vinyl chloride both decreased from 6.8 and 0.77 μg/L, respectively, to below the reporting limit of 0.5 μg/L providing strong evidence of the ability of the endophytic inoculated trees to effectively remove TCE from affected groundwater. The combination of native pollutant-degrading endophytic bacteria and fast-growing poplar tree systems offers a readily deployable, cost-effective approach for the degradation of TCE, and may help mitigate potential transfer up

Draft Genome Sequence of a Kale (Brassica oleracea L.) Root Endophyte, Pseudomonas sp. Strain C9.

PubMed

Laugraud, Aurelie; Young, Sandra; Gerard, Emily; O'Callaghan, Maureen; Wakelin, Steven

2017-04-13

Pseudomonas sp. strain C9 is a plant growth-promoting bacterium isolated from the root tissue of Brassica oleracea L. grown in soil from Marlborough, New Zealand. Its draft genome of 6,350,161 bp contains genes associated with plant growth promotion and biological control. Copyright © 2017 Laugraud et al.

Purification and antibiofilm activity of AHL-lactonase from endophytic Enterobacter aerogenes VT66.

PubMed

Rajesh, P S; Rai, V Ravishankar

2015-11-01

The opportunistic pathogen Pseudomonas aeruginosa uses biofilm lifestyle to resist antibiotic treatment. In our study, endophytic bacterium Enterobacter aerogenes VT66 quenched the N-acyl homoserine lactone (AHL) molecules produced by P. aeruginosa PAO1. The quorum quenching activity was attributed to the presence of AHL-lactonase. The AHL-lactonase was purified using column chromatography and purified AHL-lactonase was applied for the control of biofilm formation in P. aeruginosa PAO1. The results showed that purified AHL-lactonase obtained with a molecular weight about 30kDa was able to inhibit more than 70% of biofilm in P. aeruginosa PAO1 (P<0.001). Antibiofilm activity of AHL-lactonase was correlated well with results from staining technique used to determine inhibition of biomass and viable cell activity. Therefore, results unambiguously confirm that the AHL-lactonase from E. aerogenes VT66 could be used as antibiofilm therapeutics in P. aeruginosa associated biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Construction of the Syngonium podophyllum-Pseudomonas sp. XNN8 Symbiotic Purification System and Investigation of Its Capability of Remediating Uranium Wastewater.

PubMed

Deng, Qin-Wen; Wang, Yong-Dong; Ding, De-Xin; Hu, Nan; Sun, Jing; He, Jia-Dong; Xu, Fei

2017-02-01

The endophyte Pseudomonas sp. XNN8 was separated from Typha orientalis which can secrete indole-3-acetic acid and 1-aminocyclopropane-1-carboxylate deaminase and siderophores and has strong resistance to uranium it was then colonized in the Syngonium podophyllum; and the S. podophyllum-Pseudomonas sp. XNN8 symbiotic purification system (SPPSPS) for uranium-containing wastewater was constructed. Afterwards, the hydroponic experiments to remove uranium from uranium-containing wastewater by the SPPSPS were conducted. After 24 days of treatment, the uranium concentrations of the wastewater samples with uranium concentrations between 0.5 and 5.0 mg/L were lowered to below 0.05 mg/L. Furthermore, the uranium in the plants was assayed using Fourier transform infrared spectroscopy (FTIR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The Pseudomonas sp. XNN8 was found to generate substantial organic groups in the roots of the Syngonium podophyllum, which could improve the complexing capability of S. podophyllum for uranium. The uranium in the roots of S. podophyllum was found to be the uranyl phosphate (47.4 %) and uranyl acetate (52.6 %).

Characterization of Pseudomonas syringae from blueberry fields in Oregon and Washington

USDA-ARS?s Scientific Manuscript database

Bacterial canker, caused by Pseudomonas syringae, is a common disease that kills buds and stems in blueberry fields in Oregon and western Washington. Management is primarily through application of copper; antibiotics are not registered for blueberry. Little is known about the diversity of P. syringa...

Characterization of cellulases of fungal endophytes isolated from Espeletia spp.

PubMed

Cabezas, Luisa; Calderon, Carolina; Medina, Luis Miguel; Bahamon, Isabela; Cardenas, Martha; Bernal, Adriana Jimena; Gonzalez, Andrés; Restrepo, Silvia

2012-12-01

Endophytes are microorganisms that asymptomatically invade plant tissues. They can stimulate plant growth and/or provide defense against pathogen attacks through the production of secondary metabolites. Most endophyte species are still unknown, and because they may have several applications, the study of their metabolic capabilities is essential. We characterized 100 endophytes isolated from Espeletia spp., a genus unique to the paramo ecosystem, an extreme environment in the Andean mountain range. We evaluated the cellulolytic potential of these endophytes on the saccharification of the oil palm empty fruit bunch (OPEFB). The total cellulolytic activity was measured for each endophyte on filter paper (FPA). In addition, the specific carboxymethyl cellulase (CMCase), exoglucanase, and β-glucosidase activities were determined. We found four fungi positive for cellulases. Of these fungi, Penicillium glabrum had the highest cellulolytic activity after partial purification, with maximal CMCase, exoglucanase and β-glucosidase enzyme activities of 44.5, 48.3, and 0.45 U/ml, respectively. Our data showed that the bioprospection of fungi and the characterization of their enzymes may facilitate the process of biofuel production.

Efficient phytoremediation of organic contaminants in soils using plant-endophyte partnerships.

PubMed

Feng, Nai-Xian; Yu, Jiao; Zhao, Hai-Ming; Cheng, Yu-Ting; Mo, Ce-Hui; Cai, Quan-Ying; Li, Yan-Wen; Li, Hui; Wong, Ming-Hung

2017-04-01

Soil pollution with organic contaminants is one of the most intractable environmental problems today, posing serious threats to humans and the environment. Innovative strategies for remediating organic-contaminated soils are critically needed. Phytoremediation, based on the synergistic actions of plants and their associated microorganisms, has been recognized as a powerful in situ approach to soil remediation. Suitable combinations of plants and their associated endophytes can improve plant growth and enhance the biodegradation of organic contaminants in the rhizosphere and/or endosphere, dramatically expediting the removal of organic pollutants from soils. However, for phytoremediation to become a more widely accepted and predictable alternative, a thorough understanding of plant-endophyte interactions is needed. Many studies have recently been conducted on the mechanisms of endophyte-assisted phytoremediation of organic contaminants in soils. In this review, we highlight the superiority of organic pollutant-degrading endophytes for practical applications in phytoremediation, summarize alternative strategies for improving phytoremediation, discuss the fundamental mechanisms of endophyte-assisted phytoremediation, and present updated information regarding the advances, challenges, and new directions in the field of endophyte-assisted phytoremediation technology. Copyright © 2017 Elsevier B.V. All rights reserved.

Endophytic bacteria from wheat grain as biocontrol agents of Fusarium graminearum and deoxynivalenol production in wheat.

PubMed

Pan, D; Mionetto, A; Tiscornia, S; Bettucci, L

2015-08-01

In Uruguay, Fusarium graminearum is the most common species that infects wheat and is responsible for Fusarium head blight (FHB) and contamination of grain with deoxynivalenol (DON). The aim of this work was to select bacterial endophytes isolated from wheat grain to evaluate their antagonistic ability against F. graminearum and DON production in vitro and under field conditions. Four strains identified as Bacillus megaterium (BM1) and Bacillus subtilis (BS43, BSM0 y BSM2) significantly reduced fungal growth and spore germination of F. graminearum. This antagonist activity remained unchanged after the bacterial cultures were heat treated. Under field conditions, treatments with antagonist BM1 was the most effective, reducing the FHB incidence and severity by 93 and 54 %, respectively, and the production of DON by 89.3 %.

Evidence for the endophytic colonization of Phaseolus vulgaris (common bean) roots by the diazotroph Herbaspirillum seropedicae.

PubMed

Schmidt, M A; Souza, E M; Baura, V; Wassem, R; Yates, M G; Pedrosa, F O; Monteiro, R A

2011-03-01

Herbaspirillum seropedicae is an endophytic diazotrophic bacterium, which associates with important agricultural plants. In the present study, we have investigated the attachment to and internal colonization of Phaseolus vulgaris roots by the H. seropedicae wild-type strain SMR1 and by a strain of H. seropedicae expressing a red fluorescent protein (DsRed) to track the bacterium in the plant tissues. Two-day-old P. vulgaris roots were incubated at 30°C for 15 min with 6 x 10(8) CFU/mL H. seropedicae SMR1 or RAM4. Three days after inoculation, 4 x 10(4) cells of endophytic H. seropedicae SMR1 were recovered per gram of fresh root, and 9 days after inoculation the number of endophytes increased to 4 x 10(6) CFU/g. The identity of the recovered bacteria was confirmed by amplification and sequencing of the 16SrRNA gene. Furthermore, confocal microscopy of P. vulgaris roots inoculated with H. seropedicae RAM4 showed that the bacterial cells were attached to the root surface 15 min after inoculation; fluorescent bacteria were visible in the internal tissues after 24 h and were found in the central cylinder after 72 h, showing that H. seropedicae RAM4 is capable of colonizing the roots of the dicotyledon P. vulgaris. Determination of dry weight of common bean inoculated with H. seropedicae SMR1 suggested that this bacterium has a negative effect on the growth of P. vulgaris.

Bacterial communities in the fruit bodies of ground basidiomycetes

NASA Astrophysics Data System (ADS)

Zagryadskaya, Yu. A.; Lysak, L. V.; Chernov, I. Yu.

2015-06-01

Fruit bodies of basidiomycetes at different stages of decomposition serve as specific habitats in forest biocenoses for bacteria and differ significantly with respect to the total bacterial population and abundance of particular bacterial genera. A significant increase in the total bacterial population estimated by the direct microscopic method with acridine orange staining and in the population of saprotrophic bacteria (inoculation of glucose peptone yeast agar) in fruit bodies of basidiomycetes Armillaria mellea and Coprinus comatus was recorded at the final stage of their decomposition in comparison with the initial stage. Gramnegative bacteria predominated in the tissues of fruit bodies at all the stages of decomposition and were represented at the final stage by the Aeromonas, Vibrio, and Pseudomonas genera (for fruit bodies of A. mellea) the Pseudomonas genus (for fruit bodies of C. comatus). The potential influence of bacterial communities in the fruit bodies of soil basidiomycetes on the formation of bacterial communities in the upper soil horizons in forest biocenoses is discussed. The loci connected with the development and decomposition of fruit bodies of basidiomycetes on the soil surface are promising for targeted search of Gram-negative bacteria, the important objects of biotechnology.

Athlete's foot caused by pseudomonas aeruginosa.

PubMed

Abramson, C

1983-01-01

An enzymatically active pigment-producing clinical isolate of Pseudomonas aeruginosa was found to produce a diffusible antifungal product that was shown to be inhibitory to the growth of several dermatophytes, specifically, Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum gypseum, and Microsporum audouini. In this study, Trichophyton rubrum was used as the test organism. The antifungal product was partially purified by Sephadex column chromatography and was found to be stable at 5 degrees, 25 degrees, and 37 degrees C. Several investigators have alluded to the fact that as asymptomatic cases of dermatophytosis simplex progress to symptomatic dermatophytosis complex, the bacterial profile changes from a gram-positive bacterial ecosystem to a gram-negative bacterial over-growth. The primary event in the pathogenesis of interdigital athlete's foot is the invasion of the horny layer by dermatophytes. This presents as a mild to moderate scaly lesion and is asymptomatic. As a result of predisposing factors, such as hyperhidrosis, occlusion by tight shoes, minute abrasions due to friction, and fungal-infected skin surfaces, dynamic overgrowth of opportunistic gram-negative bacilli prevails. As the gram-negative population increases, the recovery of dermatophytes dramatically diminishes, until a point is reached when no dermatophytes can be recovered from clinically symptomatic tinea pedis. Pseudomonas aeruginosa is inhibiting its fungal competitor Trichophyton rubrum by producing a diffusible antifungal agent into the infectious environment of the intertriginous foot lesion. Clinically, the patient is diagnosed as having tinea pedis; laboratory culture for fungus and KOH are negative, and what was a paradox just a few years ago can currently be identified and treated appropriately as gram-negative athlete's foot.

Insect Feeding Deterrents in Endophyte-Infected Tall Fescue †

PubMed Central

Johnson, M. C.; Dahlman, D. L.; Siegel, M. R.; Bush, L. P.; Latch, G. C. M.; Potter, D. A.; Varney, D. R.

1985-01-01

The presence of an endophytic fungus, Acremonium coenophialum, in tall fescue (Festuca arundinacea) deterred aphid feeding by Rhopalosiphum padi and Schizaphis graminum. Both species of aphid were unable to survive when confined to endophyte-infected tall fescue plants. Feeding deterrents and toxic factors to R. padi and Oncopeltus fasciatus, large milkweed bug, were primarily associated with a methanol extract obtained when endophyte-infected tall fescue seed was serially extracted with hexane, ethyl acetate, and methanol. The concentrations of pyrrolizidine alkaloids were determined to be 30 to 100 times greater in the methanol extract than in the hexane and ethyl acetate extracts. PMID:16346751

Diversity of fungal endophytes in non-native Phragmites australis in the Great Lakes

USGS Publications Warehouse

Clay, Keith; Shearin, Zachery; Bourke, Kimberly; Bickford, Wesley A.; Kowalski, Kurt P.

2016-01-01

Plant–microbial interactions may play a key role in plant invasions. One common microbial interaction takes place between plants and fungal endophytes when fungi asymptomatically colonize host plant tissues. The objectives of this study were to isolate and sequence fungal endophytes colonizing non-native Phragmites australis in the Great Lakes region to evaluate variation in endophyte community composition among three host tissue types and three geographical regions. We collected entire ramets from multiple clones and populations, surface sterilized plant tissues, and plated replicate tissue samples from leaves, stems, and rhizomes on corn meal agar plates to culture and isolate fungal endophytes. Isolates were then subjected to Sanger sequencing of the ITS region of the nuclear ribosomal DNA. Sequences were compared to fungal databases to define operational taxonomic units (OTUs) that were analyzed statistically for community composition. In total, we obtained 173 endophyte isolates corresponding to 55 OTUs, 39 of which were isolated only a single time. The most common OTU corresponded most closely to Sarocladium strictum and comprised 25 % of all fungal isolates. More OTUs were found in stem tissues, but endophyte diversity was greatest in rhizome tissues. PERMANOVA analyses indicated significant differences in endophyte communities among tissue types, geographical regions, and the interaction between those factors, but no differences among individual ramets were detected. The functional role of the isolated endophytes is not yet known, but one genus isolated here (Stagonospora) has been reported to enhance Phragmites growth. Understanding the diversity and functions of Phragmites endophytes may provide targets for control measures based on disrupting host plant/endophyte interactions.

The Effect of Endophytic Fungi on Nematode Populations in Summer-dormant and Summer-active Tall Fescue.

PubMed

Rogers, James K; Walker, Nathan R; Young, Carolyn A

2016-06-01

Summer-active (continental) and summer-dormant (Mediterranean) tall fescue morphotypes are each adapted to different environmental conditions. Endophyte presence provides plant parasitic nematode resistance, but not with all endophyte strains and cultivar combinations. This study sought to compare effects of four nematode genera on continental and Mediterranean cultivars infected with common toxic or novel endophyte strains. A 6-mon greenhouse study was conducted with continental cultivars, Kentucky 31 (common toxic) and Texoma MaxQ II (novel endophyte) and the Mediterranean cultivar Flecha MaxQ (novel endophyte). Endophyte-free plants of each cultivar were controls. Each cultivar × endophyte combination was randomly assigned to a control, low or high inoculation rate of a mixed nematode culture containing stunt nematodes (Tylenchorhynchus spp.), ring nematodes (Criconemella spp.), spiral nematodes (Helicotylenchus spp.), and lesion nematodes (Pratylenchus spp.). Endophyte infection had no effect on nematode population densities. The cultivar × endophyte interaction was significant. Population densities of stunt nematode, spiral nematode, and ring nematodes were higher for Flecha MaxQ than other cultivar × endophyte combinations. Novel endophyte infection enhances suitability of Flecha MaxQ as a nematode host.

Pseudomonas-related populations associated with reverse osmosis in drinking water treatment.

PubMed

Sala-Comorera, Laura; Blanch, Anicet R; Vilaró, Carles; Galofré, Belén; García-Aljaro, Cristina

2016-11-01

Reverse osmosis membrane filtration technology (RO) is used to treat drinking water. After RO treatment, bacterial growth is still observed in water. However, it is not clear whether those microorganisms belong to species that can pose a health risk, such as Pseudomonas spp. The goal of this study is to characterize the bacterial isolates from a medium that is selective for Pseudomonas and Aeromonas which were present in the water fraction before and after the RO. To this end, isolates were recovered over two years and were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. They were then biochemically phenotyped and the population similarity indexes were calculated. The isolates were analysed for their capacity to form biofilms in vitro and antimicrobial susceptibility. There were significant differences between the microbial populations in water before and after RO. Furthermore, the structures of the populations analysed at the same sampling point were similar in different sampling campaigns. Some of the isolates had the capacity to form a biofilm and showed resistance to different antibiotics. A successful level filtration via RO and subsequent recolonization of the membrane with different species from those in the feed water was found. Pseudomonas aeruginosa was not recovered from among the isolates. This study increases the knowledge on the microorganisms present in water after RO treatment, with focus in one of the genus causing problems in RO systems associated with human health risk, Pseudomonas. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Friendly Relationship between Endophytic Fungi and Medicinal Plants: A Systematic Review

PubMed Central

Jia, Min; Chen, Ling; Xin, Hai-Liang; Zheng, Cheng-Jian; Rahman, Khalid; Han, Ting; Qin, Lu-Ping

2016-01-01

Endophytic fungi or endophytes exist widely inside the healthy tissues of living plants, and are important components of plant micro-ecosystems. Over the long period of evolution, some co-existing endophytes and their host plants have established a special relationship with one and another, which can significantly influence the formation of metabolic products in plants, then affect quality and quantity of crude drugs derived from medicinal plants. This paper will focus on the increasing knowledge of relationships between endophytic fungi and medicinal plants through reviewing of published research data obtained from the last 30 years. The analytical results indicate that the distribution and population structure of endophytes can be considerably affected by factors, such as the genetic background, age, and environmental conditions of their hosts. On the other hand, the endophytic fungi can also confer profound impacts on their host plants by enhancing their growth, increasing their fitness, strengthening their tolerances to abiotic and biotic stresses, and promoting their accumulation of secondary metabolites. All the changes are very important for the production of bioactive components in their hosts. Hence, it is essential to understand such relationships between endophytic fungi and their host medicinal plants. Such knowledge can be well exploited and applied for the production of better and more drugs from medicinal plants. PMID:27375610

Isolation, morphological identification and in vitro antibacterial activity of endophytic bacteria isolated from Azadirachta indica (neem) leaves

PubMed Central

Singh, Ankit Kumar; Sharma, Rajesh Kumar; Sharma, Varsha; Singh, Tanmay; Kumar, Rajesh; Kumari, Dimple

2017-01-01

Aim: The objective of this study was to isolate endophytic bacteria from Azadirachta indica (neem) leaves, their identification and investigate their antibacterial activity against three Gram-positive bacteria, Staphylococcus aureus, Streptococcus pyogenes and Bacillus cereus and Gram-negative bacteria Escherichia coli, Salmonella Typhimurium and Klebsiella pneumoniae. Materials and Methods: Fresh leaves of A. indica (neem) was procured from the Department of Botany, JNKVV, Jabalpur. Five samples were taken, and each sample was divided into five subsamples and separated for further isolation of endophytic bacteria. For sterilization leaves were treated with double distilled water, 0.1% sodium hypochlorite, 0.01% bavistin, 0.05% and 70% ethanol. Sterilized leaves of the plants were embedded in Kings B (KB) petri plates and incubated at 37°C for 24 h. Characterization of the bacteria was done according to its morphology and by Gram-staining. After that, a single colony was transferred into brain heart infusion (BHI) broth and incubated at 37°C for 24 h. The antibacterial effect was studied by the disk diffusion method with known antibiotic ciprofloxacin (Ci) as standard. Results: A total of 25 bacterial isolates from A. indica (neem) were obtained and identified morphologically. Most of the samples on KB media depicted irregular shape, flat elevation, undulated, rough, opaque, and white in color. Most of the samples on blood agar showed irregular, raise elevation, undulated, smooth, opaque and all the isolates were nonhemolytic and nonchromogenic. The growth of endophytic bacteria in BHI broth were all isolates showed turbidity. The microscopic examination revealed that maximum isolates were Gram-positive and rod shaped. Good antibacterial activity was observed against S. aureus, Streptococcus pyogenes, E. coli, Salmonella Typhimurium, and K. pneumoniae. Conclusions: Endophytic bacteria are present in leaves of A. indica (neem) and it possesses antibacterial

Sugar administration is an effective adjunctive therapy in the treatment of Pseudomonas aeruginosa pneumonia

PubMed Central

Bucior, Iwona; Abbott, Jason; Song, Yuanlin; Matthay, Michael A.

2013-01-01

Treatment of acute and chronic pulmonary infections caused by opportunistic pathogen Pseudomonas aeruginosa is limited by the increasing frequency of multidrug bacterial resistance. Here, we describe a novel adjunctive therapy in which administration of a mix of simple sugars—mannose, fucose, and galactose—inhibits bacterial attachment, limits lung damage, and potentiates conventional antibiotic therapy. The sugar mixture inhibits adhesion of nonmucoid and mucoid P. aeruginosa strains to bronchial epithelial cells in vitro. In a murine model of acute pneumonia, treatment with the sugar mixture alone diminishes lung damage, bacterial dissemination to the subpleural alveoli, and neutrophil- and IL-8-driven inflammatory responses. Remarkably, the sugars act synergistically with anti-Pseudomonas antibiotics, including β-lactams and quinolones, to further reduce bacterial lung colonization and damage. To probe the mechanism, we examined the effects of sugars in the presence or absence of antibiotics during growth in liquid culture and in an ex vivo infection model utilizing freshly dissected mouse tracheas and lungs. We demonstrate that the sugar mixture induces rapid but reversible formation of bacterial clusters that exhibited enhanced susceptibility to antibiotics compared with individual bacteria. Our findings reveal that sugar inhalation, an inexpensive and safe therapeutic, could be used in combination with conventional antibiotic therapy to more effectively treat P. aeruginosa lung infections. PMID:23792737

Experimental Keratitis Due to Pseudomonas aeruginosa: Model for Evaluation of Antimicrobial Drugs

PubMed Central

Davis, Starkey D.; Chandler, John W.

1975-01-01

An improved method for experimental keratitis due to Pseudomonas aeruginosa is described. Essential features of the method are use of inbred guinea pigs, intracorneal injection of bacteria, subconjunctival injection of antibiotics, “blind” evaluation of results, and statistical analysis of data. Untreated ocular infections were most severe 5 to 7 days after infection. Sterilized bacterial suspensions caused no abnormalities on day 5. Tobramycin and polymyxin B were more active than gentamicin against two strains of Pseudomonas. This model is suitable for many types of quantitative studies on experimental keratitis. Images PMID:810084

HoPaCI-DB: host-Pseudomonas and Coxiella interaction database

PubMed Central

Bleves, Sophie; Dunger, Irmtraud; Walter, Mathias C.; Frangoulidis, Dimitrios; Kastenmüller, Gabi; Voulhoux, Romé; Ruepp, Andreas

2014-01-01

Bacterial infectious diseases are the result of multifactorial processes affected by the interplay between virulence factors and host targets. The host-Pseudomonas and Coxiella interaction database (HoPaCI-DB) is a publicly available manually curated integrative database (http://mips.helmholtz-muenchen.de/HoPaCI/) of host–pathogen interaction data from Pseudomonas aeruginosa and Coxiella burnetii. The resource provides structured information on 3585 experimentally validated interactions between molecules, bioprocesses and cellular structures extracted from the scientific literature. Systematic annotation and interactive graphical representation of disease networks make HoPaCI-DB a versatile knowledge base for biologists and network biology approaches. PMID:24137008

The type III secretion system is necessary for the development of a pathogenic and endophytic interaction between Herbaspirillum rubrisubalbicans and Poaceae

PubMed Central

2012-01-01

Background Herbaspirillum rubrisubalbicans was first identified as a bacterial plant pathogen, causing the mottled stripe disease in sugarcane. H. rubrisubalbicans can also associate with various plants of economic interest in a non pathogenic manner. Results A 21 kb DNA region of the H. rubrisubalbicans genome contains a cluster of 26 hrp/hrc genes encoding for the type three secretion system (T3SS) proteins. To investigate the contribution of T3SS to the plant-bacterial interaction process we generated mutant strains of H. rubrisubalbicans M1 carrying a Tn5 insertion in both the hrcN and hrpE genes. H. rubrisulbalbicans hrpE and hrcN mutant strains of the T3SS system failed to cause the mottled stripe disease in the sugarcane susceptible variety B-4362. These mutant strains also did not produce lesions on Vigna unguiculata leaves. Oryza sativa and Zea mays colonization experiments showed that mutations in hrpE and hrcN genes reduced the capacity of H. rubrisulbalbicans to colonize these plants, suggesting that hrpE and hrcN genes are involved in the endophytic colonization. Conclusions Our results indicate that the T3SS of H. rubrisubalbicans is necessary for the development of the mottled stripe disease and endophytic colonization of rice. PMID:22672506

The type III secretion system is necessary for the development of a pathogenic and endophytic interaction between Herbaspirillum rubrisubalbicans and Poaceae.

PubMed

Schmidt, Maria Augusta; Balsanelli, Eduardo; Faoro, Hellison; Cruz, Leonardo M; Wassem, Roseli; de Baura, Valter A; Weiss, Vinícius; Yates, Marshall G; Madeira, Humberto M F; Pereira-Ferrari, Lilian; Fungaro, Maria H P; de Paula, Francine M; Pereira, Luiz F P; Vieira, Luiz G E; Olivares, Fábio L; Pedrosa, Fábio O; de Souza, Emanuel M; Monteiro, Rose A

2012-06-06

Herbaspirillum rubrisubalbicans was first identified as a bacterial plant pathogen, causing the mottled stripe disease in sugarcane. H. rubrisubalbicans can also associate with various plants of economic interest in a non pathogenic manner. A 21 kb DNA region of the H. rubrisubalbicans genome contains a cluster of 26 hrp/hrc genes encoding for the type three secretion system (T3SS) proteins. To investigate the contribution of T3SS to the plant-bacterial interaction process we generated mutant strains of H. rubrisubalbicans M1 carrying a Tn5 insertion in both the hrcN and hrpE genes. H. rubrisulbalbicans hrpE and hrcN mutant strains of the T3SS system failed to cause the mottled stripe disease in the sugarcane susceptible variety B-4362. These mutant strains also did not produce lesions on Vigna unguiculata leaves. Oryza sativa and Zea mays colonization experiments showed that mutations in hrpE and hrcN genes reduced the capacity of H. rubrisulbalbicans to colonize these plants, suggesting that hrpE and hrcN genes are involved in the endophytic colonization. Our results indicate that the T3SS of H. rubrisubalbicans is necessary for the development of the mottled stripe disease and endophytic colonization of rice.

Fungal endophytes in germinated seeds of the common bean, Phaseolus vulgaris

PubMed Central

Parsa, Soroush; García-Lemos, Adriana M.; Castillo, Katherine; Ortiz, Viviana; López-Lavalle, Luis Augusto Becerra; Braun, Jerome; Vega, Fernando E.

2016-01-01

We conducted a survey of fungal endophytes in 582 germinated seeds belonging to 11 Colombian cultivars of the common bean (Phaseolus vulgaris). The survey yielded 394 endophytic isolates belonging to 42 taxa, as identified by sequence analysis of the ribosomal DNA internal transcribed spacer (ITS) region. Aureobasidium pullulans was the dominant endophyte, isolated from 46.7 % of the samples. Also common were Fusarium oxysporum, Xylaria sp., and Cladosporium cladosporioides, but found in only 13.4 %, 11.7 %, and 7.6 % of seedlings, respectively. Endophytic colonization differed significantly among common bean cultivars and seedling parts, with the highest colonization occurring in the first true leaves of the seedlings. PMID:27109374

Resources and testing of endophyte-infected germplasm in national grass repository collections

Treesearch

A. D. Wilson

1996-01-01

Clavicipitaceous endophytes have been known to exist in grasses since the discovery of an endophyte in seeds of damel (Lolium temulentum L.) by Vogl in 1898 (26). The oldest known specimens of damel with endophytic mycelium were seeds retrieved from a pharoah's tomb in an Egyptian pyramid dating back to 3400 B.C. (16). Subsequent work by...

[Diversity of endophytic fungi associated with Ferula sinkiangensis K. M. Shen].

PubMed

Sun, Li; Zhu, Jun; Li, Xiaojin; Shi, Shubing; Guo, Shunxing

2014-08-04

We studied the diversity of endophytic fungi associated with Ferula sinkiangensis K. M. Shen. Endophytic fungi from different years (1-2 years, 3-4 years and > 5 years) and different parts (root, stemand leaf) of Ferula sinkiangensis K. M. Shen were isolated by tissue expand method. Strains were classified by morphology and similarity of internal transcribed spacer (ITS) sequence by Clustal X method. Composition, diversity and preference of endophytic fungal community were analyzed by the isolation rate (IR), isolation frequency (IF), Shannon-Wiener biodiversity index (H'), Margalef Richness index (R). In total 140 endophytic fungi were isolated from F. sinkiangensis K. M. Shen and classified into 18 genera. Among the 140 isolates, Aureobasidium (25.7%), Alternaria (16.4%) and Phyllosticta (15.7%) were the dominant genera. The isolation results show that there were some notable differences between distribution and composition of the endophytic fungi isolated from different years and different parts of Ferula sinkiangensis K. M. Shen. Meanwhile, a certain degree of years and tissue preference were also obvious. The results obtained in this study will be helpful to exploit the endophytic fungal resources of Ferula sinkiangensis K. M. Shen, which can also provide a new way for the realization of the artificial breeding of Ferula sinkiangensis K. M. Shen.

Ergot Alkaloids Produced by Endophytic Fungi of the Genus Epichloë

PubMed Central

Guerre, Philippe

2015-01-01

The development of fungal endophytes of the genus Epichloë in grasses results in the production of different groups of alkaloids, whose mechanism and biological spectrum of toxicity can differ considerably. Ergot alkaloids, when present in endophyte-infected tall fescue, are responsible for “fescue toxicosis” in livestock, whereas indole-diterpene alkaloids, when present in endophyte-infected ryegrass, are responsible for “ryegrass staggers”. In contrast, peramine and loline alkaloids are deterrent and/or toxic to insects. Other toxic effects in livestock associated with the consumption of endophyte-infected grass that contain ergot alkaloids include the “sleepy grass” and “drunken horse grass” diseases. Although ergovaline is the main ergopeptine alkaloid produced in endophyte-infected tall fescue and is recognized as responsible for fescue toxicosis, a number of questions still exist concerning the profile of alkaloid production in tall fescue and the worldwide distribution of tall fescue toxicosis. The purpose of this review is to present ergot alkaloids produced in endophyte-infected grass, the factors of variation of their level in plants, and the diseases observed in the mammalian species as relate to the profiles of alkaloid production. In the final section, interactions between ergot alkaloids and drug-metabolizing enzymes are presented as mechanisms that could contribute to toxicity. PMID:25756954

PCR-DGGE analysis of bacterial community dynamics in kava beverages during refrigeration.

PubMed

Dong, J; Kandukuru, P; Huang, A S; Li, Y

2011-07-01

Kava beverages are highly perishable even under refrigerated conditions. This study aimed to investigate the bacterial community dynamics in kava beverages during refrigeration.  Four freshly made kava beverages were obtained from kava bars and stored at 4°C. On days 0, 3 and 6, the aerobic plate count (APC), lactic acid bacteria (LAB) count and yeast and mould count (YMC) of the samples were determined. Meanwhile, bacterial DNA was extracted from each sample and subjected to the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Moreover, species-specific PCR assays were employed to identify predominant Pseudomonas spp. involved in kava spoilage. Over the storage period, the APC, LAB count and YMC of the four kava beverages all increased, whereas their pH values decreased. The DGGE profile revealed diverse bacterial populations in the samples. LAB, such as Weissella soli, Lactobacillus spp. and Lactococcus lactis, were found in the kava beverages. Species-specific PCR assays detected Pseudomonas putida and Pseudomonas fluorescens in the samples; Ps. fluorescens became dominant during refrigeration. LAB and Pseudomonas may play a significant role in the spoilage of kava beverages. This study provides important information that may be used to extend the shelf life of kava beverages. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

Behavior Performance of Diuraphis noxia (Homoptera: Aphididae) on Fungal Endophyte-Infected and Uninfected Perennial Ryegrass

Treesearch

S.L. Clement; D.G. Lester; A. Dan Wilson; K.S. Pike

1992-01-01

The behavior and performance of the Russian wheat aphid, Diuraphis noxia (Mordvilko), on fungal endophyte-infected and endophyte-free perennial ryegrass, Lolium perenne L., was investigated in the laboratory and field. Aphids did not select endophyte-free over endophyte-infected leaf sheaths and stem segments in petri dish preference tests....

Endophytic Fungi in Indigenous Australasian Grasses Associated with Toxicity to Livestock

PubMed Central

Miles, Christopher O.; di Menna, Margaret E.; Jacobs, Surrey W. L.; Garthwaite, Ian; Lane, Geoffrey A.; Prestidge, Ron A.; Marshall, Sergio L.; Wilkinson, Heather H.; Schardl, Christopher L.; Ball, Olivier J.-P.; Latch, Garrick C. M.

1998-01-01

Grazing of Echinopogon spp. by livestock in Australia has caused symptoms similar to those of perennial ryegrass staggers. We observed an endophytic fungus in the intercellular spaces of the leaves and seeds of New Zealand and Australian specimens of Echinopogon ovatus. Culture of surface-sterilized seeds from New Zealand specimens yielded a slow-growing fungus. An examination in which immunoblotting and an enzyme-linked immunosorbent assay (ELISA) were used indicated that E. ovatus plants from Australia and New Zealand were infected with fungi serologically related to Neotyphodium lolii (the endophyte of perennial ryegrass) and other Epichloe and Neotyphodium spp. endophytic in pooid grasses. No lolitrems (the indole–diterpenoids implicated as the causative agents of perennial ryegrass staggers), peramine analogs, or ergot alkaloids were detected in the infected specimens by high-performance liquid chromatography or ELISA. However, in endophyte-infected E. ovatus plants from New Zealand, analogs of the indole–diterpenoid paxilline (thought to be a biosynthetic precursor of the lolitrems and related tremorgens) were detected by ELISA, and N-formylloline was detected by gas chromatography. Endophyte-free specimens of New Zealand E. ovatus did not contain detectable paxilline analogs or lolines and were more palatable than infected specimens to adults of the pasture pest Listronotus bonariensis (Argentine stem weevil). Hyphae similar to those of the E. ovatus endophyte were also found in herbarium specimens of Echinopogon nutans var. major, Echinopogon intermedius, Echinopogon caespitosus, and Echinopogon cheeli. This appears to be the first time that an endophytic Neotyphodium species has been identified in grasses endemic to New Zealand or Australia. PMID:9464398

Unexpected diversity of basidiomycetous endophytes in sapwood and leaves of Hevea.

PubMed

Martin, Rachael; Gazis, Romina; Skaltsas, Demetra; Chaverri, Priscila; Hibbett, David

2015-01-01

Research on fungal endophytes has expanded dramatically in recent years, but little is known about the diversity and ecological roles of endophytic basidiomycetes. Here we report the analysis of 310 basidiomycetous endophytes isolated from wild and planted populations of the rubber tree genus, Hevea. Species accumulation curves were nonasymptotic, as in the majority of endophyte surveys, indicating that more sampling is needed to recover the true diversity of the community. One hundred eighteen OTUs were delimited, representing nine orders of Basidiomycota (Agaricales, Atheliales, Auriculariales, Cantharellales, Hymenochaetales, Polyporales, Russulales, Septobasidiales, Tremellales). The diversity of basidiomycetous endophytes found inhabiting wild populations of Hevea was comparable to that present in plantations. However, when samples were segregated by tissue type, sapwood of wild populations was found to contain a higher number of species than sapwood of planted trees. Seventy-five percent of isolates were members of the Polyporales, the majority in the phlebioid clade. Most of the species belong to clades known to cause a white-rot type of wood decay. Two species in the insect-associated genus Septobasidium were isolated. The most frequently isolated genera included Bjerkandera, Ceriporia, Phanerochaete, Phlebia, Rigidoporus, Tinctoporellus, Trametes (Polyporales), Peniophora, Stereum (Russulales) and Coprinellus (Agaricales), all of which have been reported as endophytes from a variety of hosts, across wide geographic locations. Literature records on the geographic distribution and host association of these genera revealed that their distribution and substrate affinity could be extended if the endophytic niche was investigated as part of fungal biodiversity surveys. © 2015 by The Mycological Society of America.

Endophytic fungi: expanding the arsenal of industrial enzyme producers.

PubMed

Corrêa, Rúbia Carvalho Gomes; Rhoden, Sandro Augusto; Mota, Thatiane Rodrigues; Azevedo, João Lúcio; Pamphile, João Alencar; de Souza, Cristina Giatti Marques; Polizeli, Maria de Lourdes Teixeira de Moraes; Bracht, Adelar; Peralta, Rosane Marina

2014-10-01

Endophytic fungi, mostly belonging to the Ascomycota, are found in the intercellular spaces of the aerial plant parts, particularly in leaf sheaths, sometimes even within the bark and root system without inducing any visual symptoms of their presence. These fungi appear to have a capacity to produce a wide range of enzymes and secondary metabolites exhibiting a variety of biological activities. However, they have been only barely exploited as sources of enzymes of industrial interest. This review emphasizes the suitability and possible advantages of including the endophytic fungi in the screening of new enzyme producing organisms as well as in studies aiming to optimize the production of enzymes through well-known culture processes. Apparently endophytic fungi possess the two types of extracellular enzymatic systems necessary to degrade the vegetal biomass: (1) the hydrolytic system responsible for polysaccharide degradation consisting mainly in xylanases and cellulases; and (2) the unique oxidative ligninolytic system, which degrades lignin and opens phenyl rings, comprises mainly laccases, ligninases and peroxidases. The obvious ability of endophytic fungi to degrade the complex structure of lignocellulose makes them useful in the exploration of the lignocellulosic biomass for the production of fuel ethanol and other value-added commodity chemicals. In addition to this, endophytic fungi may become new sources of industrially useful enzymes such as lipases, amylases and proteases.

From the Lab Bench: Should you plant a non-toxic endophyte tall fescue?

USDA-ARS?s Scientific Manuscript database

A column was written to discuss planting novel endophyte tall fescue for alleviating fescue toxicosis. Endophyte-free tall fescue cultivars can be grazed as a non-toxic alternative, but it maust be understood that it is the endophyte, through production of alkaloids other than ergot alkaloids, that...

The isolation and identification of endophytic bacteria from mangrove (Sonneratia alba) that produces gelatinase

NASA Astrophysics Data System (ADS)

Nursyam, H.; Prihanto, A. A.; Warasari, N. I.; Saadah, M.; Masrifa, R. E.; Nabila, N. A.; Istiqfarin, N.; Siddiq, I. J.

2018-04-01

Gelatinase is an enzyme that hydrolyze gelatin into gelatin hydrolyzate. The purpose of this study was to isolate and to identify endophytic bacteria from Sonneratia alba mangrove which able to produce gelatinase enzyme. Sonneratia alba mangroves was obtained from Bajul Mati Beach, Malang Regency. The samples in this study were, stems, and leaves. Pure cultured bacteria were investigated for its capability for producing gelatinase enzyme by using gelatin media. Best producer would further be analyzed its species using microbact system. Screening process resulted in 3 positive isolates, namely code isolate of R, B, and L. R which was isolate from root of S. alba was the best producer for gelatinase. Identification process with morphology and microbact system revelaed that A. SBM is a Gram-negative bacterium that has a basil cell shape, with a diameter colony of 2.19 mm. Based on the microbact system test carried out, the bacteria is Pseudomonas aeruginosa.

Endophytic fungal communities of Polygonum acuminatum and Aeschynomene fluminensis are influenced by soil mercury contamination

PubMed Central

Mello, Ivani Souza; Vendruscullo, Suzana Junges; da Silva, Gilvan Ferreira; da Cunha, Cátia Nunes; White, James Francis

2017-01-01

The endophytic fungal communities of Polygonum acuminatum and Aeschynomene fluminensis were examined with respect to soil mercury (Hg) contamination. Plants were collected in places with and without Hg+2 for isolation and identification of their endophytic root fungi. We evaluated frequency of colonization, number of isolates and richness, indices of diversity and similarity, functional traits (hydrolytic enzymes, siderophores, indoleacetic acid, antibiosis and metal tolerance) and growth promotion of Aeschynomene fluminensis inoculated with endophytic fungi on soil with mercury. The frequency of colonization, structure and community function, as well as the abundant distribution of taxa of endophytic fungi were influenced by mercury contamination, with higher endophytic fungi in hosts in soil with mercury. The presence or absence of mercury in the soil changes the profile of the functional characteristics of the endophytic fungal community. On the other hand, tolerance of lineages to multiple metals is not associated with contamination. A. fluminensis depends on its endophytic fungi, since plants free of endophytic fungi grew less than expected due to mercury toxicity. In contrast plants containing certain endophytic fungi showed good growth in soil containing mercury, even exceeding growth of plants cultivated in soil without mercury. The data obtained confirm the hypothesis that soil contamination by mercury alters community structure of root endophytic fungi in terms of composition, abundance and species richness. The inoculation of A. fluminensis with certain strains of stress tolerant endophytic fungi contribute to colonization and establishment of the host and may be used in processes that aim to improve phytoremediation of soils with toxic concentrations of mercury. PMID:28742846

Endophytic fungal communities of Polygonum acuminatum and Aeschynomene fluminensis are influenced by soil mercury contamination.

PubMed

Pietro-Souza, William; Mello, Ivani Souza; Vendruscullo, Suzana Junges; Silva, Gilvan Ferreira da; Cunha, Cátia Nunes da; White, James Francis; Soares, Marcos Antônio

2017-01-01

The endophytic fungal communities of Polygonum acuminatum and Aeschynomene fluminensis were examined with respect to soil mercury (Hg) contamination. Plants were collected in places with and without Hg+2 for isolation and identification of their endophytic root fungi. We evaluated frequency of colonization, number of isolates and richness, indices of diversity and similarity, functional traits (hydrolytic enzymes, siderophores, indoleacetic acid, antibiosis and metal tolerance) and growth promotion of Aeschynomene fluminensis inoculated with endophytic fungi on soil with mercury. The frequency of colonization, structure and community function, as well as the abundant distribution of taxa of endophytic fungi were influenced by mercury contamination, with higher endophytic fungi in hosts in soil with mercury. The presence or absence of mercury in the soil changes the profile of the functional characteristics of the endophytic fungal community. On the other hand, tolerance of lineages to multiple metals is not associated with contamination. A. fluminensis depends on its endophytic fungi, since plants free of endophytic fungi grew less than expected due to mercury toxicity. In contrast plants containing certain endophytic fungi showed good growth in soil containing mercury, even exceeding growth of plants cultivated in soil without mercury. The data obtained confirm the hypothesis that soil contamination by mercury alters community structure of root endophytic fungi in terms of composition, abundance and species richness. The inoculation of A. fluminensis with certain strains of stress tolerant endophytic fungi contribute to colonization and establishment of the host and may be used in processes that aim to improve phytoremediation of soils with toxic concentrations of mercury.

Titanium Surface Chemical Composition Interferes in the Pseudomonas aeruginosa Biofilm Formation.

PubMed

Nunes Filho, Antonio; Aires, Michelle de Medeiros; Braz, Danilo Cavalcante; Hinrichs, Ruth; Macedo, Alexandre José; Alves, Clodomiro

2018-02-01

Bacterial adhesion on three different surfaces: untreated Ti, plasma nitriding, and plasma carbonitriding Ti substrates were investigated. The samples were placed in bacterial cultures of Pseudomonas aeruginosa to assess biofilm formation. The correlation between the amount of bacteria attached to the surface after a lapse of time with nanotopography and physicochemical properties was performed. TiN showed the highest capacity to avoid bacterial adhesion, while presenting intermediate roughness and wettability. Although the surface of TiCN had the highest surface roughness and low contact angle (high wettability), bacterial adhesion was intermediate on this sample. Untreated Ti, even though presenting a smooth surface and low wettability, had the highest tendency to form biofilms. © 2018 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Microbial endophytes: future challenges

USDA-ARS?s Scientific Manuscript database

Endophytes are represented by a diverse group of prokaryotic (bacteria or cyanobacteria) or eukaryotic (fungi or parasitic vascular plants) organisms that form life-long associations within tissues of plants. Ecologically, these associations are usually viewed as advantageous although in some insta...

The endophyte Curtobacterium flaccumfaciens reduces symptoms caused by Xylella fastidiosa in Catharanthus roseus.

PubMed

Lacava, Paulo Teixeira; Li, Wenbin; Araújo, Welington Luiz; Azevedo, João Lúcio; Hartung, John Stephen

2007-10-01

Citrus variegated chlorosis (CVC) is a disease of the sweet orange [Citrus sinensis (L.)], which is caused by Xylella fastidiosa subsp. pauca, a phytopathogenic bacterium that has been shown to infect all sweet orange cultivars. Sweet orange trees have been occasionally observed to be infected by Xylella fastidiosa without evidencing severe disease symptoms, whereas other trees in the same grove may exhibit severe disease symptoms. The principal endophytic bacterial species isolated from such CVC-asymptomatic citrus plants is Curtobacterium flaccumfaciens. The Madagascar periwinkle [Citrus sinensis (L.)] is a model plant which has been used to study X. fastidiosa in greenhouse environments. In order to characterize the interactions of X. fastidiosa and C. flaccumfaciens, periwinkle plants were inoculated separately with C. flaccumfaciens, X. fastidiosa, and both bacteria together. The number of flowers produced by the plants, the heights of the plants, and the exhibited disease symptoms were evaluated. PCR-primers for C. flaccumfaciens were designed in order to verify the presence of this endophytic bacterium in plant tissue, and to complement an existing assay for X. fastidiosa. These primers were capable of detecting C. flaccumfaciens in the periwinkle in the presence of X. fastidiosa. X. fastidiosa induced stunting and reduced the number of flowers produced by the periwinkle. When C. flaccumfaciens was inoculated together with X. fastidiosa, no stunting was observed. The number of flowers produced by our doubly- inoculated plants was an intermediate between the number produced by the plants inoculated with either of the bacteria separately. Our data indicate that C. flaccumfaciens interacted with X. fastidiosa in C. roseus, and reduced the severity of the disease symptoms induced by X. fastidiosa. Periwinkle is considered to be an excellent experimental system by which the interaction of C. flaccumfaciens and other endophytic bacteria with X. fastidiosa can be

Apple endophytic microbiota of different rootstock/scion combinations suggests a genotype-specific influence.

PubMed

Liu, Jia; Abdelfattah, Ahmed; Norelli, John; Burchard, Erik; Schena, Leonardo; Droby, Samir; Wisniewski, Michael

2018-01-27

High-throughput amplicon sequencing spanning conserved portions of microbial genomes (16s rRNA and ITS) was used in the present study to describe the endophytic microbiota associated with three apple varieties, "Royal Gala," "Golden Delicious," and "Honey Crisp," and two rootstocks, M.9 and M.M.111. The objectives were to (1) determine if the microbiota differs in different rootstocks and apple varieties and (2) determine if specific rootstock-scion combinations influence the microbiota composition of either component. Results indicated that Ascomycota (47.8%), Zygomycota (31.1%), and Basidiomycota (11.6%) were the dominant fungal phyla across all samples. The majority of bacterial sequences were assigned to Proteobacteria (58.4%), Firmicutes (23.8%), Actinobacteria (7.7%), Bacteroidetes (2%), and Fusobacteria (0.4%). Rootstocks appeared to influence the microbiota of associated grafted scion, but the effect was not statistically significant. Pedigree also had an impact on the composition of the endophytic microbiota, where closely-related cultivars had a microbial community that was more similar to each other than it was to a scion cultivar that was more distantly-related by pedigree. The more vigorous rootstock (M.M.111) was observed to possess a greater number of growth-promoting bacterial taxa, relative to the dwarfing rootstock (M.9). The mechanism by which an apple genotype, either rootstock or scion, has a determinant effect on the composition of a microbial community is not known. The similarity of the microbiota in samples with a similar pedigree suggests the possibility of some level of co-evolution or selection as proposed by the "holobiont" concept in which metaorganisms have co-evolved. Clearly, however, the present information is only suggestive, and a more comprehensive analysis is needed.

Diversity and antimicrobial activity of endophytic fungi associated with the alpine plant Saussurea involucrata.

PubMed

Lv, Ya-li; Zhang, Fu-sheng; Chen, Juan; Cui, Jin-long; Xing, Yong-mei; Li, Xiang-dong; Guo, Shun-xing

2010-01-01

Endophytic fungi are rich in species diversity and may play an important role in the fitness of their host plants. This study investigated the diversity and antimicrobial potential of endophytic fungi obtained from Saussurea involucrata KAR. et KIR. A total of 49 endophytic fungi were isolated from S. involucrata and identified using morphological and molecular techniques. Extracts of fermentation broth from the 49 fungi were tested for antimicrobial activity against pathogenic microorganisms using the agar diffusion method. Forty-eight out of the 49 endophytic fungi were identified and grouped into 14 taxa. Cylindrocarpon sp. was the dominant species isolated from S. involucrata, followed by Phoma sp. and Fusarium sp. Among the 49 endophytic fungi, 9 root isolates having darkly pigmented, septate hyphae were identified as dark septate endophytic (DSE) fungus, and 12 fungi inhibited at least one test microorganism. Moreover, 5 strains showed a broader spectrum of antimicrobial activity and 4 strains displayed strong inhibition (+++) against pathogenic fungi. The results indicate that endophytic fungi isolated from S. involucrata are diverse in species and a potential source of antimicrobial agents.

First report of clavicipitaceous anamorphic endophytes in hordeum species

Treesearch

A.D. Wilson; S.L. Clement; W.J. Kaiser; D.G. Lester

1991-01-01

Clavicipitaceous endophytes systemically infect many grass species and produce alkaloids that confer resistance to insects (2) and toxicity to mammals (1). The mutualistic anamorphic forms (e.g., Acremonium spp.) do not sporulate or cause symptoms, but they produce distinctive mycelium in their hosts. The incidence of anamorphic endophytes in a portion of the U.S....

Endophyte mediated plant-herbivore interactions or cross resistance to fungi and insect herbivores

Treesearch

Kari Saikkonen; Marjo Helander

2012-01-01

Endophytic fungi are generally considered to be plant mutualists that protect the host plant from pathogens and herbivores. Defensive mutualism appears to hold true particularly for seed-transmitted, alkaloid producing, grass endophytes. However, we propose that the mutualistic nature of plant-endophyte interactions via enhanced plant resistance to pathogens and...

Endophytic microorganisms--promising applications in bioremediation of greenhouse gases.