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pseudomonas protegens sp. nov., widespread plant-protecting bacteria producing the biocontrol compounds 2,4-diacetylphloroglucinol and pyoluteorin.fluorescent pseudomonas strains producing the antimicrobial secondary metabolite 2,4-diacetylphloroglucinol (phl) play a prominent role in the biocontrol of plant diseases. a subset of phl-producing fluorescent pseudomonas strains, which can additionally synthesize the antimicrobial compound pyoluteorin (plt), appears to cluster separately from other fluorescent pseudomonas spp. based on 16s rrna gene analysis and shares at most 98.4% 16s rrna gene sequence identity with any other pseudomonas sp ...201121392918
the effect of zinc limitation on the transcriptome of pseudomonas protegens pf-5.zinc is an important nutrient but can be lacking in some soil environments, influencing the physiology of soil-dwelling bacteria. hence, we studied the global effect of zinc limitation on the transcriptome of the rhizosphere biocontrol strain pseudomonas protegens pf-5 (formerly pseudomonas fluorescens). we observed that the expression of the putative zinc uptake regulator (zur) gene was upregulated, and we mapped putative zur binding sites in the pf-5 genome using bioinformatic approaches. in l ...201322900619
ferric-pyoverdine recognition by fpv outer membrane proteins of pseudomonas protegens pf-5.the soil bacterium pseudomonas protegens pf-5 (previously called p. fluorescens pf-5) produces two siderophores, enantio-pyochelin and a compound in the large and diverse pyoverdine family. using high-resolution mass spectroscopy, we determined the structure of the pyoverdine produced by pf-5. in addition to producing its own siderophores, pf-5 also utilizes ferric complexes of some pyoverdines produced by other strains of pseudomonas spp. as sources of iron. previously, phylogenetic analysis of ...201323222724
genes expressed by the biological control bacterium pseudomonas protegens pf-5 on seed surfaces under the control of the global regulators gaca and rpos.gene expression profiles of the biological control strain pseudomonas protegens pf-5 inhabiting pea seed surfaces were revealed using a whole-genome oligonucleotide microarray. we identified genes expressed by pf-5 under the control of two global regulators (gaca and rpos) known to influence biological control and secondary metabolism. transcript levels of 897 genes, including many with unknown functions as well as those for biofilm formation, cyclic diguanylate (c-di-gmp) signalling, iron homeo ...201323297839
effect of clay mineralogy on iron bioavailability and rhizosphere transcription of 2,4-diacetylphloroglucinol biosynthetic genes in biocontrol pseudomonas protegens.pseudomonas strains producing 2,4-diacetylphloroglucinol (dapg) can protect plants from soilborne phytopathogens and are considered the primary reason for suppressiveness of morainic swiss soils to thielaviopsis basicola-mediated black root-rot disease of tobacco, even though they also occur nearby in conducive sandstone soils. the underlying molecular mechanisms accounting for this discrepancy are not understood. in this study, we assessed the hypothesis that the presence of iron-rich vermiculi ...201323405868
effect of tannic acid on the transcriptome of the soil bacterium pseudomonas protegens pf-5.tannins are a diverse group of plant-produced, polyphenolic compounds with metal-chelating and antimicrobial properties that are prevalent in many soils. using transcriptomics, we determined that tannic acid, a form of hydrolysable tannin, broadly affects the expression of genes involved in iron and zinc homeostases, sulfur metabolism, biofilm formation, motility, and secondary metabolite biosynthesis in the soil- and rhizosphere-inhabiting bacterium pseudomonas protegens pf-5.201323435890
engineering pseudomonas protegens pf-5 for nitrogen fixation and its application to improve plant growth under nitrogen-deficient conditions.nitrogen is the second most critical factor for crop production after water. in this study, the beneficial rhizobacterium pseudomonas protegens pf-5 was genetically modified to fix nitrogen using the genes encoding the nitrogenase of pseudomonas stutzeri a1501 via the x940 cosmid. pf-5 x940 was able to grow in l medium without nitrogen, displayed high nitrogenase activity and released significant quantities of ammonium to the medium. pf-5 x940 also showed constitutive expression and enzymatic ac ...201323675499
identification of orfamide a as an insecticidal metabolite produced by pseudomonas protegens f6.the use of biosurfactants for agricultural crop protection has been gaining interest because they are generally biodegradable and environmentally friendly. in the present study, we identified an insecticidal biosurfactant produced by pseudomonas protegens f6 (f6) and examined its use for aphid control. the growth of f6 was accompanied by increased aphid mortality and decreased water surface tension. bioassay-guided chromatography coupled with instrumental analyses, nuclear magnetic resonance (nm ...201323763636
identification, structure, and function of a novel type vi secretion peptidoglycan glycoside hydrolase effector-immunity pair.bacteria employ type vi secretion systems (t6sss) to facilitate interactions with prokaryotic and eukaryotic cells. despite the widespread identification of t6sss among gram-negative bacteria, the number of experimentally validated substrate effector proteins mediating these interactions remains small. here, employing an informatics approach, we define novel families of t6s peptidoglycan glycoside hydrolase effectors. consistent with the known intercellular self-intoxication exhibited by the t6s ...201323878199
in vitro-binding of the natural siderophore enantiomers pyochelin and enantiopyochelin to their arac-type regulators pchr in pseudomonas.the enantiomeric siderophores pyochelin and enantiopyochelin of pseudomonas aeruginosa and pseudomonas protegens promote growth under iron limitation and activate transcription of their biosynthesis and uptake genes via the arac-type regulator pchr. here we investigated siderophore binding to pchr in vitro using fluorescence spectroscopy. a fusion of the n-terminal domain of p. aeruginosa pchr with maltose binding protein (mbp-pchr'pao) bound iron-loaded (ferri-) pyochelin with an affinity (kd) ...201324037597
biofilm development and enhanced stress resistance of a model, mixed-species community biofilm.most studies of biofilm biology have taken a reductionist approach, where single-species biofilms have been extensively investigated. however, biofilms in nature mostly comprise multiple species, where interspecies interactions can shape the development, structure and function of these communities differently from biofilm populations. hence, a reproducible mixed-species biofilm comprising pseudomonas aeruginosa, pseudomonas protegens and klebsiella pneumoniae was adapted to study how interspecie ...201324152718
cell culturability of pseudomonas protegens cha0 depends on soil ph.pseudomonas inoculants may lose colony-forming ability in soil, but soil properties involved are poorly documented. here, we tested the hypothesis that soil acidity could reduce persistence and cell culturability of pseudomonas protegens cha0. at 1 week in vitro, strain cha0 was found as culturable cells at ph 7, whereas most cells at ph 4 and all cells at ph 3 were noncultured. in 21 natural soils of contrasted ph, cell culturability loss of p. protegens cha0 took place in all six very acidic s ...201424224494
gamma-glutamyl transpeptidase from two plant growth promoting rhizosphere fluorescent pseudomonads.glutathione is the most abundant non-protein thiol compound present in many cells. because this molecule is involved in many physiological processes, each cell maintains a critical level of glutathione. gamma-glutamyl transpeptidase (ggt, e.c.2.3.2.2) is the key enzyme involved in the glutathione cycle. in the present study, ggt was isolated from two plant growth promoting rhizosphere isolates, pseudomonas protegens strain pf-5 and pseudomonas fluorescens strain pft-1. ggt in these strains is lo ...201424232936
[isolation, identification and characterization of five pseudomonas strains].we isolated pseudomonas strains from soil samples collected from changsha, hunan province, catalogued them and studied the antimicrobial and antitumor activity.201324377248
lon protease negatively affects gaca protein stability and expression of the gac/rsm signal transduction pathway in pseudomonas protegens.in pseudomonas protegens cha0 and other fluorescent pseudomonads, the gac/rsm signal transduction pathway controls secondary metabolism and suppression of fungal root pathogens via the expression of regulatory small rnas (srnas). because of its high cost, this pathway needs to be protected from overexpression and to be turned off in response to environmental stress such as the lack of nutrients. however, little is known about its underlying molecular mechanisms. in this study, we demonstrated th ...201424428244
molecular identification of lipase lipa from pseudomonas protegens pf-5 and characterization of two whole-cell biocatalysts pf-5 and top10lipa.to identify lipase lipa (pfl_0617) from pseudomonas protegens pf-5, a lipa deletion mutant (pf0617) and a complementary strain (pf0617lipa) were constructed, and their effects on the lipase production were examined. pf0617 remarkably decreased its whole-cell lipase activity, whereas pf0617lipa made its whole-cell lipase activity not only restore to wild-type level but also get a further increment. however, the deletion and overexpression of lipa did not affect the extracellular lipase activity. ...201424548931
domain shuffling in a sensor protein contributed to the evolution of insect pathogenicity in plant-beneficial pseudomonas protegens.pseudomonas protegens is a biocontrol rhizobacterium with a plant-beneficial and an insect pathogenic lifestyle, but it is not understood how the organism switches between the two states. here, we focus on understanding the function and possible evolution of a molecular sensor that enables p. protegens to detect the insect environment and produce a potent insecticidal toxin specifically during insect infection but not on roots. by using quantitative single cell microscopy and mutant analysis, we ...201424586167
rhizosphere ecology and phytoprotection in soils naturally suppressive to thielaviopsis black root rot of tobacco.soil suppressiveness to disease is an intriguing emerging property in agroecosystems, with important implications because it enables significant protection of susceptible plants from soil-borne pathogens. unlike many soils where disease suppressiveness requires crop monoculture to establish, certain soils are naturally suppressive to disease, and this type of specific disease suppressiveness is maintained despite crop rotation. soils naturally suppressive to thielaviopsis basicola-mediated black ...201424650207
to settle or to move? the interplay between two classes of cyclic lipopeptides in the biocontrol strain pseudomonas cmr12a.pseudomonas cmr12a is a biocontrol strain that produces phenazine antibiotics and as yet uncharacterized cyclic lipopeptides (clps). the clps of cmr12a were studied by chemical structure analysis and in silico analysis of the gene clusters encoding the non-ribosomal peptide synthetases responsible for clp biosynthesis. cmr12a produces two different classes of clps: orfamides b, d and e, whereby the latter two represent new derivatives of the orfamide family, and sessilins a-c. the orfamides are ...201424673852
functional analysis of pyochelin-/enantiopyochelin-related genes from a pathogenicity island of pseudomonas aeruginosa strain pa14.genomic islands are foreign dna blocks inserted in so-called regions of genomic plasticity (rgp). depending on their gene content, they are classified as pathogenicity, symbiosis, metabolic, fitness or resistance islands, although a detailed functional analysis is often lacking. here we focused on a 34-kb pathogenicity island of pseudomonas aeruginosa pa14 (pa14gi-6), which is inserted at rgp5 and carries genes related to those for pyochelin/enantiopyochelin biosynthesis. these enantiomeric side ...201424682869
complete genome sequence of the biocontrol strain pseudomonas protegens cab57 discovered in japan reveals strain-specific diversity of this species.the biocontrol strain pseudomonas sp. cab57 was isolated from the rhizosphere of shepherd's purse growing in a field in hokkaido by screening the antibiotic producers. the whole genome sequence of this strain was obtained by paired-end and whole-genome shotgun sequencing, and the gaps between the contigs were closed using gap-spanning pcr products. the p. sp. cab57 genome is organized into a single circular chromosome with 6,827,892 bp, 63.3% g+c content, and 6,186 predicted protein-coding seque ...201424695768
pseudomonas protegens pf-5 causes discoloration and pitting of mushroom caps due to the production of antifungal metabolites.bacteria in the diverse pseudomonas fluorescens group include rhizosphere inhabitants known for their antifungal metabolite production and biological control of plant disease, such as pseudomonas protegens pf-5, and mushroom pathogens, such as pseudomonas tolaasii. here, we report that strain pf-5 causes brown, sunken lesions on peeled caps of the button mushroom (agaricus bisporus) that resemble brown blotch symptoms caused by p. tolaasii. strain pf-5 produces six known antifungal metabolites u ...201424742073
full-genome sequence of the plant growth-promoting bacterium pseudomonas protegens cha0.we report the complete genome sequence of the free-living bacterium pseudomonas protegens (formerly pseudomonas fluorescens) cha0, a model organism used in plant-microbe interactions, biological control of phytopathogens, and bacterial genetics.201424762936
n-terminal transmembrane domain of lipase lipa from pseudomonas protegens pf-5: a must for its efficient folding into an active conformation.lipa from pseudomonas protegens pf-5 has been proven not to be secreted into the extracytoplasmic space, proposing that it is a membrane protein in virtue of its n-terminal transmembrane domain predicted by the tmhmm 2.0. however, lipa was confirmed to be an intracellular protein through determining the effects of lipa deletion or overexpression on the lipase activities in the whole-cell, lysis supernatant and lysis pellet, even through its transmembrane domain being able to make heterologous la ...201425038570
structure revision of n-mercapto-4-formylcarbostyril produced by pseudomonas fluorescens g308 to 2-(2-hydroxyphenyl)thiazole-4-carbaldehyde [aeruginaldehyde].an antibiotic substance isolated from pseudomonas fluorescens strain g308 was earlier assigned the structure of n-mercapto-4-formylcarbostyril, but computational predictions of the 1h and 13c nmr magnetic shielding tensors show this structure to be incompatible with the published spectroscopic data. the same is true for six quinoline derivatives related to n-mercapto-4-formylcarbostyril by permutation of the o and s atoms. in contrast, 2-(2-hydroxyphenyl)thiazole-4-carbaldehyde [aeruginaldehyde] ...201425115080
the two-component gacs-gaca system activates lipa translation by rsme but not rsma in pseudomonas protegens pf-5.in pseudomonas spp., the gac-rsm signal transduction system is required for the production of lipases. the current model assumes that the system induces lipase gene transcription mediated through the quorum-sensing (qs) system. however, there are no reports of a qs system based upon n-acyl homoserine lactones or the regulation of lipase gene expression in pseudomonas protegens. in this study, we investigated the regulatory mechanism acting on lipa expression activated by the gac-rsm system in p. ...201425128345
biocontrol and plant growth-promoting activity of rhizobacteria from chinese fields with contaminated soils.the aim of this study was to inventory the types of plant growth-promoting rhizobacteria (pgpr) present in the rhizosphere of plants grown in soils contaminated with heavy metals, recalcitrant organics, petroleum sewage or salinity in china. we screened 1223 isolates for antifungal activity and about 24% inhibited rhizoctonia solani or sclerotinia sclerotiorum. twenty-four strains inhibitory to r. solani, gaeumannomyces graminis var. tritici and/or s. sclerotiorum and representing the dominant m ...201425219642
characterization of the ability to form biofilms by plant-associated pseudomonas species.successful colonization is the initial step for plant-bacteria interactions; therefore, the development of strategies to improve adherence to plant surfaces is critically important for environmental bacteria. biofilm formation is thought to be one such strategy for bacteria to establish stable colonization on inert and living surfaces. although biofilms play potential roles in enabling persistent bacterial colonization, little attention has been paid to biofilms formed by plant-associated bacter ...201525487118
rhizoxin analogs contribute to the biocontrol activity of a newly isolated pseudomonas strain.two strains of pseudomonas sp., os17 and st29, were newly isolated from the rhizosphere of rice and potato, respectively, by screening for 2,4-diacetylphloroglucinol producers. these strains were found to be the same species and were the closest to but different from pseudomonas protegens among the sequenced pseudomonads, based on 16s ribosomal rna gene and whole-genome analyses. strain os17 was as effective a biocontrol agent as reported for p. protegens cab57, whereas strain st29 was less effe ...201525496595
production of siderophores increases resistance to fusaric acid in pseudomonas protegens pf-5.fusaric acid is produced by pathogenic fungi of the genus fusarium, and is toxic to plants and rhizobacteria. many fluorescent pseudomonads can prevent wilt diseases caused by these fungi. this study was undertaken to evaluate the effect of fusaric acid on p. protegens pf-5 and elucidate the mechanisms that enable the bacterium to survive in the presence of the mycotoxin. the results confirm that fusaric acid negatively affects growth and motility of p. protegens. moreover, a notable increase in ...201525569682
against friend and foe: type 6 effectors in plant-associated bacteria.bacterial secretion systems play critical roles in communication with neighboring bacteria and in the modulation of host immune responses via the secretion of small proteins called effectors. several secretion systems have been identified and these are denoted types i-vii. of these, the type vi secretion system (t6ss) and its effectors were only recently elucidated. most studies on the role and significance of the t6ss and its effectors have focused on human pathogens. in this review, type 6 eff ...201525732741
inhibition of cell differentiation in bacillus subtilis by pseudomonas protegens.interspecies interactions have been described for numerous bacterial systems, leading to the identification of chemical compounds that impact bacterial physiology and differentiation for processes such as biofilm formation. here, we identified soil microbes that inhibit biofilm formation and sporulation in the common soil bacterium bacillus subtilis. we did so by creating a reporter strain that fluoresces when the transcription of a biofilm-specific gene is repressed. using this reporter in a co ...201525825426
investigations into the biosynthesis, regulation, and self-resistance of toxoflavin in pseudomonas protegens pf-5.pseudomonas spp. are prolific producers of natural products from many structural classes. here we show that the soil bacterium pseudomonas protegens pf-5 is capable of producing trace levels of the triazine natural product toxoflavin (1) under microaerobic conditions. we evaluated toxoflavin production by derivatives of pf-5 with deletions in specific biosynthesis genes, which led us to propose a revised biosynthetic pathway for toxoflavin that shares the first two steps with riboflavin biosynth ...201526077901
evolutionary patchwork of an insecticidal toxin shared between plant-associated pseudomonads and the insect pathogens photorhabdus and xenorhabdus.root-colonizing fluorescent pseudomonads are known for their excellent abilities to protect plants against soil-borne fungal pathogens. some of these bacteria produce an insecticidal toxin (fit) suggesting that they may exploit insect hosts as a secondary niche. however, the ecological relevance of insect toxicity and the mechanisms driving the evolution of toxin production remain puzzling.201526275815
antimicrobial resistance of pseudomonas spp. isolated from wastewater and wastewater-impacted marine coastal zone.in this study, species distribution and antimicrobial susceptibility of cultivated pseudomonas spp. were studied in influent (inf), effluent (eff), and marine outfall (mout) of wastewater treatment plant (wwtp). the susceptibility was tested against 8 antimicrobial classes, active against pseudomonas spp.: aminoglycosides, carbapenems, broad-spectrum cephalosporins from the 3rd and 4th generation, extended-spectrum penicillins, as well as their combination with the β-lactamase inhibitors, monoba ...201526286796
potential impacts of aquatic pollutants: sub-clinical antibiotic concentrations induce genome changes and promote antibiotic resistance.antibiotics are disseminated into aquatic environments via human waste streams and agricultural run-off. here they can persist at low, but biologically relevant, concentrations. antibiotic pollution establishes a selection gradient for resistance and may also raise the frequency of events that generate resistance: point mutations; recombination; and lateral gene transfer. this study examined the response of bacteria to sub-inhibitory levels of antibiotics. pseudomonas aeruginosa and pseudomonas ...201526300869
phloroglucinol functions as an intracellular and intercellular chemical messenger influencing gene expression in pseudomonas protegens.bacteria can be both highly communicative and highly competitive in natural habitats and antibiotics are thought to play a role in both of these processes. the soil bacterium pseudomonas protegens pf-5 produces a spectrum of antibiotics, two of which, pyoluteorin and 2,4-diacetylphloroglucinol (dapg), function in intracellular and intercellular communication, both as autoinducers of their own production. here, we demonstrate that phloroglucinol, an intermediate in dapg biosynthesis, can serve as ...201626337778
pseudomonas aeruginosa pao1 exopolysaccharides are important for mixed species biofilm community development and stress tolerance.pseudomonas aeruginosa pao1 produces three polysaccharides, alginate, psl, and pel that play distinct roles in attachment and biofilm formation for monospecies biofilms. considerably less is known about their role in the development of mixed species biofilm communities. this study has investigated the roles of alginate, psl, and pel during biofilm formation of p. aeruginosa in a defined and experimentally informative mixed species biofilm community, consisting of p. aeruginosa, pseudomonas prote ...201526347731
exploring the ancestral mechanisms of regulation of horizontally acquired nitrogenases.the vast majority of pseudomonas species are unable to fix atmospheric nitrogen. although several studies have demonstrated that some strains belonging to the genus pseudomonas sensu stricto do have the ability to fix nitrogen by the expression of horizontally acquired nitrogenase, little is known about the mechanisms of nitrogenase adaptation to the new bacterial host. recently, we transferred the nitrogen fixation island from pseudomonas stutzeri a1501 to the non-nitrogen-fixing bacterium pseu ...201526374754
an interspecies signaling system mediated by fusaric acid has parallel effects on antifungal metabolite production by pseudomonas protegens strain pf-5 and antibiosis of fusarium spp.pseudomonas protegens strain pf-5 is a rhizosphere bacterium that suppresses soilborne plant diseases and produces at least seven different secondary metabolites with antifungal properties. we derived mutants of pf-5 with single and multiple mutations in biosynthesis genes for seven antifungal metabolites: 2,4-diacetylphoroglucinol (dapg), pyrrolnitrin, pyoluteorin, hydrogen cyanide, rhizoxin, orfamide a, and toxoflavin. these mutants were tested for inhibition of the pathogens fusarium verticil ...201526655755
insect pathogenicity in plant-beneficial pseudomonads: phylogenetic distribution and comparative genomics.bacteria of the genus pseudomonas occupy diverse environments. the pseudomonas fluorescens group is particularly well-known for its plant-beneficial properties including pathogen suppression. recent observations that some strains of this group also cause lethal infections in insect larvae, however, point to a more versatile ecology of these bacteria. we show that 26 p. fluorescens group strains, isolated from three continents and covering three phylogenetically distinct sub-clades, exhibited dif ...201626894448
living on the edge: emergence of spontaneous gac mutations in pseudomonas protegens during swarming motility.swarming motility is a flagella-driven multicellular behaviour that allows bacteria to colonize new niches and escape competition. here, we investigated the evolution of specific mutations in the gacs/gaca two-component regulatory system in swarming colonies of pseudomonas protegens pf-5. experimental evolution assays showed that repeated rounds of swarming by wildtype pf-5 drives the accumulation of gacs/gaca spontaneous mutants on the swarming edge. these mutants cannot swarm on their own beca ...201626945503
biosynthesis, chemical structure, and structure-activity relationship of orfamide lipopeptides produced by pseudomonas protegens and related species.orfamide-type cyclic lipopeptides (clps) are biosurfactants produced by pseudomonas and involved in lysis of oomycete zoospores, biocontrol of rhizoctonia and insecticidal activity against aphids. in this study, we compared the biosynthesis, structural diversity, in vitro and in planta activities of orfamides produced by rhizosphere-derived pseudomonas protegens and related pseudomonas species. genetic characterization together with chemical identification revealed that the main orfamide compoun ...201627065956
rhizoxin analogs, orfamide a and chitinase production contribute to the toxicity of pseudomonas protegens strain pf-5 to drosophila melanogaster.pseudomonas protegens strain pf-5 is a soil bacterium that was first described for its capacity to suppress plant diseases and has since been shown to be lethal to certain insects. among these is the common fruit fly drosophila melanogaster, a well-established model organism for studies evaluating the molecular and cellular basis of the immune response to bacterial challenge. pf-5 produces the insect toxin fitd, but a δfitd mutant of pf-5 retained full toxicity against d. melanogaster in a nonin ...201627130686
the rare codon aga is involved in regulation of pyoluteorin biosynthesis in pseudomonas protegens pf-5.the soil bacterium pseudomonas protegens pf-5 can colonize root and seed surfaces of many plants, protecting them from infection by plant pathogenic fungi and oomycetes. the capacity to suppress disease is attributed to pf-5's production of a large spectrum of antibiotics, which is controlled by complex regulatory circuits operating at the transcriptional and post-transcriptional levels. in this study, we analyzed the genomic sequence of pf-5 for codon usage patterns and observed that the six ra ...201627148187
major cereal crops benefit from biological nitrogen fixation when inoculated with the nitrogen-fixing bacterium pseudomonas protegens pf-5 x940.a main goal of biological nitrogen fixation research has been to expand the nitrogen-fixing ability to major cereal crops. in this work, we demonstrate the use of the efficient nitrogen-fixing rhizobacterium pseudomonas protegens pf-5 x940 as a chassis to engineer the transfer of nitrogen fixed by bnf to maize and wheat under non-gnotobiotic conditions. inoculation of maize and wheat with pf-5 x940 largely improved nitrogen content and biomass accumulation in both vegetative and reproductive tis ...201627198923
a rifampicin-resistant (rpob) mutation in pseudomonas protegens pf-5 strain leads to improved antifungal activity and elevated production of secondary metabolites.ribosome engineering has proven to be a practical method for increasing antibiotic production, and is extensively applied to strain improvement in antibiotic production and activation of silent genes in several prokaryotes. in this study, ribosome engineering was used to improve production of bioactive secondary metabolites produced by pseudomonas protegens pf-5. rifampicin-resistant mutants that bear the h531n in the β-subunit of rna polymerase showed improved antifungal activity and morphologi ...201627208659
the importance of correcting for variable probe-sample interactions in afm-ir spectroscopy: afm-ir of dried bacteria on a polyurethane film.afm-ir is a combined atomic force microscopy-infrared spectroscopy method that shows promise for nanoscale chemical characterization of biological-materials interactions. in an effort to apply this method to quantitatively probe mechanisms of microbiologically induced polyurethane degradation, we have investigated monolayer clusters of ∼200 nm thick pseudomonas protegens pf-5 bacteria (pf) on a 300 nm thick polyether-polyurethane (pu) film. here, the impact of the different biological and polyme ...201627403761
disruption of transporters affiliated with enantio-pyochelin biosynthesis gene cluster of pseudomonas protegens pf-5 has pleiotropic effects.pseudomonas protegens pf-5 (formerly pseudomonas fluorescens) is a biocontrol bacterium that produces the siderophore enantio-pyochelin under conditions of iron starvation in a process that is often accompanied by the secretion of its biosynthesis intermediates, salicylic acid and dihydroaeruginoic acid. in this study, we investigated whether several transporters that are encoded by genes within or adjacent to the enantio-pyochelin biosynthetic cluster, serve as efflux systems for enantio-pyoche ...201627442435
carbon catabolite repression and impranil polyurethane degradation in pseudomonas protegens strain pf-5.polyester polyurethane (pu) coatings are widely used to help protect underlying structural surfaces but are susceptible to biological degradation. pus are susceptible to degradation by pseudomonas species, due in part to the degradative activity of secreted hydrolytic enzymes. microorganisms often respond to environmental cues by secreting enzymes or secondary metabolites to benefit their survival. this study investigated the impact of exposing several pseudomonas strains to select carbon source ...201627496773
specific surface glycan decorations enable antimicrobial peptide resistance in plant-beneficial pseudomonads with insect-pathogenic properties.some plant-beneficial pseudomonads can invade and kill pest insects in addition to their ability to protect plants from phytopathogens. we explored the genetic basis of o-polysaccharide (o-ps, o-antigen) biosynthesis in the representative insecticidal strains pseudomonas protegens cha0 and pseudomonas chlororaphis pcl1391 and investigated its role in insect pathogenicity. both strains produce two distinct forms of o-ps, but differ in the organization of their o-ps biosynthesis clusters. biosynth ...201627727519
interspecific cooperation: enhanced growth, attachment and strain-specific distribution in biofilms through azospirillum brasilense-pseudomonas protegens co-cultivation.plant-growth-promoting bacteria belonging to azospirillum and pseudomonas genera are major inhabitants of the rhizosphere. both are increasingly commercialized as crops inoculants. interspecific interaction in the rhizosphere is critical for inoculants aptness. the objective of this work was to evaluate azospirillum and pseudomonas interaction in mixed biofilms by co-cultivation of the model strains azospirillum brasilense sp245 and pseudomonas protegens cha0. the results revealed enhanced growt ...201627742715
candidate nematicidal proteins in a new pseudomonas veronii isolate identified by its antagonistic properties against xiphinema index.the nematode xiphinema index affects grape vines and transmits important viruses associated with fanleaf degeneration. pseudomonas spp. are an extensive bacterial group in which important biodegradation and/or biocontrol properties can occur for several strains in the group. the aim of this study was to identify new pseudomonas isolates with antagonist activity against x. index. forty bacterial isolates were obtained from soil and root samples from chilean vineyards. thirteen new fluorescent pse ...201727989999
transport capabilities of environmental pseudomonads for sulfur compounds.sulfur is an essential element in plant rhizospheres and microbial activity plays a key role in increasing the biological availability of sulfur in soil environments. to better understand the mechanisms facilitating the exchange of sulfur-containing molecules in soil, we profiled the binding specificities of eight previously uncharacterized abc transporter solute-binding proteins from plant-associated pseudomonads. a high-throughput screening procedure indicated eighteen significant organosulfur ...201728127814
pseudomonas protegens cs1 from the lemon phyllosphere as a candidate for citrus canker biocontrol agent.citrus canker is a worldwide-distributed disease caused by xanthomonas citri subsp. citri. one of the most used strategies to control the disease is centred on copper-based compounds that cause environmental problems. therefore, it is of interest to develop new strategies to manage the disease. previously, we reported the ability of the siderophore pyochelin, produced by the opportunistic human pathogen pseudomonas aeruginosa, to inhibit in vitro several bacterial species, including x. citri sub ...201728194866
antimicrobial and insecticidal: cyclic lipopeptides and hydrogen cyanide produced by plant-beneficial pseudomonas strains cha0, cmr12a, and pcl1391 contribute to insect killing.particular groups of plant-beneficial fluorescent pseudomonads are not only root colonizers that provide plant disease suppression, but in addition are able to infect and kill insect larvae. the mechanisms by which the bacteria manage to infest this alternative host, to overcome its immune system, and to ultimately kill the insect are still largely unknown. however, the investigation of the few virulence factors discovered so far, points to a highly multifactorial nature of insecticidal activity ...201728217113
novel mechanism of metabolic co-regulation coordinates the biosynthesis of secondary metabolites in pseudomonas protegens.metabolic co-regulation between biosynthetic pathways for secondary metabolites is common in microbes and can play an important role in microbial interactions. here, we describe a novel mechanism of metabolic co-regulation in which an intermediate in one pathway is converted into signals that activate a second pathway. our study focused on the co-regulation of 2,4-diacetylphloroglucinol (dapg) and pyoluteorin, two antimicrobial metabolites produced by the soil bacterium pseudomonas protegens. we ...201728262092
pseudomonas fluorescens transportome is linked to strain-specific plant growth promotion in aspen seedlings under nutrient stress.diverse communities of bacteria colonize plant roots and the rhizosphere. many of these rhizobacteria are symbionts and provide plant growth promotion (pgp) services, protecting the plant from biotic and abiotic stresses and increasing plant productivity by providing access to nutrients that would otherwise be unavailable to roots. in return, these symbiotic bacteria receive photosynthetically-derived carbon (c), in the form of sugars and organic acids, from plant root exudates. pgp activities h ...201728377780
the pseudomonas transcriptional regulator algr controls lipa expression via the noncoding rna rsmz in pseudomonas protegens pf-5.pseudomonas lipases are well studied enzymes. however, few studies have been conducted to explore the mechanism underlying the regulation of lipases expression. algr, a global regulator, controls the expression of multiple genes, regulates bacterial peristalsis, and participates in the regulation of quorum-sensing (qs) system, and so on. in this study, the effect of algr on lipase expression was investigated by knocking out the algr and rsmz genes or overexpressing them. it is found out that alg ...201728400281
complete genome sequence of pseudomonas protegens h78, a plant growth-promoting rhizobacterium.the plant growth-promoting rhizobacterium pseudomonas protegens h78, which was isolated from the rhizosphere of oilseed rape in shanghai, can produce a large array of antibiotics with a broad spectrum of activities. here, we report the annotated complete genome sequence of p. protegens h78.201728428310
watasemycin biosynthesis in streptomyces venezuelae: thiazoline c-methylation by a type b radical-sam methylase homologue.2-hydroxyphenylthiazolines are a family of iron-chelating nonribosomal peptide natural products that function as virulence-conferring siderophores in various gram-negative bacteria. they have also been reported as metabolites of gram-positive streptomyces species. transcriptional analyses of streptomyces venezuelae atcc 10712 revealed that its genome contains a putative 2-hydroxyphenylthiazoline biosynthetic gene cluster. heterologous expression of the gene cluster in streptomyces coelicolor m11 ...201728553520
pseudomonas protegens pf-5 favours self-produced siderophore over free-loading in interspecies competition for iron.many microorganisms compete for extracellular iron using strain-specific chelators known as siderophores. the ferric-siderophore complex limits local access to iron because import requires a suitable cognate receptor. interestingly, many species carry receptors that enable 'cross-feeding' on heterologous siderophores made by neighboring organisms, although little is known about how this ubiquitous behaviour is regulated. here, we investigated the soil bacterium pseudomonas protegens pf-5, a stra ...201728631403
multiple pseudomonas species secrete exolysin-like toxins and provoke caspase-1-dependent macrophage death.pathogenic bacteria secrete protein toxins that provoke apoptosis or necrosis of eukaryotic cells. here, we developed a live-imaging method, based on incorporation of a dna-intercalating dye into membrane-damaged host cells, to study the kinetics of primary bone marrow-derived macrophages (bmdms) mortality induced by opportunistic pathogen pseudomonas aeruginosa expressing either type iii secretion system (t3ss) toxins or the pore-forming toxin, exolysin (exla). we found that exla promotes the a ...201728654176
a matter of hierarchy: activation of orfamide production by the post-transcriptional gac-rsm cascade of pseudomonas protegens cha0 through expression upregulation of the two dedicated transcriptional regulators.in this work, we surveyed the genome of p. protegens cha0 in order to identify novel mrnas possibly under the control of the gac-rsm cascade that might, for their part, serve to elucidate as-yet-unknown functions involved in the biocontrol of plant pathogens and/or in cellular processes required for fitness in natural environments. in view of the experimental evidence from former studies on the gac-rsm cascade, we developed a computational screen supported by a combination of sequence, structura ...201728703431
gacs/gaca activates pyoluteorin biosynthesis through gac/rsm-rsme cascade and rsma/rsme-driven feedback loop in pseudomonas protegens h78.the gac/rsm regulatory pathway in pseudomonas spp. activates the production of various secondary metabolites, such as antibiotics, siderophores and exoenzymes. however, the biosynthesis of antifungal compound pyoluteorin (plt) in pseudomonas protegens h78 is almost entirely inhibited by double deletion of two csra/rsma family genes, namely, rsma and rsme. here, we investigated the complicated regulatory mechanism of rsma and rsme in plt biosynthesis in p. protegens h78. rsme negatively regulated ...201728710872
an enterotoxin-like binary protein from pseudomonas protegens with potent nematicidal activity.soil microbes are a major food source for free-living soil nematodes. it is known that certain soil bacteria have evolved systems to combat predation. we identified the nematode-antagonistic pseudomonas protegens strain 15g2 from screening of microbes. through protein purification we identified a binary protein, designated as pp-anp, that is responsible for the nematicidal activity. this binary protein inhibits caenorhabditis elegans growth and development by arresting larvae at l1 stage and kil ...201728733289
the cyclic lipopeptide orfamide induces systemic resistance in rice to cochliobolus miyabeanus but not to magnaporthe oryzae.the pseudomonas- derived cyclic lipopeptide orfamide can induce resistance to cochliobolus miyabeanus but not to magnaporthe oryzae in rice. abscisic acid signaling is involved in the induced systemic resistance response triggered by orfamide. diverse natural products produced by beneficial pseudomonas species have the potential to trigger induced systemic resistance (isr) in plants, and thus may contribute to control of diseases in crops. some beneficial pseudomonas spp. can produce cyclic lipo ...201728801742
the role of hfq in regulation of lipa expression in pseudomonas protegens pf-5.pseudomonas lipase is a well-studied lipase. however, few studies have been conducted to examine the mechanisms underlying the regulation of the lipase expression. hfq is a global regulatory protein that, among others, controls the expression of multiple genes, regulate bacterial peristalsis, and participates in the regulation of quorum-sensing (qs) system. in this study, the effects of hfq on lipase expression were investigated by knocking out the hfq and rsmy genes or overexpressing of hfq and ...201728871123
gaba, a primary metabolite controlled by the gac/rsm regulatory pathway, favors a planktonic over a biofilm lifestyle in pseudomonas protegens cha0.in pseudomonas protegens cha0 and other fluorescent pseudomonads, the gac/rsm signal transduction pathway is crucial for the expression of secondary metabolism and the biological control of fungi, nematodes, and insects. based on the findings of a previous metabolomic study, the role of intracellular γ-aminobutyrate (gaba) as a potential signal in the gac/rsm pathway was investigated herein. the function and regulation of a gabdt (c01870-c01880) gene cluster in strain cha0 were described. the ga ...201828990487
biocontrol activity of volatile-producing bacillus megaterium and pseudomonas protegens against aspergillus flavus and aflatoxin production on stored rice grains.in our previous study, three bacterial strains, bacillus megaterium ku143, microbacterium testaceum ku313, and pseudomonas protegens as15, were selected as effective biocontrol agents against aspergillus flavus on stored rice grains. in this study, we evaluated the inhibitory effects of the volatiles produced by the strains on a. flavus growth and aflatoxin production on stored rice grains. the three strains significantly reduced mycelial growth of a. flavus in dual-culture assays compared with ...201729138628
fluorescent pseudomonads pursue media-dependent strategies to inhibit growth of pathogenic verticillium fungi.verticillium species represent economically important phytopathogenic fungi with bacteria as natural rhizosphere antagonists. growth inhibition patterns of verticillium in different media were compared to saprophytic aspergillus strains and were significantly more pronounced in various co-cultivations with different pseudomonas strains. the brassica napus rhizosphere bacterium pseudomonas fluorescens dsm8569 is able to inhibit growth of rapeseed (verticillium longisporum) or tomato (verticillium ...201829151161
antagonistic bacteria disrupt calcium homeostasis and immobilize algal cells.photosynthetic unicellular organisms, known as microalgae, are key contributors to carbon fixation on earth. their biotic interactions with other microbes shape aquatic microbial communities and influence the global photosynthetic capacity. so far, limited information is available on molecular factors that govern these interactions. we show that the bacterium pseudomonas protegens strongly inhibits the growth and alters the morphology of the biflagellated green alga chlamydomonas reinhardtii. th ...201729170415
diverse nadase effector families mediate interbacterial antagonism via the type vi secretion system.the bacterial type vi secretion system (t6ss) mediates antagonistic cell-cell interactions between competing gram-negative bacteria. in plant-beneficial bacteria, this pathway has been shown to suppress the growth of bacterial pathogens; however, the identification and mode of action of t6ss effector proteins that mediate this protective effect remain poorly defined. here, we identify two previously uncharacterized effectors required for interbacterial antagonism by the plant commensal bacterium ...201729237732
secondary metabolism and interspecific competition affect accumulation of spontaneous mutants in the gacs-gaca regulatory system in pseudomonas protegens.secondary metabolites are synthesized by many microorganisms and provide a fitness benefit in the presence of competitors and predators. secondary metabolism also can be costly, as it shunts energy and intermediates from primary metabolism. in pseudomonas spp., secondary metabolism is controlled by the gacs-gaca global regulatory system. intriguingly, spontaneous mutations in gacs or gaca (gac- mutants) are commonly observed in laboratory cultures. here we investigated the role of secondary meta ...201829339425
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