-
BMC Genomics Dec 2015While the taxonomy and genomics of environmental strains from the P. fluorescens species-complex has been reported, little is known about P. fluorescens strains from...
BACKGROUND
While the taxonomy and genomics of environmental strains from the P. fluorescens species-complex has been reported, little is known about P. fluorescens strains from clinical samples. In this report, we provide the first genomic analysis of P. fluorescens strains in which human vs. environmental isolates are compared.
RESULTS
Seven P. fluorescens strains were isolated from respiratory samples from cystic fibrosis (CF) patients. The clinical strains could grow at a higher temperature (>34 °C) than has been reported for environmental strains. Draft genomes were generated for all of the clinical strains, and multi-locus sequence analysis placed them within subclade III of the P. fluorescens species-complex. All strains encoded type- II, -III, -IV, and -VI secretion systems, as well as the widespread colonization island (WCI). This is the first description of a WCI in P. fluorescens strains. All strains also encoded a complete I2/PfiT locus and showed evidence of horizontal gene transfer. The clinical strains were found to differ from the environmental strains in the number of genes involved in metal resistance, which may be a possible adaptation to chronic antibiotic exposure in the CF lung.
CONCLUSIONS
This is the largest comparative genomics analysis of P. fluorescens subclade III strains to date and includes the first clinical isolates. At a global level, the clinical P. fluorescens subclade III strains were largely indistinguishable from environmental P. fluorescens subclade III strains, supporting the idea that identifying strains as 'environmental' vs 'clinical' is not a phenotypic trait. Rather, strains within P. fluorescens subclade III will colonize and persist in any niche that provides the requirements necessary for growth.
Topics: Bacterial Secretion Systems; Base Composition; Cystic Fibrosis; Genetic Loci; Genome, Bacterial; Genomics; Genotype; Humans; Metals; Multigene Family; Phenotype; Phylogeny; Pneumonia, Bacterial; Pseudomonas Infections; Pseudomonas fluorescens; Secondary Metabolism; Sequence Analysis, DNA
PubMed: 26644001
DOI: 10.1186/s12864-015-2261-2 -
Current Microbiology Apr 2011A rhizobacterium with high antifungal activity was isolated from a potato field at Inneruulalik, South Greenland. Phylogenetic analysis based on multi locus sequence...
A rhizobacterium with high antifungal activity was isolated from a potato field at Inneruulalik, South Greenland. Phylogenetic analysis based on multi locus sequence typing showed that the bacterium was affiliated with strains of Pseudomonas fluorescens. The bacterium, denoted as Pseudomonas fluorescens In5, inhibited in vitro a broad range of phytopathogenic fungi, and the antifungal activity increased with decreasing temperature. Microcosm experiments demonstrated that P. fluorescens In5 protected tomato seedlings from Rhizoctonia solani. Transposon mutagenesis showed that the major cause for the antifungal activity of P. fluorescens In5 was a novel non-ribosomal peptide synthase (NRPS) gene. In addition, transposon mutagenesis showed that P. fluorescens In5 also contained a putative quinoprotein glucose dehydrogenase gene, which was involved in growth inhibition of phytopathogenic fungi. Although P. fluorescens In5 contained the capacity to synthesize hydrogen cyanide, β-1,3-glucanase, protease, and chitinase, these did not seem to play a role in the in vitro and microcosm antifungal assays.
Topics: Antibiosis; Fungal Proteins; Greenland; Solanum lycopersicum; Molecular Sequence Data; Phylogeny; Plant Diseases; Pseudomonas fluorescens; Rhizoctonia; Soil Microbiology; Solanum tuberosum
PubMed: 21165740
DOI: 10.1007/s00284-010-9846-4 -
Journal of General Microbiology Oct 1980The relationships among 93 strains of Pseudomonas fluorescens were investigated by (1) a numerical taxonomic analysis on the results of 150 phenotypic tests, (2) DNA... (Comparative Study)
Comparative Study
The relationships among 93 strains of Pseudomonas fluorescens were investigated by (1) a numerical taxonomic analysis on the results of 150 phenotypic tests, (2) DNA hybridization studies using 16 reference strains, (3) quantitative microcomplement fixation studies using six reference strains with antibodies directed against the protein azurin. In general, the strains fell into distinct clusters. Assignment to these clusters on the basis of azurin immunological similarity showed 98% agreement with assignment based on DNA homology, suggesting that many genes will follow the same pattern. Of the strains that clustered on the basis of genotype (DNA, azurin) 88% also clustered on the basis of phenotype. The occasional noncongruency observed between the genotypic and phenotypic data may be due to the variable rates of phenotypic evolution. These results provide a perspective on the roles of horizontal and vertical transfer of genes in the evolution of this bacterial group.
Topics: Azurin; Biological Evolution; DNA, Bacterial; Genotype; Phenotype; Pseudomonas aeruginosa; Pseudomonas fluorescens
PubMed: 6785387
DOI: 10.1099/00221287-120-2-485 -
PloS One 2017Type VI secretion systems (T6SSs) are widespread in Gram-negative bacteria, including Pseudomonas. These macromolecular machineries inject toxins directly into...
Type VI secretion systems (T6SSs) are widespread in Gram-negative bacteria, including Pseudomonas. These macromolecular machineries inject toxins directly into prokaryotic or eukaryotic prey cells. Hcp proteins are structural components of the extracellular part of this machinery. We recently reported that MFE01, an avirulent strain of Pseudomonas fluorescens, possesses at least two hcp genes, hcp1 and hcp2, encoding proteins playing important roles in interbacterial interactions. Indeed, P. fluorescens MFE01 can immobilise and kill diverse bacteria of various origins through the action of the Hcp1 or Hcp2 proteins of the T6SS. We show here that another Hcp protein, Hcp3, is involved in killing prey cells during co-culture on solid medium. Even after the mutation of hcp1, hcp2, or hcp3, MFE01 impaired biofilm formation by MFP05, a P. fluorescens strain isolated from human skin. These mutations did not reduce P. fluorescens MFE01 biofilm formation, but the three Hcp proteins were required for the completion of biofilm maturation. Moreover, a mutant with a disruption of one of the unique core component genes, MFE01ΔtssC, was unable to produce its own biofilm or inhibit MFP05 biofilm formation. Finally, MFE01 did not produce detectable N-acyl-homoserine lactones for quorum sensing, a phenomenon reported for many other P. fluorescens strains. Our results suggest a role for the T6SS in communication between bacterial cells, in this strain, under biofilm conditions.
Topics: Biofilms; Humans; Mutation; Pseudomonas fluorescens; Skin
PubMed: 28114423
DOI: 10.1371/journal.pone.0170770 -
Folia Microbiologica Jul 2017Polychlorinated aromatic compounds, including pentachlorobenzenes and hexachlorobenzenes, are recalcitrant industrial pollutants that cause adverse effects on living...
Polychlorinated aromatic compounds, including pentachlorobenzenes and hexachlorobenzenes, are recalcitrant industrial pollutants that cause adverse effects on living cells. In this paper, the isolation of Pseudomonas fluorescens species with high resistance to pentachlorobenzene (PeCB) is reported. It was found that, in contrast to its slightly negative effect on P. fluorescens growth, PeCB readily inhibited the cell growth of Serratia spp. and Escherichia coli strains, thus indicating that inhibition of bacterial growth by PeCB is species-dependent. Analysis of a P. fluorescens isolate revealed that the exposure to PeCB induced production of reactive oxygen species and led to an increase in the level of alkyl hydroperoxide reductase C (AhpC), an important enzyme enhancing the cell tolerance to organic hydroperoxides usually accumulated under oxidative stress. The putative mechanism conferring PeCB resistance to P. fluorescens and the potential use of P. fluorescens in bioremediation are discussed.
Topics: Bacterial Proteins; Chlorobenzenes; Drug Resistance, Bacterial; Oxidative Stress; Pseudomonas fluorescens; Reactive Oxygen Species; Soil Microbiology
PubMed: 28188482
DOI: 10.1007/s12223-017-0501-3 -
Letters in Applied Microbiology May 2009Many strains of Pseudomonas fluorescens show potential for biological control of phytopathogens especially root pathogens. In taxonomic terms, several of them are indeed...
Many strains of Pseudomonas fluorescens show potential for biological control of phytopathogens especially root pathogens. In taxonomic terms, several of them are indeed P. fluorescens sensu stricto, while others belong in fact to neighbouring species of the 'P. fluorescens' complex or to ill-defined related species within the fluorescent Pseudomonas spp. These bacteria have become prominent models for rhizosphere ecological studies and analysis of bacterial secondary metabolism, and in recent years knowledge on their plant-beneficial traits has been considerably enhanced by widening the focus beyond the case of phytopathogen-directed antagonism. Current genomic analyses of rhizosphere competence and biocontrol traits will likely lead to the development of novel tools for effective management of indigenous and inoculated P. fluorescens biocontrol agents and a better exploitation of their plant-beneficial properties for sustainable agriculture.
Topics: Animals; Antibiosis; Pest Control, Biological; Plant Diseases; Pseudomonas fluorescens; Soil; Soil Microbiology
PubMed: 19291210
DOI: 10.1111/j.1472-765X.2009.02566.x -
Biology Letters Feb 2015While social interactions play an important role for the evolution of bacterial siderophore production in vitro, the extent to which siderophore production is a social...
While social interactions play an important role for the evolution of bacterial siderophore production in vitro, the extent to which siderophore production is a social trait in natural populations is less clear. Here, we demonstrate that siderophores act as public goods in a natural physical environment of Pseudomonas fluorescens: soil-based compost. We show that monocultures of siderophore producers grow better than non-producers in soil, but non-producers can exploit others' siderophores, as shown by non-producers' ability to invade populations of producers when rare. Despite this rare advantage, non-producers were unable to outcompete producers, suggesting that producers and non-producers may stably coexist in soil. Such coexistence is predicted to arise from the spatial structure associated with soil, and this is supported by increased fitness of non-producers when grown in a shaken soil-water mix. Our results suggest that both producers and non-producers should be observed in soil, as has been observed in marine environments and in clinical populations.
Topics: Iron; Pseudomonas fluorescens; Siderophores; Soil; Soil Microbiology
PubMed: 25694506
DOI: 10.1098/rsbl.2014.0934 -
Journal of Microbiology and... Jun 2012Pseudomonas fluorescens 2112, isolated in Korea as an indigenous antagonistic bacteria, can produce 2,4- diacetylphloroglucinol (2,4-DAPG) and the siderophore...
Pseudomonas fluorescens 2112, isolated in Korea as an indigenous antagonistic bacteria, can produce 2,4- diacetylphloroglucinol (2,4-DAPG) and the siderophore pyoveridin2112 for the control of phytophthora blight of red-pepper. P. fluorescens 2112 was classified into a new genotype C among the 17 genotypes of 2,4-DAPG producers, by phlD restriction fragment length polymorphism (RFLP). The colonizing ability of P. fluorescens 2112 in pea rhizosphere was equal to the well-known pea colonizers, P. fluorescens Q8r1 (genotype D) and MVP1-4 (genotype P), after 6 cycling cultivations for 18 weeks. Four tested 2,4- DAPG-producing Pseudomonas spp. could colonize with about a 96% dominance ratio against total bacteria in pea rhizosphere. The strain P. fluorescens 2112 was as good a colonizer as other Pseudomonas spp. genotypes in pea plant growth-promoting rhizobacteria.
Topics: Antibiosis; Biota; DNA, Bacterial; Genotype; Korea; Molecular Typing; Pisum sativum; Phloroglucinol; Polymorphism, Restriction Fragment Length; Pseudomonas fluorescens; Rhizosphere; Soil Microbiology
PubMed: 22573152
DOI: 10.4014/jmb.1112.12039 -
Journal of Applied Microbiology Oct 2014To explore specific mechanisms of endophytic Pseudomonas fluorescens antagonizing Athelia rolfsii, causing southern blight of Atractylodes lancea and to evaluate the...
AIMS
To explore specific mechanisms of endophytic Pseudomonas fluorescens antagonizing Athelia rolfsii, causing southern blight of Atractylodes lancea and to evaluate the potential of this Ps. fluorescens strain to control southern blight.
METHODS AND RESULTS
Endophytic Ps. fluorescens strain ALEB 7B isolated from A. lancea can significantly inhibit the growth of A. rolfsii strain SY4. Pre-inoculating A. lancea seedlings with Ps. fluorescens ALEB 7B reduces the southern blight morbidity rate significantly. In situ observation using scanning electron microscopy shows Ps. fluorescens ALEB 7B colonizing the plant cells. Volatile organic compounds (VOCs) from Ps. fluorescens ALEB 7B can kill A. rolfsii SY4 and dimethyl disulphide (DMDS) plays a major role. 2-Piperidinone is a unique substance having antifungal activity in dichloromethane extracts of bacterial cell-free culture filtrates. Other antagonistic mechanisms include ecological niche occupation, antibiotic production and lytic exoenzymes secretion.
CONCLUSIONS
Specific antagonistic mechanisms of Ps. fluorescens ALEB 7B on A. rolfsii SY4 were detailed, including release of DMDS, production of 2-piperidone, secretion of antibiotics and lytic exoenzymes and competition for spaces and nutrients.
SIGNIFICANCE AND IMPACT OF THE STUDY
This work firstly reports the significant inhibition of VOCs released by Ps. fluorescens on the growth of A. rolfsii. 2-Piperidinone is firstly found synthesized by Ps. fluorescens, having antifungal activity. This work provides an antagonistic bacterium with practical convenience and ecologically amity, which has potential for control to A. rolfsii in vitro.
Topics: Antibiosis; Antifungal Agents; Atractylodes; Basidiomycota; Microscopy, Electrochemical, Scanning; Piperidones; Pseudomonas fluorescens; Volatile Organic Compounds
PubMed: 24962812
DOI: 10.1111/jam.12586 -
FEMS Microbiology Letters Jan 2015Snakin-1, a peptide produced by higher plants, has broad-spectrum antibiotic activity, inhibiting organisms ranging from Bacteria to Eukaryotes. However, the mode of...
Snakin-1, a peptide produced by higher plants, has broad-spectrum antibiotic activity, inhibiting organisms ranging from Bacteria to Eukaryotes. However, the mode of action against target organisms is poorly understood. As a first step to elucidate the mechanism, we screened a mutation library of Pseudomonas fluorescens Pf-5 in LB and agar medium supplemented with alfalfa snakin-1 (MsSN1). We identified three biofilm formation-related Pseudomonas mutants that showed increased resistance to MsSN1. Genetic, physiological and bioinformatics analysis validated the results of the mutant screens, indicating that bacterial adhesion protein lapA is probably the target of MsSN1. Collectively, these findings suggest that snakin-1 acts on microbial adhesion properties.
Topics: Anti-Bacterial Agents; Bacterial Adhesion; Bacterial Proteins; Biofilms; Computational Biology; Drug Resistance, Bacterial; Genome, Bacterial; High-Throughput Screening Assays; Medicago sativa; Molecular Docking Simulation; Mutation; Peptides; Phenotype; Pseudomonas fluorescens
PubMed: 25670697
DOI: 10.1093/femsle/fnu006