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Journal of Bacteriology Oct 1974Pseudomonas fluorescens ATCC 13525 and a particulate glucose oxidase (d-glucose:oxygen oxidoreductase, EC 1.1.3.4) mutant of this organism, gox-7, were examined to... (Comparative Study)
Comparative Study
Pseudomonas fluorescens ATCC 13525 and a particulate glucose oxidase (d-glucose:oxygen oxidoreductase, EC 1.1.3.4) mutant of this organism, gox-7, were examined to determine if glucose oxidation via particulate glucose oxidase is a required first step for glucose uptake. Initial [(14)C]glucose-uptake rates in parent and gox-7 cells were qualitatively similar. Initial [(14)C]glucose-uptake product analysis revealed that glucose was accumulated via active transport and was rapidly metabolized to glucose-6-phosphate and gluconate-6-phosphate in both parent and gox-7 cells. Cell extracts contained soluble adenosine 5'-triphosphate specific kinase activity for phosphorylation of glucose. Glucose uptake was induced by glucose and not gluconate, thus, establishing independent regulation of glucose transport and glucose catabolism in p. fluorescens. The results prove that glucose oxidase was not an obligatory reaction for glucose carbon permeation in P. fluorescens. A general unifying scheme for glucose utilization in the aerobic fluorescent pseudomonads is suggested for the purpose of clarifying glucose uptake in these bacteria.
Topics: Aerobiosis; Biological Transport, Active; Carbon Radioisotopes; Cell-Free System; Enzyme Induction; Glucokinase; Gluconates; Glucose; Glucose Oxidase; Glucosephosphates; Mutation; Oxidative Phosphorylation; Pseudomonas fluorescens
PubMed: 4214229
DOI: 10.1128/jb.120.1.147-153.1974 -
Microbial Cell Factories Aug 2018Lipopeptides are a promising group of surface-active compounds of microbial origin (biosurfactants). These diverse molecules are produced mainly by Bacillus and...
BACKGROUND
Lipopeptides are a promising group of surface-active compounds of microbial origin (biosurfactants). These diverse molecules are produced mainly by Bacillus and Pseudomonas strains. Because of their attractive physiochemical and biological properties, biosurfactants are considered to be "green and versatile molecules of the future". The main obstacles in widespread use of biosurfactants are mainly their low yields and high production costs. Pseudofactin (PF) is a lipopeptide produced by Pseudomonas fluorescens BD5. Recently, we identified two analogues, PF1 (C-Val) and PF2 (C-Leu), and reported that PF2 has good emulsification and foaming activities, as well as antibacterial, antifungal, anticancer, and antiadhesive properties. Reported production of PF in a mineral salt medium was approximately 10 mg/L.
RESULTS
Here, we report successful high-throughput optimization of culture medium and conditions for efficient PF production using P. fluorescens BD5. Compared with production in minimal medium, PF yield increased almost 120-fold, up to 1187 ± 13.0 mg/L. Using Plackett-Burman and central composite design methodologies we identified critical factors that are important for efficient PF production, mainly high glycerol concentration, supplementation with amino acids (leucine or valine) and complex additives (e.g. tryptone), as well as high culture aeration. We also detected the shift in a ratio of produced PF analogues in response to supplementation with different amino acids. Leucine strongly induces PF2 production, while valine addition supports PF1 production. We also reported the identification of two new PF analogues: PF3 (C-Val) and PF4 (C-Leu).
CONCLUSIONS
Identification of critical culture parameters that are important for lipopeptide production and their high yields can result in reduction of the production costs of these molecules. This may lead to the industrial-scale production of biosurfactants and their widespread use. Moreover, we produced new lipopeptide pure analogues that can be used to investigate the relationship between the structure and biological activity of lipopeptides.
Topics: Lipopeptides; Pseudomonas fluorescens; Surface-Active Agents
PubMed: 30077177
DOI: 10.1186/s12934-018-0968-x -
Biology Letters Mar 2022Interactions between microbes can both constrain and enhance their adaptation to the environment. However, most studies to date have employed simplified microbial...
Interactions between microbes can both constrain and enhance their adaptation to the environment. However, most studies to date have employed simplified microbial communities and environmental conditions. We determined how the presence of a commercial potting compost microbial community affected adaptation of the soil bacterium SBW25 in potting compost. clones isolated from populations evolved in both the presence and absence of the community showed similar fitness increases when measured in the absence of the community. This suggests the presence of the community did not constrain adaptation. By contrast, fitness measured in the presence of the community increased for community-evolved populations, but decreased below the ancestral state for populations evolved in the absence of the community. This suggests some, but not all, mutations that were beneficial with respect to the abiotic environment were costly in the presence of the community, with the former selected against in the presence of the community. Whole-genome sequencing supports this interpretation: most mutations underpinning fitness changes were clone-specific, suggesting multiple genetic pathways to adaptation. Such extreme mutational effects have not been observed in comparable studies, suggesting that caution is needed when extrapolating results from simplified systems to natural contexts.
Topics: Acclimatization; Adaptation, Physiological; Pseudomonas fluorescens; Soil; Soil Microbiology
PubMed: 35259940
DOI: 10.1098/rsbl.2021.0593 -
Applied Microbiology Jan 1973Strains of Pseudomonas producing fluorescin but no pyocyanin or pyorubrin were studied by biochemical and antibiotic sensitivity testing. A rapid nitrate test was found...
Strains of Pseudomonas producing fluorescin but no pyocyanin or pyorubrin were studied by biochemical and antibiotic sensitivity testing. A rapid nitrate test was found to be useful in distinguishing P. aeruginosa (positive) from P. fluorescens and P. putida (both negative). A shortened gelatin test differentiated P. fluorescens (positive) from P. putida (negative). P. fluorescens and P. putida were very sensitive to low levels of kanamycin and resistant to carbenicillin, a pattern just the opposite of that obtained with P. aeruginosa.
Topics: Anti-Bacterial Agents; Bacteriological Techniques; Carbenicillin; Gelatin; Kanamycin; Nitrates; Penicillin Resistance; Pigments, Biological; Pseudomonas; Pseudomonas fluorescens; Species Specificity
PubMed: 4631431
DOI: 10.1128/am.25.1.107-110.1973 -
Journal of Applied Microbiology May 2018The study was focused on Pseudomonas fluorescens strains isolated from Mozzarella cheese, with the aim of evaluating the effects of Origanum vulgare L. essential oil...
AIMS
The study was focused on Pseudomonas fluorescens strains isolated from Mozzarella cheese, with the aim of evaluating the effects of Origanum vulgare L. essential oil (OEO) on the biofilm formation and eradication, as well as on the motility and blue pigment production at 10°C.
METHODS AND RESULTS
Microdilution method was used to determine the minimum inhibitory and bactericidal concentration of the OEO, which ranged between 10 and 40 μl ml . In vitro studies demonstrated that a sublethal concentration of OEO influenced not only P. fluorescens growth and motility but also the capability to form biofilm and, in a lower degree, the biofilm eradication at 10°C. Analysis by confocal microscopy revealed a dramatic reduction in biofilm formation and thickness, with scattered damage or death of cells, stained by propidium iodide. In addition, a concentration of 5 μl ml of OEO affected the motility of the cells and, in particular, their ability to swim. However, the essential oil did not inhibit the blue pigment production by any of the tested strains.
CONCLUSIONS
The present findings suggest that oregano essential oil inhibits the biofilm formation of P. fluorescens strains and alters their motility. Moreover, in the preformed biofilm, OEO contributes to the detachment of the cells, deteriorating the architecture of the biofilm and reducing its thickness.
SIGNIFICANCE AND IMPACT OF THE STUDY
The O. vulgare L. essential oil was revealed as a promising agent against biofilm formation and for its detaching; these results suggest that oregano EO could be used in the dairy food industry to control biofilm formation, as an alternative, or in combination with conventional sanitizers.
Topics: Anti-Bacterial Agents; Biofilms; Cell Movement; Cheese; Oils, Volatile; Origanum; Pseudomonas fluorescens
PubMed: 29356249
DOI: 10.1111/jam.13707 -
Antimicrobial Agents and Chemotherapy 2015A major challenge in microbial biofilm control is biocide resistance. Phenotypic adaptations and physical protective effects have been historically thought to be the...
A major challenge in microbial biofilm control is biocide resistance. Phenotypic adaptations and physical protective effects have been historically thought to be the primary mechanisms for glutaraldehyde resistance in bacterial biofilms. Recent studies indicate the presence of genetic mechanisms for glutaraldehyde resistance, but very little is known about the contributory genetic factors. Here, we demonstrate that efflux pumps contribute to glutaraldehyde resistance in Pseudomonas fluorescens and Pseudomonas aeruginosa biofilms. The RNA-seq data show that efflux pumps and phosphonate degradation, lipid biosynthesis, and polyamine biosynthesis metabolic pathways were induced upon glutaraldehyde exposure. Furthermore, chemical inhibition of efflux pumps potentiates glutaraldehyde activity, suggesting that efflux activity contributes to glutaraldehyde resistance. Additionally, induction of known modulators of biofilm formation, including phosphonate degradation, lipid biosynthesis, and polyamine biosynthesis, may contribute to biofilm resistance and resilience. Fundamental understanding of the genetic mechanism of biocide resistance is critical for the optimization of biocide use and development of novel disinfection strategies. Our results reveal genetic components involved in glutaraldehyde resistance and a potential strategy for improved control of biofilms.
Topics: Anti-Bacterial Agents; Biofilms; Disinfectants; Drug Resistance, Bacterial; Glutaral; Pseudomonas aeruginosa; Pseudomonas fluorescens
PubMed: 25824217
DOI: 10.1128/AAC.05152-14 -
International Journal of Food... Feb 2008Application of antimicrobial chemicals is a general procedure in the cleaning and disinfection of food-contacting surfaces. Adhesion to glass surfaces and chemically...
Application of antimicrobial chemicals is a general procedure in the cleaning and disinfection of food-contacting surfaces. Adhesion to glass surfaces and chemically induced detachment of Pseudomonas fluorescens ATCC 13525(T) were studied in situ, under flow conditions, in a well-controlled parallel plate flow chamber (PPFC). Ortho-phthalaldehyde (OPA) and cetyltrimethyl ammonium bromide (CTAB) were applied separately, at several concentrations, to attached bacteria and their subsequent detachment was monitored. Following treatments the remaining adhered bacteria were characterized in terms of viability and cell size. Simultaneously, the planktonic cell surface was characterized in order to correlate PPFC results with thermodynamic approaches for adhesion evaluation, and surface free energy of chemically treated cells with adhesion strength. About 2.8x10(6) cells/cm(2) adhered to the glass surface after 30 min of bacterial flow, although thermodynamic analyses evidenced unfavourable adhesion. The independent application of OPA and CTAB promoted bacterial detachment to a small extent (16% of total cells). The remaining adhering bacteria were totally non-viable for OPA> or =0.75 mM and CTAB> or =0.25 mM, showing a lack of correlation between bacterial viability and detachment. The cellular size decreased as attachment proceeded and with chemical treatment. Both chemicals altered the cell surface properties, increasing the cell-glass adhesion strength, and promoting the emergence of polar characteristics. The overall results emphasize that OPA and CTAB were markedly ineffective in removing glass-attached P. fluorescens, demonstrating that bacteria can be non-viable but remain strongly attached to the adhesion surface.
Topics: Bacterial Adhesion; Biofilms; Cetrimonium Compounds; Colony Count, Microbial; Dermoscopy; Disinfectants; Dose-Response Relationship, Drug; Glass; Pseudomonas fluorescens; Surface-Active Agents; Water Movements; o-Phthalaldehyde
PubMed: 18155793
DOI: 10.1016/j.ijfoodmicro.2007.11.041 -
PloS One 2015Pseudomonas fluorescens PCL1751 is a rod-shaped Gram-negative bacterium isolated from the rhizosphere of a greenhouse-grown tomato plant in Uzbekistan. It controls...
Pseudomonas fluorescens PCL1751 is a rod-shaped Gram-negative bacterium isolated from the rhizosphere of a greenhouse-grown tomato plant in Uzbekistan. It controls several plant root diseases caused by Fusarium fungi through the mechanism of competition for nutrients and niches (CNN). This mechanism does not rely on the production of antibiotics, so it avoids the concerns of resistance development and is environmentally safe. Additionally, this bacterium promotes plant growth by alleviating salt stress for its plant host. To investigate the genetic mechanisms that may explain these observations, we determined the complete genome sequence of this bacterium, examined its gene content, and performed comparative genomics analysis with other Pseudomonas strains. The genome of P. fluorescens PCL1751 consisted of one circular chromosome that is 6,143,950 base-pairs (bp) in size; no plasmid was found. The annotation included 19 rRNA, 70 tRNA, and 5,534 protein-coding genes. The gene content analysis identified a large number of genes involved in chemotaxis and motility, colonization of the rhizosphere, siderophore biosynthesis, and osmoprotectant production. In contrast, the pathways involved in the biosynthesis of phytohormones or antibiotics were not found. Comparison with other Pseudomonas genomes revealed extensive variations in their genome size and gene content. The presence and absence of secretion system genes were highly variable. As expected, the synteny conservation among strains decreased as a function of phylogenetic divergence. The integration of prophages appeared to be an important driver for genome rearrangements. The whole-genome gene content analysis of this plant growth-promoting rhizobacterium (PGPR) provided some genetic explanations to its phenotypic characteristics. The extensive and versatile substrate utilization pathways, together with the presence of many genes involved in competitive root colonization, provided further support for the finding that this strain achieves biological control of pathogens through effective competition for nutrients and niches.
Topics: Bacterial Adhesion; Carbon; Chemotaxis; Evolution, Molecular; Genome, Bacterial; Solanum lycopersicum; Molecular Sequence Data; Plant Diseases; Plant Roots; Pseudomonas fluorescens; Rhizosphere; Salts; Soil Microbiology; Stress, Physiological
PubMed: 26452056
DOI: 10.1371/journal.pone.0140231 -
Journal of Food Protection Oct 1998The relationship between bacterial growth and oxymyoglobin oxidation in vitro and in meat was studied. In the in vitro study, oxymyoglobin was combined with Pseudomonas...
The relationship between bacterial growth and oxymyoglobin oxidation in vitro and in meat was studied. In the in vitro study, oxymyoglobin was combined with Pseudomonas fluorescens or sterile nutrient broth (control) in an airtight vessel. P. fluorescens samples showed greater metmyoglobin formation and oxygen consumption than controls. The P. fluorescens population in the reaction vessels was correlated with metmyoglobin formation (r = 0.85, P < 0.05) and oxygen consumption (r = 0.91, P < 0.05). When P. fluorescens and oxymyoglobin were combined in an airtight vessel, reducing the headspace from 13 ml and 9 ml to 3 ml resulted in greater metmyoglobin formation (P < 0.05). In the meat study, beef cores prepared from longissimus lumborum were inoculated with P. fluorescens (10(7) CFU/cm2) or sterile peptone water (control), packaged under 1% O2 (+99% N2), air, or 100% O2 and stored at 4 degrees C. Inoculated beef cores showed higher bacterial loads and metmyoglobin formation than their respective controls during 10 h storage in 1% O2, 3 days in air, and 7 days in 100% O2 (P < 0.05). This finding indicated that P. fluorescens could accelerate beef discoloration. Overall, studies demonstrated that oxygen consumption concomitant with P. fluorescens growth decreased partial oxygen pressure, which accelerated oxymyoglobin oxidation.
Topics: Animals; Cattle; Culture Media; Meat; Metmyoglobin; Myoglobin; Oxidation-Reduction; Oxygen Consumption; Pseudomonas fluorescens
PubMed: 9798152
DOI: 10.4315/0362-028x-61.10.1341 -
BMC Microbiology Apr 2013Pseudomonas fluorescens is a common inhabitant of soil and the rhizosphere environment. In addition to potential applications in biocontrol and bioremediation, P....
BACKGROUND
Pseudomonas fluorescens is a common inhabitant of soil and the rhizosphere environment. In addition to potential applications in biocontrol and bioremediation, P. fluorescens is of interest as a model for studying bacterial survival and fitness in soil. A previous study using in vivo expression technology (IVET) identified 22 genes in P. fluorescens Pf0-1 which are up-regulated during growth in Massachusetts loam soil, a subset of which are important for fitness in soil. Despite this and other information on adaptation to soil, downstream applications such as biocontrol or bioremediation in diverse soils remain underdeveloped. We undertook an IVET screen to identify Pf0-1 genes induced during growth in arid Nevada desert soil, to expand our understanding of growth in soil environments, and examine whether Pf0-1 uses general or soil type-specific mechanisms for success in soil environments.
RESULTS
Twenty six genes were identified. Consistent with previous studies, these genes cluster in metabolism, information storage/processing, regulation, and 'hypothetical', but there was no overlap with Pf0-1 genes induced during growth in loam soil. Mutation of both a putative glutamine synthetase gene (Pfl01_2143) and a gene predicted to specify a component of a type VI secretion system (Pfl01_5595) resulted in a decline in arid soil persistence. When examined in sterile loam soil, mutation of Pfl01_5595 had no discernible impact. In contrast, the Pfl01_2143 mutant was not impaired in persistence in sterile soil, but showed a significant reduction in competitive fitness.
CONCLUSIONS
These data support the conclusion that numerous genes are specifically important for survival and fitness in natural environments, and will only be identified using in vivo approaches. Furthermore, we suggest that a subset of soil-induced genes is generally important in different soils, while others may contribute to success in specific types of soil. The importance of glutamine synthetase highlights a critical role for nitrogen metabolism in soil fitness. The implication of Type 6 secretion underscores the importance of microbial interactions in natural environments. Understanding the general and soil-specific genes will greatly improve the persistence of designed biocontrol and bioremediation strains within the target environment.
Topics: Desert Climate; Gene Expression Profiling; Genes, Bacterial; Microbial Viability; Nevada; Pseudomonas fluorescens; Soil Microbiology; Stress, Physiological
PubMed: 23622502
DOI: 10.1186/1471-2180-13-92