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Microbiology Spectrum Apr 2022The genus Pseudomonas, a complex Gram-negative genus, includes species isolated from various environments, plants, animals, and humans. We compared whole-genome...
The genus Pseudomonas, a complex Gram-negative genus, includes species isolated from various environments, plants, animals, and humans. We compared whole-genome sequencing (WGS) with clinical bacteriological methods and evaluated matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify Pseudomonas species. Clinical isolates ( = 42) identified as P. putida or P. fluorescens by a bacterial identification system based on biochemical properties were reexamined by another identification system based on biochemical properties, two systems based on MALDI-TOF MS, and WGS. WGS revealed that 30 of the 42 isolates belonged to one of 14 known Pseudomonas species, respectively. The remaining 12 belonged to one of 9 proposed novel Pseudomonas species, respectively. MALDI-TOF MS analysis showed that the 9 novel species had unique major peaks. These results suggest that WGS is the optimal method to identify Pseudomonas species and that MALDI-TOF MS may complement WGS in identification. Based on their morphologic, physiologic, and biochemical properties, we propose nine novel Pseudomonas species. Most of the clinical isolates, identified as P. putida or P. fluorescens, were misidentified in clinical laboratories. Whole-genome sequencing (WGS) revealed that these isolates belonged to different Pseudomonas species, including novel species. WGS is a gold-standard method to identify Pseudomonas species, and MALDI-TOF MS analysis has the potential to complement WGS to reliably identify them.
Topics: Animals; Bacteriological Techniques; Pseudomonas fluorescens; Pseudomonas putida; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Whole Genome Sequencing
PubMed: 35389240
DOI: 10.1128/spectrum.02491-21 -
Bioprocess and Biosystems Engineering Mar 2022Citronellyl acetate as an important flavor, can be effectively synthesized by lipase catalysis in nonaqueous system. But lipases usually behave low catalytic activity...
Citronellyl acetate as an important flavor, can be effectively synthesized by lipase catalysis in nonaqueous system. But lipases usually behave low catalytic activity due to aggregation and denaturation of them in organic phase. To enhance the nonaqueous catalysis, based on the mechanism of lipases activated at water/oil (organic phase) interface, the inexpensive race straw was processed into powder and filaments on which Pseudomonas fluorescens lipase was immobilized by physical adsorption, used for synthesis of citronellyl acetate via transesterification of citronellol and vinyl acetate. Results showed that the desired loading was 10 mg lipase immobilized on 30 mg rice straw filaments or 25 mg rice straw powder. When the two immobilized lipases were employed in the reaction system consisted of 1-mL citronellol and 2-mL vinyl acetate at 37 ℃ and 160 rpm, the conversions all reached 99.8% after 12 h. Under the reaction condition, the conversion catalyzed by 10 mg native lipase was 85.1%. Undergoing six times of 8-h reuses in the organic system, the filament and power immobilized lipases had weak activity attenuation rates 0.36 and 0.32% h, lower than 1.52% h of native lipase. Even at the room temperature and the static state without shaking and stirring, the rice straw filaments immobilized lipase could brought conversion 62.9% after 10 h but the native lipase only gave 37.0%. Obviously, the rice straw, especially its filaments, is an inexpensive and available natural material to prepare immobilized lipase with desired catalysis in organic phase, meant significant potential in flavor industry.
Topics: Catalysis; Enzymes, Immobilized; Esterification; Lipase; Monoterpenes; Oryza; Pseudomonas fluorescens
PubMed: 34686911
DOI: 10.1007/s00449-021-02659-8 -
International Journal of Molecular... May 2023The search for and characterization of new lipases with excellent properties has always been urgent and is of great importance to meet industrial needs. In this study, a...
The search for and characterization of new lipases with excellent properties has always been urgent and is of great importance to meet industrial needs. In this study, a new lipase, from SBW25, belonging to the lipase subfamily I.3, was cloned and expressed in WB800N. Enzymatic properties studies of recombinant LipB found that it exhibited the highest activity towards -nitrophenyl caprylate at 40 °C and pH 8.0, retaining 73% of its original activity after incubation at 70 °C for 6 h. In addition, Ca, Mg, and Ba strongly enhanced the activity of LipB, while Cu, Zn, Mn, and CTAB showed an inhibiting effect. The LipB also displayed noticeable tolerance to organic solvents, especially acetonitrile, isopropanol, acetone, and DMSO. Moreover, LipB was applied to the enrichment of polyunsaturated fatty acids from fish oil. After hydrolyzing for 24 h, it could increase the contents of polyunsaturated fatty acids from 43.16% to 72.18%, consisting of 5.75% eicosapentaenoic acid, 19.57% docosapentaenoic acid, and 46.86% docosahexaenoic acid, respectively. The properties of LipB render it great potential in industrial applications, especially in health food production.
Topics: Lipase; Pseudomonas fluorescens; Fatty Acids, Unsaturated; Docosahexaenoic Acids; Eicosapentaenoic Acid; Enzyme Stability
PubMed: 37240270
DOI: 10.3390/ijms24108924 -
Microbiological Research Jun 2021Microbial co-inoculation strategy utilizes a combination of microbes to stimulate plant growth concomitant with an increased phytopathogen tolerance. In the present...
Chickpea (Cicer arietinum L.) as model legume for decoding the co-existence of Pseudomonas fluorescens and Mesorhizobium sp. as bio-fertilizer under diverse agro-climatic zones.
Microbial co-inoculation strategy utilizes a combination of microbes to stimulate plant growth concomitant with an increased phytopathogen tolerance. In the present study, 15 endophytic bacterial isolates from rhizosphere and roots of wild chickpea accessions (Cicer pinnatifidum, C. judiacum, C. bijugum and C. reticulatum) were characterized for morphological, biochemical and physiological traits. Two promising isolates were identified as Pseudomonas fluorescens strain LRE-2 (KR303708.1) and Pseudomonas argentinensis LPGPR-1 (JX239745.1) based on 16S rRNA gene sequencing. Biocompatibility of selected endophytes with Mesorhizobium sp. CH1233, a standard isolate used as a national check in All India Coordinated Research Project (AICRP) was assessed to develop functional combinations capable of producing Indole acetic acid, gibberellins, siderophores and improving seed vigour (in vitro). In vivo synergistic effect of promising combinations was further evaluated under national AICRP, (Chickpea) at two different agro-climatic zones [North-West plain (Ludhiana and Hisar) and Central zones (Sehore)] for three consecutive Rabi seasons (2015-18) to elucidate their effect on symbiotic, soil quality and yield parameters. On the pooled mean basis across locations over the years, combination of Mrh+LRE-2 significantly enhanced symbiotic, soil quality traits and grain yield over Mrh alone and highly positive correlation was obtained between the nodulation traits and grain yield. Superior B: C ratio (1.12) and additional income of Rs 6,505.18 ha was obtained by application of Mrh+LRE-2 over Mrh alone and un-inoculated control. The results demonstrate that dual combination of Mrh and Pseudomonas sp. from wild Cicer relatives can be exploited as a potential bio-fertilizer for increasing soil fertility and improving chickpea productivity under sustainable agriculture.
Topics: Agriculture; Cicer; Endophytes; Fabaceae; Fertilizers; Indoleacetic Acids; Mesorhizobium; Phylogeny; Plant Development; Plant Roots; Pseudomonas; Pseudomonas fluorescens; RNA, Ribosomal, 16S; Rhizosphere; Seeds; Soil; Soil Microbiology; Symbiosis
PubMed: 33592359
DOI: 10.1016/j.micres.2021.126720 -
Journal of Applied Microbiology Apr 2020Pseudomonas spp. have been widely studied for their plant growth-promoting effects. However, their capacity to promote lipid accumulation in oilseed crops is not well...
AIMS
Pseudomonas spp. have been widely studied for their plant growth-promoting effects. However, their capacity to promote lipid accumulation in oilseed crops is not well characterized. In this study, we evaluated the effect of Pseudomonas fluorescens LBUM677 on lipid accumulation in three oilseed crops: soybean (Glycine max), canola (Brassica napus) and corn gromwell (Buglossoides arvensis), a plant of high nutraceutical interest for its accumulation of the omega-3 stearidonic acid.
METHODS AND RESULTS
Pot experiments were conducted under controlled conditions where seeds were inoculated or not with LBUM677 and plants were harvested at 4, 8 and 12 weeks. A qPCR assay specifically targeting LBUM677 was used in parallel to correlate LBUM677 soil rhizosphere competency to growth promotion and seed lipid accumulation. Total oil seed content and fatty acid composition were analysed at seed maturity. Results showed that LBUM677 was able to establish itself in the rhizosphere of the three plant species at similar levels, but it differentially increased plant biomass, total oil content and lipid composition in a plant-specific manner.
CONCLUSIONS
Despite some species-specific differences observed in P. fluorescens LBUM677's effect on different crops, the strain appears to be a generalist plant growth-promoting rhizobacteria of oilseed crops.
SIGNIFICANCE AND IMPACT OF THE STUDY
LBUM677 shows great potential to be used as an inoculum to promote oil yield and fatty acid accumulation in oilseed crops.
Topics: Biomass; Crops, Agricultural; Fatty Acids; Lipids; Plant Oils; Pseudomonas fluorescens; Rhizosphere; Seeds; Soil Microbiology; Species Specificity
PubMed: 31793115
DOI: 10.1111/jam.14536 -
Canadian Journal of Microbiology Mar 2018As the "kidneys of the Earth", wetlands play important roles as biodiversity reservoirs, in water purification, and in flood control. In this study, 2 lytic cold-active...
As the "kidneys of the Earth", wetlands play important roles as biodiversity reservoirs, in water purification, and in flood control. In this study, 2 lytic cold-active bacteriophages, named VW-6S and VW-6B, infecting Pseudomonas fluorescens W-6 cells from the Napahai plateau wetland in China were isolated and characterized. Electron microscopy showed that both VW-6S and VW-6B had an icosahedral head (66.7 and 61.1 nm, respectively) and a long tail (8.3 nm width × 233.3 nm length and 11.1 nm width × 166.7 nm length, respectively). The bacteriophages VW-6S and VW-6B were classified as Siphoviridae and had an approximate genome size of 30-40 kb. The latent and burst periods of VW-6S were 60 and 30 min, whereas those of VW-6B were 30 and 30 min, respectively. The optimal pH values for the bacteriophages VW-6S and VW-6B were 8.0 and 10.0, respectively, and their activity decreased rapidly at temperatures higher than 60 °C. These cold-active bacteriophages provide good materials for further study of cold-adaptation mechanisms and interaction with the host P. fluorescens.
Topics: Bacteriophages; China; Cold Temperature; DNA, Viral; Genome, Viral; Host Specificity; Hydrogen-Ion Concentration; Pseudomonas fluorescens; Water Microbiology; Wetlands
PubMed: 29253355
DOI: 10.1139/cjm-2017-0572 -
Ultrasonics Sonochemistry Feb 2022A combined ultrasonic and thermal (US-TM) treatment was developed in this study to achieve a high efficacy of P. fluorescens biofilm control. The present study...
In vitro and in silico approaches to investigate antimicrobial and biofilm removal efficacies of combined ultrasonic and mild thermal treatment against Pseudomonas fluorescens.
A combined ultrasonic and thermal (US-TM) treatment was developed in this study to achieve a high efficacy of P. fluorescens biofilm control. The present study demonstrated that combined a moderate ultrasound treatment (power ≥ 80 W) and a mild heat (up to 50 °C) largely destroyed biofilm structure in 15 min and removed>65.63% of biofilm from a glass slide where cultivated the P. fluorescens biofilm. Meanwhile, the viable cell count was decreased from 10.72 to 6.48 logCUF/mL. Differences in biofilm removal and lethal modes of US-TM treatment were confirmed through microscopies analysis in vitro. The ultrasound first contributed to releasing the bacteria in the biofilm to the environment and simultaneously exposing inner bacteria at the deep layer of biofilm depending on shear force, shock waves, acoustic streaming, etc. When the biofilm structure was destroyed, US-TM treatment would synergistically inactivate P. fluorescens cells. In silico studies adopted COMSOL to simulate acoustic pressure and temperature distribution in the bioreactor; both of them were significantly influenced by various factors, such as input power, sonotrode position, materials and volume of container, etc. Facing the biofilm issue existing on the surface of container, boundary conditions were exported and thereby pointing out potential "dead ends" where the ultrasound may not be effectively transduced. Both in vitro and in silico results may inspire the food industry to adopt US-TM treatment to achieve biofilm control.
Topics: Anti-Bacterial Agents; Biofilms; Bioreactors; Pseudomonas fluorescens; Ultrasonics
PubMed: 35114554
DOI: 10.1016/j.ultsonch.2022.105930 -
New Biotechnology Jul 2017Alginate denotes a family of linear polysaccharides with a wide range of industrial and pharmaceutical applications. Presently, all commercially available alginates are... (Review)
Review
Alginate denotes a family of linear polysaccharides with a wide range of industrial and pharmaceutical applications. Presently, all commercially available alginates are manufactured from brown algae. However, bacterial alginates have advantages with regard to compositional homogeneity and reproducibility. In order to be able to design bacterial strains that are better suited for industrial alginate production, defining limiting factors for alginate biosynthesis is of vital importance. Our group has been studying alginate biosynthesis in Pseudomonas fluorescens using several complementary approaches. Alginate is synthesised and transported out of the cell by a multiprotein complex spanning from the inner to the outer membrane. We have developed an immunogold labelling procedure in which the porin AlgE, as a part of this alginate factory, could be detected by transmission electron microscopy. No time-dependent correlation between the number of such factories on the cell surface and alginate production level was found in alginate-producing strains. Alginate biosynthesis competes with the central carbon metabolism for the key metabolite fructose 6-phosphate. In P. fluorescens, glucose, fructose and glycerol, are metabolised via the Entner-Doudoroff and pentose phosphate pathways. Mutational analysis revealed that disruption of the glucose 6-phosphate dehydrogenase gene zwf-1 resulted in increased alginate production when glycerol was used as carbon source. Furthermore, alginate-producing P. fluorescens strains cultivated on glucose experience acid stress due to the simultaneous production of alginate and gluconate. The combined results from our studies strongly indicate that the availability of fructose 6-phosphate and energy requires more attention in further research aimed at the development of an optimised alginate production process.
Topics: Alginates; Biosynthetic Pathways; Biotechnology; Genes, Bacterial; Glucose; Glucosephosphate Dehydrogenase; Glucuronic Acid; Hexuronic Acids; Immunohistochemistry; Industrial Microbiology; Pseudomonas fluorescens; Stress, Physiological
PubMed: 27593394
DOI: 10.1016/j.nbt.2016.08.005 -
International Journal of Biological... Jul 2021Preserving the efficacy of plant probiotic bacteria in soil is a major challenge to the biological control of plant diseases. The microencapsulation technique is an...
Preserving the efficacy of plant probiotic bacteria in soil is a major challenge to the biological control of plant diseases. The microencapsulation technique is an important step in preserving the viability and activity of probiotics in adverse environmental conditions. The main objective of this study was to choose an appropriate coating for probiotic encapsulation. For this purpose, the survivability and controlled release of Pseudomonas fluorescens VUPF506 encapsulated with alginate (Alg) combined with whey protein concentrate (WPC), carboxymethyl cellulose (CMC), and peanut butter (PB) were evaluated. Moreover, the encapsulated cells were evaluated to control for Rhizoctonia solani in potato plants under in vivo conditions. The results showed that all tested wall material maintained more than 80% of the bacterial cells. The Alg-WPC microcapsules provided a better controlled release over two months. Interestingly, the greenhouse experiment also revealed that the treatment of potato plants with Alg-WPC microcapsules was the most effective treatment, suppressing 90% of the pathogen. The results showed that Alg-WPC is the most promising combination to improve the survivability of P. fluorescens VUPF506. Moreover, it can be used as a fertilizer due to its content of valuable amino acids.
Topics: Alginates; Capsules; Delayed-Action Preparations; Pest Control, Biological; Plant Diseases; Plant Roots; Probiotics; Pseudomonas fluorescens; Rhizoctonia; Solanum tuberosum; Time Factors
PubMed: 33957198
DOI: 10.1016/j.ijbiomac.2021.04.159 -
International Journal of Food... Mar 2021Since Pseudomonas fluorescens is the main microorganism causing severe spoilage in refrigerated aquatic products, the searching for non-antibiotic antibacterial agents...
Since Pseudomonas fluorescens is the main microorganism causing severe spoilage in refrigerated aquatic products, the searching for non-antibiotic antibacterial agents effective against it continues to receive increasing interest. This study aimed to investigate the antibacterial effects and mechanisms of alkyl gallic esters against P. fluorescens isolated from the Russian sturgeon (Acipenser gueldenstaedti), as well as the effectiveness in combination with chitosan films on the preservation of sturgeon meats at 4 °C. Our data shows that the alkyl chain length plays a significant role in eliciting their antibacterial activities and octyl gallate (GAC8) exhibited an outstanding inhibitory efficacy. GAC8 can rapidly enter into the membrane lipid bilayer portion to disorder the membrane, and further inhibit the growth of the P. fluorescens through interfering both tricarboxylic acid cycle related to energy supply and amino acid metabolism associated with cell membranes, suppressing oxygen consumption and disturbing the respiration chain. Moreover, the alteration in membrane fatty acids indicated that GAC8 could disrupt the composition of cell membrane fatty acids, rendering the bacteria more sensitive to the antibacterial. The SEM results also substantiate the damage of the structure of the bacterial membrane caused by GAC8. Additionally, the edible chitosan-based films incorporated with GAC8 showed the enhanced antibacterial efficacy to remarkably extend the shelf life of Russian sturgeon. Overall, our findings not only provide new insight into the mode of action of GAC8 against P. fluorescens but also demonstrate composite films containing GAC8, as a kind of safe and antibacterial material, have a great promise for application in food preservations.
Topics: Animals; Anti-Bacterial Agents; Cell Membrane; Chitosan; Edible Films; Energy Metabolism; Fishes; Food Preservation; Gallic Acid; Pseudomonas fluorescens
PubMed: 33607540
DOI: 10.1016/j.ijfoodmicro.2021.109093