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Microbiology Spectrum Jun 2023Several variants of the plasmid-carried tigecycline resistance gene cluster, , have been identified. This study characterized another novel variant, , located on the...
Several variants of the plasmid-carried tigecycline resistance gene cluster, , have been identified. This study characterized another novel variant, , located on the chromosome of environmental-origin Pseudomonas mendocina. TMexC6D6-TOprJ1 mediates resistance to multiple drugs, including tigecycline. The promoter activity of and negative transcriptional repression by the upstream regulator tnfxB6 are crucial for the expression of . was found in the plasmids or chromosomes of different Pseudomonas species from six countries. Two genetic backgrounds, class 1 integrons and -carrying integrase units, were found adjacent to the gene cluster and might mediate the transfer of this novel efflux pump gene cluster in Pseudomonas. Further phylogenetic analysis revealed Pseudomonas as the major reservoir of variants, warranting closer monitoring in the future. Tigecycline is one of the treatment options for serious infections caused by multidrug-resistant bacteria, and tigecycline resistance has gained extensive attention. The emergence of a transferable tigecycline resistance efflux pump gene cluster, , severely challenged the efficiency of tigecycline. In this study, we identified another novel variant, , which could confer resistance to multiple classes of antibiotics, including tigecycline. Although was found only in Pseudomonas species, might spread to hosts via mobile genetic elements resembling those of other variants, compromising the therapeutic strategies. Meanwhile, novel transferable variants are constantly emerging and mostly exist in Pseudomonas spp., indicating Pseudomonas as the important hidden reservoir and origin of variants. Continuous monitoring and investigations of are urgent to control its spread.
Topics: Tigecycline; Pseudomonas; Phylogeny; Anti-Bacterial Agents; Plasmids; Microbial Sensitivity Tests
PubMed: 37067462
DOI: 10.1128/spectrum.00767-23 -
Bioprocess and Biosystems Engineering May 2019Excess inorganic nitrogen in water poses a severe threat to enviroment. Removal of inorganic nitrogen by heterotrophic nitrifying-aerobic denitrifying microorganism is...
Excess inorganic nitrogen in water poses a severe threat to enviroment. Removal of inorganic nitrogen by heterotrophic nitrifying-aerobic denitrifying microorganism is supposed to be a promising and applicable technology only if the removal rate can be maintained sufficiently high in real wastewater under various conditions, such as high concentration of salt and wide range of different nitrogen concentrations. Here, a new heterotrophic nitrifying-aerobic denitrifying bacterium was isolated and named as Pseudomonas mendocina TJPU04, which removes NH-N, NO-N and NO-N with average rate of 4.69, 5.60, 4.99 mg/L/h, respectively. It also maintains high nitrogen removal efficiency over a wide range of nitrogen concentrations. When concentration of NH-N, NO-N and NO-N was up to 150, 150 and 50 mg/L, 98%, 93%, and 100% removal efficiency could be obtained, respectively, after 30-h incubation under sterile condition. When it was applied under non-sterile condition, the ammonia removal efficiency was slightly lower than that under sterile condition. However, the nitrate and nitrite removal efficiencies under non-sterile condition were significantly higher than those under sterile condition. Strain TJPU04 also showed efficient nitrogen removal performance in the presence of high concentration of salt and nitrogen. In addition, the removal efficiencies of NH-N, NO-N and TN in real wastewater were 91%, 52%, and 75%, respectively. These results suggest that strain TJPU04 is a promising candidate for efficient removal of inorganic nitrogen in wastewater treatment.
Topics: Ammonia; Biodegradation, Environmental; Denitrification; Nitrates; Nitrification; Nitrogen; Pseudomonas mendocina
PubMed: 30963243
DOI: 10.1007/s00449-019-02088-8 -
Biotechnology Letters Feb 2016To enhance the biosynthesis of medium-chain-length polyhydroxyalkanoates (PHAMCL) from glucose in Pseudomonas mendocina NK-01, metabolic engineering strategies were used...
OBJECTIVES
To enhance the biosynthesis of medium-chain-length polyhydroxyalkanoates (PHAMCL) from glucose in Pseudomonas mendocina NK-01, metabolic engineering strategies were used to block or enhance related pathways.
RESULTS
Pseudomonas mendocina NK-01 produces PHAMCL from glucose. Besides the alginate oligosaccharide biosynthetic pathway proved by our previous study, UDP-D-glucose and dTDP-L-rhamnose biosynthetic pathways were identified. These might compete for glucose with the PHAMCL biosynthesis. First, the alg operon, galU and rmlC gene were deleted one by one, resulting in NK-U-1(∆alg), NK-U-2 (∆alg∆galU), NK-U-3(alg∆galU∆rmlC). After fermentation for 36 h, the cell dry weight (CDW) and PHAMCL production of these strains were determined. Compared with NK-U: 1) NK-U-1 produced elevated CDW (from 3.19 ± 0.16 to 3.5 ± 0.11 g/l) and equal PHAMCL (from 0.78 ± 0.06 to 0.79 ± 0.07 g/l); 2) NK-U-2 produced more CDW (from 3.19 ± 0.16 to 3.55 ± 0.23 g/l) and PHAMCL (from 0.78 ± 0.06 to 1.05 ± 0.07 g/l); 3) CDW and PHAMCL dramatically decreased in NK-U-3 (1.53 ± 0.21 and 0.41 ± 0.09 g/l, respectively). Additionally, the phaG gene was overexpressed in strain NK-U-2. Although CDW of NK-U-2/phaG decreased to 1.29 ± 0.2 g/l, PHA titer (%CDW) significantly increased from 24.5 % up to 51.2 %.
CONCLUSION
The PHAMCL biosynthetic pathway was enhanced by blocking branched metabolic pathways in combination with overexpressing phaG gene.
Topics: Gene Expression; Gene Knockout Techniques; Glucose; Metabolic Engineering; Metabolic Networks and Pathways; Polyhydroxyalkanoates; Pseudomonas mendocina
PubMed: 26476529
DOI: 10.1007/s10529-015-1980-4 -
International Journal of Systematic and... May 2020A short rod-shaped, Gram-stain-negative strain that can degrade multiple polymers was isolated from forest soil in China and designated as DSWY01. The results of 16S...
A short rod-shaped, Gram-stain-negative strain that can degrade multiple polymers was isolated from forest soil in China and designated as DSWY01. The results of 16S rRNA gene sequence analysis showed that this isolate shared high similarities with NBRC 102411 (99.3 %), NBRC 14162 (99.2%) and NBRC 13583 (99.0%). The results of phylogenetic analysis based on 16S rRNA gene sequence and multilocus sequence analysis (, , , and ) indicated that strain DSWY01 belongs to the genus and is a member of the group in an independent branch. The average nucleotide identity and digital DNA-DNA hybridization between the genome of strain DSWY01 and the genomes of other species (ANIb 77.72-89.65 %; GGDC 15.50-31.10 %) showed that the isolate represents a novel species. The DNA G+C content of strain DSWY01 was 63.67 mol%, and the major cellular fatty acids (>15 %) were a mixture of Cω7/Cω6 and C. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and two unidentified lipids, and the major quinone was CQ-10. The morphological, physiological and biochemical characteristics of the isolate were then compared with those of reference type strains. The isolate differed considerably from its closest relatives and is representative of a novel species of , for which the name sp. nov. is proposed. The type strain is DSWY01 (=DSM 106702=CCTCC AB 2018053).
Topics: Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Fatty Acids; Forests; Genes, Bacterial; Multilocus Sequence Typing; Nucleic Acid Hybridization; Phospholipids; Phylogeny; Polymers; Pseudomonas; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Soil Microbiology; Ubiquinone
PubMed: 32242797
DOI: 10.1099/ijsem.0.004129 -
Bioengineered Sep 2016The straw can be degraded efficiently into humus by powerful enzymes from microorganisms, resulting in the accelerated circulation of N,P,K and other effective elements...
The straw can be degraded efficiently into humus by powerful enzymes from microorganisms, resulting in the accelerated circulation of N,P,K and other effective elements in ecological system. We isolated a strain through screening the straw degradation strains from natural humic straw in the low temperature area in northeast of china, which can produce cellulase efficiently. The strain was identified as Pseudomonas mendocina by using morphological, physiological, biochemical test, and molecular biological test, with the functional clarification on producing cellulase for Pseudomonas mendocina for the first time. The enzyme force constant Km and the maximum reaction rate (Vmax) of the strain were 0.3261 g/L and 0.1525 mg/(min.L) through the enzyme activity detection, and the molecular weight of the enzyme produced by the strain were 42.4 k and 20.4 k based on SDS-PAGE. The effects of various ecological factors such as temperature, pH and nematodes on the enzyme produced by the strain in the micro ecosystem in plant roots were evaluated. The result showed that the optimum temperature was 28°C, and the best pH was 7.4∼7.8, the impact heavy metal was Pb and the enzyme activity and biomass of Pseudomonas mendocina increased the movement and predation of nematodes.
Topics: Biomass; Cellulase; Enzyme Stability; Hydrogen-Ion Concentration; Metals, Heavy; Molecular Weight; Pseudomonas mendocina; Substrate Specificity; Temperature
PubMed: 27710430
DOI: 10.1080/21655979.2016.1227143 -
Biotechnology Letters Nov 2013Two polyhydroxyalkanoate depolymerases, PHAase I and PHAase II, were purified to homogeneity from the culture supernatant of an effective PHA-degrading bacterium,...
Two polyhydroxyalkanoate depolymerases, PHAase I and PHAase II, were purified to homogeneity from the culture supernatant of an effective PHA-degrading bacterium, Pseudomonas mendocina DS04-T. The molecular masses of PHAase I and PHAase II were determined by SDS-PAGE as 59.4 and 33.8 kDa, respectively. Their optimum pH values were 8.5 and 8, respectively. Enzymatic activity was optimal at 50 °C. Both purified enzymes could degrade PHB, PHBV, and P(3HB-co-4HB). Addition of Na(+) and K(+) slightly increased the rate of PHAase II. EDTA significantly inhibited PHAase II but not PHAase I. Mercaptoethanol and H2O2 also inhibited the activities of both enzymes.
Topics: Carboxylic Ester Hydrolases; Edetic Acid; Electrophoresis, Polyacrylamide Gel; Enzyme Activators; Enzyme Inhibitors; Enzyme Stability; Hydrogen Peroxide; Hydrogen-Ion Concentration; Mercaptoethanol; Molecular Weight; Potassium; Pseudomonas mendocina; Sodium; Substrate Specificity; Temperature
PubMed: 23881326
DOI: 10.1007/s10529-013-1288-1 -
Journal of Basic Microbiology 2003The effect of carbon source on the regulation of the de novo pyrimidine biosynthetic enzymes in the bacterium Pseudomonas mendocina was studied. When glucose was the...
The effect of carbon source on the regulation of the de novo pyrimidine biosynthetic enzymes in the bacterium Pseudomonas mendocina was studied. When glucose was the carbon source, orotic acid supplementation of P. mendocina cells produced the greatest depression of aspartate transcarbamoylase, dihydroorotate dehydrogenase and orotate phosphoribosyltransferase activities while P. mendocina cells grown in the presence of uracil caused the maximal decrease in dihydroorotase and OMP decarboxylase activities. After the pyrimidine starvation of an orotate phosphoribosyltransferase mutant strain of P. mendocina grown on glucose, the pyrimidine biosynthetic pathway enzyme activities were generally diminished. With respect to pyrimidine starvation studies, the carbon source glucose appeared to lessen regulation at the level of enzyme synthesis compared to what has been observed when succinate served as the carbon source. The regulation of the pyrimidine biosynthetic pathway by carbon source in P. mendocina appeared to differ from how carbon source influenced the control of pyrimidine biosynthesis in the closely-related species Pseudomonas stutzeri.
Topics: Aspartate Carbamoyltransferase; Dihydroorotase; Dihydroorotate Dehydrogenase; Enzyme Repression; Glucose; Orotate Phosphoribosyltransferase; Orotidine-5'-Phosphate Decarboxylase; Oxidoreductases Acting on CH-CH Group Donors; Pseudomonas mendocina; Pyrimidines; Succinic Acid
PubMed: 14625904
DOI: 10.1002/jobm.200310297 -
Journal of Hazardous Materials Oct 2021Two-phase partitioning bioreactors (TPPBs) have been extensively used for volatile organic compounds (VOCs) removal. To date, most studies have focused on improving the...
Two-phase partitioning bioreactors (TPPBs) have been extensively used for volatile organic compounds (VOCs) removal. To date, most studies have focused on improving the mass transfer of gas phases/non-aqueous phases (NAPs)/aqueous phases, whereas the NAP/biological phases and gas/biological phases transfer has been neglected. Herein, chitosan was introduced into a TPPB to increase cell surface hydrophobicity (CSH) and improve the n-hexane mass transfer. The performance and stability of the TPPB with chitosan for n-hexane biodegradation were investigated, and it was found out that the TPPB with chitosan achieved maximum removal efficiency and elimination capacity of 80.6% and 26.5 g m h, thereby reaching much higher values than those obtained without chitosan (61.3% and 15.2 g m h). Chitosan not only obvio usly increased cell surface hydrophobicity and cell dry biomass on the surface of silicone oil, but might also allow hydrophobic cells in aqueous phases to directly capture and biodegrade n-hexane, resulting in an obvious improvement of mass transfer from the gas phase to biomass. Stability enhancement was another attractive advantage from chitosan addition. This study might provide a new strategy for the development of TPPB in the hydrophobic VOCs treatment.
Topics: Biodegradation, Environmental; Bioreactors; Chitosan; Hexanes; Pseudomonas mendocina
PubMed: 34171668
DOI: 10.1016/j.jhazmat.2021.126330 -
Journal of Bacteriology Nov 2012Pseudomonas mendocina DLHK is an aerobic bacterium isolated from a biotrickling reactor which can remove nitric oxide, a common air pollutant from combustion exhaust...
Pseudomonas mendocina DLHK is an aerobic bacterium isolated from a biotrickling reactor which can remove nitric oxide, a common air pollutant from combustion exhaust gas. Here, we present the draft genome of Pseudomonas mendocina DLHK.
Topics: Bioreactors; Genome, Bacterial; Molecular Sequence Data; Pseudomonas mendocina
PubMed: 23105066
DOI: 10.1128/JB.01618-12 -
Archives of Microbiology Sep 2018Mine tailings and wastewater generate man-made environments with several selective pressures, including the presence of heavy metals, arsenic and high cyanide...
Mine tailings and wastewater generate man-made environments with several selective pressures, including the presence of heavy metals, arsenic and high cyanide concentrations, but severe nutritional limitations. Some oligotrophic and pioneer bacteria can colonise and grow in mine wastes containing a low concentration of organic matter and combined nitrogen sources. In this study, Pseudomonas mendocina P6115 was isolated from mine tailings in Durango, Mexico, and identified through a phylogenetic approach of 16S rRNA, gyrB, rpoB, and rpoD genes. Cell growth, cyanide consumption, and ammonia production kinetics in a medium with cyanide as sole nitrogen source showed that at the beginning, the strain grew assimilating cyanide, when cyanide was removed, ammonium was produced and accumulated in the culture medium. However, no clear stoichiometric relationship between both nitrogen sources was observed. Also, cyanide complexes were assimilated as nitrogen sources. Other phenotypic tasks that contribute to the strain's adaptation to a mine tailing environment included siderophores production in media with moderate amounts of heavy metals, arsenite and arsenate tolerance, and the capacity of oxidizing arsenite. P. mendocina P6115 harbours cioA/cioB and aoxB genes encoding for a cyanide-insensitive oxidase and an arsenite oxidase, respectively. This is the first report where P. mendocina is described as a cyanotrophic and arsenic oxidizing species. Genotypic and phenotypic tasks of P. mendocina P6115 autochthonous from mine wastes are potentially relevant for biological treatment of residues contaminated with cyanide and arsenic.
Topics: Ammonia; Arsenic; Arsenites; Bacterial Proteins; Cyanides; Mexico; Mining; Oxidoreductases; Phylogeny; Pseudomonas mendocina; RNA, Ribosomal, 16S; Soil Microbiology
PubMed: 29644379
DOI: 10.1007/s00203-018-1514-2