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Bioresource Technology Jan 2021The performance of nitrate removal by Pseudomonas mendocina GL6 cells immobilized on bamboo biochar was investigated. The results showed that immobilized bacterial cells...
The performance of nitrate removal by Pseudomonas mendocina GL6 cells immobilized on bamboo biochar was investigated. The results showed that immobilized bacterial cells performed better nitrate removal than the free bacterial cells, and the nitrate removal rate increased from 6.51 mg/(L·h) of free cells to 8.34 mg/(L·h) of immobilized cells. The nitrate removal of immobilized bacterial cells fitted well to the zero-order kinetics model. Moreover, bath experiments showed that immobilized bacterial cells displayed more nitrate removal capacity under different conditions than free bacterial cells due to the protection of biochar carrier. The subsequent mechanistic study suggested that biochar promoted the expression level of denitrification functional genes (napA and nirK) and electron transfer genes involved in denitrification (napB and napC), which resulted in the increase of nitrate removal efficiency. Thus, biochar-immobilized P. mendocina GL6 has much potential to remove nitrate from wastewater via aerobic denitrification.
Topics: Charcoal; Denitrification; Nitrates; Nitrogen; Pseudomonas mendocina; Sasa
PubMed: 33147528
DOI: 10.1016/j.biortech.2020.124324 -
Bioresource Technology Jan 2021Six bacterial strains with simultaneous nitrification-denitrification abilities were isolated from a Beijing sewage treatment plant to improve nitrogen biodegradation...
Six bacterial strains with simultaneous nitrification-denitrification abilities were isolated from a Beijing sewage treatment plant to improve nitrogen biodegradation efficiency. One of these strains, X49, was identified as Pseudomonas mendocina, and was characterized as the best strain with which to rapidly degrade a high concentration of inorganic nitrogen. X49 completely converted 5-100 mg.L of ammonia in 12 h, with no nitrite accumulation; the maximum removal rate of 26.39 mg (N).L.h was achieved between 4 h and 6 h. In 16 h, the strain removed 100 mg.L nitrite and 72.61 mg.L nitrate under aerobic conditions, at degredation rates which reached 4.54 and 6.25 mg (N).L.h, respectively. Our results suggest that P. mendocina X49 achieved efficient and simultaneous nitrification and denitrification ability under heterotrophic aerobic conditions.
Topics: Aerobiosis; Ammonium Compounds; Beijing; Denitrification; Heterotrophic Processes; Nitrification; Nitrites; Nitrogen; Pseudomonas mendocina
PubMed: 33038648
DOI: 10.1016/j.biortech.2020.124198 -
International Journal of Biological... Nov 2020Pseudomonas mendocina NK-01 previously isolated by our lab is able to accumulate medium-chain-length polyhydroxyalkanoate (mcl-PHA) intracellularly and secrete alginate...
Pseudomonas mendocina NK-01 previously isolated by our lab is able to accumulate medium-chain-length polyhydroxyalkanoate (mcl-PHA) intracellularly and secrete alginate oligosaccharide (AO) to the extracellular milieu. The present study aimed at investigating whether improved production of mcl-PHA and AO by P. mendocina can be accomplished by genome reduction. In this study, 14 large genomic fragments accounting for 7.7% of the genome of P. mendocina NK-01 were sequentially deleted to generate a series of genome-reduced strains by an upp-based markerless knockout method. As a result, the intracellular ATP/ADP ratio of the strain NKU421 with the largest deletion improved by 11 times compared to NK-01. More importantly, the mcl-PHA and AO yields of NKU421 increased by 114.8% and 27.8%, respectively. Enhancing mcl-PHA and AO production by NKU421 may be attributed to improved transcriptional levels of PHA synthase genes and AO secretion-related genes. The present study suggests that rational reduction of bacterial genome is a feasible approach to construct an optimal chassis for enhanced production of bacterial metabolites. In the future, further reduction of the NKU421 genome can be expected to create high-performance chassis for the development of microbial cell factories.
Topics: Acyltransferases; Alginates; Genome, Bacterial; Metabolic Engineering; Oligosaccharides; Polyhydroxyalkanoates; Pseudomonas mendocina
PubMed: 32941898
DOI: 10.1016/j.ijbiomac.2020.09.067 -
Current Microbiology Nov 2020Even though organisms with squalene hopene cyclase activity involved in hopanoid synthesis has been reported earlier, their existence along with carotenoid synthesis is...
Even though organisms with squalene hopene cyclase activity involved in hopanoid synthesis has been reported earlier, their existence along with carotenoid synthesis is rarely reported. Here, we report the existence of hopanoid and C carotenoid biosynthetic pathway in Pseudomonas mendocina, the squalene hopene cyclase producing endophyte of the medicinal plant Murraya koenigii. The enzyme squalene hopene cyclase from Pseudomonas mendocina is involved in the synthesis of dehydrosqualene-mediated alternate pathway for carotenoid biosynthesis. The hopanoids are involved in membrane stability and integrity, and the carotene chromophores are involved in the photo protection of the cell. The orange-colored C carotenoid pigment 4-4' diaponeurosporenic acid in the extracellular extract of Pseudomonas mendocina with squalene cyclase activity was detected by the combination of UV/Vis spectrometry, FTIR, and Mass Spectrometry. 4-4' diaponeurosporenic acid could be traced as the end product of the carotenoid pathway and belonged to the xanthophyll group of carotenoids.
Topics: Biosynthetic Pathways; Carotenoids; Lyases; Pseudomonas mendocina
PubMed: 32894325
DOI: 10.1007/s00284-020-02180-3 -
Molecular Biotechnology Sep 2020Squalene hopene cyclases catalyse the conversion of a linear substrate squalene to a cyclic product with high stereo-selectivity.The enzyme squalene hopene cyclase from...
Squalene hopene cyclases catalyse the conversion of a linear substrate squalene to a cyclic product with high stereo-selectivity.The enzyme squalene hopene cyclase from Pseudomonas mendocina expressed in E. coli BL21 (DE3) was evaluated for its synthetic drug transforming ability. Nine synthetic drugs were selected as substrates for biotransformation reactions by the enzyme. The homology modelling of the protein and docking of the selected ligands were performed using GOLD suite docking software. The drug which showed maximum binding with the active-site residues of the enzyme was selected for biotransformation studies. On transformation with the enzyme, Glibenclamide, the selected antidiabetic drug alone showed significant changes in the FT/IR spectra; hence, it was selected for LCMS analysis to confirm the transformations. From the chromatogram and MS spectra, the mono-oxygenation of the product due to the enzymatic activity was confirmed. The drug transforming ability of the purified SHC could be used as an ideal tool for the generation of new and active substrate derivatives.
Topics: Bacterial Proteins; Escherichia coli; Glyburide; Intramolecular Transferases; Pseudomonas mendocina; Recombinant Proteins
PubMed: 32757148
DOI: 10.1007/s12033-020-00264-w -
Environmental Science and Pollution... Oct 2020The correct unit in Table 2 is Lipase activity (U/g).
The correct unit in Table 2 is Lipase activity (U/g).
PubMed: 32700266
DOI: 10.1007/s11356-020-10152-0 -
Environmental Science and Pollution... Oct 2020Lipase enzyme has a critical role in deinking process along with other lignocellulosic enzymes. In this paper, we try to demonstrate the role of lipase in the enzyme...
Lipase enzyme has a critical role in deinking process along with other lignocellulosic enzymes. In this paper, we try to demonstrate the role of lipase in the enzyme cocktail used for enzymatic deinking. For this, we identified a potential lipolytic bacterium, Pseudomonas mendocina ED9 isolated from elephant dung with a molecular weight of 35 kDa. During the Box-Benhken model optimization, a maximum lipase activity of 105.12 U/g, which was 12.36-fold higher than the initial enzyme activity and 1.3-fold higher than the activity obtained during the Plackett Burman design, was achieved. A maximum lipase activity of 105.12 U/g was obtained after optimization. Ammonium sulphate (60%) precipitation resulted in a specific activity of 68.19 U/mg with a 1.4-fold purification and yield of 64%. Lipase from P. mendocina ED9 exhibited a Km of 0.5306 mM and Vmax of 25.0237 μmol/min/mg. A Δ brightness of approximately 14.5% were achieved during the enzymatic deinking using cocktail comprised of cellulase, xylanase and lipase. This reports the significant role and efficacy of lipase in enzyme cocktails for deinking applications. This formulation will reduce the pollution and environmental toxicity of conventional chemical deinking.
Topics: Cellulase; Hydrogen-Ion Concentration; Ink; Lipase; Paper; Pseudomonas mendocina
PubMed: 32562224
DOI: 10.1007/s11356-020-09641-z -
International Journal of Systematic and... Jun 2020Strains of a Gram-negative, aerobic, rod-shaped, non-spore-forming bacterium, designated MY50, MY63 and MY101, were isolated from wound samples of three hospitalized...
Strains of a Gram-negative, aerobic, rod-shaped, non-spore-forming bacterium, designated MY50, MY63 and MY101, were isolated from wound samples of three hospitalized patients in Yangon, Myanmar. Strains MY50, MY63 and MY101 grew at temperatures of 4-44 °C, in media containing 1.0-7.0 % (w/v) NaCl and at pH 6.0-9.5. Phylogenetic analysis based on 16S rRNA gene and whole genome sequences showed that these strains belonged to the genus and were part of the group and located close to and . Whole-genome comparisons, using average nucleotide identity and digital DNA-DNA hybridization analyses, confirmed that strains MY50, MY63 and MY101 were the same strain and they were a distinct species in the group. Results of phenotypic characterization tests demonstrated that utilization of p-hydroxy-phenylacetic acid, glycerol, l-pyroglutamic acid and quinic acid could distinguish these strains from other species of the group. These genetic and phenotypic characteristics suggest that they should be classified as representing a novel species, under the proposed name sp. nov. The type strain is MY50 (=LMG 31602,=JCM 33396), with a DNA G+C content of 62.82 mol%.
Topics: Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Fatty Acids; Genes, Bacterial; Hospitals; Humans; Myanmar; Nucleic Acid Hybridization; Phylogeny; Pseudomonas; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Wounds and Injuries
PubMed: 32501786
DOI: 10.1099/ijsem.0.004181 -
Tropical Medicine and Infectious Disease May 2020is a Gram-negative, rod-shaped, aerobic bacterium that belongs in the family Pseudomonadaceae and has been isolated from water and soil. Even though it is thought to... (Review)
Review
is a Gram-negative, rod-shaped, aerobic bacterium that belongs in the family Pseudomonadaceae and has been isolated from water and soil. Even though it is thought to cause infections quite rarely in humans, it can cause severe infections even in immunocompetent individuals. The aim of this study was to systemically review all cases of human infection by in the literature and describe their epidemiology, microbiology, antimicrobial susceptibility, treatment and outcomes. Thus, a systematic review of PubMed for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of infections was conducted. In total, 12 studies, containing data of 16 patients, were included. The commonest infections were infective endocarditis, central nervous system infections and skin and soft tissue infections (SSTIs). Fever was the main presenting symptom, while sepsis was evident in almost half the patients. was susceptible to most antibiotics tested. Mortality was low in all different infection types. Third or fourth generation cephalosporins and quinolones are the commonest agents used for treatment, irrespectively of the infection site.
PubMed: 32375225
DOI: 10.3390/tropicalmed5020071 -
Journal of Functional Biomaterials Apr 2020A medium chain-length polyhydroxyalkanoate (PHA) was produced by CH50 using a cheap carbon substrate, sugarcane molasses. A PHA yield of 14.2% dry cell weight was...
A medium chain-length polyhydroxyalkanoate (PHA) was produced by CH50 using a cheap carbon substrate, sugarcane molasses. A PHA yield of 14.2% dry cell weight was achieved. Chemical analysis confirmed that the polymer produced was a medium chain-length PHA, a copolymer of 3-hydroxyoctanoate and 3-hydroxydecanoate, P(3HO--3HD). Lime oil, an essential oil with known antimicrobial activity, was used as an additive to P(3HO--3HD) to confer antibacterial properties to this biodegradable polymer. The incorporation of lime oil induced a slight decrease in crystallinity of P(3HO-co-3HD) films. The antibacterial properties of lime oil were investigated using ISO 20776 against 6538P and 8739, showing a higher activity against the Gram-positive bacteria. The higher activity of the oil against 6538P defined the higher efficiency of loaded polymer films against this strain. The effect of storage on the antimicrobial properties of the loaded films was investigated. After one-year storage, the content of lime oil in the films decreased, causing a reduction of the antimicrobial activity of the materials produced. However, the films still possessed antibacterial activity against 6538P.
PubMed: 32290046
DOI: 10.3390/jfb11020024