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ACS Biomaterials Science & Engineering Jan 2020Silver nanocrystals have been successfully fabricated by the bioreduction route using the ethanolic extract of (neem) leaves as the reducing and capping agent without...
Silver nanocrystals have been successfully fabricated by the bioreduction route using the ethanolic extract of (neem) leaves as the reducing and capping agent without solvent interference. The silver nanocrystals were grown in a single-step method, without the influence of external energy or surfactants, and at room temperature. The nanoparticles were prepared from different ratios of silver ions to reducing agent molecules and were characterized by UV-vis spectroscopy and transmission electron microscopy (TEM). The nanoparticles were roughly spherical and polydispersed with diameters of less than 40 nm, as determined with high-resolution transmission electron microscopy (HRTEM). Fast Fourier transform (FFT) analysis and X-ray diffraction (XRD) analysis elucidated the crystalline nature of the nanoparticles. The presence of participating functional groups was determined with Fourier transform infrared (FTIR) spectroscopy. The synthesized silver nanoparticles were analyzed as a potential surface-enhanced Raman spectroscopy (SERS) substrate by incorporating rhodamine B as the Raman reporter molecule. The bioreduction process was monitored through SERS fingerprint, which was evaluated by the change in vibrational energies of metal-ligand bonds. It was possible to detect the SERS spectral pattern of the probe molecules on the Ag nanoparticles without the use of any aggregating agent. Thus, the formation of probable intra- and interparticle hot spots was attributed to evaporation-induced aggregation. Furthermore, stirring and precursor salt concentration influenced the kinetics involved in the fabrication process. The thermal stability of the lyophilized nanoparticles prepared from 0.1 M AgNO was evaluated with thermogravimetric analysis (TGA) and had a residual mass of 60% at 600 °C. X-ray photoelectron spectroscopy (XPS) studies were used to validate the compositional and chemical-state information. The biomass-capped silver nanoparticles provided antimicrobial activity by inhibiting the growth of , a biofilm-forming bacterium, and the fungus, (NII 08123).
Topics: Anti-Infective Agents; Aspergillus; Metal Nanoparticles; Plant Extracts; Pseudomonas; Silver
PubMed: 33463216
DOI: 10.1021/acsbiomaterials.9b01257 -
International Journal of Systematic and... Feb 2021A Gram-stain-negative, aerobic, motile, short-rod-shaped bacterium with nicosulfuron-degrading ability, designated strain LAM1902, was isolated from a microbial...
A Gram-stain-negative, aerobic, motile, short-rod-shaped bacterium with nicosulfuron-degrading ability, designated strain LAM1902, was isolated from a microbial consortium enriched with nicosulfuron as a sole nitrogen and energy source. The optimal temperature and pH for growth of strain LAM1902 were 30 °C and pH 6.0, respectively. Strain LAM1902 could grow in the presence of NaCl with concentration up to 4.0 % (w/v). Comparative analysis of 16S rRNA gene sequences revealed that LAM1902 was closely related to the members of the family to the genus , with the highest similarity to DSM 14399 (99.6 %), WZBFD3-5A2 (99.3 %) and Esp-1 (98.8 %). Multi-locus sequence analysis based on both concatenated sequences of the 16S rRNA gene and three housekeeping genes (, and ) further confirmed the intrageneric phylogenetic position of strain LAM1902. The genomic DNA G+C content of LAM1902 was 64.8 mol%. The low values of DNA-DNA hybridization (less than 43.7 %) and average nucleotide identity (less than 90.9 %) also showed that the strain was distinctly different from known species of the genus . The major fatty acids were C, C cyclo and anteiso C. Ubiquinone Q-9 was detected as the predorminant respiratory quinone. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and aminophospholipid. Based on phylogenetic, phenotypic and chemotaxonomic analyses and genome comparisons, we conclude that strain LAM1902 represents a novel species, for which the name sp. nov. is proposed. The type strain is LAM1902 (=JCM 33860=KCTC 72830).
Topics: Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Fatty Acids; Genes, Bacterial; Microbial Consortia; Phospholipids; Phylogeny; Pseudomonas; Pyridines; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Sulfonylurea Compounds; Ubiquinone
PubMed: 33411665
DOI: 10.1099/ijsem.0.004632 -
Applied Biochemistry and Biotechnology Apr 2021Currently, the biotechnological preparation of fragrances using natural materials attracted growing attention. Enzymatic synthesis of vanillin from isoeugenol by...
Currently, the biotechnological preparation of fragrances using natural materials attracted growing attention. Enzymatic synthesis of vanillin from isoeugenol by recombinant isoeugenol monooxygenase from Pseudomonas nitroreducens Jin1 was systematically investigated herein. With series of work on the construction of recombinant E. coli over-expressing isoeugenol monooxygenase, optimization of the culture conditions for enzyme production and reaction process for converting isoeugenol into vanillin, an increase of 22-fold in the enzyme activity (2050 U/L) was obtained, and the conversion was significantly increased at high substrate concentration with the aid of magnetic chitosan membrane for product isolation in situ. Under optimal conditions, the product concentration and space-time yield reached 252 mM and 115 g/L/d, respectively, and vanillin was obtained in 82.3% yield and > 99% purity in the gram preparative scale. The developed bioprocess showed application potential for efficient preparation of vanillin from inexpensive natural resources.
Topics: Bacterial Proteins; Benzaldehydes; Eugenol; Mixed Function Oxygenases; Pseudomonas; Recombinant Proteins
PubMed: 33411131
DOI: 10.1007/s12010-020-03478-5 -
Biochemical and Biophysical Research... Jan 2021γ-Glutamyltranspeptidase (GGT) is a ubiquitous enzyme that catalyzes the hydrolysis of the γ-glutamyl linkage of γ-glutamyl compounds and the transfer of their...
γ-Glutamyltranspeptidase (GGT) is a ubiquitous enzyme that catalyzes the hydrolysis of the γ-glutamyl linkage of γ-glutamyl compounds and the transfer of their γ-glutamyl moiety to acceptor substrates. Pseudomonas nitroreducens GGT (PnGGT) is used for the industrial synthesis of theanine, thus it is important to determine the structural basis of hydrolysis and transfer reactions and identify the acceptor site of PnGGT to improve the efficient of theanine synthesis. Our previous structural studies of PnGGT have revealed that crucial interactions between three amino acid residues, Trp385, Phe417, and Trp525, distinguish PnGGT from other GGTs. Here we report the role of Trp525 in PnGGT based on site-directed mutagenesis and structural analyses. Seven mutant variants of Trp525 were produced (W525F, W525V, W525A, W525G, W525S, W525D, and W525K), with substitution of Trp525 by nonaromatic residues resulting in dramatically reduced hydrolysis activity. All Trp525 mutants exhibited significantly increased transfer activity toward hydroxylamine with hardly any effect on acceptor substrate preference. The crystal structure of PnGGT in complex with the glutamine antagonist, 6-diazo-5-oxo-l-norleucine, revealed that Trp525 is a key residue limiting the movement of water molecules within the PnGGT active site.
Topics: Bacterial Proteins; Catalytic Domain; Crystallography, X-Ray; Models, Molecular; Mutagenesis, Site-Directed; Mutant Proteins; Pseudomonas; Static Electricity; Substrate Specificity; Tryptophan; gamma-Glutamyltransferase
PubMed: 33288198
DOI: 10.1016/j.bbrc.2020.11.093 -
Bioresource Technology Dec 2020
Corrigendum to 'Rapid degradation of the organophosphate pesticide - Chlorpyrifos by a novel strain of pseudomonas nitroreducens AR-3', [Bioresource Technology 292 (2019) 122025].
PubMed: 32919286
DOI: 10.1016/j.biortech.2020.124093 -
Environmental Technology Feb 2022N-acyl homoserine lactones (AHLs) based quorum sensing controls various phenotype expressions, including biofilm formation, hence its interruption is considered to be an...
N-acyl homoserine lactones (AHLs) based quorum sensing controls various phenotype expressions, including biofilm formation, hence its interruption is considered to be an ideal option for membrane biofouling control. Bead entrapped quorum quenching bacteria was reported to be an efficient approach for degradation of signal molecules in recent years. In the present study, we investigated the potential of quorum quenching (QQ) bacteria immobilised magnetic nanocomposite beads (IMN) in degradation of signalling molecule, n-hexanoyl homoserine lactone (C6-HSL). Three QQ bacteria, named JYQ2, JYQ3 and JYQ4 isolated from dairy industry waste activated sludge (WAS) were immobilised in the magnetic nanocomposite (IMN) beads. The scanning electron microscopy (SEM) of the IMN beads has indicated the successful entrapment of QQ bacteria within the alginate matrix. The GC-MS analysis showed that all the QQ bacteria immobilised magnetic nanocomposite (IMN) beads degraded the signalling molecule, n-hexanoyl homoserine lactone (C6-HSL) within 72 h of incubation. The nanocomposite beads containing the QQ bacteria JYQ4 showed the maximum degradation percentage of 97 ± 0.13% leaving a residual HSL of 0.7 mg/L. All the other isolates showed C6-HSL degradation percentage in the range of 87% to 95%. The data suggest the potential of C6-HSL degradation by QQ bacteria IMN beads. Hence, the study offers possibilities of controlling biofilm developed on the membrane surface during wastewater treatment processes.
Topics: 4-Butyrolactone; Bacteria; Magnetic Phenomena; Nanocomposites; Quorum Sensing
PubMed: 32814501
DOI: 10.1080/09593330.2020.1811389 -
Genes Aug 2020The sewage sludge isolate HBP-1 was the first bacterium known to completely degrade the fungicide 2-hydroxybiphenyl. PacBio and Illumina whole-genome sequencing...
The sewage sludge isolate HBP-1 was the first bacterium known to completely degrade the fungicide 2-hydroxybiphenyl. PacBio and Illumina whole-genome sequencing revealed three circular DNA replicons: a chromosome and two plasmids. Plasmids were shown to code for putative adaptive functions such as heavy metal resistance, but with unclarified ability for self-transfer. About one-tenth of strain HBP-1's chromosomal genes are likely of recent horizontal influx, being part of genomic islands, prophages and integrative and conjugative elements (ICEs). carries two large ICEs with different functional specialization, but with homologous core structures to the well-known ICE of B13. The variable regions of ICE1 (96 kb) code for, among others, heavy metal resistances and formaldehyde detoxification, whereas those of ICE2 (171 kb) encodes complete -cleavage pathways for catabolism of 2-hydroxybiphenyl and salicylate, a protocatechuate pathway and peripheral enzymes for 4-hydroxybenzoate, ferulate, vanillin and vanillate transformation. Both ICEs transferred at frequencies of 10-10 per HBP-1 donor into , where they integrated site specifically into -gene targets, as expected. Our study highlights the underlying determinants and mechanisms driving dissemination of adaptive properties allowing bacterial strains to cope with polluted environments.
Topics: Computational Biology; Conjugation, Genetic; DNA Transposable Elements; DNA, Bacterial; Disinfectants; Fatty Acids; Gene Order; Gene Transfer, Horizontal; Genome, Bacterial; Genomic Islands; Genomics; High-Throughput Nucleotide Sequencing; Molecular Sequence Annotation; Plasmids; Prophages; Pseudomonas
PubMed: 32806781
DOI: 10.3390/genes11080930 -
Journal of the Science of Food and... Mar 2021L-Glutaminase is considered to be an important industrial enzyme in both the pharmaceutical and food industries, especially for producing functional glutamyl compounds,...
BACKGROUND
L-Glutaminase is considered to be an important industrial enzyme in both the pharmaceutical and food industries, especially for producing functional glutamyl compounds, such as l-theanine. Pseudomonas nitroreducens SP.001 with intracellular l-glutaminase activity has been screened previously. In the present study, three physical permeabilization methods were used to improve l-glutaminase activity. Then, the whole-cell immobilization conditions of permeabilized cells using sodium alginate as an embedding agent were optimized to enhance the enzyme's stability and reusability. The characteristics of the immobilized cells were investigated in comparison with those of permeabilized cells.
RESULTS
The results obtained showed that cell permeabilization using osmotic shock with 155 g L sucrose markedly improved enzyme activity. Then, an effective procedure for immobilization of permeabilized P. nitroreducens cells was established. The optimum conditions for cell immobilization were: sodium alginate 40 g L , calcium chloride 30 g L , cell mass 100 g L and a curing time of 3 h. After successful immobilization, characterization studies revealed that the thermostability and pH resistance of l-glutaminase from immobilized cells were enhanced compared to those from permeabilized cells. Moreover, the immobilized biocatalyst could be reused up to 10 times and retained 80% of its activity.
CONCLUSION
The stability and reusability of the permeabilized cells were improved through the immobilization. These findings indicated that immobilized whole-cell l-glutaminase from P. nitroreducens SP.001 possesses more potential for various industrial biotechnological applications than free cells. © 2020 Society of Chemical Industry.
Topics: Alginates; Bacterial Proteins; Biocatalysis; Cells, Immobilized; Glutamates; Glutaminase; Pseudomonas
PubMed: 32790072
DOI: 10.1002/jsfa.10736 -
Bioscience, Biotechnology, and... Nov 2020Maltol derivatives are used in a variety of fields due to their metal-chelating abilities. In the previous study, it was found that cytochrome P450 monooxygenase,...
Maltol derivatives are used in a variety of fields due to their metal-chelating abilities. In the previous study, it was found that cytochrome P450 monooxygenase, P450nov, which has the ability to effectively convert the 2-methyl group in a maltol derivative, transformed 3-benzyloxy-2-methyl-4-pyrone (BMAL) to 2-(hydroxymethyl)-3-(phenylmethoxy)-4-pyran-4-one (BMAL-OH) and slightly to 3-benzyloxy-4-oxo-4 -pyran-2-carboxaldehyde (BMAL-CHO). We isolated SB32154 with the ability to convert BMAL-CHO to BMAL-COOH from soil. The enzyme responsible for aldehyde oxidation, a BMAL-CHO dehydrogenase, was purified from SB32154 and characterized. The purified BMAL-CHO dehydrogenase was found to be a xanthine oxidase family enzyme with unique structure of heterodimer composed of 75 and 15 kDa subunits containing a molybdenum cofactor and [Fe-S] clusters, respectively. The enzyme showed broad substrate specificity toward benzaldehyde derivatives. Furthermore, one-pot conversion of BMAL to BMAL-COOH via BMAL-CHO by the combination of the BMAL-CHO dehydrogenase with P450nov was achieved.
Topics: Aldehyde Dehydrogenase; Biocatalysis; Molybdenum; Oxidation-Reduction; Pseudomonas; Pyrones
PubMed: 32729393
DOI: 10.1080/09168451.2020.1799749 -
Bioresource Technology Nov 2020The main aim of this work was to study the allethrin binding interactions with esterase and its bioremediation potential using an isolated bacterial strain CW7,...
The main aim of this work was to study the allethrin binding interactions with esterase and its bioremediation potential using an isolated bacterial strain CW7, identified as Pseudomonas nitroreducens. The degradation conditions with strain CW7 were optimized using response surface methodology at pH 7.0, a temperature of 32 °C, and an inocula concentration of 150 mg·L, with 96% allethrin degradation observed over 7 days. The kinetic parameters q, K and K were calculated to be 0.512 day, 4.97 mg·L and 317.13 mg·L, respectively. Nine intermediate metabolites were identified after analysing the degradation products by gas chromatography-mass spectrometry. Strain CW7 effectively degraded a wide variety of pyrethroids as a carbon source. Molecular modeling, docking, and enzyme kinetics were used to investigate the binding pocket of the esterase containing amino acids such as alanine, arginine, valine, proline, cysteine, glycine, isoleucine, phenylalanine, serine, asparagine, and threonine, which play active roles in allethrin degradation.
Topics: Alanine; Allethrins; Arginine; Biodegradation, Environmental; Esterases; Glutamates; Histidine; Leucine; Lysine; Methionine; Pseudomonas; Serine; Tyrosine
PubMed: 32707504
DOI: 10.1016/j.biortech.2020.123845