Phylogenetic position and emended description of the genus Methylovorus.
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The genus Methylovorus, currently represented by the restricted facultative methylotroph Methylovorus glucosotrophus Govorukhina and Trotsenko 1991 and the obligate methylotroph Methylovorus mays Doronina et al. 2001, is here established by direct sequencing of amplified 16S rRNA genes and DNA-DNA hybridization to be clearly separated from the extant ribulose monophosphate (RuMP) pathway methylobacteria and to form a distinct branch within the beta-Proteobacteria. (+info)
Molecular cloning of the DNA gyrase genes from Methylovorus sp. strain SS1 and the mechanism of intrinsic quinolone resistance in methylotrophic bacteria.
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The genes encoding the DNA gyrase A (GyrA) and B subunits (GyrB) of Methylovorus sp. strain SS1 were cloned and sequenced. gyrA and gyrB coded for proteins of 846 and 799 amino acids with calculated molecular weights of 94,328 and 88,714, respectively, and complemented Escherichia coli gyrA and gyrB temperature sensitive (ts) mutants. To analyze the role of type II topoisomerases in the intrinsic quinolone resistance of methylotrophic bacteria, the sequences of the quinolone resistance-determining regions (QRDRs) in the A subunit of DNA gyrase and the C subunit (ParC) of topoisomerase IV (Topo IV) of Methylovorus sp. strain SS1, Methylobacterium extorquens AM1 NCIB 9133, Methylobacillus sp, strain SK1 DSM 8269, and Methylophilus methylotrophus NCIB 10515 were determined. The deduced amino acid sequences of the QRDRs of the ParCs in the four methylotrophic bacteria were identical to that of E. coli ParC. The sequences of the QRDR in GyrA were also identical to those in E. coli GyrA except for the amino acids at positions 83, 87, or 95. The Ser83 to Thr substitution in Methylovorus sp. strain SS1, and the Ser83 to Leu and Asp87 to Asn substitutions in the three other methylotrophs, agreed well with the minimal inhibitory concentrations of quinolones in the four bacteria, suggesting that these residues play a role in the intrinsic susceptibility of methylotrophic bacteria to quinolones. (+info)
Methylotenera mobilis gen. nov., sp. nov., an obligately methylamine-utilizing bacterium within the family Methylophilaceae.
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A novel obligate methylamine utilizer (strain JLW8(T)), isolated from Lake Washington sediment, was characterized taxonomically. The isolate was an aerobic, Gram-negative bacterium. Cells were rod-shaped and motile by means of a single flagellum. Reproduction was by binary fission and no resting bodies were formed. Growth was observed within a pH range of 5-8.5, with optimum growth at pH 7.5. It utilized methylamine as a single source of energy, carbon and nitrogen. Methylamine was oxidized via methylamine dehydrogenase and formaldehyde was assimilated via the ribulose monophosphate cycle. The cellular fatty acid profile was dominated by C(16 : 0)omega7c and C(16 : 0) and the major phospholipid was phosphatidylethanolamine. The DNA G+C content was 54 mol%. 16S rRNA gene sequence analysis indicated that the new isolate was closely related (97-98 % similarity) to a broad group of sequences from uncultured or uncharacterized Betaproteobacteria, but only distantly related (93-96 % similarity) to known methylotrophs of the family Methylophilaceae. Strain JLW8(T) (=ATCC BAA-1282(T)=DSM 17540(T)) is proposed as the type strain of a novel species in a new genus within the family Methylophilaceae, Methylotenera mobilis gen. nov., sp. nov. (+info)
Theanine production by coupled fermentation with energy transfer using gamma-glutamylmethylamide synthetase of Methylovorus mays No. 9.
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Gamma-glutamylmetylamide synthetase (GMAS) of Methylovorus mays No. 9, produced by Eschericia coli AD494 (DE3) harboring pET21aGM, formed theanine from glutamic acid and ethylamine with coupling of the reaction with sugar fermentation of baker's yeast cells as an ATP-regeneration system. Theanine formation was stimulated by the addition of Mn(2+) to the reaction mixture, whereas Mg(2+) was less effective. Increases to a certain level in the concentrations of GMAS and the substrates in the mixture were effective in increasing theanine formation, but high concentrations of ethylamine (900 mM or more) inhibited yeast sugar fermentation, and eventually decreased theanine formation. The inhibitory effect of ethylamine was restored by increasing the concentration of potassium phosphate buffer in the mixture. Approximately 600 mM (110 mg/ml) theanine was formed in 48 h in an improved reaction mixture containing 600 mM sodium glutamate, 600 mM ethylamine.HCl, 300 mM glucose, 200 mM potassium phosphate buffer (pH 7.0), 30 mM MgCl(2), 5 mM MnCl(2), 5 mM AMP, 30 units/ml of GMAS, and 40 mg/ml of yeast cells. The yield of theanine was 100% on the substrates (glutamic acid and ethylamine) and also on the energy source (glucose consumed). (+info)
Insights into the physiology of Methylotenera mobilis as revealed by metagenome-based shotgun proteomic analysis.
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Novel methylotrophic isolates from lake sediment, description of Methylotenera versatilis sp. nov. and emended description of the genus Methylotenera.
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