Methylophaga alcalica sp. nov., a novel alkaliphilic and moderately halophilic, obligately methylotrophic bacterium from an East Mongolian saline soda lake

Abstract

A moderately haloalkaliphilic and obligately methylotrophic bacterium (strain M39^T) with the ribulose monophosphate pathway of carbon assimilation is described. Cells of this methanol and methylamine utilizer are aerobic, Gram-negative, asporogenous, motile short rods, multiplying by binary fission. It is auxotrophic for vitamin B₁₂ and requires NaHCO₃ or NaCl for growth in alkaline medium. Its cellular fatty acid profile consists primarily of straight-chain saturated C_16 : 0 and unsaturated C_16 : 1 and C_18 : 1 acids. The major ubiquinone is Q-8. The dominant phospholipids are phosphatidylethanolamine and phosphatidylglycerol. Diphosphatidylglycerol is also present. Optimal growth conditions are 25–29 °C, pH 9·0–9·5 and 3–4 % (w/v) NaCl. Cells accumulate the cyclic amino acid ectoine as the main compatible solute. The DNA G+C content is 48·3 mol%. Based on 16S rDNA sequence analysis and DNA–DNA relatedness (25–30 %) with the type strains of marine methylotrophs belonging to the genus Methylophaga, the novel isolate M39^T (=VKM B-2251^T =ATCC BAA-297^T) was classified as the type strain of Methylophaga alcalica sp. nov.