Methylophaga lonarensis sp. nov., a moderately haloalkaliphilic methylotroph isolated from the soda lake sediments of a meteorite impact crater

Abstract

A moderately haloalkaliphilic methylotrophic bacterium possessing the ribulose monophosphate pathway for carbon assimilation, designated MPLT, was isolated from Lonar Lake sediment microcosms that were oxidizing methane for two weeks. The isolate utilized methanol and was an aerobic, Gram-negative, asporogenous, motile, short rod that multiplied by binary fission. The isolate required NaHCO3 or NaCl for growth and, although not auxotrophic for vitamin B12, had enhanced growth with vitamin B12. Optimal growth occurred with 0.5–2 % (w/v) NaCl, at 28–30 °C and at pH 9.0–10.0. The cellular fatty acid profile consisted primarily of straight-chain saturated C16 : 0 and unsaturated C16 : 1ω7c and C18 : 1ω7c. The major ubiquinone was Q-8. The dominant phospholipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Cells accumulated ectoine as the main compatible solute. The DNA G+C content was 50.0 mol%. The isolate exhibited 94.0–95.4 % 16S rRNA gene sequence similarity with the type strains of methylotrophs belonging to the genus Methylophaga and 31 % DNA–DNA relatedness with the reference strain, Methylophaga alcalica VKM B-2251T. It is proposed that strain MPLT represents a novel species, Methylophaga lonarensis sp. nov. (type strain MPLT = VKM B-2684T = MCC 1002T).