Methylophilus quaylei sp. nov., a new aerobic obligately methylotrophic bacterium

Abstract

A new obligately methylotrophic bacterium (strain MT T) with the ribulose monophosphate pathway of carbon assimilation is described. The isolate, utilizing only methanol, is an aerobic, Gram-negative, asporogenous, non-motile short rod multiplying by binary fission. Its cellular fatty acids profile consists primarily of straight-chain saturated C 16:0 and unsaturated C 16:1 acids. The major ubiquinone is Q-8. The dominant phospholipids are phosphatidylethanolamine and phosphatidylglycerol. Diphosphatidylglycerol (cardiolipin) is absent. Optimal growth conditions are 25–29 °C, pH 6.5–7.5, 0.5% CH 3OH and 0.05% NaCl. Strain MT T lacks α -ketoglutarate dehydrogenase, the glyoxylate shunt enzymes, and glutamate dehydrogenase. Ammonium is assimilated by the operation of the glutamate cycle enzymes: glutamine synthetase and glutamate synthase. An exopolysaccharide consisting of rhamnose, glucose and galactose is formed under nitrogen limitation. The G+C content of the DNA is 54.0 mol%. Based on 16S rDNA sequence analysis and DNA–DNA relatedness (29–34%) with type strains of the genus Methylophilus, the novel isolate was classified as a new species of this genus and named Methylophilus quaylei MT T (VKM B-2338 T, DSMZ, etc.).