Methylophilus flavus sp. nov. and Methylophilus luteus sp. nov., aerobic, methylotrophic bacteria associated with plants

Novel yellow, obligately methylotrophic and restricted facultatively methylotrophic bacteria, respectively designated strains Ship T and Mim T , with the ribulose monophosphate pathway of C 1 assimilation are described. Cells were strictly aerobic, Gram-negative, asporogenous, non-motile rods that multiply by binary fission, were mesophilic and neutrophilic and synthesized indole-3-acetic acid and exopolysaccharide. The predominant cellular fatty acids were C 16 : 0 and C 16 : 1 . The major ubiquinone was Q-8. The predominant phospholipids were phosphatidylethanolamine and phosphatidylglycerol; diphosphatidylglycerol was absent. The two strains lacked α -ketoglutarate dehydrogenase and glutamate dehydrogenase. They assimilated ammonium via the glutamate cycle enzymes glutamine synthetase and glutamate synthase. The DNA G+C contents of strains Ship T and Mim T were 50.7 and 54.5 mol% ( T m ), respectively. The level of 16S rRNA gene sequence similarity between these strains was very high (99.8 %) but they shared a low level of DNA–DNA relatedness (44 %). Based on 16S rRNA gene sequence analysis and low levels of DNA–DNA relatedness with the type strains of recognized species of the genus Methylophilus (31–36 %), strains Ship T and Mim T are considered to represent novel species of the genus Methylophilus , for which the names Methylophilus flavus sp. nov. (type strain Ship T =DSM 23073 T =VKM B-2547 T =CCUG 58411 T ) and Methylophilus luteus sp. nov. (type strain Mim T =DSM 22949 T =VKM B-2548 T =CCUG 58412 T ) are proposed.