Methylobacterium terrae sp. nov., a radiation-resistant bacterium isolated from gamma ray-irradiated soil

Abstract

A Gram-stain-negative, asporogenous, aerobic rods, motile by means of a single polar flagellum, catalase- and oxidase-positive, methylotrophic bacterium, designated 17Sr1-28(T), was isolated from gamma ray-irradiated soil. The 16S rRNA gene sequence analysis showed that strain 17Sr1-28(T) was phylogenetically related to Methylobacterium currus PR1016A(T) (96.8%), Methylobacterium platani PMB02(T) (96.2%), Methylobacterium aquaticum DSM 16371(T) (96.3%), Methylobacterium tarhaniae N4211(T) (96.4%), Methylobacterium frigidaeris IER25-16(T) (95.8%), and Methylobacterium organophilum JCM 2833(T) (92.7%). The G+C content calculated based on genome sequence was 71.6%. The average nucleotide identity and in silico DNA-DNA hybridization values between strain 17Sr128(T) and M. currus, M. platani, M. aquaticum, M. tarhaniae, M. frigidaeris, and M. organophilum were 77.7-90.4% and 22-39.6%, respectively. The major fatty acids of strain 17Sr128(T) were summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c), and summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c). The predominant quinone was ubiquinone 10 and the major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol. On the basis of the data from phenotypic tests and genotypic differences between strain 17Sr1-28(T) and its close phylogenetic relatives, strain 17Sr1-28(T) represents a new species belonging to the genus Methylobacterium, for which the name Methylobacterium terrae sp. nov. (= KCTC 52904(T) = NBRC 112873(T)) is proposed.