Methylobacterium terricola sp. nov., a gamma radiation-resistan bacterium isolated from gamma ray-irradiated soil

Abstract

A gamma radiation-resistant and pink-pigmented bacterial strain, designated as 17Sr1-39(T), was isolated from a gamma ray-irradiated soil sample collected in the Republic of Korea. Cells were Gram-stain-negative, strictly aerobic, flagellated. asporogenous, rod-shaped and methylotrophic. Results of 16S rRNA gene sequence analysis showed that strain 17Sr1-39(T)was phylogenetically related to Methylobacterium currus PR1016A(T) (97.3%), Methylobacterium aquaticum DSM 16371(T) (97.2%), Methylobacterium platani PMB02(T) (97.0%), Methylobacterium frigidaeris IER25-16(T) (96.6%), Methylobacterium terrae 17Sr1-28(T) (96.6%) and Methylobacterium organophilum JCM 2833(T) (93.4%). The G+C content calculated based on the genome sequence was 70.4mol%. The average nucleotide identity and in silico DNA-DNA hybridization values between strain 17Sr1-39(T) and M. currus, M. aquaticum, M. platani, M. frigidaeris, M. terrae and M. organophilum were 77.3-89.9 and 22-38.2%, respectively. The predominant fatty acids 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, phosphatidylglycerol and phosphatidylethanolamine. Based on the data from phenotypic tests and genotypic differences between strain 17Sr1-39(T) and its close phylogenetic relatives, strain 17Sr1-39(T) represented a new species belonging to the genus Methylobacterium, for which the name Methylobacterium terricola sp. nov. (=KACC 52905(T)=NBRC 112874(T)) is proposed.