Two bacterial strains isolated from air samples, 5317S-33T and 5413S-11T, were characterized by determining their phenotypic characteristics, cellular fatty acid profiles and phylogenetic positions based on 16S rRNA gene sequence analysis. 16S rRNA gene sequence analysis showed that these isolates belonged to the genus Methylobacterium. Strain 5317S-33T was most closely related to Methylobacterium adhaesivum AR27T (97.9 % sequence similarity). Strain 5413S-11T was most closely related to Methylobacterium fujisawaense DSM 5686T (97.3 % sequence similarity), Methylobacterium oryzae CBMB20T (97.1 % similarity) and Methylobacterium radiotolerans JCM 2831T (97.0 % similarity). Cells of both strains were strictly aerobic, Gram-negative, motile and rod-shaped. The major fatty acid was C18 : 1ω7c. The G+C contents of the genomic DNA were 68.0 mol% for strain 5317S-33T and 73.2 mol% for strain 5413S-11T. According to DNA–DNA hybridization data, strain 5317S-33T showed a level of DNA–DNA relatedness of 33 % with M. adhaesivum DSM 17169T, and strain 5413S-11T showed low levels of DNA–DNA relatedness (<35 %) with M. fujisawaense DSM 5686T, M. oryzae CBMB20T and M. radiotolerans DSM 1819T. On the basis of this polyphasic analysis, it was concluded that strains 5317S-33T and 5413S-11T represent two novel species within the genus Methylobacterium, for which the names Methylobacterium iners sp. nov. (type strain 5317S-33T =KACC 11765T =DSM 19015T) and Methylobacteriumaerolatum sp. nov. (type strain 5413S-11T =KACC 11766T =DSM 19013T) are proposed.
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