Methylobacterium frigidaeris sp nov., isolated from an air conditioning system

Abstract

A reddish pink-pigmented, Gram-stain-negative, aerobic and methylotrophic bacterial strain, designated strain IER25-16(T), was isolated from a laboratory air conditioning system in the Republic of Korea. Cells were motile rods showing catalase-and oxidase-positive reactions. Strain IER25-16(T) grew at 10-40 degrees C (optimum, 30 degrees C), at pH 4.0-7.0 (optimum, pH 5.0-7.0) and in the presence of 0-1.0% (w/v) NaCl (optimum, 0 %). The major respiratory quinone was ubiquinone-10 and ubiquinone-9 was also detected as the minor respiratory quinone. Summed feature 8 (comprising C-18:1 omega 7c and/or C-18:1 omega 6c) was detected as the predominant fatty acids. The genomic DNA G+C content of strain IER25-16(T) was 70.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that strain IER25-16(T) belonged to the genus Methylobacterium of the class Alphaproteobacteria. Strain IER25-16(T) was most closely related to Methylobacterium platani PMB02(T) (97.9 %), Methylobacterium aquaticum GR16(T) (97.9 %) and Methylobacterium tarhaniae N4211(T) (97.5 %). The average nucleotide identity and in silico DNADNA hybridization values between strain IER25-16(T) and M. platani, M. aquaticum and M. tarhaniae were 88.3, 88.8 and 89.6% and 36.2, 37.3 and 39.3 %, respectively. The phenotypic and chemotaxonomic features and the phylogenetic inference clearly suggested that strain IER25-16(T) represents a novel species of the genus Methylobacterium, for which the name Methylobacterium frigidaeris sp. nov. is proposed. The type strain is strain IER25-16(T) (=KACC 19280(T)=JCM 32048(T)).