Methylobacterium alsaeris sp. nov. and Methylobacterium carpenticola sp. nov., isolated from a car air conditioning system.

Abstract

Two novel pink-pigmented bacteria, designated strains MA0201^T and ID0610^T, were isolated from a car air conditioning system. The isolates were Gram-stain-negative, aerobic, non-spore-forming, rod-shaped and facultatively methylotrophic. Cells of strains MA0201^T and ID0610^T are motile with polar flagella (lophotrichous) and a polar flagellum (monotrichous), respectively. Both strains indicated catalase- and oxidase-positive activities. The growth of strain MA0201^T was observed at 15-35 °C, at pH 5.0-7.5 and in the presence of 0-0.5% (w/v) NaCl, while the growth of strain ID0610^T indicated at 20-40 °C, at pH 5.0-7.5 and in the presence of 0-0.5% (w/v) NaCl. Ubiquinone-10 was the major respiratory quinone in both strains. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol were identified as the major polar lipids in both strains, and an unidentified lipid and an unidentified aminolipid were additionally identified in strains MA0201^T and ID0610^T, respectively. The major cellular fatty acids (>5%) were summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c) and C_19 : 0 cyclo ω8c in strain MA0201^T, while strain ID0610^T contained summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c) and C_18 : 0. Phylogenetic and phylogenomic analyses showed that strains MA0201^T and ID0610^T formed distinct phylogenic lineages within the genus Methylobacterium. Strain MA0201^T exhibited high 16S rRNA gene sequence similarity to Methylobacterium platani PMB02^T (98.8%), and digital DNA-DNA hybridization (dDDH) and orthologous average nt identity (ANI) values were 38.8% and 90.0%, respectively. Strain ID0610^T showed high 16S rRNA gene sequence similarity to Methylobacterium isbiliense AR24^T (98.5%), and dDDH and ANI values were 27.2% and 83.4%, respectively, indicating that both strains represent novel species of the genus Methylobacterium. Based on their phenotypic, chemotaxonomic and molecular properties, strains MA0201^T and ID0610^T are proposed to represent two novel species within the genus Methylobacterium, namely, Methylobacterium alsaeris sp. nov. (type strain MA0201^T=KACC 23846^T=JCM 37404^T) and Methylobacterium carpenticola sp. nov. (type strain ID0610^T=KACC 23847^T=JCM 37403^T).