Methylobacterium currus sp nov., isolated from a car air conditioning system

Abstract

A novel bacterial strain, designated PR1016A(T), was isolated from a car air conditioning system. This rod-shaped strain showed catalase and oxidase activities, was aerobic and methylotrophic, and had a reddish pink colour. The genomic DNA G+C content of strain PR1016A(T) was 70.2 mol%, as determined by genome sequencing. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strain PR1016A(T) was most closely related to Methylobacterium aquaticum GR16(T) (98.86 %), M. variabile GR3(T) (98.43 %), M. platani PMB 02(T) (98.36 %) and M. tarhaniae N4211(T) (98.14 %). The average nucleotide identity and digital DNA-DNA hybridization values between strain PR1016A(T) and M. aquaticum GR16(T), M. platani PMB02 T and M. variabile GR3(T) were 88.61, 88.14 and 87.88 %, and 36.4, 35.8 and 34.7 %, respectively. Numerous insertion sequences are present in the genome of strain PR1016A T, which has a larger genome than the four Methylobacterium species described above. Cells grew at 18-42 degrees C (optimum, 30 ffi C), at pH 4.0-9.0 (optimum, pH 7.0) and in the presence of 0-1.0% (w/v) NaCl (optimum, 0 %). The major respiratory quinone was Q10. Fatty acid methyl ester analysis revealed that summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c) was the predominant cellular fatty acid in strain PR1016A(T). Two-dimensional TLC indicated that the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The genotypic and phenotypic characteristics indicate that strain PR1016A(T) represents a novel species of the genus Methylobacterium, for which the name Methylobacterium currus sp. nov. is proposed. The type strain is PR1016A(T) (= KACC 19662(T) = JCM 32670(T)).