Description of Undibacterium oligocarboniphilum sp. nov., isolated from purified water, and Undibacterium pigrum strain CCUG 49012 as the type strain of Undibacterium parvum sp. nov., and emended descriptions of the genus Undibacterium and the species Undibacterium pigrum
A Gram-negative, oxidase- and catalase-positive, flagellated, rod-shaped bacterium, designated strain EM 1T, was isolated from purified water. 16S rRNA gene sequence analysis indicated that the novel strain belonged to the family Oxalobacteraceae within the class Betaproteobacteria; the closest phylogenetic relative was Undibacterium pigrum DSM 19792T (96.7 % gene sequence similarity). The new isolate could be distinguished from the type strain of U. pigrum DSM 19792T (=CCUG 49009T=CIP 109318T) and from strain CCUG 49012T, which has been described as a second genomovar of this species, on the basis of genotypic data and several phenotypic properties. An S-layer was present in the cell envelope in U. pigrum DSM 19792T, but was absent in strains EM 1T and CCUG 49012T. Test conditions were established that enabled strain CCUG 49012T to be distinguished from U. pigrum DSM 19792T. As found for U. pigrum, the main fatty acids of strains EM 1T and CCUG 49012T were summed feature 3 (including unsaturated C16 : 1 ω7c), straight-chain C16 : 0 and unsaturated C18 : 1 ω7c (low percentage in strain CCUG 49012T), and C10 : 0 3-OH was the sole hydroxylated fatty acid. The polar lipid profile consisted of the predominant lipids phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The polyamine profile was mainly composed of the major compound putrescine and moderate amounts of 2-hydroxyputrescine. In contrast to U. pigrum and strain CCUG 49012T, where ubiquinone Q8 was reported as the sole quinone component, the quinone system of strain EM 1T consisted of ubiquinone Q-8 (64 %) and Q-7 (36 %). The 16S rRNA gene sequence similarity, the polar lipid profile and the absence of C12-hydroxylated fatty acids all indicated that strain EM 1T was affiliated with the genus Undibacterium. 16S rRNA gene sequence similarity values lower than 97.0 % and several differentiating phenotypic traits demonstrated that strain EM 1T represents a novel species for which the name Undibacterium oligocarboniphilum sp. nov. is proposed (type strain EM 1T=DSM 21777T=CCUG 57265T). In addition, based on previously published results and this study, a separate species, Undibacterium parvum sp. nov., is proposed with strain CCUG 49012T (=DSM 23061T=CIP 109317T) as the type strain.