A Gram-stain-negative, aerobic, flagellated, non-spore-forming, rod-shaped bacterium, named B2R-29T, was isolated from water collected from a crater lake on Da Hinggan mountain, PR China. Strain B2R-29T was oxidase- and catalase-positive. On the basis of the results of 16S rRNA gene sequence analyses, strain B2R-29T clearly belonged to the family Oxalobacteraceae, class Betaproteobacteria and showed the highest similarity to Undibacterium oligocarboniphilum EM1T (97.4 %) and to the other species of Undibacterium (less than 96.8 %). In the phylogenetic tree, strain B2R-29T formed a clade with U. oligocarboniphilum EM1T and Undibacterium squillarum CMJ-9T, indicating that is a member of the genus Undibacterium. Digital DNA-DNA hybridization and average nucleotide identity analyses were performed and the values between strain B2R-29T and its closely related Undibacterium species were less than 75.1 % and 16.9 %, respectively. The chemotaxonomic data of B2R-29T were as follows: major uniquinone, Q-8; predominant polar lipids, phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol; major fatty acids, C16 : 0 and summed feature 3 (C16 : 1 ω7c / C16 : 1 ω6c); predominant polyamines, putrescine, 2-hydroxyputrescine and spermidine. The DNA G+C content was 51.7 mol% from the genomic sequencing data. In accordance with the phenotypic, physiological and chemotaxonomic properties mentioned above, strain B2R-29T represents a novel species of the genus Undibacterium for which the name Undibacterium crateris sp. nov. is proposed. The type strain is B2R-29T (=CGMCC 1.13792T=KCTC 72018T).
Keywords: Da Hinggan mountain; Undibacterium; crater lake.