ABSTRACT
A light cream color colony was isolated, using oligotrophic LB agar medium, from a water sample collected from a tube well and designated as HWB-10(T). Cells of strain HWB-10(T) were Gram-negative, motile rods, non-spore forming, positive for catalase, oxidase, nitrate reduction and esculin. The predominant fatty acids were C16:0, summed feature 4 (C16:1 ω7c/iso-C15:0 2-OH) and summed feature 7 (C18:1 ω7c, C18:1 ω9t and/or C18:1 ω12t), and the major ubiquinone was Q-8. NCBI-BLAST- and EzTaxon-based 16S rRNA gene sequence similarity search identified strain HWB-10(T) as a member of the genus Hydrogenophaga and H. atypica DSM 15342(T), H. defulvi DSM 15341(T), H. palleronii LMG2366(T) and H. taeniospiralis LMG7170(T) being the nearest phylogenetic species with a similarity (%) of 99.3, 99.1, 98.4 and 98.2, respectively, while the similarity was <98.0 % with other species of the genus. However, DNA-DNA similarities between HWB-10(T) and H. atypica DSM 15342(T) and H. defulvi DSM 15341(T) were 37.0 and 43.0 %, respectively, indicating that strain HWB-10(T) is a novel species. Further, the DNA fingerprinting, based on BOX-, ERIC-, (GTG)5- and REP-PCR amplifications, distinguished strain HWB-10(T) from its closest species, H. atypica DSM 15342(T) and H. defulvi DSM 15341(T) with similarity coefficients of 0.45 and 0.37, respectively, a value sufficient to establish the species status within the genus Hydrogenophaga. In addition, strain HWB-10(T) exhibited several phenotypic differences with its closely related species. Based on the above cumulative differentiating characteristics, strain HWB-10(T) was identified as a new species of the genus Hydrogenophaga and proposed as Hydrogenophaga laconesensis sp. nov. with strain HWB-10(T) (KTCC 42478(T) = LMG 28681(T)) as its type strain.
