Pseudomonas kribbensis sp. nov., isolated from garden soils in Daejeon, Korea

Abstract

Two bacterial strains, 46-1 and 46-2T, were isolated from garden soil. These strains were observed to be aerobic, Gram-stain negative, rod-shaped, non-spore-forming, motile and catalase and oxidase positive. Phylogenetic analysis based on 16S rRNA gene sequences showed that the two strains shared 100% sequence similarity with each other and belong to the genus Pseudomonas in the class Gammaproteobacteria. The concatenated 16S rRNA, gyrB, rpoB and rpoD gene sequences further confirmed that the isolates belong to the Pseudomonas koreensis subgroup (SG), with P. koreensis Ps 9-14T, Pseudomonas moraviensis 1B4T and Pseudomonas granadensis F-278,770T as their close relatives (>96% pairwise similarity). DNA-DNA hybridization with the closely related type strain P. koreensis SG revealed a low level of relatedness (<50%). A cladogram constructed using whole-cell matrix-assisted laser desorption/ionization time-of-flight (WC-MALDI-TOF) MS analysis showed the isolates formed a completely separate monophyletic group. The isolates were negative for utilization of glycogen, d-psicose, α-keto butyric acid, α-keto valeric acid, succinamic acid and d, l-α-glycerol phosphate. In contrast, all these reactions were positive in P.koreensis JCM 14769T and P.moraviensis DSM 16007T. The fatty acid C17:0 cyclo was detected as one of the major cellular fatty acids (>15%) in the isolates but it was a minor component (<4%) in both reference type strains. In contrast, the fatty acid, C12:0 was not observed in the isolates but was present in both reference strains. Based on differences such as phylogenetic position, low-level DNA-DNA hybridization, WC-MALDI-TOF MS analysis, fluorescence pigmentation, fatty acid profiles, and substrate utilization, we propose that the isolates 46-1 and 46-2T represent a novel species of the genus Pseudomonas, for which the name Pseudomonas kribbensis sp. nov. is proposed; the type strain is 46-2T (=KCTC 32541T=DSM 100278T).