Pseudomonas toyotomiensis sp. nov., a psychrotolerant facultative alkaliphile that utilizes hydrocarbons

Abstract

A psychrotolerant, facultatively alkaliphilic strain, HT-3T, was isolated from a sample of soil immersed in hot-spring water containing hydrocarbons in Toyotomi, Hokkaido, Japan. 16S rRNA gene sequence-based phylogeny suggested that strain HT-3T is a member of the genus Pseudomonas and belongs to the Pseudomonas oleovorans group. Cells of the isolate were Gram-negative, aerobic, straight rods, motile by a single polar flagellum. The strain grew at 4–42 °C, with optimum growth at 35 °C at pH 7, and at pH 6–10. It hydrolysed Tweens 20, 40, 60 and 80, but not casein, gelatin, starch or DNA. Its major isoprenoid quinone was ubiquinone-9 (Q-9) and the DNA G+C content was 65.1 mol%. The whole-cell fatty acid profile consisted mainly of C16 : 0, C16 : 1ω9c and C18 : 1ω9c. Phylogenetic analyses based on gyrB, rpoB and rpoD sequences revealed that the isolate could be discriminated from Pseudomonas species that exhibited more than 97 % 16S rRNA gene sequence similarity and phylogenetic neighbours belonging to the P. oleovorans group including the closest relative of the isolate, Pseudomonas alcaliphila. DNA–DNA hybridization with P. alcaliphila AL15-21T revealed 51±5 % relatedness. Owing to differences in phenotypic properties and phylogenetic analyses based on multilocus gene sequence analysis and DNA–DNA relatedness data, the isolate merits classification in a novel species, for which the name Pseudomonas toyotomiensis sp. nov. is proposed. The type strain is HT-3T ( = JCM 15604T  = NCIMB 14511T).