Arsukibacterium ikkense gen. nov., sp. nov, a novel alkaliphilic, enzyme-producing γ-Proteobacterium isolated from a cold and alkaline environment in Greenland

Abstract

A novel aerobic, Gram-negative, non-pigmented bacterium, GCM72 T, was isolated from the alkaline, low-saline ikaite columns in the Ikka Fjord, SW Greenland. Strain GCM72 T is a motile, non-pigmented, amylase- and protease-producing, oxidase-positive, and catalase-negative bacterium, showing optimal growth at pH 9.2–10.0, at 15 °C, and at 3% (w/v) NaCl. Major fatty acids were C 12:0 3-OH (12.2±0.1%), C 16:00 (18.0±0.1%), C 18:1 ω7 c (10.7±0.5%), and summed feature 3 comprising C 16:1 ω7 c and/or iso-C 15:0 2-OH (36.3±0.7%). Phylogenetic analysis based on 16S rRNA gene sequences showed that isolate GCM72 T was most closely related to Rheinheimera baltica and Alishewanella fetalis of the γ-Proteobacteria with a 93% sequence similarity to both. The G+C content of DNA isolated from GCM72 T was 49.9 mol% and DNA–DNA hybridization between GCM72 T and R. baltica was 9.5%. Fatty acid analysis and G+C content supports a relationship primarily to R. baltica, but several different features, such as a negative catalase-response and optimal growth at low temperature and high pH, together with the large phylogenetic distance and low DNA similarity to its closest relatives, lead us to propose a new genus, Arsukibacterium, gen. nov., with the new species Arsukibacterium ikkense sp. nov. (type strain is GCM72 T).