Shewanella arctica sp. nov., an iron-reducing bacterium isolated from Arctic marine sediment = 해양침전물에서 분리된 철생산 신종 세균 Shewanella arctica

Abstract

Two strains of dissimilatory iron-reducing bacteria, which could couple lactate oxidation to iron reduction for energy conservation, were isolated from Arctic marine sediment. The strains, IR12 T and IR26, were both Gram-staining-negative, catalase- and oxidase-positive and facultative anaerobes. Their cells were rod-shaped and motile by means of a polar flagellum. Both strains grew in the presence of 0.5-3.5% (w/v) NaCl, with an absolute requirement for Na +. Both were psychrotolerant since they could grow at 4-28 °C but had an optimum growth temperature of 20 °C. Both grew at pH 4.5-9.0 (optimum, pH 7.5). The major fatty acids of strains IR12 T and IR26 were summed feature 3 (C 16: 1ω6c and/or C 16: 1ω7c) and C 16: 0. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strains IR12 T and IR26 belonged to the class Gammaproteobacteria and were most closely related to Shewanella vesiculosa M7 T, Shewanella livingstonensis NF22 T and Shewanella frigidimarina ACAM 591 T (with 98.5 and 98.8%, 98.5 and 98.8%, and 98.5 and 98.8% sequence similarities, respectively). The genomic DNA G+C contents of strains IR12 T and IR26 were 40.0 and 40.3 mol%, respectively. DNA-DNA relatedness data indicated that the two novel strains represented a single species that was distinct from S. vesiculosa M7 T, S. livingstonensis NF22 T and S. frigidimarina ACAM 591 T. Based on the phylogenetic, phenotypic and DNA-DNA relatedness data, the two new strains represent a single novel species of the genus Shewanella, for which the name Shewanella arctica sp. nov. is proposed. The type strain is IR12 T (=KCTC 23109 T=JCM 16723 T).