Thiomicrorhabdus aquaedulcis sp. nov., a sulfur-oxidizing bacterium isolated from lake water

Strain HaS4(T) is an aerobic sulfur-oxidizing bacterium isolated from water of Lake Harutori in Japan. It was isolated and partially characterized in a previous study, but its taxonomic status has not been determined. The previous study revealed that the strain is an obligate chemolithoautotroph which grows at temperatures ranging from 0 to 25 degrees C (optimum, 22 degrees C) and pH from pH 6.2 to 8.8 (optimum, pH 6.6-7.4). In this study, further characterization of the strain was made to describe it as representative of a novel species. Cells of strain HaS4(T) are rod-shaped, 1.6-2.5 mu m long, 0.7-0.9 mu m wide and Gram-stain-negative. Major cellular fatty acids were summed feature 3 (C-16 : 1 omega 7c and/or C-16 : 1 omega 6c), summed feature 8 (C-18 : 1 omega 7c and/or C-18 : 1 omega 6c) and C-16 : 0. Phylogenetic analysis based on the 16S rRNA gene indicated that the strain is related to the genus Thiomicrorhabdus, but phylogenetically distinct from the type strains of existing species in the genus. On the basis of its phylogenetic and phenotypic properties, strain HaS4(T) (=NBRC 112315(T)=BCRC 81110(T)) is proposed as type strain of a new non-marine species of the genus Thiomicrorhabdus with the name Thiomicrorhabdus aquaedulcis sp. nov.