Spiribacter aquaticus sp. nov., a novel member of the genus Spiribacter isolated from a saltern.

ABSTRACT

A moderately halophilic bacterium, designated strain SP30T, was isolated from a solar saltern located in Santa Pola, Alicante, on the East coast of Spain. It was a Gram-stain-negative, strictly aerobic bacterium, able to grow in 7.5-25 % (w/v) NaCl and optimally in 12.5 % (w/v) NaCl. Phylogenetic analyses, based on 16S rRNA gene sequences, showed that the novel isolate is a member of the genus Spiribacter, with the most closely related species being Spiribacter roseus SSL50T (99.9 % sequence similarity) and Spiribacter curvatus UAH-SP71T (99.4 % sequence similarity). The 16S rRNA gene sequence similarity with the type species Spiribacter salinus M19-40T was 96.6 %. The DNA-DNA relatedness value between strain SP30T and S. roseus SSL50T and S. curvatus UAH-SP71T was 40 and 55 %, respectively; these values are lower than the 70 % threshold accepted for species delineation. The major fatty acids were C160, C18  1ω7c, C19  0 cyclo ω8c and C12  0. Similarly to other species of the genus Spiribacter, strain SP30Twas observed as curved rods and spiral cells. Metabolic versatility was reduced to the utilization of a few organic compounds as the sole carbon and energy sources, as with other members of Spiribacter. However, it differed in terms of colony pigmentation (brownish-yellow instead of pink) and in having a higher growth rate. Based on these data and on the phenotypic, genotypic and chemotaxonomic characterization, we propose the classification of strain SP30T as a novel species within the genus Spiribacter, with the name Spiribacter aquaticus sp. nov. The type strain is SP30T (=CECT 9238T=LMG 30005T).