Thioclava nitratireducens sp. nov., isolated from surface seawater.

A bacterial strain, designated 25B10_4T, was isolated from surface seawater of the Bering Sea and characterized using a polyphasic taxonomic approach. Cells of strain 25B10_4T were Gram-stain-negative, motile and short-rod-shaped. Growth was observed at 10-43 °C (optimum 28 °C), at pH 6-9 (optimum pH 7) and with 0-12 % NaCl (optimum 3-4 %, w/v). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain 25B10_4T formed an independent branch within the genus Thioclava, sharing high similarities with four related type strains, Thioclava atlantica 13D2W-2T (98.9 %), Thioclava pacifica TL 2T (98.5 %), Thioclava dalianensis DLFJ1-1T (98.4 %) and Thioclava indica DT23-4T (96.9 %), and low similarities (less than 96.5 %) with other type strains within the family Rhodobacteraceae. The major fatty acid was identified as summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The quinone was Q-10. The polar lipids comprised phosphatidylethanolamine, phosphatidylglycerol, glycolipid and five unidentified phospholipids. The DNA G+C content was 63.8 mol%. The digital DNA-DNA hybridization and average nucleotide identity values between strain 25B10_4T and the four above-mentioned type strains were, respectively, 20.5-25.7 % and 77.8-82.4 %. The phenotypic, phylogenetic and chemotaxonomic analyses clearly indicated that strain 25B10_4T represents a novel species within the genus Thioclava, for which the name Thioclava nitratireducens sp. nov. is proposed. The type strain is 25B10_4T (=MCCC 1A07302T=LMG 29614T).