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

A bacterial strain, designated DL5-4T, was isolated from the surface seawater of Dalian Bay and characterized using a polyphasic taxonomy approach. Cells of DL5-4T were Gram-staining-negative, non-motile and short-rod-shaped. Growth was observed at 8-40 °C (optimum 28-30 °C), at pH 6-9 (optimum pH 7) and in 0-7 % NaCl (optimum 1-3 %, w/v). The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that DL5-4T formed an independent branch with members of the genus Defluviimonas, sharing high similarities with five related type strains, Defluviimonas aquaemixtae CDM-7T (96.6 %), Defluviimonas denitrificans DSM 18921T (96.0 %), Defluviimonas indica 20V17T (95.8 %), Defluviimonas aestuarii BS14T (95.8 %) and Defluviimonas alba cai42T (94.5 %). The predominant fatty acid was summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The isoprenoid quinone was identified as Q-10. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, four phospholipids, an aminolipid and an unknown lipid. The DNA G+C content was 63.8 mol%. The results of the phenotypic, phylogenetic and chemotaxonomic analyses clearly indicated that DL5-4T represents a novel species of the genus Defluviimonas, for which the name Defluviimonas nitratireducens sp. nov. is proposed, with type strain DL5-4T (=MCCC 1A06955T=LMG 29616T).