Nitratireductor rhodophyticola sp. nov., isolated from marine red algae

Two Gram-stain-negative, strictly aerobic bacteria, strains L1-7-SE^T and R6, isolated from marine red algae, were characterized. They shared 99.9 % 16S rRNA gene sequence similarity and a 100 % digital DNA-DNA hybridization (DDH) value, representing members of a single species. Cells of strains L1-7-SE^T and R6 were catalase- and oxidase-positive motile rods with a single polar flagellum. Strains L1-7-SE^T and R6 optimally grew at 30-35 °C, pH 7.0-8.0 and with 1.0-2.0 % (w/v) NaCl. Ubiquinone-10 was the sole isoprenoid quinone and C_19 : 0 cyclo ω8c and summed feature 8 (comprising C_18 : 1  ω7c and/or C_18 : 1  ω6c) were detected as the major cellular fatty acids. The DNA G+C contents of strains L1-7-SE^T and R6 were both 61.62 mol%. The polar lipids of strain L1-7-SE^T consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unidentified aminolipid, an unidentified phospholipid and two unidentified polar lipids. Phylogenetic analyses based on 16S rRNA gene and 120 protein marker sequences revealed that strains L1-7-SE^T and R6 formed a phyletic lineage within the genus Nitratireductor and they were most closely related to Nitratireductor aquibiodomus NL21^T and Nitratireductor kimnyeongensis KY 101^T with both 98.8 % 16S rRNA gene sequence similarities. Digital DDH values between strain L1-7-SE^T and the type strains of N. aquibiodomus and N. kimnyeongensis were 60.3 and 29.5 %, respectively. The phenotypic, chemotaxonomic and molecular features support that strains L1-7-SE^T and R6 represents a novel species of the genus Nitratireductor, for which the name Nitratireductor rhodophyticola sp. nov. is proposed. The type strain is L1-7-SE^T (=KACC 19076^T=KCTC 92231^T=JCM 31802^T).