Nioella halotolerans sp. nov., a novel member of the family Roseobacteraceae, isolated from a saline lake.

Abstract

A Gram-stain-negative, aerobic bacterium, designated W635^T, was isolated from saline lake water collected from Lake Ayaqqum in Xinjiang province, China. Cells were catalase and oxidase positive, rod-shaped and non-motile. Growth occurred at 20-37 °C (optimum 28-30 °C), pH 7.0-9.5 (optimum 7.5-8.0) and with 0.5-16.0% NaCl (optimum 2.0-4.0%, w/v). Chemotaxonomic analysis revealed that the sole respiratory quinone was ubiquinone-10. The major fatty acids included C_16:0, C_19:0 cyclo ω8c, C_18:1  ω7c 11-methyl and summed feature 8 (C_18:1  ω7c and/or C_18:1  ω6c). The major polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, one uncharacterized phospholipid and four uncharacterized lipids. Sequence similarity analysis of the 16S rRNA gene revealed that strain W635^T presented the highest similarity to Roseovarius nitratireducens TFZ^T (95.47%), followed by members of the genus Nioella (95.11-95.25%). Phylogenetic analysis based on multilocus sequence analysis and whole-genome sequencing indicated that strain W635^T is most closely related to the genus Nioella. The genomic DNA G+C content of the strain W635^T was 65.8 mol%. The average amino acid identity values between strain W635^T and Nioella nitratireducens SSW136^T, Nioella sediminis JS7-11^T, Nioella aestuarii JCM30752^T, and Nioella ostreopsis Z7-4^T were 79.02%, 80.04%, 79.77% and 80.05%, respectively. The average nucleotide identity and in silico DNA-DNA hybridization values between strain W635^T and these strains were 78.37-79.78% and 19.8-20.80%, respectively. Based on phenotypic, chemotaxonomic, genotypic and genomic characteristics, strain W635^T represents a novel species of the genus Nioella, for which the name Nioella halotolerans is proposed. The type strain is W635^T (=KCTC 62429^T =MCCC 1K03491^T).