Tsuneonella litorea sp. nov., a novel carotenoid-producing bacterium isolated from coastal sediment

A Gram-stain-negative, aerobic, non-motile and pleomorphic bacterium designated as YG55^T was isolated from a coastal sediment sample. Growth was found to occur at 10-37 °C (optimum, 28 °C), at pH 6-9 (optimum, pH 8) and in 0-6 % NaCl (optimum, 1 %). The results of 16S rRNA gene-based analysis showed that strain YG55^T was related to the members of the genus Tsuneonella and shared the highest identity of 99.4 % with Tsuneonella dongtanensis GDMCC 1.2307^T, followed by Tsuneonella troitsensis JCM 17037^T (98.4 %). The phylogenomic results indicated that strain YG55^T formed an independent branch distinct from the reference type strains. The 22.7 and 21.8 % digital DNA-DNA hybridization (dDDH) values and 83.0 and 81.8 % average nucleotide identity (ANI) values between strain YG55^T and the two relatives were below the species definition thresholds of 70 % (dDDH) and 95-96 % (ANI), indicating that the strain represents a novel genospecies. The results of chemotaxonomic characterization indicated that the major cellular fatty acids of strain YG55^T were summed feature 8 (C_{18 : 1} ω6c and/or C_{18 : 1} ω7c), C_{14 : 0} 2OH and C_{16 : 0}; the main polar lipids comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and sphingoglycolipid; the respiratory quinone was ubiquinone-10. The genomic size and DNA G+C contents were 3.03 Mbp and 66.98 %. The strain contained carotenoid biosynthesis genes and could produce carotenoids. Based on its genotypic and phenotypic characteristics, strain YG55^T is concluded to represent a novel species of the genus Tsuneonella, for which the name Tsuneonella litorea sp. nov. is proposed. The type strain is YG55^T (=GDMCC 1.2590 ^T=KCTC 82812^T).