Homoserinimonas flava sp. nov., a novel carotenoid-producing actinobacterium isolated from saline lake sediment

An actinobacterial strain, designated TRA05-7^T, was isolated from a saline lake sediment in the Ngari Prefecture, Xizang Autonomous Region, China. The cells were Gram-stain-positive, aerobic and short-rod-shaped. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain TRA05-7^T was most closely related to members of the genus <i>Homoserinimonas</i>, with the highest sequence similarity to <i>Homoserinimonas hongtaonis</i> 194^T (98.48%). However, whole-genome phylogenetic analysis revealed a closer relationship with <i>Homoserinimonas sedimenticola</i> SYSU T00001^T, with the two strains forming a distinct cluster. The average nucleotide identity and digital DNA-DNA hybridization values between strain TRA05-7^T and <i>H. sedimenticola</i> were 77.3 and 20.7%, respectively. The genomic DNA G+C content was 65.7 mol%. Growth occurred at 4-40 °C (optimum 28 °C), pH 7-11 (optimum pH 7) and with 0-8% (w/v) NaCl (optimum 1%). The major menaquinones were MK-12, MK-11 and MK-13. Polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids and one unidentified lipid. The major cellular fatty acids were anteiso-C_15:0, anteiso-C_17:0 and anteiso-C_15:0. UV-Vis and HPLC analysis indicated that strain TRA05-7^T had the ability to produce carotenoids. Based on phylogenetic, genomic, phenotypic and chemotaxonomic analyses, strain TRA05-7^T represents a novel species of the genus <i>Homoserinimonas</i>, for which the name <i>Homoserinimonas flava</i> sp. nov. is proposed. The type strain is TRA05-7^T (=MCCC 1K10024^T=KCTC 59574^T).