Erythrobacter rubeus sp. nov., a carotenoid-producing alphaproteobacterium isolated from coastal seawater

A study based on a polyphasic taxonomic approach was carried out to identify and classify a novel marine alphaproteobacterium, designated as KMU-140(T), isolated from coastal seawater collected at Jeju Island, Republic of Korea. Cells of strain KMU-140(T) were spherical, Gram-stain-negative, reddish-orange colored, strictly aerobic, catalase- and oxidase-positive, non-motile, and chemoorganoheterotrophic. The novel isolate was able to grow at NaCl concentrations of 0-5%, pH 6.0-9.5, and 10-45 degrees C. A phylogenetic analysis based on the 16S rRNA gene sequence showed that strain KMU-140(T) belongs to the family Erythrobacteraceae and was most closely related to Erythrobacter longus OCh101(T) (98.7%). Strain KMU-140(T) contained ubiquinone-10 (Q-10) as the only respiratory quinone and C18:1 omega 7c, iso-C18:0, and C16:0 as the main (> 10%) cellular fatty acids. Strain KMU-140(T) produced carotenoid compounds that rendered the cell biomass a reddish-orange color. The assembled draft genome size of strain KMU-140(T) was 3.04 Mbp with G + C content of 60.6 mol%. The average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), and average amino acid identity (AAI) values of KMU-140(T) and the species of the genus Erythrobacter were found to be 76.6-78.4%, 14.0-18.7%, and 69.6-77.8%, respectively. Phosphatidylethanolamine, phosphatidylglycerol, an unidentified phospholipid, and two unidentified lipids were identified as major polar lipids. On the basis of the polyphasic taxonomic features presented, the strain is considered to represent a novel species of the genus Erythrobacter for which the name Erythrobacter rubeus sp. nov. is proposed. The type strain of E. rubeus sp. nov. is KMU-140(T) (= KCCM 90479(T) = NBRC 115159(T)).

Automated summary

A study identified and classified a novel marine alphaproteobacterium, named Erythrobacter rubeus sp. nov., isolated from coastal seawater collected at Jeju Island, Republic of Korea. The strain exhibited characteristics such as gram-negative, spherical cells with reddish-orange color, strict aerobic growth, and chemoorganoheterotrophic metabolism.