Roseobacter weihaiensis sp. nov., a cellulose-degrading bacterium isolated from intestinal content of Nipponacmea schrenckii collected from golden beach in Weihai, China.

A Gram-staining-negative, dark pink, rod-shaped, amastigote and cellulose-degrading strain, designated H9, was isolated from intestinal contents of Nipponacmea schrenckii. The isolate was able to grow at 4-42 °C (optimum, 25 °C), at pH 6.5-9.0 (optimum, pH 7.0), and with 0.0-11.0% (w/v) NaCl (optimum, 3.0-5.0%). Phylogenetic analysis of the 16S rRNA gene sequence suggested that isolate H9 belongs to the genus Roseobacter, neighboring Roseobacter insulae YSTF-M11, Roseobacter cerasinus AI77 and Roseobacter ponti MM-7, and the pairwise sequence showed the highest similarity of 99.1% to Roseobacter insulae YSTF-M11. The major fatty acid was summed feature 8 (Cω7c and/or Cω6c; 81.08%). The predominant respiratory quinone was Q-10. The polar lipids consisted of phosphatidylcholine, phosphatidylglycerol, an unknown lipid, and a small amount of an unknown phospholipid. The genome of strain H9 was 5,351,685 bp in length, and the DNA G + C content was 59.8%. The average amino acid identity (AAI), average nucleotide identity (ANI), and digital DNA hybridization (dDDH) values between strain H9 and closely related strains were 63.4-76.8%, 74.7-78.8%, and 13.4-19.7%, respectively. On the basis of the phenotypic, chemical taxonomic, and phylogenetic data, it is suggested that strain H9 should represent a novel species in the genus Roseobacter, for which the name Roseobacter weihaiensis sp. nov. is proposed. The type strain is H9 (= KCTC 82507 = MCCC 1K04354).