Tistrella arctica sp. nov., isolated from the surface seawater of the Bering Sea and Chukchi Sea and emended description of the genus Tistrella.

Abstract

Two Gram-stain-negative, motile, non-spore-forming, aerobic or facultative anaerobic and short rod-shaped bacterial strains, 25B02-3^T and BH-R2-4, were isolated from surface seawater collected from the Bering Sea and Chukchi Sea, respectively. The 16S rRNA gene sequences of the two strains were identical. The phylogenetic analysis of the 16S rRNA gene sequences indicated that they were related to the genus Tistrella and shared 99.6 and 98.2% sequence similarity with T. bauzanensis BZ78^T and T. mobilis IAM 14872^T, respectively. Both 16S rRNA gene and genome sequence-based phylogenetic analyses showed that the two strains formed a monophyletic clade within the genus Tistrella, indicating that they may represent a novel species. The digital DNA‒DNA hybridization (dDDH) values and average nucleotide identities (ANI) between the two strains were 93 and 99%, respectively, indicating that they are different strains. The dDDH and ANI values between the two strains and the type strains of the genus Tistrella were 22.4-58.3% and 81.0-95.0%, respectively. These data clearly demonstrated that the two strains represent a separate genomic species of the genus Tistrella. The principal fatty acids were Sum In Feature 8 (C_{18 : 1} ω7c or C_{18 : 1} ω6c), C_{19 : 0} cyclo ω8c, Sum In Feature 2 (C_{12 : 0} aldehyde or unknown 10.928) and C_{16 : 0}. The predominant respiratory quinone was Q-10, with a minor Q-9. The polar lipids included phosphatidylethanolamine, aminolipids and phospholipids. The genomic DNA G+C contents of strains 25B02-3^T and BH-R2-4 were 67.3 mol% and 67.4 mol%, respectively. On the basis of the polyphasic evidence presented in this study, the two strains represent a novel species within the genus Tistrella, for which the name Tistrella arctica sp. nov. is proposed. The type strain is 25B02-3^T (=MCCC 1A07333^T=KCTC 8340^T).