Microbaculum marinisediminis sp. nov., isolated from marine sediment

A novel Gram-stain-negative and facultatively anaerobic bacterium, designated A6E488^T, was isolated from intertidal sediment collected from Xiaoshi Island, Weihai, PR China (122° 1' E 37° 31' N). Cells of strain A6E488^T were rod-shaped with widths of 0.3-0.4 µm and lengths of 1.1-1.8 µm. The optimal growth conditions were determined to be in 1 % (w/v) NaCl, at 37 °C, and at pH 7.0. The predominant fatty acids (≥10 %) were C_19 : 0 cyclo ω8c (59.7 %) and summed feature 8 (13.8 %, C_18 : 1 ω7c and/or C_18 : 1 ω6c). The sole isoprenoid quinone was Q-10. Oxidase activity was negative but catalase activity was positive. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminolipid, one unidentified glycolipid, and one unidentified lipid. Based on phylogenetic analysis of 16S rRNA gene sequences, strain A6E488^T showed the highest sequence similarity to Microbaculum marinum MCCC 1K03192^T (97.6 %). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain A6E488^T and M. marinum MCCC 1K03192^T did not exceed 78 and 22 %, respectively. These values are below the recommended thresholds of 95 % (ANI) and 70 % (dDDH) for prokaryotic species delineation. On the basis of gene annotation, it was observed that strain A6E488^T possesses the capability for thiosulphate oxidation, suggesting that this strain might be important in the sulphur cycle. Based on the results of phenotypic, genotypic, and chemical characterization, strain A6E488^T is considered to represent a novel species of the genus Microbaculum, for which the name Microbaculum marinisediminis sp. nov. is proposed. The type strain is A6E488^T (=KCTC 92197^T=MCCC 1H00516^T).