f Ahrensia marina sp. nov., a dimethylsulfoniopropionate-cleaving bacterium isolated from seawater, and emended descriptions of the genus Ahrensia and Ahrensia kielensis

A Gram-stain-negative, strictly aerobic, light-beige, rod-shaped, motile bacterium with peritrichous flagella that cleaves dimethylsulfoniopropionate (DMSP), designated strain LZD062T, was isolated from bottom seawater of the East China Sea. The isolate required sea salts for growth and grew optimally at pH 8.0 and 28 °C and in the presence of 2 % (w/v) NaCl. The major fatty acid (>10 %) was summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and the major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, one unidentified aminolipid and one unidentified glycolipid. Ubiquinone Q-10 was the only quinone detected. Phylogenetic analyses based on 16S rRNA and atpD gene sequences placed LZD062T within the genus Ahrensia of the family Phyllobacteriaceae in the class Alphaproteobacteria. The most closely related type strain was, in both cases, Ahrensia kielensis JCM 20689T ( = IAM 12618T = DSM 5890T), which gave sequence similarities of 97.7 % in the 16S rRNA gene and 90.4 % in the atpD gene. Genome relatedness between strain LZD062T and A. kielensis JCM 20689T was computed using both genome-to-genome distance analysis and average nucleotide identity, giving values of 22.10 ± 2.35 and 79.55 %, respectively. The genomic DNA G+C content calculated from the genome sequence was 50.1 mol%. On the basis of our polyphasic analyses, strain LZD062T is considered to represent a novel species of the genus Ahrensia, for which the name Ahrensia marina sp. nov. is proposed. The type strain is LZD062T ( = MCCC 1K00254T = JCM 30117T = DSM 28886T). Emended descriptions of the genus Ahrensia and Ahrensia kielensis are also proposed.