Colwellia agarivorans sp nov., an agar-digesting marine bacterium isolated from coastal seawater

A novel Gram-stain-negative, facultatively anaerobic, yellowish and agar-digesting marine bacterium, designated strain QM50(T), was isolated from coastal seawater in an aquaculture site near Qingdao, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate represented a member of the genus Colwellia and exhibited the highest sequence similarity (97.4 %) to Colwellia aestuarii SMK-10(T). Average nucleotide identity (ANI) values based on draft genome sequences between strain QM50(T) and C. aestuarii KCTC 12480(T) showed a relatedness of 72.0% (ANIb) and 85.1% (ANIm). Cells of strain QM50(T) were approximately 0.3-0.6 x 0.8-2.5 mu m in size and motile by means of a polar flagellum. Growth occurred in the presence of 1.0-6.0% (w/v) NaCl (optimum, 2.0-3.0 %), at pH 6.5-8.5 (optimum, pH 7.0) and at 4-37 degrees C (optimum, 28-30 degrees C). Strain QM50(T) was found to contain ubiquinone 8 (Q-8) as the predominant ubiquinone and summed feature 3 (C-16 : 1 omega 7c and/or iso-C-15 : 0 2-OH), C-16 : 0 and C-17 : 1 omega 8c as the main cellular fatty acids. Phosphatidylethanolamine and phosphatidylglycerol were found to be major polar lipids. The DNA G+ C content of strain QM50(T) was determined to be 35.7 mol%. On the basis of phylogenetic and phenotypic data, strain QM50(T) represents a novel species of the genus Colwellia, for which the name Colwellia agarivorans sp. nov. is proposed. The type strain is QM50(T) (= KCTC 52273(T) = MCCC 1H00143(T)).