Stakelama algicida sp. nov., novel algicidal species of the family Sphingomonadaceae isolated from seawater

We conducted a taxonomic study of two algicidal bacteria, designated strains Yeonmyeong 1-13 T and Yeonmyeong 1-11, isolated from seawater off Geoje Island in the South Sea, Republic of Korea. The two novel strains were yellow-pigmented, halotolerant, Gram-stain-negative, strictly aerobic, non-spore-forming, rod-shaped bacteria. Both strains were able to grow at 5-39 °C, pH 5.0-10.0 and 0-11 % (w/v) NaCl concentration. Based on the 16S rRNA gene sequence analysis, strains Yeonmyeong 1-13 T and Yeonmyeong 1-11 belonged to the genus Stakelama and are closely related to Stakelama pacifica JLT832 T (98.37% and 98.22 % sequence similarity, respectively). The pairwise sequence similarity between strains Yeonmyeong 1-13 T and Yeonmyeong 1-11 was observed to be 99.50 %. In both strains, the only respiratory quinone was ubiquinone-10; the major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and sphingoglycolipid; the major fatty acids were C18 : 1ω7c, C16 : 0 and C14 : 0 2-OH. DNA G+C content values of strains Yeonmyeong 1-13 T and Yeonmyeong 1-11 were 65.1% and 64.9 mol%, respectively. The DNA-DNA relatedness between Yeonmyeong 1-13 T and S. pacifica DSM 25059 T was 28.7 %, which falls below the threshold value of 70 % for the strain to be considered as novel. The morphological, physiological, chemotaxonomic and phylogenetic analyses clearly distinguished strain Yeonmyeong 1-13 T from its closest phylogenetic neighbours. Thus, strains Yeonmyeong 1-13 T and Yeonmyeong 1-11 represent a novel species of the genus Stakelama, for which the name Stakelama algicida sp. nov. is proposed. The type strain is Yeonmyeong 1-13 T (=KEMB 9005-324 T =JCM 31498 T ).