Alteromonas gracilis sp. nov., a marine polysaccharide-producing bacterium

Abstract

A novel exopolysaccharide-producing bacterium, designated strain 9a2T, was isolated from Pacific Ocean sediment. The strain was Gram-stain-negative, motile, strictly aerobic, oxidase- and catalase-positive, and required NaCl for growth. Its major isoprenoid quinone was ubiquinone-8 (Q-8), and its cellular fatty acid profile consisted mainly of C16 : 1ω7c, C18 : 1ω9c and C16 : 0. The DNA G+C content was 46.6 mol%. 16S rRNA gene sequence analysis suggested that strain 9a2T is a member of the genus Alteromonas . Strain 9a2T exhibited closest phylogenetic affinity to Alteromonas macleodii NBRC 102226T (99.3 % 16S rRNA gene sequence similarity), A. marina SW-47T (99.3 %), A. litorea TF-22T (99.0 %), A. australica H17T (98.7 %), A. simiduii BCRC 17572T (98.5 %), A. stellipolaris LMG 21861T (98.3 %) and A. hispanica F-32T (98.2 %). The DNA–DNA reassociation values between strain 9a2T and A. macleodii JCM 20772T, A. marina JCM 11804T, A. litorea JCM 12188T, A. australica CIP 109921T, A. simiduii JCM 13896T, A. stellipolaris LMG 21861T and A. hispanica LMG 22958T were below 70 %. Strain 9a2T contained phosphatidylethanolamine, phosphatidylglycerol and an unidentified polar lipid. Owing to differences in phenotypic and chemotaxonomic characteristics, phylogenetic analysis based on 16S rRNA gene sequences and DNA–DNA relatedness data, the isolate merits classification as representing a novel species, for which the name Alteromonas gracilis sp. nov. is proposed. The type strain of this species is 9a2T ( = JCM 30236T = NCIMB 14947T).