Aquibacter zeaxanthinifaciens gen. nov., sp. nov., a zeaxanthin-producing bacterium of the family Flavobacteriaceae isolated from surface seawater, and emended descriptions of the genera Aestuariibaculum and Gaetbulibacter

摘要

A Gram-stain-negative, strictly aerobic, rod-shaped, non-flagellated, non-spore-forming and gliding marine bacterium, designated strain CC-AMZ-304T, was isolated from coastal surface seawater near Taichung harbour, Taiwan. Strain CC-AMZ-304T predominantly synthesized zeaxanthin and thus formed yellow colonies on marine agar. The novel strain showed an unstable phylogenetic position, although sharing high pairwise 16S rRNA gene sequence similarities of 95.9–94.9, 95.7 and 95.1–93.9 % with Gaetbulibacter species (n = 4), Aestuariibaculum suncheonense SC17T and Bizionia species (n = 7), respectively. The polar lipid profile of strain CC-AMZ-304T consisted of phosphatidylethanolamine, five unidentified lipids, one unidentified phospholipid, two unidentified aminolipids and one unidentified glycolipid. The major (>5 % of the total) fatty acids were iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH, iso-C15 : 0 3-OH and C15 : 1ω5c. The DNA G+C content was 36.0 mol%. Menaquinone-6 (MK-6) was the sole respiratory quinone and the major polyamine was triamine sym-homospermidine. Phylogenetic distinctiveness, unique polar lipid composition, presence of significant amounts of branched hydroxyl fatty acids (iso-C17 : 0 3-OH and iso-C15 : 0 3-OH) and a low amount of anteiso-C15 : 0, and several additional distinguishing biochemical features clearly discriminated strain CC-AMZ-304T from the type species of the genera Aestuariibaculum and Gaetbulibacter. Thus, based on data from the present polyphasic study, strain CC-AMZ-304T is considered to represent a novel species of a new genus within the family Flavobacteriaceae, for which the name Aquibacter zeaxanthinifaciens gen. nov., sp. nov. is proposed; the type strain of Aquibacter zeaxanthinifaciens is CC-AMZ-304T ( = JCM 18557T = BCRC 80463T). Emended descriptions of the genera Aestuariibaculum and Gaetbulibacter are also proposed.