Cribrihabitans marinus gen. nov., sp. nov., isolated from a biological filter in a marine recirculating aquaculture system

Abstract

A Gram-negative bacterium, strain CZ-AM5T, was isolated from an aerated biological filter in a marine recirculating aquaculture system in Tianjin, China. Its taxonomic position was investigated by using a polyphasic approach. Cells of strain CZ-AM5T were non-spore-forming rods, 0.5–0.8 µm wide and 1.2–2.0 µm long, and motile by means of one or two polar or lateral flagella. Strain CZ-AM5T was strictly aerobic, heterotrophic, oxidase-negative and catalase-positive. Growth occurred at 15–40 °C (optimum, 30–35 °C), at pH 6.5–10.5 (optimum, pH 7.0–7.5) and in the presence of 0–12.0 % (w/v) NaCl (optimum, 4.0 %). The predominant fatty acid was C18 : 1ω7c (80.3 %). Ubiquinone 10 (Q-10) was the sole respiratory quinone. The polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, an unknown aminolipid, an unknown phospholipid and three unknown lipids. The DNA G+C content was 60.4 mol%. Strain CZ-AM5T showed the highest 16S rRNA gene sequence similarity (96.5 %) to Phaeobacter caeruleus LMG 24369T; it exhibited 16S rRNA gene sequence similarity of 95.0–96.5, 95.2–96.3, 96.2, 94.6–95.7 and 94.8–95.8 % to members of the genera Phaeobacter , Ruegeria , Citreimonas , Leisingera and Donghicola , respectively. However, phylogenetic trees based on 16S rRNA gene sequences showed that strain CZ-AM5T did not join any of the above genera, but formed a distinct lineage in the trees. On the basis of phenotypic, chemotaxonomic and phylogenetic analyses, strain CZ-AM5T is considered to represent a novel genus and species of the family Rhodobacteraceae , for which the name Cribrihabitans marinus gen. nov., sp. nov. is proposed. The type strain of Cribrihabitans marinus is CZ-AM5T ( = CGMCC 1.13219T = JCM 19401T).