Marinicellulosiphila megalodicopiae gen. nov., sp. nov., a deep-sea alkaliphilic cellulolytic bacterium isolated from an endemic ascidian Megalodicopia hians.

Abstract

The strain TOYAMA8^T is a deep-sea alkaliphilic cellulolytic bacterium isolated from a slurry-adhered epiphytic site of Megalodicopia hians. Cells of this strain are Gram-negative, aerobic, curved rods or spirilla, motile with monopolar flagella, and grow on cellulose as the sole carbon source. Compared to other closely related species, this bacterium is characterized by a large number of cellulase genes. Strain TOYAMA8^T showed alkaliphilic growth within the pH range 7.5-9.0. The major cellular fatty acids were C_18 : 1 ω7, C_14 : 0, C_16 : 0 and C_16 : 1 ω7. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, unidentified phospholipids and aminolipids. A major respiratory lipoquinone was Q-9. Phylogenomic analysis using the 16S rRNA gene and whole-genome sequence data showed that the strain is related to the families Gynuellaceae, Saccharospirillaceae and Natronospirillaceae. The values of 16S rRNA gene sequence similarity, amino acid identity and percentage of conserved proteins between the strain TOYAMA8^T and related species were low, with maximum values of 90.6, 48.1 and 34.6%, respectively. These results, together with differences in phenotypic and biochemical characteristics, indicate that the new isolate TOYAMA8^T represents a novel genus and species, for which the name Marinicellulosiphila megalodicopiae gen. nov., sp. nov., is proposed. The type strain is TOYAMA8^T (JCM 31119^T=DSM 114864^T).