Oricola cellulosilytica gen. nov., sp. nov., a cellulose-degrading bacterium of the family Phyllobacteriaceae isolated from surface seashore water, and emended descriptions of Mesorhizobium loti and Phyllobacterium myrsinacearum

Abstract

A Gram-stain negative, strictly aerobic, rod-shaped, non-spore-forming, motile cellulolytic bacterium, designated strain CC-AMH-0(T), was isolated from surface seashore water of Hualien, Taiwan and subjected to polyphasic taxonomy. Strain CC-AMH-0(T) exhibited enzymatic saccharification of cellulose and active growth particularly during log-phase under nutrient-limited conditions, whereas enhanced saccharification was found in the declining growth phase under copiotrophic conditions. The novel strain shared high pairwise 16S rRNA gene sequence similarities to Mesorhizobium loti USDA 3471(T) (96.2 %), Phyllobacterium myrsinacearum IAM 13584(T) (95.9 %), Hoeflea marina LMG 128(T) (94.0 %) and other Phyllobacteriaceae members. However, phylogenetic analyses based on 16S rRNA, atpD and recA gene sequences clearly distinguished strain CC-AMH-0(T) from other representatives of related genera. In addition, strain CC-AMH-0(T) was distinguished from the above mentioned species by significantly lacking phosphatidylcholine besides accommodating major amounts of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmonomethylethanolamine and sulfoquinovosyldiacylglycerol; moderate amounts of phosphatidylethanolamine and trace amounts of an unidentified phospholipid, an unidentified aminolipid and an unidentified phosphoglycolipid. Strain CC-AMH-0(T) possessed C18:1 ω7c and/or C18:1 ω6c (summed feature 8) as predominant fatty acids, 63.3 mol% DNA G+C content and ubiquinone-10 (Q-10) as the sole respiratory quinone. On the basis of polyphasic taxonomic evidences, strain CC-AMH-0(T) is proposed to represent a novel genus and species of the family Phyllobacteriaceae, for which the name Oricola cellulosilytica gen. nov., sp. nov. is proposed. The type strain of the type species is CC-AMH-0(T) (=JCM 19534(T) =BCRC 80694(T)). Emended descriptions of M. loti and P. myrsinacearum are also proposed