Aristaeella hokkaidonensis gen. nov. sp. nov. and Aristaeella lactis sp. nov., two rumen bacterial species of a novel proposed family, Aristaeellaceae fam. nov.
Sam C. Mahoney-Kurpe, Nikola Palevich, Samantha Joan Noel, Dragana Gagić, Patrick J. Biggs, Priya Soni, Peter M. Reid, Satoshi Koike, Yasuo Kobayashi, Peter H. Janssen, Graeme T. Attwood, Christina D. Moon
Abstract
Two strains of Gram-negative, anaerobic, rod-shaped bacteria, from an abundant but uncharacterized rumen bacterial group of the order ‘ Christensenellales’ , were phylogenetically and phenotypically characterized. These strains, designated R-7 T and WTE2008 T , shared 98.6–99.0 % sequence identity between their 16S rRNA gene sequences. R-7 T and WTE2008 T clustered together on a distinct branch from other Christensenellaceae strains and had <88.1 % sequence identity to the closest type-strain sequence from Luoshenia tenuis NSJ-44 T . The genome sequences of R-7 T and WTE2008 T had 83.6 % average nucleotide identity to each other, and taxonomic assignment using the Genome Taxonomy Database indicates these are separate species within a novel family of the order ‘ Christensenellales ’. Cells of R-7 T and WTE2008 T lacked any obvious appendages and their cell wall ultra-structures were characteristic of Gram-negative bacteria. The five most abundant cellular fatty acids of both strains were C 16 : 0 , C 16 : 0 iso, C 17 : 0 anteiso, C 18 : 0 and C 15 : 0 anteiso. The strains used a wide range of the 23 soluble carbon sources tested, and grew best on cellobiose, but not on sugar-alcohols. Xylan and pectin were fermented by both strains, but not cellulose. Acetate, hydrogen, ethanol and lactate were the major fermentation end products. R-7 T produced considerably more hydrogen than WTE2008 T , which produced more lactate. Based on these analyses, Aristaeellaceae fam. nov. and Aristaeella gen. nov., with type species Aristaeella hokkaidonensis sp. nov., are proposed. Strains R-7 T (=DSM 112795 T =JCM 34733 T ) and WTE2008 T (=DSM 112788 T =JCM 34734 T ) are the proposed type strains for Aristaeella hokkaidonensis sp. nov. and Aristaeella lactis sp. nov., respectively.