Thermaurantimonas aggregans gen. nov., sp. nov., a moderately thermophilic heterotrophic aggregating bacterium isolated from microbial mats at a terrestrial hot spring

A moderately thermophilic and heterotrophic bacterial strain, LA(T), was isolated from microbial mats sampled at a hot spring in Nakabusa, Nagano, Japan. The cells of strain LA(T) were aerobic, Gram-stain-negative, non-sporulating, non-motile and rodshaped (2.0-4.1 mu m long). The formation of dense cell aggregates in liquid medium was a unique characteristic of the strain. Strain LA(T) grew optimally at 50 degrees C and at pH 7.5. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that the nearest neighbour of strain LA(T) was Schleiferia thermophila JCM 3019T with 94.1% sequence similarity. The draft genome sequence of strain LA(T) (2671880 bp) showed 18.0% digital DNA-DNA hybridization, 70.9% average nucleotide identity and 72.1 % average amino acid identity (AAI) values in comparison with the genome sequence of S. thermophila JCM 30197(T) (2606763 bp); the 165 rRNA gene sequence similarity and AAI values are lower than the cutoffs used for assignment to a separate genus. On the basis of phenotypic features, major cellular fatty acid composition, genome sequencing and phylogenetic position, a novel genus and species are proposed for strain LA(T), to be named Thermaurantimonas aggregans JCM 31826(T)=DSM 106522(T)).