Ilyobacter insuetus sp. nov., a fermentative bacterium specialized in the degradation of hydroaromatic compounds

The mesophilic, anaerobic bacterium strain VenChi2T was isolated with quinic acid (1,3,4,5-tetrahydroxy-cyclohexane-1-carboxylic acid) as the sole source of carbon and energy. Of more than 30 substrates tested, only quinic acid and shikimic acid (3,4,5-trihydroxy-1-cyclohexene-1-carboxylic acid) were utilized, yielding acetate, propionate, butyrate, H2 and CO2 as fermentation products. Sugars, alcohols, (di-)carboxylic acids, amino acids and aromatic compounds were not fermented and no external electron acceptors were used. Strain VenChi2T is a gram-negative, strictly anaerobic, coccoid rod; it does not employ the classical hydroaromatic pathway of aerobic bacteria for the degradation of hydroaromatic compounds (no aromatic intermediates involved). Comparative 16S and 23S rDNA sequence analyses placed strain VenChi2T in the fusobacteria phylum, with the closest relatives among species of the genera Ilyobacter and Propionigenium. The results indicate that, disregarding the taxonomically misplaced Ilyobacter delafieldii, which is a member of the clostridia, the validly described Ilyobacter and Propionigenium species are phylogenetically intermixed. Based on its phenotypic properties, strain VenChi2T (= DSM 6831T = ATCC BAA-291T) is assigned to the genus Ilyobacter as the type strain of a novel species, Ilyobacter insuetus sp. nov.