Abstract
Strain GolChi1(T), a mesophilic, anaerobic bacterium, 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 the hydroaromatic compounds quinic acid and shikimic acid (3,4,5-trihydroxy-1-cyclohexene-1-carboxylic acid) were utilized, yielding acetate and propionate as the only fermentation products. Sugars, alcohols, (di-)carboxylic acids, amino acids and aromatic compounds were not fermented and no external electron acceptors were used. Strain GolChi1(T) is a Gram-negative, rod-shaped, aerotolerant anaerobe that possesses superoxide dismutase; it does not employ the classical hydroaromatic pathway of aerobic bacteria for the degradation of hydroaromatic compounds (no aromatic intermediates involved). 16S-rRNA-based phylogenetic analyses revealed a common origin of this isolate and Rhodocyclus, Propionibacter and Propionivibrio species. High sequence similarity (>96%) and phenotypic traits indicated a closer relationship between strain GolChi1(T) and the type species of the monospecific genera Propionivibrio and Propionibacter but, due to its phenotypic properties, strain GolChi1(T) could not be assigned conclusively to either of these taxa. We propose (i) the amended description of the genus Propionivibrio, (ii) the reclassification of Propionibacter pelophilus Meijer et al. 1999 as Propionivibrio pelophilus comb. nov. and (iii) designation of Propionivibrio limicola sp. nov., with the type strain GolChi1(T) (=DSM 6832(T)=ATCC BAA-290(T)).