Physiology of a pentose-utilizing thermophilic Lactobacillus

Abstract During a taxonomic study of Lactobacillus acidophilus , a number of isolates from pig faeces were found not to conform in all respects to the definition of typical thermophilic lactobacilli. Although these isolates had an optimum growth temperature of between 40 and 43°C, they were able to ferment one or more pentoses.
A detailed fermentation product analysis of one of these typical dl -lactate-forming strains showed that 0.8 mol of acetate and 0.82 mol of lactate were formed from 1 mol of ribose. The G + C content (Tm) of the same organism was shown to be 42.6 mol%, and its cell walls contained no meso-diaminopimelic acid ( m -A₂pm). The implications of these findings on the taxonomy of the genus Lactobacillus are discussed.