A rapid method for differentiation of dairy lactic acid bacteria by enzyme systems

Abstract

A rapid and simple technique utilizing the APIZYM enzymatic patterns complemented with arginine dihydrolase and citratase was developed for species differentiation of 40 lactic acid bacteria relevant to the dairy industry. Streptococcus species in general produced no/?-galactosidase, except for Streptococcus thermophilus. Lactobacillus species showed strong aminopeptidases and galactosidases but contained no arginine dihydrolase and citratase. Among the group N-streptococci, Streptococcus diacetylactis produced citratase, whereas Streptococcus cremoris differed by the production of butyrate esterase. Streptococcus faecalis was readily distinguishable from Streptococcus lactis by butyrate esterase activity that was the basis of the differential agar developed. Heterofermentative lactobacilli differed from homofermentative lactobacilli in possessing arginine dihydrolase and citratase but by not producing leucine-aminopeptidase.