Differential agars medium for separating streptococcus lactis and streptococcus on the basis of butyrate esterase activity

Abstract From the Canadian patent

The characteristic ability of Streptococcus faecalis and inability of Streptococcus lactis to produce the butyrate esterase formed the basis for the development of a differential agar medium to separate these species in pure and mixed cultures. The differential agar medium contained 0.5% bacto-peptone, 0.3% bacto-yeast extract 1.0% 2-naphthyl, butyrate or 1.0% indoxyl butyrate 1.5% agar and the remaining 96.7% water (pH 6.5). S. faecalis colonies grown on naphthyl butyrate agar (24 h; 30°C) produced an intense violet color on immediately after the addition of detector reagents, while S. lactis did not. A solid medium with indoxyl butyrate as indicator was found suitable for both qualitative …