Abstract
A total of 78 strains, representing 21 Vibrio species, were examined by using taurocholate-tellurite-gelatin agar (TTGA) medium and modified TTGA medium containing 4-methylumbelliferyl-.beta.-D-galactoside (150 .mu.g/ml). Modified TTGA medium allowed for simple and direct detection of .beta.-D-galactosidase (.beta.-gal) activity. This feature, in conjunction with other differential characteristics of TTGA medium, gave improved differentiation of the vibrios tested. The modified TTGA medium allowed for easy differentiation of Vibrio cholerae (.beta.-gal+) from Vibrio parahaemolyticus (.beta.-gal-). The 4-methylumbelliferyl-.beta.-D-galactoside substrate is inexpensive and very stable. Incorporation into the agar did not affect the performance of TTGA as a differential medium. The assay for .beta.-gal activity with this substrate was specific and sensitive.