Novel screening assay for the detection of phenolic acid esterases

A novel plate assay method, developed for the screening of microorganisms or enzyme preparations for phenolic acid esterases, involves incorporating ethyl cinnamate into an agar medium. After inoculation and incubation, the plate is flooded with a pH-sensitive dye to reveal yellow zones around positive cultures against a blue background. A number of yeasts (Rhodotorula spp. and Candida spp.) and fungi (Penicillium sp. and Aspergillus sp.) gave positive results, while a number of commercial enzymes, particularly pectinases, also exhibited good phenolic acid esterase.