Direct detection of the hydantoinase activity on solid agar plates and electrophoretic acrylamide gels

A rapid and simple method to detect hydantoinase-producing microorganisms was developed using a selective agar plate containing 1% hydantoin and 0.005% Phenol Red in the typical Luria-Bertani medium. Conversion of hydantoin to hydantoic acid decreases the pH and the agar turns bright yellow. The method was used to isolate hydantoinase-producing E. coli transformants in the cloning of hydantoinase gene and screening of the hydantoinase-producing microorganisms from soils. Detection of hydantoinase activity after PAGE also used the same method.