Screening of environmental specimens was performed in order to isolate polyhydroxy - butyrate / valerate degrading bacteria. Basal mineral salts medium supplemented with the polymer was used as enrichment medium. Isolates capable of degrading the polymer and hence clearing the opacity of the polymer containing solid medium were selected. The isolates capable of degrading the polyme were obtained and characterized a Ekinella corrodenes , Alcaligenes faecalis and Klebsiella pneumoniae. The three  isolates were found to show extracellular polyhydroxy alkanoate ( PHA) depolymerase activity. Crude enzyme preparations were used to study the characteristics of these enzymes. The optimum temperatures and pHs for activity, substrate specificity, effect of dialysis , divalent cations, various inhibitors and detergents on depolymeterase and esterase activities were studied for the three isolates. The effect of cultural and nutritional conditions on enzymes production were studied for E. corrodenes .