الفهرس 
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Abstract
Three bacterial strains capable of degrading PHA were isolated, purified and identified as E.corrodens , K, pneumoniae and , A. faecalis . They released PHA depolymerases in the culture media during their active growth phases. The supernatant of the three studied isolates showed depotymerase, est erase, prolease and lipase activities. Wild type depolyincrase enzymes function maximally at 35, 40 and 45°C respectively. They were found to be stable to 45-50 C. and showed a relatively broad pH activity ranging from 6-10 but each one has a different optimum pH (6.5, 7 and 8 respectively).
The depolymerases were purified using DEAE-anion exchange HPLC. The pure depolymerases were highly specific to PH A and showed no PCL degrading activity. The three enzymes showed similarity with respect to the molecular weights ( 45.000-50.000) Daltons as determined by SDS – gel electrophoresis sensitivity to detergents , chaopotropic agents