the present invention relates to a process for producing biodegradable polymeric materials including polyhydroxyalkanoates by using the cell debris left from pha recovery and purification . the process comprises : cultivating pha - producing microbial cells in a medium solution containing an organic carbon source to form phas that are accumulated in the cells as inclusion bodies ; harvesting the cells from the spent medium and solubilizing the non - pha cell mass to obtain a pha solid and a cell debris solution ; separating the pha solid from the cell debris solution ; feeding the cell debris solution to the cultivation step . by reusing the cell debris generated from pha recovery , the invention avoids disposal of a large amount of aqueous waste . in addition , a remarkable increase of cell growth and pha synthesis is achieved , because the cell debris can be readily assimilated by the microbial cells as the nutrients .