the invention is a large - scale production and purification of beta - poly , biodegradable natural polyester of l - malic acid of molecular weight 30 , 000 to 300 , 000 from plasmodia of the physarum family , especially physarum polycephalum . this will replace previous laborious and uncontrolled production by bioreactor methods of high productivity and quality , especially to obtain pure polymer of high molecular weight . the described 20 - liter bioreactor method can be scaled up for industrial purpose at optimal production and minimum growth time to prevent degradation the invention includes the method of isolation of polymalic acid of 100 , 000 mn from the culture broth optimized towards high yields of extremely pure polymalic acid . the non - hygroscopic , water and organic solvent - soluble polymer is endotoxin and agglutinin free and ready to use in chemical syntheses . because of its high molecular weight and purity it offers a wide spectrum of applications in pharmacy and medicine .