It is generally known that among the synthetic polymers, aliphatic polyesters are susceptible to biological attack. Polycaprolactone (PCL) with Mn 25, 000 are completely degraded by Penicillium sp. strain 26-1. It is found that aliphatic polyesters are hydrolyzed by several lipases andhog liver esterase. Melting point (Tm) of aliphatic polyesters has an effect on their degradabilities by lipase. Recently, the eyes of the world are focused on aliphatic polyesters as a biodegradable synthetic plastics. Various kinds of biodegradable plastics containing ester bonds have been developing. Ester type polyurethanes, copolyesters of aliphatic and aromatic polyesters, copoly amide-esters and copolymers composed of 2-methylene-1, 3, 6-trioxocane and styrene or vinyl acetate were hydrolyzed by lipase. The biodegradability can be effectively provided to conven tional plastics/PCL blends by conducting the design of mix combining the composition and melt viscosity ratio of the blends. Furthermore, the ecological roles of lipase are discussed.
