Hydrolysis of polyesters by lipases

Abstract

INCREASING public concern about the treatment of waste materials has stimulated the study of the biodegradation of synthetic polymers. Among synthetic polymers, aliphatic polyesters are generally known to be susceptible to biological attack^1–5, but there are few reports of enzymes involved in their degradation. Bell et al.⁶ recently showed that the molecular weight of polycaprolactone (PCL) decreases on exposure to the acid protease from Rhizopus chinensis for 6–10 d (decreasing from 13,000 to 10,000). In addition, Tabushi et al.⁷ have found that polyesters composed of phenyllactic acid and lactic acid are hydrolysed by α-chymotrypsin. We showed previously that a polyester-degrading enzyme from Penicillium sp. strain 14-3, purified to a homogeneous state as exhibited by ultracentrifugal analysis and polyacrylamide gel electrophoresis, has properties resembling lipase⁸. It was not previously recognised that lipase acts on polyesters. We report here that several commercial lipases and an esterase also hydrolyse polyesters, and that Rh. delemar lipase is capable of hydrolysing various kinds of polyesters.