Microbial Degradation of Aliphatic Copolyesters of L-Lactide

Copolyesters of L-lactide (LA) were synthesized from LA and caprolactone (CL) or 4-t-butylcaprolactone (48CL). Their biodegradability against a thermophile capable of degrading poly (L-lactide) was investigated. The strain grew in a medium containing copolyesters, accompanied by decreases in their residual weight and molecular weight and an increase in their enthalpies of fusion, which showed the progress of their biodegradation. The copolymer including 4BCL was suggested to be superior in biodegradability to that of copolymer including CL, contrary to the former's inertia to such an enzyme as proteinase K.