Degradation of aliphatic polyester films by commercially available lipases with special reference to rapid and complete degradation of poly(L-lactide) film by lipase PL derived from Alcaligenes sp

Commercial lipases were examined for their degradation efficiency of aliphatic polyester films. In 100 days immersion of polyester films in lipase solutions at37 °C at pH 7.0,Lipase Asahi derived from Chromobacterium viscosum degraded polybutylene succinate-co-adipate (PBSA), poly (-caprolactone) (PCL) and polybutylene succinate (PBS), and Lipase F derived from Rhizopus niveus degraded PBSA and PCL during 4–17 days. Lipase F-AP15 derived fromRhizopus orizae could degrade PBSA in 22 days. In these cases, PBS and PBSA were mainly degraded to dimers, whereas PCL was mainly degraded to monomers. Only poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHB/V) and poly (L-lactide) (PLA) were not degraded in the experiments. However, PLA degraded completely at 55 °C, pH 8.5 with Lipase PL during 20 days. This result could be explained with the sequential reactions of the chemical hydrolysis of the polymer to oligomers at higher pH and temperature, and the succeeding enzymatic hydrolysis of oligomers to the monomers.