Biodegradation of polybutylene succinate by an extracellular esterase from Pseudomonas mendocina

An extracellular esterase (HP) with polybutylene succinate (PBS)-degrading ability was identified from Pseudomonas mendocina SA-1503. The HP also had the ability to degrade poly(3-hydroxybutyrate-co-4hydroxybutyrate) and polycaprolactone. This HP had optimal activity at pH 9.0 and 40 degrees C and remained stable at pH 8.0-9.0 and temperatures of 30-40 degrees C. Mn2+ promoted the enzyme activity. HP could hydrolyze all pNP fatty acid ester substrates containing even numbers of carbon atoms from C2 to C18 and had the highest catalytic activity for the p-NP C6 substrate. After 60 h of HP-catalyzed degradation, PBS films experienced a weight loss of more than 60%. Butanedioic acid, 1,4-butanediol, and a series of oligomers were detected in the degradation products of PBS by HP. Further structural analysis of HP revealed that it could be classified as a microbial esterase of alpha/beta hydrolase superfamily and contained a conserved catalytic triad structure (Ser-148, Asp-198, and His-228) with a relatively exposed active site.