Purification and Characterization of Poly(ethylene succinate) Hydrolase from the Mesophilic Fungus Aspergillus clavatus NKCM1003

Abstract

A poly(ethylene succinate) (PESu) hydrolase was purified from the culture supernatant of the PESu-degrading fungus Aspergillus clavatus NKCM 1003, which was cultivated on a mineral medium containing PESu as the sole carbon source. The enzyme had a molecular mass of 57,000 Da and an isoelectric point of 5.6, and it was stable in the rage pH5-8; the optimum pH was 7.0. Its PESu hydrolytic activity remained constant below 40 8C after incubation for 30 min. Liquid chromatography electrospray mass spectrometry analysis of enzymatic hydrolysates revealed that the major products are ES, ESE, SES, and ESES(S; succinate unit, E; ethylene glycol unit). This enzyme degraded not only PESu but also poly(3-hydroxybutyrate) (P(3HB)) and its copolymers. Further, it showed high binding affinity to P(3HB). It was concluded that PESu hydrolase belongs to the class of P(3HB) depolymerases.

Enzyme catalyzes ester bond synthesis and hydrolysis: The key step for sustainable usage of plastics

“…Studies found that the catalytic process of cutinase hydrolyzing PBS could be explained by endo-type mechanism, meanwhile, the cutinase hydrolyzed PBSA through the exo-type mode ( Rosato et al, 2022 ), which might be related to the hydrolysis preferentially occurring at the ester groups with much more methylene contents ( Bai et al, 2018 ). In addition, there were PES degrading enzymes in group 4 ( Figure 6A ), mainly PHB and PLA depolymerases, such as P(3HB) depolymerase from A. clavatus NKCM 1003 ( Ishii et al, 2007 ), and PHB depolymerase from A. fumigatus ( Jung et al, 2018 ). However, studies focused on PES degrading enzymes were rare and hardly any studies about the enzymatic degradation mechanism of PES was reported.…”