Enzymatic degradation of polybutylene succinate by recombinant cutinase cloned from Paraphoma chrysanthemicola.

Polybutylene succinate (PBS), a biodegradable plastic, can be used as an alternative to traditional plastics to effectively solve the growing plastic pollution. Although PBS is theoretically completely biodegradable, slow degradation remains a problem in practical applications, leading to the possibility of environmental pollution. In this study, after the PBS degradation ability of the fungus Paraphoma chrysanthemicola was determined, a P. chrysanthemicola cutinase (PCC) gene was cloned and expressed in Pichia pastoris and its PBS degradation ability was further characterized. With a molecular weight of approximately 20 kDa, PCC showed good PBS degradation activity at pH 6.0-8.0 and 20-40 °C. Metal ions have different effects on PCC activity. Specifically, Ca, Zn, and Co promoted enzyme activity, whereas Cu, Fe, and Ni inhibited enzyme activity. The weight loss of the PBS films was greater than 50% after 60 h of PCC treatment, and scanning electron microscopy revealed the appearance of cracks on the surface of the PBS films during the degradation process, which deepened with the progression of degradation time. This PBS degradation by PCC occurs via surface erosion, with the resulting degradation products being mainly 1,4-succinic acid and succinic acid butanediyl ester. This study provides a preliminary elucidation of the enzymatic mechanisms involved in PBS degradation by PCC and offers insights into the development of more effective biotechnological approaches to address the environmental challenges associated with plastic waste.