A marine fungus Alternaria alternata FB1 degrades polypropylene

Polypropylene (PP), a widely used plastic, is difficult to recycle, creating environmental challenges. Despite some microorganisms having been reported to degrade PP, their capabilities are limited and generally require pretreatment. In this study, we report a marine fungus, Alternaria alternata FB1, that degrades untreated pure PP. Integrated assays demonstrated the formation of hydroxyl and carbonyl functional groups, a 90 % reduction in crystallization peak height, and a 65 % decrease in weight-average molecular weight following fungal degradation. (E)-octadec-9-ene and nonadec-1-ene were identified as the main degradation products of PP by strain FB1. Transcriptomic analysis identified several potential PP-degrading enzymes, including a Baeyer-Villiger monooxygenase and a KatG catalase-peroxidase, whose activities were confirmed through in vitro assays. By combining gene knockout experiments to verify the functions of key degradation enzymes in vivo and transcriptomic analyses to predict the metabolic pathway of degradation products in strain FB1, we propose a comprehensive pathway for fungal degradation and utilization of PP for the first time. Our study offers significant potential for future research and industrial biodegradation applications.