The programmed sequence-based oxygenase screening for polypropylene degradation

Abstract

Enzymatic degradation of plastic is an effective means of plastic recycling and pollution control. However, the strong chemical inertness of polypropylene plastic (PP) severely impedes its oxidative cleavage, making it resistant to degradation. In this study, based on sequence screening of Hidden Markov Model (HMM), a dioxygenase (HIS1) was identified and characterized to be effective in PP oxidation. Various kinds of PP products, including plastic films, microplastics, and disposable water cups or bags, were HIS1-degraded with cracks and holes on the surface. The hydrophobic binding was the primary force driving oxidative degradation in the specific cavity of HIS1. The discovery of HIS1 achieved a zero breakthrough in PP biodegradation, providing a promising candidate for the selection and evolution of degrading enzymes.

Environmental Implication

Among plastic waste pollutants, PP plastic waste is ecologically notable for its extensive production and remarkable resistance to degradation. Although enzyme-mediated biodegradation offers promise for developing environmentally benign technologies for plastic waste remediation, the scarcity of enzymes capable of catalyzing C-C bond cleavage poses a technical challenge to the degradative process of PP plastics. Here, we found a bioenzyme HIS1 with the ability to degrade PP, which can be used for green recycling of PP plastic products. Our study provides a promising candidate for the selection and evolution of PP-degrading enzymes.