Multi-omics insights into the response of Aspergillus parasiticus to long-chain alkanes in relation to polyethylene degradation

Abstract

Plastic pollution presents a global challenge, with polyethylene (PE) being among the most persistent plastics due to its durability and environmental resilience. In this study, we employed a multi-omics approach to study the ability of Aspergillus parasiticus MM36, an isolate derived from Tenebrio molitor intestines, to metabolize long-chain alkanes (lcAlk) and secrete enzymes able to modify PE. The fungus was grown with hexadecane (C16) or a mixture of lcAlk (C24 to C36) as carbon sources and culture supernatants were tested daily for their ability to modify PE. Proteomic analysis identified induced oxidases potentially involved in lcAlk and PE functionalization. Key enzymes include multicopper oxidases, peroxidases, an unspecific peroxygenase and FAD-dependent monooxygenases. Surfactant proteins facilitating enzymatic and cellular interaction with hydrophobic PE and lcAlk, such as one hydrophobin, three hydrophobic surface-binding proteins (HsbA) and one cerato platanin, were present in all secretomes. Transcriptomic analysis comparing lcAlk to C16 cultures highlighted the enrichment of oxidoreductase activities and carboxylic acid metabolism in both lcAlk incubation days, with transmembrane transporters and transferases predominating on day 2 and biosynthetic processes on day 3. In C16 cultures, hydrolytic enzymes, including esterases, were upregulated alongside Baeyer-Villiger monooxygenases, suggesting a shift toward sub-terminal hydroxylation. Integrating transcriptomic and secretomic data, we propose a mechanism for lcAlk assimilation by A. parasiticus MM36, involving extracellular oxyfunctionalization, hydrocarbon uptake via surface-modifying proteins and channeling through membrane transporters for energy consumption and biosynthetic processes. This study provides insights into fungal mechanisms for alkane metabolism and highlights their relevance to plastic degradation. ImportancePlastic pollution presents a global challenge to marine life and human health, with polyethylene (PE) being among the most persistent plastics due to its durability and environmental resilience. Hydroxylation is regarded as the initial step of PE degradation, similar to alkane oxidation, making alkane-degrading microbes a promising source of plastic degraders. In this study, we used a multi-omics approach to investigate the ability of Aspergillus parasiticus MM36 to metabolize long-chain alkanes and secrete enzymes that modify PE. Proteomic analysis of the secretomes identified key oxidases and biosurfactants that enable the fungus to interact with and transform hydrophobic substrates like PE. Transcriptomic analysis further revealed biological processes involved in alkane assimilation and metabolism. By integrating these insights, we propose a mechanism for fungal alkane metabolism and highlight its relevance to plastic biodegradation. This work advances our understanding of fungal contributions to addressing hydrocarbon and plastic pollution.