Genomic Identification and Characterization of Microplastic Degrading Enzymes from Different Ascomycetes

Abstract

Microplastics (MPs) have significantly increased in natural habitats as a result of the extensive use and mismanagement of plastic items. MPs are persistent in nature and therefore are to degradation. However, some microorganisms have the ability to enzymatically breakdown them. This study focuses on the in-silico identification, characterization, and molecular docking analysis of different lipases and polygalacturonases found in various fungal species, specifically aiming to assess their potential for microplastic degradation. A total of 71 lipases and 96 polygalacturonases were identified from 13 and 10 fungal species respectively, on the basis of presence of the lipase 3 and glycoside hydrolase 28 domain. Most of the proteins were predicted to be extracellularly localized. Based on the results of molecular dockings, in terms of binding affinities, all the proteins were found to have high binding affinity towards PC, which suggests that it is the most biodegradable plastic type. However, PVC exhibited low binding energies with both lipases and polygalacturonases, indicating its resistance against degradation via fungal enzymes. Key amino acids primarily involved in binding interactions of polycarbonate (PC) were found to be alanine, glycine, and valine. The binding interactions encompass hydrogen bonding, van der Waals forces and Pi interactions. These findings highlighted the potential of enzymes sourced from fungal species for microplastic degradation purposes. Furthermore, the results of the in vitro experiment revealed that A. flavus exhibited limited growth on PVC, and lipase production remained minimal. Additionally, no discernible change in weight was observed in the PVC film after incubation with A. flavus.