Abstract Description

Plastic pollution poses a significant threat to ecosystems worldwide, with microplastics contaminating both terrestrial and marine environments. Alternative materials, such as bioplastics, are being produced and promoted to encourage more “sustainable” plastic production and consumption. Bioplastics are defined as biomass-based and/or biodegradable under appropriate conditions. The products of this biodegradation process generally do not have an ecotoxic effect, making this type of plastic more environmentally friendly than plastics derived from fossil fuels. However, the degradation of bioplastic waste may take several years and can be expedited with enzymes that break down the polymeric substrates. Recombinant microbial enzymes with optimised hydrolysing abilities have emerged as potential mediators in the management and recycling of various types of bioplastic waste. This study aims to improve the bioplastic-hydrolysing capabilities of a cutinase-like enzyme, CLE1, isolated from Cryptococcus sp. S-2, which has shown activity against various types of bioplastics. Protein engineering with a rational design approach will be used to introduce site-directed and site-saturated mutations in CLE1. The enzyme variants will be expressed in Saccharomyces cerevisiae and screened for activity against several bioplastic substrates to select suitable candidates for further study. Efficient bioplastic hydrolysis will be assessed using a variety of assays, including plate screening and turbidity-based activity assays, as well as hydrolysis trials and bioreactor runs. The results from these experiments will determine the most efficient CLE variant for each bioplastic substrate. This research will contribute to ongoing efforts to develop efficient enzyme-based bioplastic waste processes.