Genetic engineering approach to address microplastic environmental pollution: a review

Polymeric materials have desirable chemical and physical properties, leading to a wide range of applications in consumer industries. However, such properties, which include high hydrophobicity, crystallinity, strong chemical bonds and high molecular weight, inhibit natural biodegradation of plastics by wild-type microbes. This has led to the accumulation of microplastics and nanoplastics in the environment, which is projected to be 12 000 million metric t by the year 2050. Such accumulation bears serious health side effects on both terrestrial and marine ecosystems. Current methods used to control microplastics in the environment have proved inadequate due to high plastic production and extensive uses. Biological methods of controlling plastic pollution, which involve enzymes from various microbes, have emerged as an efficient, eco-friendly and sustainable alternative to plastic treatment and recycling. However, naturally occurring plastic-biodegrading enzymes possess limited biodegradation capacity due to low thermostability and biocatalytic activities, thus limiting large-scale applications. This review focuses on leveraged protein enzyme genetic engineering techniques intended to improve the catalytic performance of putative plastic-biodegrading enzymes and production of environmentally friendly bioplastics from natural fibres as a substitute for synthetic petroleum-based plastics. Genetically modified plastic-degrading enzymes possess boosted substrate interaction, increased hydrophobicity, better catalytic efficiency, increased thermostability and optimised plastic biodegradability.