Abstract Description

Plastics have been manufactured in high volumes since the 1950s, with global production exceeding 359 million tons annually. Plastics, particularly those derived from polyethylene terephthalate (PET), have become a pervasive hazard to the delicate balance of marine ecosystems, thus encouraging extensive research. To date, chemical and thermal degradation have been common methods used to degrade plastic waste despite their high cost and low efficiency. Microorganisms have comparably provided a cost-effective and environmentally friendly approach to plastic degradation. Bacterial taxonomic groups, such as Ideonella sakaiensis and Alcaivorax borkumensis, have been shown to possess genes that degrade plastics. Although current knowledge suggests that PET has a slow degradation rate, there are limited studies that cover the functional genes and metabolic pathways involved in PET degradation by marine microorganisms. This study aims to assess the genetic basis of marine microorganisms and their potential to degrade microplastics in plastic-polluted marine environments along the South African coastline. This study is particularly important in unravelling the potential of the plastisphere as an effective solution to mitigate plastic pollution. The degrading potential of the key genes will be predicted using metagenomics and bioinformatics. Candidate gene products will thereafter be cloned, expressed and purified for biochemical characterisation. The enzymatic activity of each candidate gene will be assessed against PET microplastics under controlled laboratory conditions, using assays that quantify microplastic degradation, such as weight loss and particle size decrease of the microplastics, and chromatographic analysis of degradation products. The genetic basis of the plastisphere and its association with microplastics will inform the development of innovative strategies that will help reduce the burden of microplastic pollution in the environment. Moreover, this research has the potential to make a notable contribution to global efforts, particularly towards SDG’s 13, 14, and 15, which seek to combat climate change and improve life below water and on land.