A Review of Microalgae as Catalysts for Plastic Degradation in Marine Environments

Plastic pollution poses a significant threat to aquatic ecosystems due to the material's longevity and its common use. This review covers the sources, types, and environmental impacts of plastic debris, with a focus on biodegradation processes in aquatic environments. Worldwide plastic production was driven by the material's adaptability and low cost. Common plastic types include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). Plastic degradation occurs through physio-chemical and biological series. Physio-chemical degradation is usually initiated by UV radiation, heat, or hydrolysis, and biodegradation involves microbial enzymatic process. Key enzymes identified in plastic biodegradation include cutinase, lipase, PETase, lignase and Peroxidase. The initial steps involve biofilm formation on plastic surfaces that can facilitate degradation, with diatoms being early colonizers along with bacteria. Multiple factors affect biodegradation, including polymer characteristics, environmental conditions, and microbial community composition. Various analytical techniques are used to assess plastic degradation, such as mass loss measurements, gel permeation chromatography, spectroscopic methods, and microscopy. The persistence of plastics in marine environments, coupled with their potential to release harmful additives and adsorbing pollutants, represent an ongoing challenge. Understanding degradation mechanisms is important for developing effective mitigation strategies and biodegradable alternatives. Further research is needed to understand the complex interactions between plastics, microalgae, and marine ecosystems, as well as to enhance biodegradation processes for more sustainable materials management.