Potential environmental impacts of bioplastic degradation in natural marine environments: A comprehensive review

The rapid increase in plastic waste has emerged as a major environmental challenge worldwide. Biodegradable plastics (BPs), once considered a promising solution, have raised significant concerns regarding their contribution to environmental pollution. Recent studies, particularly on their adverse effects in marine environments, underscore the need to reevaluate their viability as substitutes for petroleum-based plastics. However, a comprehensive understanding of the effects of BPs in the environment, especially at their microscale level, remains incomplete. This review examines the degradation of BPs by marine microorganisms, including bacteria, fungi, microalgae, archaea, and viruses, focusing on the enzymatic mechanisms driving their breakdown. It also explores the interactions of microplastics derived from BPs with toxic contaminants such as heavy metals, polyaromatic hydrocarbons, and persistent organic pollutants and their adsorption behavior. Moreover, the review highlights the potential role of biodegradable microplastics (BMPs) in spreading pathogens and antibiotic resistance genes. Key limitations of previous research are identified, emphasizing challenges in BP degradation and the role of surrounding pollutants in enhancing BMPs as vectors. Our comprehensive analysis identifies key limitations in current research, such as an overreliance on laboratory-scale experiments that fail to replicate in situ marine conditions. We also highlight significant gaps in understanding the long-term fate and ecological consequences of BP degradation products. To address these challenges, we recommend developing advanced simulation models, integrating multidisciplinary approaches, and establishing rigorous, standardized methodologies. These efforts are crucial for ensuring that implementing BPs does not compromise the integrity of marine ecosystems. Rigorous interdisciplinary research is key to protecting marine ecosystems and achieving sustainable plastic management.