Microplastic-Microorganism Interaction in Marine Ecosystems

Plastic waste represents one of the most significant environmental challenges facing the world today, with microplastics emerging as a focal point for researchers over the past few decades. Pollution from microplastics is accumulating in aquatic ecosystems at an unprecedented scale, serving as new surfaces for biofilm formation and gene exchange. Recent studies have highlighted the negative impacts of microplastics on marine life. The effects of microplastics on sea creatures primarily occur through the direct ingestion of plastic particles, leading to internal damage. Additionally, these pollutants adversely affect the distribution of certain marine species that utilize these materials as sites for laying eggs. Consequently, the presence of microplastics in seawater-especially given the high consumption of seafood (fish and shellfish) in some countries-raises concerns regarding their potential impact on human health. Many researchers emphasize that one of the most critical effects of microplastics in marine environments is their ability to absorb chemical pollutants. Beyond merely transporting these contaminants, microplastics also enhance the environmental stability of these substances. Microplastics provide an extensive and suitable substrate for microbial accumulation in aquatic ecosystems. The formation of microplastic-microorganism complexes, such as biofilms, facilitates the degradation of organic matter and horizontal gene transfer. In this context, microplastics influence the structure and function of microbial communities, revealing both physical and chemical effects that pose challenges for microbiology, ecology, and ecotoxicology. The dispersion of microplastics is diverse, encompassing associated microorganisms and genetic elements, including antibiotic resistance genes, pathogenicity islands, and metabolic pathways. Functional changes within aquatic microbiomes can alter carbon metabolism and food webs, leading to unknown consequences for both organisms and human microbiomes-and, consequently, human health. The spread of antibiotic resistance through microplastics poses a significant risk for the evolution of aquatic bacteria and represents an often-overlooked threat to human health. Studies indicate that horizontal gene transfer in this habitat can significantly impact the ecology of aquatic microbial communities on a global scale. Therefore, comprehensive research on microplastics and nanoplastics and their effects within the food chain is essential. This article aims to review various studies on this pollutant and highlight some of its effects in marine environments.