Polystyrene microplastics induce microbial dysbiosis and dysfunction in surrounding seawater

Area of Science:

• Environmental Science
• Microbiology
• Ecotoxicology

Background:

• Microplastics are pervasive environmental contaminants, accumulating in aquaculture systems and impacting aquatic organisms.
• The ecological role of microplastics in shaping microbial communities and functions in aquaculture water remains poorly understood.
• Microplastics can serve as substrates for microbial colonization, potentially altering aquatic microbial ecosystems.

Purpose of the Study:

• To investigate the impact of polystyrene microplastics (PS) on microbial community structure and function in seawater used for marine medaka (Oryzias melastigmas) aquaculture.
• To identify potential bacterial biomarkers indicative of microplastic-induced dysbiosis and associated metabolic changes in marine medaka.
• To elucidate the relationship between microplastic exposure, microbial alterations, and host metabolism.

Main Methods:

• 16S rRNA gene sequencing was used to analyze microbial community composition in seawater exposed to 10- and 200-µm PS.
• Functional analysis of microbial communities was performed to assess changes in metabolic pathways.
• Correlation networks were established to link microbial taxa and host liver metabolism.

Main Results:

• Polystyrene microplastic exposure significantly altered the relative abundance of 26 bacterial taxa, primarily within the Proteobacteria and Bacteroidetes phyla.
• Microbial metabolic functions related to photosynthesis, carbon, amino acid, lipid, and nucleotide metabolism were suppressed, while stress response pathways increased.
• Changes in specific bacterial taxa were strongly correlated with alterations in the liver metabolism of marine medaka.

Conclusions:

• Polystyrene microplastics induce significant microbial dysbiosis and functional shifts in aquaculture seawater.
• Eight bacterial taxa were identified as highly accurate biomarkers (100% diagnostic accuracy) for assessing microplastic-induced ecological impacts and host metabolic responses.
• This study highlights the ecotoxicological effects of microplastics on aquatic microbial ecosystems and provides tools for environmental monitoring.