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Microplastic exposure drives divergent assembly mechanisms in riverine microorganisms: Poly(butylene adipate-co-terephthalate) triggers metabolic shifts vs polyethylene-enhanced network complexity
Summary
Researchers compared how conventional polyethylene and biodegradable PBAT microplastics affect microbial communities in river water over 60 days. They found that both types significantly altered bacterial diversity, but through different mechanisms: PBAT triggered metabolic shifts in microorganisms while polyethylene increased the complexity of microbial networks. The study suggests that even biodegradable plastics can meaningfully disrupt aquatic microbial ecosystems.
As an emerging pollutant, microplastics have attracted increasing global attention due to their widespread presence and potential ecological risks. In this study, a 60-day indoor incubation experiment was conducted to systematically compare the effects of conventional polyethylene (PE) and biodegradable poly (butylene adipate-co-terephthalate) (PBAT) microplastics, at both low and high concentrations, on microbial community structure and metabolic functions in aquatic environments. Water samples were collected on days 0, 15, 30, 45, and 60 for 16S/18S rRNA gene amplicon sequencing and untargeted metabolomics analysis. The results showed that microplastic exposure significantly altered the diversity and composition of bacterial communities, with PE and PBAT exerting different degrees of impact. The PE treatment, especially at low concentrations, markedly increased microbial diversity and enhanced the complexity of microbial co-occurrence networks. In contrast, the PBAT had a stronger effect on reshaping bacterial community composition. Although eukaryotic communities showed weaker responses in terms of taxonomic shifts, network analysis revealed their key role in maintaining microbial co-occurrence structures. PE exposure primarily enhanced network complexity, whereas PBAT treatment more strongly promoted cooperative interactions among microorganisms. Metabolomic analysis further revealed distinct metabolic pathway alterations induced by different types of microplastics. PBAT exposure led to broader metabolic responses, particularly involving amino acid metabolism, lipid metabolism, and secondary metabolite biosynthesis. Overall, this study provides comprehensive insights into the differential ecological impacts of traditional PE and biodegradable PBAT microplastics on microbial diversity, community assembly, and metabolic function, offering a scientific basis for the ecological risk assessment of various types of microplastics.