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Effects of polymer type and aging on enrichment of antibiotic resistance genes and pathogens in biofilm on microplastics in biological wastewater treatment
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Tiny plastic particles in wastewater treatment plants act like magnets for bacteria, and this study found that the type of plastic and how much it's been broken down by sunlight both affect how much antibiotic-resistant bacteria build up on its surface. Plastics that break down more easily (like biodegradable PLA) and plastics that had been "aged" by UV light collected especially high levels of antibiotic resistance genes, meaning these microplastics could help spread drug-resistant germs back into our water and environment. This matters because it suggests not all plastics pose the same risk, and even "eco-friendly" biodegradable plast
Microplastics (MPs) in biological wastewater treatment provide a unique niche for the enrichment of antibiotic resistance genes (ARGs) and pathogenic bacteria, yet the comparative roles of biodegradability and aging are not well-defined. This study investigated the biofilm properties, microbial community structure, and enrichment of ARGs and pathogens on pristine and UV-aged biodegradable (polylactic acid, PLA) and non-biodegradable (polystyrene, PS; polyethylene terephthalate, PET) microplastics. Pristine and UV-aged MPs were incubated in a sequencing batch reactor for 30 days to facilitate biofilm development. Microbial community assembly was analyzed via high-throughput sequencing, while targeted ARGs and integrase genes were quantified through real-time PCR. The surface biofilm biomass was ranked as PLA > PET > PS and increased by UV-aging treatment. PLA enriched more qnrA and drfA1 genes than PS and PET, whereas PS favored tetC, aac(6')-Ib-cr and ermB genes, and UV-aging promoted selective enrichment of ARGs and integrase genes on UV-aged MPs, particularly on UV aged PLA. Stochastic processes were found to dominate community assembly, and aging was observed to increase the number of bacterial genera positively correlated with ARGs. Both polymer type and aging status are critical keys of the plastisphere's biological risks in wastewater systems. These findings offer new insights into the health risks of ARGs and pathogenic bacteria enriched on different types of MPs.
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Polymer type and aging drive the selective enrichment of antibiotic resistance genes and pathogens in microplastics biofilms
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Researchers compared how microorganisms colonize conventional polypropylene versus biodegradable polylactic acid microplastics in a wetland environment. They found that while biodegradable PLA attracted fewer total microbes, it actually enriched a higher proportion of antibiotic-resistant pathogens and resistance genes, especially after environmental aging. The findings raise important questions about whether biodegradable plastics may pose unexpected risks as carriers of antibiotic resistance in aquatic ecosystems.
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Scientists found that different types of microplastics in wastewater treatment plants can boost antibiotic-resistant bacteria in different ways, some plastics helped resistant genes spread more easily between bacteria, making the problem harder to contain. This matters because wastewater treatment plants are supposed to help protect us from pollution, but these findings suggest the type of plastic contamination present could affect how much antibiotic resistance ends up back in our environment, potentially making infections harder to treat down the line.
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Photoaged microplastics enhanced the antibiotic resistance dissemination in WWTPs by altering the adsorption behavior of antibiotic resistance plasmids
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Researchers found that microplastics exposed to UV light become significantly better at attracting and holding antibiotic resistance genes, increasing their capacity by 43 to 48 percent compared to unaged particles. This enhanced adsorption was linked to increased surface roughness and chemical changes on the plastic surface. The study suggests that UV-treated wastewater discharge may inadvertently accelerate the spread of antibiotic resistance in the environment through aged microplastics.
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