Large livestock and poultry operations can generate manure containing a mixture of emerging contaminants, including antibiotic residues, antibiotic resistance genes and microplastics. A new review suggests that these pollutants should not always be considered separately. Microplastics may act as mobile carriers that concentrate antibiotics and antibiotic resistance genes, creating hotspots where antibiotic resistance can persist and spread more easily.
"Microplastics are not simply passive particles in livestock waste. Their surfaces can provide places where antibiotics, bacteria and resistance genes come together, potentially creating favorable conditions for the spread of antibiotic resistance," said corresponding author Zhiping Zhu of the Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences.
The review, published in Agricultural Ecology and Environment, examines how microplastics, antibiotics and antibiotic resistance genes, known as ARGs, interact in livestock and poultry production environments.
Antibiotic residues can place selective pressure on microbial communities, allowing resistant bacteria to survive and multiply. At the same time, microplastics can adsorb antibiotics through hydrophobic interactions, hydrogen bonding and other surface processes. Their surfaces can also support microbial biofilms, dense communities of microorganisms in which bacteria come into close contact.
These biofilms are especially important because close contact between bacteria can facilitate horizontal gene transfer, a process through which resistance genes move between microorganisms. The review cites studies showing that aging can greatly increase the ability of some microplastics to adsorb antibiotics, while biofilm formation can promote the enrichment and exchange of ARGs.
The authors describe a potential microplastic, antibiotic and ARG complex in which microplastics function as a central carrier. Antibiotics accumulate on the plastic surface, resistant microorganisms colonize biofilms, and resistance genes become concentrated in the same microscopic environment.
This process can contribute to what researchers call the "Trojan horse effect." Microplastics can transport adsorbed pollutants through manure, soil and water, potentially extending their environmental reach. Once conditions change, some contaminants may be released into surrounding environments, while biofilms can continue to support microbial survival and gene exchange.
However, the authors emphasize an important limitation. Direct quantitative evidence showing that the full three-component mixture produces risks greater than the combined effects of individual or paired pollutants remains scarce. Existing findings can vary with plastic type, particle size, aging, environmental conditions and treatment systems. The review therefore calls for controlled experiments, long-term monitoring and studies under real livestock production conditions.
The review also finds that no single manure treatment method is likely to solve the problem. Physical separation can remove some particles, chemical oxidation can degrade antibiotics and damage extracellular resistance genes, and biological processes can reduce some contaminants. Each approach has limitations. The authors identify integrated physical, chemical and biological treatment as a key future direction for simultaneously controlling microplastics, antibiotics and ARGs.
"Effective pollution control will require us to consider how these contaminants interact, rather than treating microplastics, antibiotics and resistance genes as three independent problems," Zhu said.
The study was supported by the Central Public-Interest Scientific Institution Basal Research Fund and the National Waterfowl Industry Technology System of China.
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Journal Reference: Fu Y, Zhu Z, Wang W, Zhang M. 2026. Combined pollution and transmission mechanism of microplastics–antibiotics–antibiotic resistance genes in the livestock and poultry production environment. Agricultural Ecology and Environment 2: e023 doi: 10.48130/aee-0026-0021
https://www.maxapress.com/article/doi/10.48130/aee-0026-0021
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Agricultural Ecology and Environment (e-ISSN 3070-0639) is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.
