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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #405347
Research Project: Physiological, Microbiological, and Nutritional Mechanisms to Maintain Animal Productivity in the Absence of Antibiotics

Location: Agroecosystems Management Research

Title: Effects of glyphosate on antibiotic resistance in soil bacteria and its potential significance: A review

Author
item Bearson, Bradley
item DOUGLASS, CAMERON - Office Of The Chief Economist
item DUKE, STEPHEN - University Of Mississippi
item MOORMAN, THOMAS - Retired ARS Employee
item TRANEL, PATRICK - University Of Illinois

Submitted to: Journal of Environmental Quality
Publication Type: Review Article
Publication Acceptance Date: 10/28/2024
Publication Date: 1/10/2025
Citation: Bearson, B.L., Douglass, C.H., Duke, S.O., Moorman, T.B., Tranel, P.J. 2025. Effects of glyphosate on antibiotic resistance in soil bacteria and its potential significance: A review. Journal of Environmental Quality. 54(1):160-180. https://doi.org/10.1002/jeq2.20655.
DOI: https://doi.org/10.1002/jeq2.20655

Interpretive Summary: The evolution and spread of antibiotic resistance is a continuing problem with important consequences for treatment of infectious bacterial diseases. The use of antibiotics in food animal production and the subsequent export of antibiotic resistance elements in animal manure to the soil is a topic of concern. Recent reports suggest that exposure of pathogenic bacteria to the widely-used herbicide glyphosate increases resistance or tolerance to antibiotics. We review these reports and identify soil processes likely to affect the persistence of glyphosate, antibiotic resistance elements, and their interactions. Glyphosate inhibits bacterial EPSP synthase, the enzyme target of glyphosate as a herbicide. This enzyme target is not shared by any antibiotics, indicating that classical cross-resistance does not account for increased antibiotic resistance or tolerance. Glyphosate in the presence of antibiotics increases the activity of efflux pumps, which confers tolerance to glyphosate. This may allow for increased frequency of mutation to antibiotic resistance. However, such effects are not unique to glyphosate. Most evidence indicates that glyphosate is not mutagenic in bacteria. Development of bacterial resistance to glyphosate does not coincide with increased resistance to antibiotics. Some studies suggest that glyphosate enhances genetic exchange of antibiotic resistance elements through effects on membrane permeability. Glyphosate and antibiotics would be present in manure-treated soil for at least part of the crop growing season, and initial studies indicate that glyphosate may increase abundance of antibiotic resistance genes in soil, but longer-term investigations are needed.

Technical Abstract: The evolution and spread of antibiotic resistance is a continuing problem with important consequences for treatment of infectious bacterial diseases. The use of antibiotics in food animal production and the subsequent export of antibiotic resistance elements in animal manure to the soil is a topic of concern. Recent reports suggest that exposure of pathogenic bacteria to the widely-used herbicide glyphosate increases resistance or tolerance to antibiotics. We review these reports and identify soil processes likely to affect the persistence of glyphosate, antibiotic resistance elements, and their interactions. Glyphosate inhibits bacterial EPSP synthase, the enzyme target of glyphosate as a herbicide. This enzyme target is not shared by any antibiotics, indicating that classical cross-resistance does not account for increased antibiotic resistance or tolerance. Glyphosate in the presence of antibiotics increases the activity of efflux pumps, which confers tolerance to glyphosate. This may allow for increased frequency of mutation to antibiotic resistance. However, such effects are not unique to glyphosate. Most evidence indicates that glyphosate is not mutagenic in bacteria. Development of bacterial resistance to glyphosate does not coincide with increased resistance to antibiotics. Some studies suggest that glyphosate enhances genetic exchange of antibiotic resistance elements through effects on membrane permeability. Glyphosate and antibiotics would be present in manure-treated soil for at least part of the crop growing season, and initial studies indicate that glyphosate may increase abundance of antibiotic resistance genes in soil, but longer-term investigations are needed.