Published 08.09.2018

The introduction of genetically modified organisms (GMOs) in agriculture raises concerns about environmental and health effects, particularly regarding the link between GMO crops, herbicide use, and antibiotic resistance. There are specific worries about the presence of antibiotic resistance genes (ARGs) in GMOs and their potential transfer to microorganisms in the environment, contributing to the global rise of antibiotic-resistant bacteria, which poses a serious threat to public health and the ecosystem.

GMO plants may contribute to antibiotic resistance through two main pathways. First, resistance genes inserted into GMO crops for traits like herbicide tolerance often use antibiotic resistance markers for selection. If these genes are transferred to bacteria via horizontal gene transfer, they could create antibiotic-resistant strains, posing a risk to public health and the environment.

The second pathway involves environmental factors that promote the growth of antibiotic-resistant bacteria. In agricultural settings, particularly with GMO crops, bacteria are exposed to low levels of antibiotics and herbicides. These herbicides, used to control weeds in GMO crops, can alter bacteria's ability to resist antibiotics. This creates a scenario where even low levels of antibiotics can select for and enhance the survival of resistant bacterial strains in the environment.

GMO crops are often engineered to tolerate herbicides like glyphosate, dicamba, and 2,4-D, which can kill most plants. While effective against weeds, these herbicides pose a risk of promoting antibiotic resistance in microorganisms. Studies show that herbicide exposure can alter bacterial behavior, sometimes making them more resistant to antibiotics. For example, bacteria exposed to glyphosate can survive at higher antibiotic concentrations than those not exposed to the herbicide.

Surfactants used in herbicides to enhance absorption by plants may also contribute to bacterial resistance. These chemicals can alter bacterial cell membranes, allowing them to withstand higher concentrations of both herbicides and antibiotics. This is concerning, as it could lead to an increase in antibiotic-resistant pathogens in agriculture and nature. Such resistance presents a growing challenge to both public health and environmental sustainability.

The potential transfer of antibiotic resistance genes from GMOs to bacteria in the environment could have serious implications for human health. As antibiotic resistance increases globally, the effectiveness of many common antibiotics decreases, making infections harder to treat. If agricultural practices, like the use of GMOs and herbicides, contribute to this issue, it could exacerbate the problem. Research indicates that antibiotic-resistant bacteria can spread through the food chain, potentially exposing both animals and humans to resistant strains via contaminated food or water.

The use of antibiotics in livestock, often combined with herbicides in agricultural environments, exacerbates the problem. Low levels of antibiotics in animal feed or manure can create conditions where bacteria become resistant to both veterinary and human antibiotics. This accelerates the spread of antibiotic-resistant bacteria across various ecosystems, further complicating efforts to manage this growing threat to public health.

While the use of GMOs has brought significant benefits to agriculture, particularly in efficiency and weed control, the potential risks related to antibiotic resistance cannot be overlooked. The combination of herbicides, GMO crops, and low levels of antibiotics in the environment creates a dangerous environment for the development of antibiotic-resistant bacteria. It is crucial for policymakers, researchers, and agricultural stakeholders to continue monitoring and assessing the impact of GMOs and herbicide use on microbial resistance, with further research needed to better understand and mitigate these risks.

• The use of antibiotic resistance marker genes in GM plants
• Antimicrobial Use and Resistance in Plant Agriculture: A One Health Perspective
• Antimicrobial resitance (WHO)
• Herbicide ingredients change Salmonella enterica sv. Typhimurium and Escherichia coli antibiotic responses