Impact of glyphosate (RoundupTM) on the composition and functionality of the gut microbiome

Abstract

Glyphosate, the active ingredient in the broad-spectrum herbicide Roundup^TM, has been a topic of discussion for decades due to contradictory reports of the effect of glyphosate on human health. Glyphosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) of the shikimic pathway producing aromatic amino acids in plants, a mechanism that suggests that the herbicide would not affect humans as this pathway is not found in mammals. However, numerous studies have implicated glyphosate exposure in the manifestation of a variety of disorders in the human body. This review specifically outlines the potential effect of glyphosate exposure on the composition and functionality of the gut microbiome. Evidence has been building behind the hypothesis that the composition of each individual gut microbiota significantly impacts health. For this reason, the potential of glyphosate to inhibit the growth of beneficial microbes in the gut or alter their functionality is an important topic that warrants further consideration.

Keywords: Glyphosate; RoundupTM; antimicrobial; gut microbiome; human health.

Figure 1.

Shikimate pathway and resistance mechanisms to glyphosate. 1. Glyphosate inhibits the EPSPS enzyme. 2. The epsp gene can be overexpressed to combat EPSPS inhibition. 3. Efflux pumps are used to export glyphosate out of the cell as a form of resistance. 4. Amino acid biomarkers on the EPSPS enzyme determine the sensitivity of that enzyme to glyphosate. Changes in amino acid sequence can confer resistance to glyphosate. Created using Biorender.

Figure 2.

Potential effect of glyphosate exposure on the various bodily systems based on animal studies. Created using Biorender.

Figure 3.

Glyphosate degradation pathways and the subsequent products resulting. Created using Biorender.

Figure 4.

Examples of animal models used to examine the effect of glyphosate on the gut microbiome and the increase and decrease in bacterial species present. * - concentrations of glyphosate used and duration of experiment. Created using Biorender.