Abstract

Background:

There is intense debate on whether glyphosate can inhibit the shikimate pathway of gastrointestinal microorganisms, with potential health implications.

Objectives:

We tested whether glyphosate or its representative EU herbicide formulation Roundup MON 52276 affects the rat gut microbiome.

Methods:

We combined cecal microbiome shotgun metagenomics with serum and cecum metabolomics to assess the effects of glyphosate [0.5, 50, $175\mathrm{mg}/\mathrm{kg}\text{\hspace{0.17em}body\hspace{0.17em}weight\hspace{0.17em}}\left(\text{BW}\right)\text{\hspace{0.17em}per\hspace{0.17em}day}$] or MON 52276 at the same glyphosate-equivalent doses, in a 90-d toxicity test in rats.

Results:

Glyphosate and MON 52276 treatment resulted in ceca accumulation of shikimic acid and 3-dehydroshikimic acid, suggesting inhibition of 5-enolpyruvylshikimate-3-phosphate synthase of the shikimate pathway in the gut microbiome. Cysteinylglycine, $\mathrm{\gamma }\text{-glutamylglutamine}$, and valylglycine levels were elevated in the cecal microbiome following glyphosate and MON 52276 treatments. Altered cecum metabolites were not differentially expressed in serum, suggesting that the glyphosate and MON 52276 impact on gut microbial metabolism had limited consequences on physiological biochemistry. Serum metabolites differentially expressed with glyphosate treatment were associated with nicotinamide, branched-chain amino acid, methionine, cysteine, and taurine metabolism, indicative of a response to oxidative stress. MON 52276 had similar, but more pronounced, effects than glyphosate on the serum metabolome. Shotgun metagenomics of the cecum showed that treatment with glyphosate and MON 52276 resulted in higher levels of Eggerthella spp., Shinella zoogleoides, Acinetobacter johnsonii, and Akkermansia muciniphila. Shinella zoogleoides was higher only with MON 52276 exposure. In vitro culture assays with Lacticaseibacillus rhamnosus strains showed that Roundup GT plus inhibited growth at concentrations at which MON 52276 and glyphosate had no effect.

Discussion:

Our study highlights the power of multi-omics approaches to investigate the toxic effects of pesticides. Multi-omics revealed that glyphosate and MON 52276 inhibited the shikimate pathway in the rat gut microbiome. Our findings could be used to develop biomarkers for epidemiological studies aimed at evaluating the effects of glyphosate herbicides on humans. https://doi.org/10.1289/EHP6990

中文翻译：

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使用 Shotgun 宏基因组学和代谢组学评估草甘膦或农达 MON 52276 对 Sprague-Dawley 大鼠肠道微生物群和血清代谢组的影响

摘要

背景：

关于草甘膦是否可以抑制胃肠道微生物的莽草酸途径，具有潜在的健康影响，存在激烈的争论。

目标：

我们测试了草甘膦或其代表性欧盟除草剂配方农达 MON 52276 是否会影响大鼠肠道微生物群。

方法：

我们将盲肠微生物群鸟枪宏基因组学与血清和盲肠代谢组学相结合来评估草甘膦的影响 [0.5, 50, $175\mathrm{毫克}/\mathrm{公斤}\text{\hspace{0.17em}体重\hspace{0.17em}}\left(\text{体重}\right)\text{\hspace{0.17em}每天}$] 或 MON 52276 以相同的草甘膦等效剂量，在大鼠 90 天毒性试验中。

结果：

草甘膦和 MON 52276 处理导致盲肠中莽草酸和 3-脱氢莽草酸的积累，表明肠道微生物群中莽草酸途径的 5-enolpyruvylshikimate-3-磷酸合酶受到抑制。半胱氨酰甘氨酸，$\mathrm{\gamma }\text{-谷氨酰谷氨酰胺}$草甘膦和 MON 52276 处理后，盲肠微生物组中的缬氨酰甘氨酸水平升高。改变的盲肠代谢物在血清中没有差​​异表达，这表明草甘膦和 MON 52276 对肠道微生物代谢的影响对生理生化的影响有限。草甘膦处理后差异表达的血清代谢物与烟酰胺、支链氨基酸、蛋氨酸、半胱氨酸和牛磺酸代谢有关，表明对氧化应激的反应。MON 52276 对血清代谢组的影响与草甘膦相似，但效果更明显。盲肠猎枪宏基因组学表明，治疗草甘膦和MON 52276导致更高水平的Eggerthella属，Shinella zoogleoides，约氏不动杆菌和Akkermansia muciniphila。Shinella zoogleoides仅在 MON 52276 暴露时更高。鼠李糖乳杆菌菌株的体外培养试验表明，在 MON 52276 和草甘膦没有影响的浓度下，Roundup GT plus 能抑制生长。

讨论：

我们的研究强调了多组学方法在研究农药毒性作用方面的强大作用。多组学显示，草甘膦和 MON 52276 抑制了大鼠肠道微生物组中的莽草酸通路。我们的研究结果可用于开发旨在评估草甘膦除草剂对人类影响的流行病学研究的生物标志物。https://doi.org/10.1289/EHP6990