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IDAEA-CSIC and IQS analyze the effects of the herbicide glyphosate and the biocide triclosan on the gut microbiota of the aquatic microcrustacean Daphnia magna.
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Exposure to environmentally relevant concentrations alters the microbiota, neurotransmitter levels, behavior, and reproduction of the organism.
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This model opens new avenues to investigate how common pollutants may affect the nervous system, with potential implications for vertebrate and human health.
Daphnia magna, a model organism in environmental ecotoxicology / Juliette Bedrossiantz (IDAEA-CSIC)
A study conducted by the Institute of Environmental Assessment and Water Research (IDAEA-CSIC) and the Sarrià Institute of Chemistry (IQS) has shown that glyphosate and triclosan, two compounds commonly found in herbicides and personal care products, alter the gut microbiota of Daphnia magna, even at very low concentrations similar to those found in the environment.
The results, published in the journal Environmental Science & Technology, reveal for the first time that these alterations in the intestinal microbial community of the microcrustacean are associated with neurological, behavioral, and reproductive changes. This finding validates the potential of this organism as a model to study the gut microbiota–brain axis and could facilitate the early detection of pollutants with possible neurological effects.
In recent years, numerous studies have shown that the gut microbiota plays a key role in regulating the immune and nervous systems. This interaction between the gut and the brain has been mainly studied in humans and vertebrate models, from fish to mice. However, these models present ethical and experimental limitations that make long-term exposure studies to environmental pollutants more difficult. By contrast, Daphnia magna is widely used in ecotoxicology due to its sensitivity to pollutants and its key role in freshwater food webs.
The contamination of freshwater ecosystems by human-derived chemical compounds, such as herbicides and biocides, is an increasing concern within the scientific community due to its effects on biodiversity and environmental health. Among them, glyphosate, one of the most widely used herbicides worldwide, and triclosan, an antimicrobial agent present in some personal care products such as soaps and toothpaste, are commonly found in rivers, lakes, and wastewater.
Alterations in microbiota, behavior, and reproduction
In this study, researchers exposed Daphnia magna for 21 days, approximately the time it takes to reach adulthood, to low concentrations of glyphosate and triclosan comparable to those detected in aquatic ecosystems.
The results showed that exposure to these compounds altered the composition of the gut microbiota, neurotransmitter levels, and the behavior of the microcrustacean. These changes were associated with modifications in key neurotransmitters for the nervous system, such as serotonin and dopamine, both in the gut and the brain. In addition, exposed organisms showed reduced reproductive capacity.
The study also identified alterations in microbial metabolic pathways involved in the production of vitamins, essential fatty acids, and short-chain fatty acids, which play a role in gut–brain communication.
“Our study demonstrates that this microbiota–nervous system interaction mechanism also exists in Daphnia magna, opening the door to using it as a model to study how environmental pollutants may affect neurological processes in other organisms,” explains Carlos Barata, researcher at IDAEA-CSIC and lead author of the study.
The use of Daphnia magna may help reduce the use of vertebrate animals in experimentation, as it is easy to maintain in the laboratory, low-cost, and not subject to animal experimentation ethical regulations.
“What is particularly interesting is that two very different compounds, such as glyphosate and triclosan, produce similar effects in the studied organisms. This suggests that changes in the microbiome could be a common mechanism through which different pollutants influence organism behavior and physiology,” he adds.
According to the authors, this model could be used in the future for screening environmental pollutants and detecting compounds capable of altering the gut microbiota and potentially influencing the nervous system. However, the researchers stress the need for further studies to determine to what extent these effects can be reproduced in vertebrates.
Romero-Alfano, I., Julia López, A., Piña, B., Gómez-Canela, C., & Barata, C. (2026). From Gut to Brain: Glyphosate and Triclosan Impair Microbiome Composition, Neuroactive Metabolites, and Cognitive and Ecological Fitness in Daphnia magna. Environmental Science & Technology. https://doi.org/10.1021/ACS.EST.5C15302
