Biology subjects

Mestrot, A.

Publications and source records attributed to Mestrot, A..

4 recordsLinked to original sources

bioRxiv2024

Microbiota-dependent in vivo biotransformation, accumulation, and excretion of arsenic from arsenobetaine-rich diet

Arsenic (As) is a naturally occurring metalloid that is ubiquitous in the environment. Various chemical forms of As, collectively referred to as "As species", find their way into the food chain, impacting the health of millions globally. Many of these As species are products of bacterial enzymatic transformations in different environments. Yet, the in vivo gut microbial transformation of As and its consequences in the host, especially for less toxic As species like arsenobetaine (AB), remain elusive. Current regulatory assessments regard AB-rich foods, including various seafoods, as safe due to low toxicity and rapid unmodified urinary excretion of the ingested AB. This notion has been challenged by reports of AB metabolism by intestinal bacteria in vitro and by more recent evidence of in vivo AB metabolism in mice. However, these studies did not definitively establish the causal role of intestinal bacteria in AB transformation in vivo. To address this, we employed gnotobiology that allowed us to compare the biotransformation of As from a naturally AB-rich rodent diet in isogenic mice that were either completely germ-free, or colonized with gut microbiota of varying microbial diversity. Additionally, we examined the body distribution, accumulation, and clearance of the ingested As in these mice. Our results confirm the in vivo metabolism of AB in the intestine under chronic dietary exposure. The transformation of ingested As was found to be dependent on the presence/absence and complexity of the gut microbiota. Notably, specific toxic As species were absent under germ-free condition. Furthermore, gut microbial colonization was linked to increased As accumulation in the intestinal lumen as well as systemically, along with delayed clearance from the body. These findings emphasize the mammalian gut microbiota as a critical factor in evaluating the safety of AB-accumulating seafoods.

pharmacology and toxicology↗

bioRxiv2024

Component specific responses of the microbiomes to common chemical stressors in the human food chain

Along a food chain, microbiomes occur in each component and often contribute to the functioning or the health of their host or environment. One Health emphasizes the connectivity of each components health. Chemical stress typically causes dysbiotic microbiomes, but it remains unclear whether chemical stressors consistently affect the microbiomes along food chain components. Here, we systematically challenged a model food chain, including water, sediments, soil, plants, and animals, with three chemical stresses consisting of arsenic (a toxic trace element), benzoxazinoids (an abundant bioactive plant metabolites), and terbuthylazine (an herbicide typically found along a human food chain). The analysis of 1,064 microbiome profiles for commonalities and differences in their stress responses indicated that chemical stressors decreased microbiome diversity in soil and animal, but not in the other microbiomes. In response to stress, all food chain communities strongly shifted in their composition, generally becoming compositionally more similar to each other. In addition, we observed stochastic effects in host-associated communities (plant, animal). Dysbiotic microbiomes were characterized by different sets of bacteria, which responded specifically to the three chemical stressors. Microbial co-occurrence patterns significantly shifted with either decreased (water, sediment, plant, animal) or increased (soil) network sparsity and numbers of keystone taxa following stress treatments. This suggested major re-distribution of the roles that specific taxa may have, with the community stability of plant and animal microbiomes being the most affected by chemical stresses. Overall, we observed stress- and component-specific responses to chemical stressors in microbiomes along the model food chain, which could have implications on food chain health.

microbiology↗

bioRxiv2022

Plant secondary metabolite-dependent plant-soil feedbacks can improve crop yield in the field

Plant secondary metabolites that are released into the rhizosphere alter biotic and abiotic soil properties, which in turn affect the performance of other plants. How such plant-soil feedbacks affect agricultural productivity and food quality in crop rotations is unknown. Here, we assessed the impact of maize benzoxazinoids on the performance, yield and food quality of three winter wheat varieties in a two-year field experiment. Following maize cultivation, we detected benzoxazinoid-dependent chemical and microbial fingerprints in the soil. The chemical fingerprint was still visible during wheat growth, while the microbial fingerprint was no longer detected. Benzoxazinoid soil conditioning by wild-type maize led to increased wheat emergence, tillering, growth and biomass compared to soil conditioning by bx1 mutant plants. Weed cover remained unaffected, while insect damage decreased in a subset of varieties. Wheat yield was increased by over 4% without a reduction in grain quality across varieties. This improvement was directly associated with increased germination and tillering. Taken together, our experiments demonstrate that plant secondary metabolites can increase yield via plant-soil feedbacks under agronomically realistic conditions. If this phenomenon holds across different soils and environmental conditions, optimizing plant root exudation could be a powerful, genetically tractable strategy to enhance crop yields without additional inputs.

plant biology↗

bioRxiv2021

Soil chemistry determines whether defensive plant secondary metabolites promote or suppress herbivore growth

Specialized metabolites mediate important interactions in both the rhizosphere and the phyllosphere. How this compartmentalized multifunctionality influences plant-environment interactions is unknown. Here, we investigated how the dual role of maize benzoxazinoids as leaf defenses and root siderophores shapes the interaction between maize and a major global insect pest, the fall armyworm. We find that benzoxazinoids suppress fall armyworm growth in soils with low bioavailable iron but enhance growth in soils with higher bioavailable iron. Manipulation experiments confirm that benzoxazinoids suppress herbivore growth under iron-deficient conditions but enhance herbivore growth when iron is present in its free form. This reversal of the protective effect of benzoxazinoids is not associated with major changes in plant primary metabolism. Plant defense activation is modulated by the interplay between soil iron and benzoxazinoids but does not explain fall armyworm performance. Instead, increased iron supply to the fall armyworm by benzoxazinoids in the presence of free iron enhances larval performance. This work identifies soil chemistry as a decisive factor for the impact of plant secondary metabolites on herbivore growth. It also demonstrates how the multifunctionality of plant secondary metabolites drives interactions between abiotic and biotic factors, with major consequences for plant health in variable environments.

plant biology↗