PET Microplastics Affect Human Gut Microbiota Communities During Simulated Gastrointestinal Digestion. First Evidence of Plausible Polymer Biodegradation During Human Digestion

Abstract

Microplastics are a widely recognized global problem due to their prevalence in natural environments and the food chain. However, the impacts of microplastics on human microbiota and their possible biotransformations during the gastrointestinal tract have not been well reported. To evaluate the potential risks of microplastics at the digestive level, completely passing a single dose of polyethylene terephthalate (PET) through the gastrointestinal tract was simulated by combining a harmonised static model and the dynamic gastrointestinal simgi® model, which recreates the different regions of the digestive tract in physiological conditions. PET MPs started several biotransformations in the gastrointestinal tract and appeared to expose the colon in ways that were structurally different from the original forms. We report that the feeding with microplastics alters human microbial colonic community composition, and hypothesize that some members of the colonic microbiota could adhere to MPs surface promoting the formation of biofilms. The work presented here indicates that microplastics are indeed capable of digestive-level health effects. Considering this evidence and the increasing exposure to microplastics in consumer foods and beverages, the impact of plastics on the functionality of the gut microbiome and their potential biodegradation through digestion and intestinal bacteria merits critical investigation.

Role, relevance, and possibilities of in vitro fermentation models in human dietary, and gut‐microbial studies

“…SIMGI can also be used to study the dysbiotic microbiota associated with an inadequate diet or any pathological condition, such as obesity or inflammatory bowel disease, where the dysbiotic microbiota obtained from a patient is stabilized in the system (Barroso et al, 2015a; Dupont et al, 2019). Furthermore, being one of the latest systems, SIMGI is still evolving and is used successfully to study, for example, dietary substances rich in polyphenols (Cueva et al, 2015; Gil‐Sánchez et al, 2020; Tamargo, Cueva, et al, 2022), the prebiotic potential of citrus pectin (Ferreira‐Lazarte et al, 2019), prebiotic induced reduction in lipid bioaccessibility (Tamargo et al, 2020), and effect of microplastic on human gut microbiota (Tamargo, Molinero, et al, 2022).…”

The gut microbiota, a key to understanding the health implications of micro(nano)plastics and their biodegradation

“…Furthermore, both PE and tetrabromobisphenol A, a plastic additive, transformed the composition of the microbiota and the metabolism pathways, altering gut homeostasis (Huang, Yin, et al, 2021). Regarding dynamic multi‐compartmental models, of the few studies available (Godoy et al, 2020; Tamargo et al, 2022; Yan, Zhang, et al, 2022), Tamargo et al (2022) were among the first to evaluate the effects of MPs on human fecal bacteria. Simulating the entire gastrointestinal tract (stomach, small intestine, and three parts of the colon) by combining a harmonized static model and the dynamic gastrointestinal simgi® model, they showed that PET MPs (166 mg/intake, 160 ± 110 μm, irregular shape) reduced biodiversity and altered the composition of the colonic microbiota, possibly due to the attachment of some colonic microbiota to MP surfaces.…”

“…Simulating the entire gastrointestinal tract (stomach, small intestine, and three parts of the colon) by combining a harmonized static model and the dynamic gastrointestinal simgi® model, they showed that PET MPs (166 mg/intake, 160 ± 110 μm, irregular shape) reduced biodiversity and altered the composition of the colonic microbiota, possibly due to the attachment of some colonic microbiota to MP surfaces. Different types of bacteria were affected, in particular a decrease in beneficial bacteria as Christensenellaceae was observed, as well as an increase in the proportions of Escherichia/Shigella and Bilophila , often associated with a pro‐inflammatory effect in the gut (Tamargo et al, 2022). More important, the same authors described a bidirectional interaction between MPs and the microbiota for the first time.…”

“…More important, the same authors described a bidirectional interaction between MPs and the microbiota for the first time. MPs tended to change intestinal microenvironments and affected bacterial growth and composition, whereas some members of this community could be related to PET MP biotransformations in the gut and thereby altering its bioavailability or toxicity (Tamargo et al, 2022). Furthermore, using a mucosal simulator of the human intestinal microbial ecosystem (M‐SHIME), Yan, Zhang, et al (2022) investigated the differential effects of PET MPs (2 g/day, distribution of sizes with ≈80% between 100–300 μm, irregular shape) on the intestinal luminal microbiota and the mucosal microbiota.…”

“…Biofilm formation has been shown to play a significant role in plastic bacterial decomposition because it promotes the adhesion of bacteria to the polymeric surface and their persistence (Puglisi et al, 2019; Santos et al, 2022; Wright et al, 2021). Regarding the human gut, feeding with PET MPs under simulated digestive conditions promoted the formation of biofilms that could favor the biotransformation of MPs through human fecal potentially degrading microbiota, suggesting that the human intestinal microbiota could harbor this degradation ability (Tamargo et al, 2022). Therefore, these studies suggest that common dietary‐MPs may be broken down in the gut into altered or even smaller nanometer‐sized particles that can be retained for some time in the digestive system.…”