Deciphering the universal role of gut microbiota in pollutant transformation.

The gut microbiota represents a critical yet underexplored "second genome" in the host that functions as a key driver of pollutant transformation across Earth's ecosystems. This review synthesizes the current understanding of over 490 pollutants across a wide range of species, highlighting the universal role of gut microbial communities in modifying pollutant exposure. We have demonstrated that gut microbial communities transform a broad spectrum of environmental pollutants through evolutionarily conserved pathways, fundamentally altering their bioavailability, fate, and toxicity potential within the host. Transformation reactions are elucidated with connections among the metabolic enzymes that are developed by specific gut microbes, emphasizing the markedly specific and complementary signatures of microbial biotransformation compared to the host process. By integrating multidisciplinary studies, the complex and dynamic interplay between the gut microbiota, host physiology, and environmental pollutants has been elucidated, and drivers involved in the biotransformation processes have been proposed. Furthermore, current methodologies are critically evaluated, and next-generation approaches to reveal the underlying mechanisms of gut microbiota-driven pollutant transformation are outlined. This review underscores the urgent need to systematize research on "pollutant-gut microbiota-host" interactions and advocates the integration of gut microbial perspectives into interdisciplinary research paradigms of toxicology, microbiology, and ecology.