Researchers discovered that Clostridium symbiosum breaks down ergothioneine—a potent antioxidant found in mushrooms—into thiourocanic acid (TUA), which is then used by Bacteroides xylanisolvens as an electron acceptor during anaerobic respiration. This cross-feeding interaction increases bacterial ATP synthesis and growth under oxygen-limited gut conditions. The pathway is active in human fecal communities, with production and consumption of TUA varying significantly between individuals. Importantly, the ergothionase enzyme responsible for initiating this process is significantly enriched in fecal metagenomes from colorectal cancer patients, suggesting this microbial metabolic pathway may contribute to interpersonal differences in colorectal cancer risk.
