Gut mycobiome

The gut mycobiome refers to the fungal community residing within the human gastrointestinal system. While the gut microbiome (bacteria) has been extensively studied, the mycobiome remains underexplored, despite its significant role in health and disease. Fungi in the gut are far less abundant than bacteria but have crucial metabolic and immune functions, influencing various physiological processes and disease states.

Recent research has highlighted the gut mycobiome's contribution to non-alcoholic fatty liver disease (NAFLD). In a study comparing 90 NAFLD patients with 90 healthy controls, researchers found that the gut mycobiome significantly influences serum metabolites, which are critical for liver health. Although overall fungal diversity and community structure did not differ between the groups, four fungal species were enriched in NAFLD patients: Aspergillus sp. c25, Pseudopithomyces sp. c174, Mucor sp. c176, and Ascochyta c213. These fungi correlated with specific metabolites, some protective (e.g., glycoursodeoxycholic acid) and others harmful (e.g., phenylacetic acid, linked to lipid accumulation in the liver).

The study also revealed complex fungal-bacterial interaction networks, with distinct microbial connectivity patterns in NAFLD. Certain fungi, such as Alternaria alternata and Penicillium sp., emerged as key hubs in NAFLD, while others like Schizophyllum sp. were prominent in healthy controls, suggesting their protective roles. Importantly, predictive modeling using fungal and bacterial species achieved strong accuracy in differentiating NAFLD patients from healthy individuals, demonstrating the diagnostic potential of the gut mycobiome.

Mechanistically, the enriched fungi may contribute to NAFLD progression through metabolite production (e.g., ethanol, mycotoxins) or immune modulation affecting hepatic inflammation and lipid metabolism. These findings emphasize the gut mycobiome's functional importance in liver health and its potential as a therapeutic target for NAFLD.