Microbial Hydrogen Cycling in the Human Gastrointestinal Tract

This thesis explores microbial hydrogen metabolism in the human gastrointestinal tract, focusing on the key pathways, enzymes and microorganisms involved, along with the influence of diet. By integrating cohort studies, -omics analyses, and culture-dependent experimental validation, this research identifies diverse hydrogenases and pathways involved in H₂ production and consumption. The previously uncharacterised group B [FeFe]-hydrogenase emerged as the most abundant and expressed hydrogenase throughout the microbiota, and was validated as active and responsible for H₂ production in diverse isolates, and dominantly Bacteroides. These findings further clarify how H₂ is cycled by microbiota, and offers new insights into gut health.