WikiBiomeThe human microbiome encyclopediaRanked matches across titles, topics, categories, and article introductions, filtered to mechanism.
Butyrate is a four-carbon short-chain fatty acid produced when anaerobic gut microorganisms ferment dietary substrates. In the colon, it participates in epithelial energy metabolism, barrier maintenance, immune signaling, and gene regulation. Its effects depend on conce…
Acetate (acetic acid, C2) is the most abundant SCFA in the colon (~60% of total SCFAs) and the primary cross-feeding substrate for butyrate production. Produced by Bacteroides, Bifidobacterium, Prevotella, and acetogens from dietary fiber fermentation, acetate reaches p…
BDNF is the primary neurotrophin supporting neuronal survival, synaptic plasticity, and memory formation in the hippocampus and prefrontal cortex. Reduced BDNF is a consistent finding in depression, schizophrenia, and neurodegeneration. The gut microbiome modulates BDNF…
Cross-feeding (syntrophy) is the metabolic cooperation in which one organism's waste product becomes another's substrate. It is the cooperative counterpart to competitive exclusion — rather than competing for the same resource, organisms partition metabolic labor into s…
Epigenetic modifications — heritable changes in gene expression without altering the DNA sequence — are a primary mechanism through which both heavy metals and the gut microbiome influence disease across the lifespan. The three major epigenetic mechanisms (DNA methylati…
Fermentative metabolism is the set of anaerobic metabolic pathways by which bacteria break down carbohydrates and amino acids in the absence of oxygen, producing short-chain fatty acids (SCFAs) (primarily butyrate, propionate, acetate), gases (H₂, CO₂, CH₄), and organic…
Interleukin-10 is the primary anti-inflammatory cytokine, produced by Treg cells, macrophages, dendritic cells, and B cells. It suppresses pro-inflammatory cytokine production (IL-6, TNF-alpha, IL-1β), inhibits antigen presentation, and maintains immune tolerance. IL-10…
Iron-sulfur (Fe-S) clusters are among the most ancient and ubiquitous metal cofactors in biology, present in all domains of life. These inorganic prosthetic groups -- typically [2Fe-2S] or [4Fe-4S] configurations -- mediate electron transfer, enzymatic catalysis, and re…
Ketone bodies (beta-hydroxybutyrate [BHB], acetoacetate, acetone) are produced by hepatic fatty acid oxidation during carbohydrate restriction, fasting, or ketogenic diet consumption. BHB is the most abundant and is structurally and functionally analogous to butyrate — …
Mitochondrial dysfunction refers to the impairment of mitochondrial energy production, redox balance, and signaling functions. Mitochondria are the primary targets of heavy metal toxicity in human cells, and they are also the organelles most dependent on metal cofactors…
Oxygen state is a master ecological variable in the gut that determines which microorganisms thrive and which are excluded. The healthy colon maintains a steep oxygen gradient — oxygenated tissue at the epithelial surface drops to near-anaerobic conditions in the lumen,…
A three-carbon short-chain fatty acid (SCFA) produced primarily by Bacteroidetes and certain Firmicutes through anaerobic fermentation of dietary substrates. At physiological concentrations in healthy gut microbiomes, propionic acid (PPA) is a normal fermentation produc…
Saccharolytic fermentation is the microbial breakdown of carbohydrates (dietary fiber, resistant starch, host glycans) to produce short chain fatty acids (acetate, propionate, butyrate) and gases (H₂, CO₂, CH₄). It is the beneficial fermentation mode — the metabolic act…
The most extensively referenced missing concept in this wiki. SCFAs -- acetate (C2), propionate (C3), and butyrate (C4) -- are the primary metabolic products of anaerobic bacterial fermentation of dietary fiber in the colon. They serve as the critical molecular link bet…
The Th17/Treg balance is the immunological equilibrium between pro-inflammatory T helper 17 (Th17) cells and anti-inflammatory regulatory T (Treg) cells. This balance is the master switch between immune tolerance and autoimmune/inflammatory pathology — and the gut micro…
Tight junctions are the multiprotein complexes that seal the paracellular space between intestinal epithelial cells, forming the physical barrier that separates the gut lumen (with its ~10^13 bacteria, LPS, and dietary antigens) from the underlying lamina propria and sy…