Mycobiome

Candida#

Most abundant and best-studied gut fungus; C. albicans is the dominant species. Enriched in obesity (contributes to elevated intestinal free fatty acids), T2DM, coronary artery disease, and heart failure.^{[1]Gut mycobiome in cardiometabolic disease progression: current evidence and future directionsXiaoyu Wei, Zixin Guo, Jingyang Wang et al. · 2025Open reference 1 ↓}

In colon cancer, Candida-dominant tumors show reduced survival via IL-22, TP53, and CD44 pathways.^{[2]The mycobiome in human cancer: analytical challenges, molecular mechanisms, and therapeutic implicationsTing Ding, Chang Liu, Zhengyu Li · 2025Open reference 2 ↓} Capable of yeast-to-hyphal transition, forming biofilms and invading epithelium when immune surveillance is compromised.

Saccharomyces#

S. cerevisiae is commensal; S. boulardii is used as a probiotic. Enriched in some cardiometabolic diseases; S. boulardii supplementation failed to improve cardiac function in the GutHeart trial. Saccharomycetes-dominant GI cancers show distinct patterns from Candida-dominant ones.

Malassezia#

Lipophilic yeast; primarily skin-associated but detected in gut. Significantly enriched in hypertension cohorts, positively correlated with immunoglobulin light chains.^{[3]Gut mycobiome dysbiosis contributes to the development of hypertension and its response to immunoglobulin light chainsYeqing Zou, Anxing Ge, Brako Lydia et al. · 2022Open reference 3 ↓} M. restricta increased in obesity; Malassezia spp. enriched in pancreatic ductal adenocarcinoma (PDAC), where antifungal therapy shows therapeutic promise.

Aspergillus#

Environmental mold; A. fumigatus is a major opportunistic pathogen. Produces siderophores (TAFC, ferricrocin) for iron acquisition—detectable in urine as infection biomarkers.^{[4]Infection metallomics for critical care in the post-COVID eraPatil RH, Luptakova D, Havlicek V · 2021Open reference 4 ↓} A. dublinensis cell wall components induce islet-resident macrophage infiltration in diabetes models.

Cross-Kingdom Interactions#

The mycobiome does not exist in isolation. Fungi and bacteria interact through.

Competition for nutrients: Bacteria and fungi compete for iron, carbon sources, and mucosal adhesion sites. Mutual inhibition: Bacterial SCFAs lower pH, suppressing fungal overgrowth; antibiotic-induced bacterial depletion triggers Candida bloom. Immune co-stimulation: Fungal beta-glucan (Dectin-1 ligand) and bacterial LPS (TLR4 ligand) synergistically activate innate immunity.

Biofilm cooperation: Mixed bacterial-fungal biofilms are more resistant to antimicrobials than single-kingdom biofilms.

Disease Associations#

IBD: Increased Candida, decreased Saccharomyces; anti-S. cerevisiae antibodies (ASCA) are a diagnostic marker for Crohn's disease.

CRC: Intratumoral mycobiome detectable; oral fungi can reach the colon within 30 minutes via the sphincter of Oddi.^{[2]The mycobiome in human cancer: analytical challenges, molecular mechanisms, and therapeutic implicationsTing Ding, Chang Liu, Zhengyu Li · 2025Open reference 2 ↓}

CVD/Hypertension: Malassezia and Candida enrichment; Mortierella appears protective in normotensive populations.^{[1]Gut mycobiome in cardiometabolic disease progression: current evidence and future directionsXiaoyu Wei, Zixin Guo, Jingyang Wang et al. · 2025Open reference 1 ↓} MS: Altered fungal diversity; cross-kingdom shifts under dietary intervention.

Metal Connections#

Candida biosorption: C. albicans can biosorb Heavy Metals (cadmium (Cd), lead (Pb), copper (Cu)), potentially sequestering metals in the gut lumen but also shifting competitive dynamics with metal-sensitive bacteria.

Aspergillus siderophores: Iron-chelating metallophores (TAFC, ferricrocin, coprogen) are virulence factors that compete with host Nutritional Immunity (Metal Sequestration) for iron. Metal-driven fungal bloom: Heavy metal-induced bacterial dysbiosis (loss of SCFA producers and pH control) creates conditions permissive for fungal overgrowth, paralleling antibiotic-induced candidiasis.