WikiBiomeThe human microbiome encyclopediaRanked matches across titles, topics, categories, and article introductions.
A fundamental ordering of divalent transition metal ion binding affinities, established by Harry Irving and Robert Williams in 1953: Mg2+ < Mn2+ < Fe2+ < Co2+ < Ni2+ < Cu2+ Zn2+ This series holds for virtually all ligands and biological chelators. It means that copper b…
Pathogens deploy dedicated cellular machinery to import, store, regulate, and when necessary export transition metals. These systems complement the extracellular siderophores metallophores that scavenge metals from the host environment by providing the membrane transpor…
This knowledge-base record is being expanded from WikiBiome’s evidence graph.
An acidic microenvironment is a local drop in pH — typically into the 4.5–6.5 range — inside a tissue, organ, or ecological niche. Acidification arises from three recurring sources: bacterial fermentative metabolism that releases short-chain fatty acids and lactate (lou…
A Gram-negative, aerobic, non-fermenting coccobacillus and a member of the ESKAPE group of priority pathogens (Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, Enterobacter). Acinetobacter baumannii is among the most problematic nosocomial pathogens…
WHO Priority 1: Critical. A Gram-negative, strictly aerobic coccobacillus and one of the most dangerous nosocomial pathogens on the planet. A. baumannii belongs to the ESKAPE group and causes ventilator-associated pneumonia, wound infections, and bloodstream infections …
Aeromonas is a genus of Gram-negative, facultatively anaerobic bacteria found in aquatic environments and, increasingly recognized as an opportunistic gut pathogen. Several species — particularly Aeromonas hydrophila, A. veronii, and A. caviae — are associated with gast…
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that functions as a master sensor at the intersection of gut microbial metabolism, environmental chemical exposure, and immune regulation. It is expressed broadly across immune cells, intesti…
Alishewanella is a genus of Gram-negative, facultative anaerobic bacteria within the class Gammaproteobacteria. Primarily known as environmental organisms, Alishewanella species have been identified in the microbiome of deep endometriosis — both in vaginal samples and w…
An anti-aging protein that has emerged as a critical mediator between heavy metal exposure and chronic kidney disease progression. Originally discovered as a gene whose mutation caused premature aging in mice, alpha-klotho is now understood to be a multifunctional prote…
A non-essential metal and the most abundant metallic element in the Earth's crust. Unlike manganese, iron, or selenium, aluminum has no known biological function in humans. Its significance in metal toxicology stems from two major concerns: proven neurotoxicity at eleva…
The most common form of dementia, affecting an estimated 55 million people worldwide and projected to triple by 2050 zhang 2024 recent advances alzheimers mechanisms trials. Characterized by progressive memory loss, cognitive decline, amyloid-beta plaques, and neurofibr…
Ammonia is a nitrogen-containing product of microbial urease activity. When urease hydrolyzes urea, ammonia and bicarbonate are produced; in the microbial systems covered by WikiBiome, those products can provide nitrogen and raise local pH maier 2019 nickel microbial pa…
A genus of Gram-positive obligate anaerobes in the family Lachnospiraceae (Clostridium cluster XIVa) that occupy a critical metabolic relay position in gut ecosystem stability: converting lactate to butyrate. Anaerostipes is one of the most consistently depleted genera …
Antimicrobial metals are metal ions and metal-based materials that kill or inhibit microorganisms. Copper, silver, zinc, and gallium are the principal agents, each exploiting different aspects of microbial metal biology. What makes this field particularly relevant to Wi…
The ability of microorganisms to survive and replicate in the presence of antimicrobial agents — antibiotics, antifungals, antivirals, antiparasitic drugs — at concentrations that would normally inhibit or kill them. Antimicrobial resistance (AMR) is designated by the W…
Anxiety disorders are the most prevalent mental health conditions globally, affecting ~280 million people (~4.8% of the world population). They encompass generalized anxiety disorder (GAD), social anxiety, panic disorder, and phobias. In the WikiBiome context, anxiety f…
Arsenic is a metalloid and potent carcinogen (IARC Group 1) that ranks among the most widespread environmental toxicants affecting human health. An estimated 225 million people worldwide are chronically exposed through contaminated drinking water alone ghosh 2023 heavy …
Progressive inflammatory disease of the arterial wall characterized by lipid accumulation, immune cell infiltration, and fibrous plaque formation. In the metallomics framework, atherosclerosis sits at the convergence of three interacting systems: heavy metal toxicity, g…
Atopobium is a genus of obligate anaerobic, Gram-positive bacteria in the phylum Actinobacteria. The primary species of clinical relevance is A. vaginae (recently reclassified as Fannyhessea vaginae), which is one of the hallmark organisms of bacterial vaginosis (BV) an…
A neurodevelopmental condition affecting approximately 1 in 36 children (US CDC 2023 estimate), characterized by differences in social communication, restricted interests, and repetitive behaviors. From a metallomics perspective, ASD presents a compelling convergence of…
Bacteremia is the presence of viable bacteria in the bloodstream. In the WikiBiome framework, bacteremia results from bacterial translocation across compromised barriers — the gut epithelium (→ portal bacteremia) or the oral mucosa (→ systemic bacteremia during dental p…
A Gram-negative obligate anaerobe that exemplifies the commensal-pathobiont spectrum. B. vulgatus is a common component of the healthy gut microbiota, yet is significantly enriched in colorectal cancer and depression, suggesting a context-dependent pathogenic potential.…
Beta-lactamases are bacterial enzymes that hydrolyze the beta-lactam ring of penicillins, cephalosporins, and carbapenems, rendering them inactive. They are the most common mechanism of antibiotic resistance and a central concern in the antimicrobial resistance crisis. …
Bifidobacteriales is an order of Gram-positive, strictly anaerobic bacteria within the phylum Actinobacteria. The order contains the family Bifidobacteriaceae, which includes the genus Bifidobacterium — among the most widely studied probiotic organisms and a hallmark of…
Bifidobacterium adolescentis is a Gram-positive, obligate anaerobic species within the phylum Actinobacteria and the dominant Bifidobacterium species in the adult human gut. It is a specialist degrader of resistant starch and dietary fiber, producing acetate and lactate…
Bifidobacterium breve is a Gram-positive, obligate anaerobic species within the phylum Actinobacteria, predominantly found in the infant gut and breast milk. It is among the earliest colonizers of the neonatal intestine and plays a key role in human milk oligosaccharide…
Structured microbial communities encased in a self-produced extracellular polymeric substance (EPS) matrix. Biofilms are the predominant mode of bacterial and fungal growth in chronic infections, device-associated infections, and the gut. From a metallomics perspective,…
Bipolar disorder is a chronic neuropsychiatric condition characterized by recurrent episodes of mania (or hypomania) and depression, affecting approximately 1-2.4% of the global population. It carries significant morbidity -- reduced life expectancy by 10-15 years, high…
A heavy metal traditionally considered safe enough for over-the-counter gastrointestinal remedies (Pepto-Bismol, De-Nol), bismuth is re-emerging as a potent antimicrobial synergist. Its key property: Bi3+ competes with Fe3+ for binding sites on siderophores and bacteria…
Burkholderiales is an order of Gram-negative Betaproteobacteria that includes environmentally versatile genera such as Ralstonia, Burkholderia, and Sutterella. Many members are notable for their metal resistance mechanisms, which enable survival in heavy metal-contamina…
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…
A genus of Gram-positive, strictly anaerobic, butyrate-producing bacteria in the order Clostridiales (phylum Firmicutes). The type species, Butyricicoccus pullicaecorum, was originally isolated from chicken caecal content but has since been identified as a significant m…
A Gram-negative, obligate anaerobic genus within the Bacteroidetes phylum (family Odoribacteraceae). Despite its relatively recent characterization, Butyricimonas has gained significant attention as a member of the protective butyrate-producing consortium that is consis…
Cadmium is a toxic non-essential heavy metal (IARC Group 1 carcinogen) with a biological half-life of 17--30 years in mammals, primarily accumulating in the renal cortex via proximal tubular reabsorption of the Cd-metallothionein complex rasin 2025 cadmium exposure heal…
Candida tropicalis is an opportunistic fungal pathogen and occasional gut commensal, increasingly recognized as one of the most clinically significant non-albicans Candida (NAC) species. Once considered a distant runner-up to C. albicans, it has emerged as a major drive…
Cardiovascular disease (CVD) -- encompassing atherosclerosis, coronary artery disease, hypertension, myocardial infarction, heart failure, and stroke -- is the leading cause of death globally. The gut-heart axis has emerged as a central paradigm linking microbial metabo…
Catalase is a heme-iron enzyme that decomposes hydrogen peroxide into water and oxygen. In microbial peroxide defense, it acts downstream of superoxide dismutase: superoxide dismutase converts superoxide to hydrogen peroxide, and catalase removes that hydrogen peroxide …
Caulobacter is a genus of Gram-negative obligate aerobic Alphaproteobacteria, with C. crescentus serving as one of the premier model organisms for studying bacterial cell biology. Found primarily in oligotrophic freshwater environments, Caulobacter is not a gut commensa…
Chelation therapy uses high-affinity metal-binding molecules to form stable, excretable complexes with toxic metals, removing them from the body. The term derives from Greek "chele" (claw) -- the chelator grips the metal ion at multiple coordination sites. While chelati…
Chromium is a transition metal (atomic number 24) whose toxicology is defined by a stark oxidation-state divide. Hexavalent chromium, Cr(VI), is an IARC Group 1 human carcinogen that causes DNA damage through a unique mechanism of intracellular reduction and ternary add…
A progressive loss of kidney function affecting approximately 850 million people worldwide (10–14% of adults), causing 1.2 million deaths annually. CKD is unique among diseases in this wiki because it occupies both sides of the metal-disease equation: heavy metals (Cd, …
Clostridium symbiosum is a Gram-positive, obligately anaerobic bacterium within the Clostridium cluster XIVa — a taxonomic group enriched for short-chain fatty acid (SCFA) producers and specialized bile acid metabolizers. Despite its ambiguous name (suggesting symbiotic…
The process by which selection pressure from one agent — typically a heavy metal — simultaneously selects for resistance to a structurally unrelated agent such as an antibiotic, because the resistance determinants are genetically linked on the same mobile genetic elemen…
A transition metal that is essential to human health exclusively as a component of cobalamin (vitamin B12), but toxic at higher levels of exposure. Cobalt occupies a distinctive position in metal biology: it is the only metal whose essential biological function in mamma…
A genus of Gram-positive, obligate anaerobic bacteria within the Actinobacteria phylum (family Coriobacteriaceae) that has emerged as a consistent pathobiont enriched in cardiometabolic and autoimmune diseases. C. aerofaciens is the most studied species, with establishe…
The collective ability of the resident gut microbiome to prevent colonization by exogenous pathogens and suppress expansion of resident pathobionts. Colonization resistance is not a property of any single organism but an emergent function of the whole microbial communit…
Colorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer death. Over 90% of cases are sporadic, driven by a complex interplay between genetic predisposition, dietary habits, gut microbiome composition, and environmental ex…
The co-occurrence of multiple diseases in the same individual at rates exceeding chance. Comorbidity patterns are a central puzzle in medicine -- why do IBD patients develop CVD? Why does PCOS cluster with T2D? Why do neurodegenerative diseases associate with depression…
Competitive exclusion is the ecological principle that two species competing for the same limiting resource cannot coexist indefinitely — one will outcompete the other. In the gut microbiome, competitive exclusion is the primary mechanism by which commensal bacteria pre…
An essential trace element with a striking dual nature: required for survival as a cofactor for critical enzymes (SOD1, cytochrome c oxidase, ceruloplasmin), yet toxic in excess through Fenton-like redox cycling and mis metallation of iron-sulfur clusters. Copper is ele…
A Gram-positive, obligate anaerobic genus within the lachnospiraceae family (Firmicutes phylum). Coprococcus is one of the most important butyrate-producing commensals in the human gut and has gained particular attention as the "happiness bug" -- one of very few taxa di…
A chronic, relapsing-remitting inflammatory bowel disease (IBD) characterized by transmural inflammation of the gastrointestinal tract, most commonly affecting the terminal ileum and colon but capable of involving any segment from mouth to anus zhang 2017 intestinal mic…
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…
Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the CFTR gene, producing defective chloride and bicarbonate transport across epithelial membranes. While the genetic defect affects multiple organ systems, chronic lung infection is the prima…
Debaryomyces is a genus of ascomycetous fungi, with D. hansenii being the most clinically relevant species, that represents a prominent opportunistic pathobiont enriched in inflammatory bowel disease, particularly crohns disease. Unlike many commensal fungi, Debaryomyce…
Depression is the most prevalent mental health disorder globally, affecting over 280 million people zhu 2025 microbiota gut brain axis depression review, and one of the most metal-sensitive conditions in this wiki. It sits at the convergence of nearly every pathway cata…
Dermatitis herpetiformis (DH) is the cutaneous manifestation of celiac disease, presenting as intensely pruritic, grouped vesicles on the elbows, knees, buttocks, and scalp. It is driven by IgA antibodies against epidermal transglutaminase (eTG), the skin homolog of tis…
This page unifies the infant formula contamination, pregnancy complications, autism spectrum disorder, necrotizing enterocolitis, and neurodevelopmental toxicity threads around a single organizing insight: metal toxicity is disproportionately severe during specific deve…
arsenic (As) is unique among dietary heavy metals because it exists in two fundamentally different forms with dramatically different toxicities: inorganic arsenic (iAs, the dangerous form) and organic arsenic (arsenobetaine, arsenosugars — largely non-toxic). Understand…
iron occupies a unique position among dietary metals: it is both an essential nutrient and a selective pressure that shapes the gut microbial ecosystem. The form, quantity, and bioavailability of dietary iron determines which microbes thrive and which are competitively …
This page identifies the contradictions and clinical dilemmas that become visible only when the 236 source pages in this wiki are read together. Each paradox describes a situation where evidence-based dietary or supplementation advice -- advice that is correct for most …
Every meal delivers metals to the gut lumen — essential minerals, trace elements, and contaminants alike. These metals do not passively transit the GI tract. They actively reshape the microbial ecosystem, selecting for metal-tolerant organisms, enabling virulence in met…
Dimethylglyoxime (DMG) is a high-affinity, nickel-specific chelator — two DMG molecules coordinate one Ni²⁺ ion to form a characteristic red complex (Tschugaeff reaction). Unlike broad-spectrum chelation agents (EDTA, DMSA) that bind multiple divalent cations indiscrimi…
Dopamine is a catecholamine neurotransmitter central to reward, motivation, motor control, and executive function. Its synthesis is directly dependent on iron -- the rate-limiting enzyme tyrosine hydroxylase (TH) requires Fe2+ as a cofactor. This iron dependency makes d…
A Gram-positive, obligate anaerobic genus within the lachnospiraceae family (Firmicutes phylum). Dorea occupies a mixed role in the gut ecosystem -- while it is a core member of the healthy human microbiome, several species are consistently enriched in autoimmune and ne…
Dysmenorrhea -- painful menstruation -- is the most common gynecological complaint, affecting 50-90% of reproductive-age women. It is classified as primary (no identifiable pelvic pathology) or secondary (caused by conditions such as endometriosis, adenomyosis, or fibro…
Membrane-spanning protein complexes that actively export substrates from the bacterial cell, using energy from ATP hydrolysis or the proton motive force. In the context of metal-microbiome biology, efflux pumps serve a dual role that has profound clinical consequences: …
Eggerthella is a genus of Gram-positive, strictly anaerobic, non-spore-forming bacteria in the family Eggerthellaceae (phylum Actinobacteria). The most studied species, Eggerthella lenta, was originally classified as Eubacterium lentum before reclassification. It is a n…
Endometriosis is a chronic estrogen-dependent inflammatory condition affecting approximately 10% of reproductive-age women, characterized by the growth of endometrial-like tissue outside the uterus colonetti 2023 gut vaginal microbiota endometriosis meta analysis. The c…
A genus of Gram-positive bacteria (primarily E. faecalis and E. faecium) that exemplifies the metal-antibiotic resistance co-selection crisis. Enterococci carry diverse metal tolerance genes for mercury, arsenic, copper, and cadmium on the same mobile genetic elements a…
Enterococcus faecalis is a Gram-positive, facultatively anaerobic coccus that inhabits the gastrointestinal tract, oral cavity, and genitourinary tract of humans. It is a commensal in the healthy gut at low abundance but is one of the most clinically significant opportu…
This page addresses the practical question: how do toxic metals get into people? Metal toxicology research identifies the mechanisms of harm, but understanding exposure routes -- dietary, occupational, environmental, and consumer product-mediated -- is essential for pre…
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…
Epigenetics is the study of heritable changes in gene expression that occur without alterations to the DNA sequence itself. These changes -- primarily DNA methylation, histone modifications, and non-coding RNA regulation -- represent a molecular memory system that can b…
Escherichia is a genus of Gram-negative, facultatively anaerobic bacteria in the Enterobacteriaceae family. The primary species E. coli is simultaneously the most studied bacterium in biology and one of the most consistently enriched organisms in disease-associated micr…
A Gram-negative bacterium that spans the commensal-pathogen spectrum, with pathogenic variants (UPEC, STEC, EHEC) deploying nickel-dependent enzymes as virulence factors. E. coli is the model organism for nickel transport biology -- the NikABCDE system was first charact…
Essential oils are volatile aromatic compounds extracted from plants, composed primarily of terpenes, phenylpropanoids, and their oxygenated derivatives. In the WikiBiome context, essential oils are relevant not as aromatherapy but as sources of bioactive molecules with…
The transfer of processed stool from a healthy donor into a recipient's gastrointestinal tract to restore a disrupted microbial community. FMT is the most direct form of microbiome intervention -- replacing the entire community rather than supplementing individual strai…
Fecal microbiota transplant (FMT) for ASD aims to replace the dysbiotic gut community with a diverse donor microbiome. Open-label results show improvements in both GI symptoms and behavioral measures, but benefits are lost within weeks after cessation.