WikiBiomeThe human microbiome encyclopediaRanked matches across titles, topics, categories, and article introductions.
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…
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 …
Actinobacteria (reclassified as Actinomycetota in 2021) is a major Gram-positive, high-GC-content bacterial phylum with remarkable ecological breadth. In the gut, it typically comprises 1-10% of the community -- a distant third behind firmicutes and bacteroidetes -- but…
A genus of Gram-positive, facultatively anaerobic, filamentous bacteria that are among the most abundant colonizers of the human oral cavity. Actinomyces species, particularly A. naeslundii, play dual roles as early dental plaque colonizers and as opportunistic pathogen…
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…
A 140-amino-acid presynaptic protein whose misfolding into insoluble fibrils and their deposition in Lewy bodies is the defining neuropathological hallmark of parkinsons disease and the broader family of synucleinopathies (including Lewy body dementia and multiple syste…
Alternaria is a ubiquitous environmental mold genus comprising over 300 species, with A. alternata as the most common human-associated species. Primarily recognized as an outdoor allergen and plant pathogen, Alternaria is increasingly documented as a component of the hu…
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…
Amyloid-beta (Aβ) is a 36–43 amino acid peptide derived from the proteolytic cleavage of amyloid precursor protein (APP) by beta-secretase (BACE1) and gamma-secretase. Its aggregation from soluble monomers into insoluble fibrillar plaques in the brain is the defining ne…
Anaerococcus is a genus of Gram-positive, obligate anaerobic cocci within the phylum Firmicutes. It is a normal inhabitant of the human vaginal, skin, and gastrointestinal microbiota, but is recognized as an opportunistic pathogen in dysbiotic states, particularly when …
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…
A ubiquitous filamentous fungal genus that is both an environmental saprophyte and an opportunistic human pathogen. A. fumigatus is the primary cause of invasive aspergillosis in immunocompromised patients, while A. niger is relevant to food contamination. The genus is …
Autophagy (from Greek, "self-eating") is the cellular process of degrading and recycling damaged organelles, misfolded proteins, and intracellular pathogens through lysosomal digestion. It is the cell's primary quality control mechanism -- a housekeeping system that bec…
A Gram-positive, aerobic to facultatively anaerobic, spore-forming genus that bridges environmental and human microbiology. The genus encompasses both beneficial species (B. subtilis, B. coagulans as probiotics) and pathogens (B. cereus causing food poisoning, B. anthra…
The bacterial contamination hypothesis proposes that bacterial endotoxin (LPS) contamination of menstrual blood and endometrial tissue is a key driver of endometriosis pathogenesis. First formalized by Khan et al. (2018), this hypothesis shifts endometriosis from a pure…
Bacterial vaginosis (BV) is the most common vaginal infection in women of reproductive age, affecting an estimated 29% of women globally. Rather than an infection by a single pathogen, BV represents a polymicrobial dysbiotic state -- a collapse of the protective Lactoba…
Bacteroides is the most abundant genus in the Western adult gut and a cornerstone of intestinal polysaccharide metabolism. As members of the bacteroidetes phylum, Bacteroides species encode enormous repertoires of carbohydrate-active enzymes (CAZymes) organized into pol…
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-glucuronidase (β-glucuronidase, EC 3.2.1.31) is an enzyme that catalyzes the hydrolysis of glucuronidated compounds, cleaving the β-1,4-glycosidic bond between a sugar and a glucuronic acid group. In the microbiome, beta-glucuronidase is the key enzyme of the estro…
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…
A selective semipermeable border formed by brain endothelial cells connected by tight junctions, pericytes, and astrocytic end-feet. The BBB restricts passage of most molecules from blood to brain, protecting the CNS from toxins, pathogens, and inflammatory mediators. M…
A genus of Gram-negative intracellular pathogens causing brucellosis, the most common bacterial zoonosis worldwide. Brucella species depend on nickel-activated urease for gastrointestinal survival during the initial phase of infection, and urease immunization has been s…
CagA is an effector protein produced by some strains of helicobacter pylori. Its name derives from “cytotoxin-associated gene A.” CagA is delivered into gastric epithelial cells through the bacterium's type IV secretion system and is therefore different from a freely se…
A heterodimer of S100A8 and S100A9 calcium-binding proteins that constitutes approximately 60% of the cytosolic protein content of neutrophils. Calprotectin is a central effector of nutritional immunity, sequestering essential transition metals from invading pathogens a…
The leading bacterial cause of diarrheal disease worldwide, with an estimated 400-500 million cases annually. C. jejuni is notable in the metallomics context for possessing a nickel-dependent [NiFe] hydrogenase essential for colonization but lacking urease -- a striking…
An opportunistic fungal pathogen whose relationship with metals is multifaceted: C. albicans can biosorb heavy metals from its environment, heavy metal exposure promotes its virulence in immunocompromised hosts, and metal nanoparticles are being developed as antifungal …
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…
Candidozyma auris is the current name for NCBITaxon:498019. Liu and colleagues established the combination in 2024 as MycoBank MB 848169; Candida auris Satoh & Makimura 2009 is its basionym, not a separate species ncbi taxonomy candidozyma auris index fungorum candidozy…
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…
Celiac disease is a chronic autoimmune condition triggered by dietary gluten (gliadin proteins from wheat, barley, and rye) in genetically susceptible individuals (HLA-DQ2/DQ8, carried by ~30-40% of Europeans but penetrant in only ~1% of carriers). Gluten exposure cause…
Cerebral palsy (CP) is the most common motor disability in childhood, affecting 2-3 per 1,000 live births allen 2021 multi organ dysfunction cerebral palsy. Characterized by non-progressive disturbances in movement and posture arising from injury to the developing brain…
Chitotriosidase (CHIT1) is a human chitinase that degrades chitin — the structural polysaccharide of fungal cell walls, insect exoskeletons, and parasitic helminths. It is the most abundant chitinase in human serum and represents a direct arm of innate nutritional immun…
Chlamydia is a genus of obligate intracellular, Gram-negative bacteria with a unique biphasic developmental cycle. The genus includes three species pathogenic to humans: chlamydia trachomatis (STI and trachoma), C. pneumoniae (respiratory infections, atherosclerosis ass…
Citrobacter is a genus of Gram-negative, facultatively anaerobic bacteria in the Enterobacteriaceae family, named for its ability to utilize citrate as a sole carbon source. Species include C. freundii, C. koseri, and C. rodentium (a mouse model for EHEC infection). In …
A class of Gram-positive, obligate anaerobic bacteria within the phylum Firmicutes that represents the most functionally diverse and clinically significant taxonomic class in the human gut microbiome. Clostridia encompasses the dominant butyrate producers sustaining col…
Clostridioides difficile is the current NCBI name for NCBITaxon:1496 and the correct, medically recommended combination recorded by LPSN. Both records retain Clostridium difficile as a validly published homotypic synonym of the same organism rather than a separate speci…
A large, polyphyletic genus of Gram-positive, obligate anaerobic, spore-forming bacteria encompassing both critical beneficial commensals and dangerous pathogens. Former Clostridium clusters IV and XIVa are now reclassified into ruminococcus-family Ruminococcaceae and l…
Clostridium perfringens is a Gram-positive, strictly anaerobic, spore-forming bacterium infamous for causing gas gangrene, food poisoning, and necrotizing enterocolitis (NEC) in premature infants. It is one of the most widely distributed pathogenic bacteria in nature, f…
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…
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…
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…
Corynebacterium is a large genus of Gram-positive, club-shaped bacteria with over 130 species spanning commensals, opportunistic pathogens, and the classic pathogen C. diphtheriae. In the WikiBiome context, Corynebacterium is most notable for its dominance in the male r…
An encapsulated basidiomycete yeast that causes cryptococcal meningitis -- the leading cause of meningitis in HIV/AIDS patients and responsible for an estimated 180,000 deaths annually. Its nickel-dependent urease has been called the organism's "Achilles' heel" because …
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…
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…
Drug repurposing (also called drug repositioning) is the strategy of identifying new therapeutic uses for existing approved drugs. It dramatically accelerates the path from bench to bedside because safety, pharmacokinetics, and manufacturing are already established. In …
A Gram-positive obligate anaerobe and key estrobolome member that links metabolic dysbiosis to hormone-driven diseases, particularly endometriosis. E. lenta is remarkable for its ability to inactivate cardiac glycosides (like digoxin) and to produce beta-glucuronidase, …
Enterobacter is a genus of Gram-negative, facultatively anaerobic bacteria in the enterobacteriaceae family. Key species include enterobacter cloacae (the most clinically relevant) and E. hormaechei. Like other Enterobacteriaceae, Enterobacter possesses iron-dependent s…
Enterobacter cloacae is a Gram-negative, facultatively anaerobic member of the Enterobacteriaceae. Ubiquitous in soil, water, and the mammalian gut, it is a leading cause of nosocomial infections and carries clinically significant antibiotic resistance through inducible…
A family of Gram-negative, facultative anaerobic Gammaproteobacteria that includes many of the most important human pathogens: escherichia coli, klebsiella pneumoniae, salmonella typhimurium, shigella flexneri, yersinia pestis, proteus mirabilis, Morganella, and Serrati…
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…
Enterococcus faecium is a Gram-positive, facultatively anaerobic bacterium that epitomizes the metal-antibiotic co selection problem in modern medicine. As one of the six ESKAPE pathogens (the group responsible for the majority of hospital-acquired infections that fail …
Erysipelotrichaceae is a family within the phylum Firmicutes that has drawn increasing attention for its consistent enrichment in metabolic disorders. Members of this family are Gram-positive, obligate anaerobes found throughout the mammalian gastrointestinal tract, whe…
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…
Functional shielding is the phenomenon in which one microorganism — typically a fungus — physically and immunologically protects a co-resident pathogen from host immune attack, antimicrobial agents, and oxidative stress. The shielding organism's biofilm matrix acts as a…
A Gram-negative obligate anaerobe that has emerged as a major pathogen in colorectal cancer (CRC) and inflammatory bowel disease. F. nucleatum is significantly enriched in CRC tissue and tumors compared to healthy mucosa, making it one of the strongest microbe-cancer as…
A Gram-negative obligate anaerobe that occupies a paradoxical niche in the gut microbiota: as a weak butyrate producer (short-chain fatty acid), it has anti-inflammatory potential; as a virulent invasive pathobiont in inflammatory bowel disease (particularly ulcerative …
Gardnerella vaginalis is a Gram-variable, facultatively anaerobic bacterium that is the key organism in bacterial vaginosis (BV), the most common vaginal infection in women of reproductive age. Its sialidase production, biofilm-forming capacity, and associations with he…
See also the genus page: gardnerella Gardnerella vaginalis is the primary causative agent of bacterial vaginosis (BV), the most common vaginal infection worldwide. This species page focuses on the species-level biology — particularly the vaginolysin cytotoxin and biofil…
The fifth most common cancer worldwide and third leading cause of cancer death, with over 1 million new cases annually. Gastric cancer stands unique in this wiki as the disease where a single microorganism -- helicobacter pylori -- provides the dominant causal pathway, …
Gene regulation in bacteria is the process by which cells control when and how much of each gene product is made. In the metallomics context, gene regulation is the mechanism by which bacteria respond to the metal environment -- sensing metal availability and adjusting …
Alphabetical definitions of specialist terms used throughout this wiki. Where a full concept page exists, the term links to it. --- AhR (aryl hydrocarbon receptor) -- A ligand-activated transcription factor that senses microbial metabolites (especially indoles from tryp…
The third nickel-dependent enzyme class in human pathogens, after urease and hydrogenase. Glyoxalase I detoxifies methylglyoxal, a reactive and toxic byproduct of glycolysis. While less well-known than urease or hydrogenase as a virulence factor, GloI is emerging as a s…
Haemophilus is a genus of small, Gram-negative, facultatively anaerobic coccobacilli that inhabit the upper respiratory tract, oral cavity, and gastrointestinal tract. The genus name literally means "blood-loving" -- a direct reference to its absolute requirement for he…
A Gram-negative, microaerophilic bacterium within the Epsilonproteobacteria (family Helicobacteraceae) that is the primary murine model of hepatobiliary and intestinal disease. Unlike its more famous relative helicobacter pylori, which colonizes the stomach, H. hepaticu…
A gastric pathogen that is arguably the most nickel-dependent human pathogen known. Two of its key virulence factors — urease and [NiFe] hydrogenase — require nickel, and the bacterium has evolved an elaborate nickel trafficking, storage, and regulation system to suppor…
[NiFe] hydrogenases are the second major nickel-dependent virulence factor class in human pathogens. Less widespread than urease but critical for energy metabolism in gastric, enteric, and intracellular pathogens. The discovery that H. pylori hydrogenase powers CagA tra…
Interferon gamma (IFN-γ) is the signature Th1 cytokine and the primary activator of macrophage antimicrobial functions. In the WikiBiome framework, IFN-γ is critical for two reasons: it drives nutritional immunity (iron restriction against intracellular pathogens) and i…
Innate immunity is the body's first-line, non-specific defense against pathogens — comprising physical barriers (epithelium, mucus), antimicrobial molecules (calprotectin, lactoferrin, defensins), pattern recognition receptors (TLRs, NOD-like receptors), and phagocytic …