WikiBiomeThe human microbiome encyclopediaRanked matches across titles, topics, categories, and article introductions.
16S rRNA gene sequencing is the most widely used method for characterizing bacterial communities in this wiki. It targets the ~1,500 base pair 16S ribosomal RNA gene, which contains nine hypervariable regions (V1–V9) flanked by conserved sequences. Universal primers amp…
A class of Gram-negative bacteria within the phylum Proteobacteria that has emerged as a causal risk factor for schizophrenia and bipolar disorder through Mendelian randomization studies. Betaproteobacteria includes genera with notable metal tolerance -- particularly wi…
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…
Measurable indicators of biological state, exposure, or disease. In the metallomics context, biomarkers span three interconnected domains: metal biomarkers (quantifying exposure and body burden), microbiome biomarkers (reflecting microbial community disruption), and met…
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…
Cholestasis is the impairment or cessation of bile flow from the liver to the duodenum. It can be intrahepatic (hepatocyte or bile ductule dysfunction) or extrahepatic (mechanical obstruction). Beyond its direct hepatic consequences, cholestasis profoundly disrupts the …
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 butyricum is a spore-forming, obligate anaerobic, Gram-positive bacterium and one of the leading next-generation probiotic candidates. The MIYAIRI 588 strain (CBM 588) is approved as a pharmaceutical probiotic in Japan and has expanding clinical evidence acr…
Deinococcus is a genus of extremophilic bacteria famous for extraordinary resistance to ionizing radiation, desiccation, and oxidative stress. D. radiodurans — "Conan the Bacterium" — can survive radiation doses 1,000 times greater than those lethal to humans. This resi…
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…
lead (Pb) has no safe level of exposure. Unlike most dietary metals, lead does not play any known biological role — every atom absorbed represents toxic burden. While environmental lead exposure (paint, soil, air) has decreased dramatically since leaded gasoline phase-o…
Direct DNA damage is the primary carcinogenic mechanism for chromium but is notably absent or minor for nickel and arsenic. This distinction is fundamental to understanding why these three metals cause cancer through such different pathways.
Endothelial dysfunction is the impairment of the vascular endothelium's ability to produce nitric oxide (NO), regulate vascular tone, and prevent thrombosis. It is the earliest detectable stage of atherosclerosis and the mechanistic link between gut dysbiosis, systemic …
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…
Erectile dysfunction (ED) affects 30-50% of men aged 40-70 Feldman et al. 1994, with prevalence increasing with age. Conventionally understood as a vascular and/or neurogenic disorder, ED is now recognized as a condition with a significant gut microbiome component -- th…
Research summary — not medical advice. This page synthesizes published research on a mechanism-level intervention. It is not a clinical recommendation. Consult a qualified healthcare provider before making any changes to diet, supplementation, or treatment.
Ferroptosis is a form of iron-dependent regulated cell death driven by the accumulation of lipid peroxides on cellular membranes pendergrass 2026 microbial metallomics parkinsons ferroptosis, riederer 2021 iron concert master parkinsons. Unlike apoptosis or necrosis, fe…
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 gut-kidney axis describes the bidirectional relationship between the gut microbiome and kidney function. As kidney disease progresses, the resulting biochemical changes (uremia, altered pH, fluid shifts) reshape the gut microbiome. The dysbiotic microbiome, in turn,…
The gut-penis axis is an emerging concept describing the systemic pathway by which gut microbiome dysbiosis impairs erectile function through endothelial nitric oxide (NO) suppression and chronic inflammation. Though less established than the gut-brain or gut-heart axes…
The gut-testis axis describes the bidirectional communication between the gut microbiome and the male reproductive system. Gut-derived microbial metabolites, immune signals, and systemic inflammatory mediators influence testicular function, testosterone biosynthesis, an…
Hashimoto's thyroiditis (HT) is the most common autoimmune disease globally and the leading cause of hypothyroidism. Chronic lymphocytic infiltration of the thyroid gland progressively destroys follicular architecture, reducing thyroid hormone output. Prevalence is 5-10…
Hypoxia refers to a state of low oxygen tension (partial pressure of O₂ < 5% in tissue, vs. ~21% in air). In the context of microbiome metallomics, hypoxia is a critical ecological determinant that reshapes bacterial community structure by favoring obligate and facultat…
Interleukin-22 (IL-22) is an immune signaling protein that helps coordinate host responses at epithelial surfaces. In the gut evidence represented by WikiBiome, group 3 innate lymphoid cells (ILC3s) are a prominent source, while Th17-associated responses can also includ…
Lactococcus lactis is a Gram-positive, facultatively anaerobic, lactic acid bacterium best known as the workhorse of the dairy fermentation industry. It holds GRAS (Generally Recognized As Safe) status and has emerged as a versatile platform for probiotic and therapeuti…
Lead is a purely toxic heavy metal with no known biological function. It is the most extensively studied metal in relation to neurodevelopmental harm and is increasingly recognized as a contributor to chronic disease across virtually every organ system, even at levels o…
Leptin is an adipokine (hormone produced by adipose tissue) that signals satiety to the hypothalamus — suppressing appetite and increasing energy expenditure. Leptin resistance (elevated leptin with impaired signaling) is a hallmark of obesity, paralleling insulin resis…
Post-acute sequelae of SARS-CoV-2 infection (PASC), affecting an estimated 10-30% of COVID-19 survivors (WHO and CDC post-acute surveillance estimates) with symptoms persisting 12 weeks. Characterized by fatigue, cognitive dysfunction ("brain fog"), exercise intolerance…
A cluster of conditions — high blood pressure, impaired fasting glucose, insulin resistance, abdominal obesity (BMI ≥25), high triglycerides, low HDL-C — defined by the presence of ≥3 components. Emerging evidence links MetS to environmental nickel exposure, though find…
The ability of certain metals to cause cancer has been known since the 19th century. The three metals covered in this wiki — nickel, arsenic, and chromium — represent distinct mechanistic paradigms that collectively illustrate the diversity of metal-induced carcinogenes…
Methylobacterium is a genus of methylotrophic alpha-Proteobacteria (phylum Pseudomonadota) predominantly found in soil, water, plant surfaces, and air environments. It is a methylotroph — capable of using one-carbon compounds such as methanol as a carbon and energy sour…
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…
Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease of the central nervous system, with a global prevalence of approximately 2.8 million attfield 2022 immunology ms nature review. The conventional framing centers on genetic susceptibility (HLA-DRB115:0…
Necrotizing enterocolitis (NEC) is the most common and lethal gastrointestinal emergency in premature infants, affecting 5-12% of very low birth weight neonates (<1500 g) with mortality rates of 20-30%. Characterized by intestinal inflammation, necrosis, and perforation…
Neuroinflammation is an immune response within the central nervous system (CNS)—the brain and spinal cord. It involves changing states of microglia, astrocytes, cells of the neurovascular unit, and, in some settings, immune cells recruited from the circulation. The resp…
Chronic nickel exposure can damage the central nervous system, causing behavioral and cognitive deficits through oxidative stress in the hippocampus and disruption of multiple neurotransmitter systems.
A family of Gram-positive obligate anaerobes (formerly classified as the genus Oscillospira, now reclassified into Oscillibacter and related genera within Oscillospiraceae) that serve as keystone butyrate producers in the healthy human distal colonic microbiota (Konikof…
Pancreatitis is inflammation of the pancreas, occurring in acute (AP) and chronic (CP) forms. Acute pancreatitis ranges from mild self-limiting disease to severe necrotizing pancreatitis with 20-30% mortality. Chronic pancreatitis is a risk factor for pancreatic cancer …
Postpartum depression (PPD) affects 10-20% of women after delivery, with profound consequences for maternal health, infant bonding, and child neurodevelopment chao 2025 microbiota gut brain perinatal depression. The standard framing centers on hormonal withdrawal (estro…
Premenstrual syndrome (PMS) affects an estimated 20-40% of women of reproductive age, characterized by cyclical physical and psychological symptoms in the luteal phase (post-ovulation, pre-menstruation). While PMS has traditionally been attributed solely to hormonal flu…
The semen microbiome refers to the microbial community inhabiting the male reproductive tract and seminal fluid. Core genera identified through shotgun metagenomic sequencing include Corynebacterium, Staphylococcus, Streptococcus, and Prevotella, though composition vari…
A genus of Gram-positive, facultative anaerobic cocci that includes some of the most clinically significant human pathogens. Staphylococci are defined by their exceptionally comprehensive metal acquisition arsenal -- arguably the most thoroughly characterized of any bac…
Streptococcus thermophilus is a Gram-positive, facultative anaerobic coccus that is the primary probiotic species used in commercial yogurt fermentation and thermophilic dairy fermentation worldwide. Distinct from pathogenic Streptococcus species, S. thermophilus produc…
Vitamin C (ascorbate) is broadly protective: it reduces nickel absorption from food (acting as a competitive inhibitor in the GI tract), is the most commonly recommended adjunct to low-nickel diets zirwas 2009 dietary nickel dermatitis, and is a critical cofactor for DN…
The exposome is the totality of environmental exposures an individual experiences from conception to death. Coined by Christopher Wild in 2005, it complements the genome by capturing the environmental side of the gene-environment equation. Metals are among the most quan…
Iron deficiency is common and clinically significant across multiple conditions: postpartum anemia increases PPD risk 1.89-fold (RR = 1.887), low ferritin (<1 ug) increases PPD risk 3.98-fold azami 2019 anemia ppd meta analysis, iron deficiency impairs thyroid peroxidas…
Type 2 diabetes (T2D) is a metabolic disease characterized by insulin resistance and progressive beta-cell dysfunction, affecting over 500 million people worldwide (IDF Diabetes Atlas 2021). The conventional framing centers on caloric excess and sedentary behavior. The …
Vitamin B12 (cobalamin) is an essential cobalt-containing cofactor required for homocysteine metabolism, methylation reactions, and neurological function. Its core corrin ring chelates a cobalt ion, placing B12 at the intersection of metallomics and microbial ecology. C…