WikiBiomeThe human microbiome encyclopediaRanked matches across titles, topics, categories, and article introductions, filtered to microbe.
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…
Adlercreutzia is a genus of Gram-positive, strictly anaerobic gut bacteria within the phylum Actinobacteria, named after Finnish researcher Herman Adlercreutz who pioneered phytoestrogen research. The genus is best known for producing equol, a potent bioactive metabolit…
Aerococcus is a genus of Gram-positive, alpha-hemolytic, catalase-negative cocci. The primary species of clinical relevance are A. urinae (a cause of urinary tract infections, particularly in elderly men) and A. christensenii (a vaginal commensal). In the WikiBiome vaul…
A Gram-negative, obligate anaerobic, mucin-degrading bacterium that colonizes the intestinal mucus layer and has emerged as one of the most important next-generation probiotics. A. muciniphila is consistently depleted in disease states associated with metal dyshomeostas…
A Gram-negative, obligate anaerobic genus within the Bacteroidetes phylum (family Rikenellaceae). Alistipes occupies a complex and context-dependent role in the gut ecosystem — some species carry well-documented anti-inflammatory properties, while the genus is paradoxic…
Alloprevotella is a genus of Gram-negative, obligate anaerobic bacteria within the family Prevotellaceae that represents a distinct clade from prevotella with specific protective roles in type 2 diabetes prevention and metabolic health. Alloprevotella depletion is one o…
Bacteroidales is an order of obligate anaerobic, Gram-negative bacteria within the phylum Bacteroidetes. It includes the families Bacteroidaceae (bacteroides), Prevotellaceae (prevotella), Rikenellaceae, and Porphyromonadaceae (porphyromonas). Bacteroidales are among th…
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…
Bacteroides caccae is a Gram-negative, obligate anaerobic member of the bacteroidetes phylum and a common fiber-degrading commensal in the human colon. While less individually prominent than bacteroides fragilis or bacteroides thetaiotaomicron, B. caccae has emerged as …
A Gram-negative obligate anaerobe and the most clinically significant member of the Bacteroides genus. B. fragilis occupies a unique dual position in gut microbiology: as a non-toxigenic commensal (NTBF), it produces polysaccharide A (PSA) that shapes immune tolerance; …
Bacteroides thetaiotaomicron is one of the most abundant and metabolically versatile commensals of the human gut, routinely cited as a model organism for studying host-microbe symbiosis. Its genome was one of the first human gut bacterial genomes fully sequenced, and su…
A Gram-negative, obligate anaerobic bacterium within the phylum Bacteroidetes and a common member of the healthy human gut microbiota. B. uniformis is a versatile polysaccharide degrader with emerging significance as an anti-inflammatory commensal whose depletion appear…
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.…
Bacteroidetes (recently reclassified as Bacteroidota) is one of the two dominant bacterial phyla in the human gut, together with firmicutes typically comprising 90% of the intestinal microbiota. Bacteroidetes are Gram-negative, obligately anaerobic, non-spore-forming ro…
Bifidobacteriaceae is the family containing bifidobacterium and related genera (alloscardovia). It is the dominant family in the healthy infant gut and a significant commensal family in adults. Family-level depletion is documented in ASD (marked reduction of Actinobacte…
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 genus of Gram-positive, obligate anaerobic bacteria that dominate the infant gut microbiome and remain important commensals throughout life. Bifidobacterium species are distinctive in the metallomics context because some species possess Ni-dependent urease -- an unusu…
Bifidobacterium bifidum is an obligate anaerobic, Gram-positive species that specializes in human milk oligosaccharide (HMO) and mucin glycan degradation. It is one of the earliest colonizers of the infant gut and a widely used probiotic species.
Bifidobacterium longum is a Gram-positive, obligate anaerobic bacterium and one of the most important commensal species in human health from infancy through old age. Its subspecies — B. longum subsp. longum (adult gut), B. longum subsp. infantis (infant gut, HMO degrade…
A genus of Gram-positive, obligate anaerobic bacteria within the lachnospiraceae family that produces short chain fatty acids and plays a significant role in bile acid metabolism. Key species include B. obeum, B. wexlerae, B. hydrogenotrophica, and B. producta. While pr…
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…
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…
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…
Christensenellaceae is a family of Gram-negative, strictly anaerobic bacteria within the order Clostridiales (phylum Firmicutes) that has emerged as one of the most consistently health-associated and heritable members of the human gut microbiome. First formally describe…
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 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 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…
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…
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…
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…
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…
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…
A genus of Gram-positive, obligate anaerobic bacteria within the Firmicutes phylum that includes several of the most important butyrate producers in the human colon. Key species are E. rectale, E. hallii (now reclassified as Anaerobutyricum hallii), and E. limosum. Cons…
Faecalibacterium is a genus of obligate anaerobic, Gram-positive bacteria in the family Ruminococcaceae (phylum Firmicutes). It is the most abundant genus in the healthy human colon (5–15% of fecal bacteria) and its depletion is the single most reproducible microbiome f…
The most abundant bacterium in the healthy human colon (5-15% of total fecal microbiota), F. prausnitzii is the premier butyrate producer in the gut and a cornerstone of anti-inflammatory intestinal homeostasis. Its depletion is one of the most consistent microbiome sig…
Firmicutes (recently reclassified as Bacillota) is the dominant bacterial phylum in the Western adult gut, comprising the core community of short-chain fatty acid (SCFA) producers that maintain intestinal barrier integrity, regulate immune function, and influence system…
Fusicatenibacter is a Gram-positive obligate anaerobic genus within the Lachnospiraceae (Firmicutes). The primary species, F. saccharivorans, was isolated from human feces and is recognized as a beneficial commensal that produces butyrate and modulates intestinal immune…
A Gram-negative, obligate anaerobic bacterium that has emerged as the most consistently CRC-associated microorganism in human gut microbiome studies. F. nucleatum is the primary species of concern, originally a commensal of the oral cavity that translocates to colorecta…
Gemella is a genus of Gram-positive, facultatively anaerobic cocci that are normal commensals of the oral cavity. Species include G. morbillorum, G. haemolysans, and G. sanguinis. In the WikiBiome context, Gemella is notable for its oral-gut translocation pattern — an o…
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 genus of Gram-positive, strictly anaerobic bacteria in the family Erysipelotrichaceae (phylum Firmicutes) that is emerging as one of the most consistently protective gut commensals in human disease. Holdemanella is depleted across a striking range of conditions -- inf…
Lachnobacterium is a genus of Gram-positive, obligate anaerobic bacteria within the family Lachnospiraceae (phylum Firmicutes). It is a commensal member of the healthy human gut microbiota, though relatively understudied compared to other Lachnospiraceae genera. Lachnob…
Lachnoclostridium is a genus of obligate anaerobic, Gram-positive bacteria in the lachnospiraceae family. It is a butyrate-producing commensal with emerging clinical significance as a treatment response biomarker and diagnostic marker.
Lachnospira is a genus of Gram-positive, obligate anaerobic bacteria within the lachnospiraceae family (Firmicutes phylum). L. pectinoschiza, the type species, is a specialist pectin fermenter that produces short chain fatty acids from plant-derived polysaccharides. The…
A genus of Gram-positive, facultatively anaerobic lactic acid bacteria (LAB) that are among the most extensively studied probiotics. In the metallomics context, Lactobacillus species are critical for two reasons: they actively detoxify heavy metals through binding and s…
A Gram-positive, facultatively anaerobic bacterium that is the dominant species in the healthy human vaginal microbiome and a defining member of Community State Type I (CST-I). L. crispatus dominance is associated with reproductive health, pathogen resistance, and reduc…
Lactobacillus gasseri is a vaginal and gut commensal that defines Community State Type II (CST-II) in the vaginal microbiome. It is a common probiotic species with anti-obesity properties in clinical trials.
Lactobacillus jensenii defines Community State Type V (CST-V) in the vaginal microbiome. It produces hydrogen peroxide and lactic acid, contributing to vaginal defense against pathogens, though less dominant than lactobacillus crispatus (CST-I).
A Gram-negative obligate anaerobe traditionally considered an oral commensal, but increasingly recognized as an opportunistic pathobiont with the ability to translocate from oral biofilms to the gastrointestinal tract and bloodstream. Leptotrichia species are prominentl…
A genus of lipophilic basidiomycete yeasts that is the dominant fungus on human skin and has recently been recognized as a significant component of the gut mycobiome. M. restricta, M. globosa, and M. furfur are the primary species. Originally studied as the cause of dan…
A Gram-positive, obligate anaerobic genus within the family lachnospiraceae (phylum Firmicutes) that was recently reclassified from Ruminococcus based on phylogenomic evidence. The key species Mediterraneibacter faecis (formerly Ruminococcus gnavus clade relatives) is a…
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…
Morganella morganii is a Gram-negative, facultatively anaerobic rod belonging to the family Morganellaceae (formerly classified within Enterobacteriaceae). It inhabits the human gastrointestinal tract as a low-abundance commensal but becomes an opportunistic pathogen in…
Odoribacter splanchnicus is a Gram-negative, obligate anaerobic bacterium belonging to the family Odoribacteraceae within the phylum Bacteroidota (formerly Bacteroidetes). It is a commensal resident of the human colon recognized primarily as a producer of short chain fa…
A Gram-negative, obligate anaerobic genus within the Bacteroidetes phylum, closely related to bacteroides fragilis. The best-characterized species, P. distasonis, has emerged as a key anti-inflammatory commensal with significant roles in bile acid metabolism and metabol…
Parabacteroides distasonis is a Gram-negative obligate anaerobe formerly classified within Bacteroides. It is a core member of the healthy human gut microbiome, typically found in the colon where it contributes to polysaccharide degradation and bile acid metabolism.
Paraprevotella is a genus of obligate anaerobic, Gram-negative bacteria in the family Prevotellaceae, related to prevotella. It is a gut commensal with emerging associations across neuropsychiatric and reproductive conditions. - Schizophrenia: Altered in gut-brain axis …
Parasutterella excrementihominis is a Gram-negative, obligate anaerobic bacterium within the Betaproteobacteria class that has gained attention as an emerging biomarker across metabolic, inflammatory, and endocrine conditions. Despite its relatively recent characterizat…
Parvimonas micra is a small (0.5–1.0 µm), Gram-positive, obligately anaerobic coccus originally isolated from the human oral cavity that has emerged as one of the most consistent and universally enriched pathobionts in colorectal cancer across all geographic regions, ag…
Peptostreptococcus stomatis is a Gram-positive, obligately anaerobic coccus originally isolated from the human oral cavity (oral streptococcal species) that has emerged as a carcinogenic oral pathobiont enriched in colorectal cancer, particularly in advanced stages. Unl…
A Gram-negative, obligate anaerobic genus within the Firmicutes phylum (family Acidaminococcaceae, class Negativicutes). The primary species P. faecium and the recently characterized P. succinatutens are specialized propionate producers that utilize succinate as their m…
A Gram-negative, obligate anaerobic genus within the Bacteroidetes phylum that exemplifies context-dependent microbiome effects -- beneficial in some settings, pathogenic in others. P. copri is the dominant species in the human gut and a hallmark of plant-rich, fiber-ri…
A Gram-negative obligate anaerobe that occupies a unique context-dependent niche in the human gut microbiome. P. copri is significantly enriched in rheumatoid arthritis patients and is associated with metabolic syndrome and obesity, yet in other contexts it can function…
Propionibacterium (largely reclassified as Cutibacterium for skin species) is a genus of Gram-positive, anaerobic to aerotolerant bacteria that produce propionic acid as their primary fermentation product. P. acnes (now Cutibacterium acnes) is the dominant skin commensa…
Proteobacteria (recently reclassified as Pseudomonadota) is the phylum that signals trouble. In a healthy adult gut, Proteobacteria comprise less than 1% of the community. When they bloom to 10-50% of the microbiome, it marks a fundamental ecological shift -- the collap…
Rikenella is a genus of obligate anaerobic, Gram-negative bacteria in the family Rikenellaceae (phylum Bacteroidetes). The primary species is R. microfusus. In the WikiBiome vault, Rikenella is consistently depleted across disease states — a protective commensal whose l…
A genus of Gram-positive, obligate anaerobic, flagellated bacteria within the lachnospiraceae family that ranks among the most important butyrate producers in the human gut. Key species include R. intestinalis and R. hominis. Roseburia is consistently depleted across in…
Roseburia intestinalis is a Gram-positive, obligate anaerobic member of the Lachnospiraceae family (Firmicutes). It is one of the most important butyrate producers in the human colon, converting dietary fiber into butyrate — the primary energy source for colonocytes and…
Rothia is a genus of Gram-positive, facultatively anaerobic bacteria in the family Micrococcaceae (phylum Actinobacteria). The most commonly identified species in microbiome studies are Rothia dentocariosa and Rothia mucilaginosa, both of which are primary inhabitants o…
Ruminococcaceae is a family of obligate anaerobic, Gram-positive bacteria in the order Clostridiales (phylum Firmicutes) that represents one of the most important butyrate-producing and fiber-degrading families in the human gut. Key genera include faecalibacterium (incl…
A genus of Gram-positive, obligate anaerobic cocci within the Firmicutes phylum that exemplifies dual-nature microbiology — containing both keystone beneficial species and disease-associated pathobionts within the same genus. The genus spans multiple former taxonomic gr…
A Gram-positive obligate anaerobe that has emerged as a pro-inflammatory pathobiont enriched across multiple disease states including crohns disease, depression, and multiple sclerosis. R. gnavus produces a species-specific inflammatory polysaccharide that activates int…
A genus of ascomycete yeasts that includes both a proven therapeutic probiotic (S. boulardii) and species associated with disease states (S. cerevisiae enriched in CRC mycobiome). This dual nature -- commensal/probiotic versus disease-associated -- parallels the bacteri…
Saccharomyces cerevisiae is a unicellular budding fungus (ascomycete) ubiquitous in fermentation, brewing, bread-making, and increasingly used as a pharmaceutical probiotic (Hatoum et al. 2012). The strain S. boulardii (also called S. cerevisiae var. boulardii) is the m…
A genus of Gram-negative, crescent-shaped, strictly anaerobic bacteria found in both the oral cavity and the gastrointestinal tract. Selenomonas species are characterized by their distinctive morphology -- a curved rod with a tuft of flagella arising from the concave si…
Staphylococcus epidermidis is a Gram-positive, facultative anaerobic coagulase-negative staphylococcus and one of the most abundant commensals of human skin and mucosal surfaces. While generally benign, it is a leading cause of nosocomial infections associated with indw…
A genus of Gram-positive facultative anaerobes that occupy niches ranging from benign commensals (dental plaque, skin) to acute pathogens (pharyngitis, impetigo, invasive disease). Streptococci are uniquely manganese-dependent for catalytic scavenging of reactive oxygen…
Streptococcus agalactiae, also known as Group B Streptococcus (GBS), is a Gram-positive, facultatively anaerobic coccus that exists in two clinical contexts: (1) as a major neonatal pathogen causing life-threatening meningitis and sepsis in newborns, and (2) as an enric…
The primary architect of dental caries -- the most prevalent chronic infectious disease worldwide. S. mutans is a Gram-positive, facultative anaerobe that colonizes tooth surfaces and produces the acid-rich, metal-managed biofilms known as dental plaque. What sets this …