Faecalibacterium prausnitzii
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Its ID gene: the stretch scientists read to tell microbes apart. Each bar is one letter of its DNA. Every species has its own order of letters, so the pattern works like a fingerprint. Close relatives share most of it.
16S rRNA gene, V4 region: the 253 letters between the standard primers (515F/806R), which are the same in every species. One reference sequence; strains can differ by a letter or two. NCBI NR_028961.1
Formerly Bacillus mucosus anaerobius.
Mid-sized for a gut microbe: longer than 49% of the 2,354 we have genomes for.
56% G+C, higher than 67% of gut microbes.
To scale: if its ID gene were 1 cm long, its genome would stretch 21 meters. Yours would stretch 21 kilometers. One reference genome; strains vary. NCBI GCF_000154385.1
What it can do
- Can make butyrate A short-chain fatty acid that feeds the cells lining the colon.
- Can make lactic acid What yogurt bacteria make; other microbes turn it into butyrate.
- Can ferment fiber Breaks down dietary fiber that our own enzymes can't.
- Can eat inulin A fiber in onions, garlic, leeks, chicory and bananas (also sold as FOS).
- Can eat pectin A fiber in apples, citrus and other fruit.
- Can change bile acids Modifies the bile acids the liver makes to digest fat. 3 of 9 strains can
Not seen in its genomes: make propionate, eat resistant starch, use lactose, feed on gut mucus, make B vitamins, make hydrogen sulfide, make methane.
All 13 capabilities and their evidence
| Capability | Verdict | Genome analysis | Lab tests | Published research |
|---|---|---|---|---|
| Can make butyrate | Can | 9 of 9 genomes | — | Papers say yes |
| Can make propionate | Not seen | 0 of 9 genomes | — | No papers |
| Can make lactic acid | Can | 9 of 9 genomes | — | Papers say yes |
| Can ferment fiber | Can | 9 of 9 genomes | 0 of 3 strains · strip test Strip tests often miss fiber-eaters, so this doesn't override the genomes. | Papers say yes |
| Can eat inulin | Can | 9 of 9 genomes | — | Papers say yes |
| Can eat resistant starch | Not seen | 0 of 9 genomes | — | No papers |
| Can eat pectin | Can | 4 of 9 genomes | — | Papers say yes |
| Can use lactose | Not seen | 0 of 9 genomes | — | No papers |
| Can feed on gut mucus | Not seen | 0 of 9 genomes | — | No papers |
| Can change bile acids | Some strains | 3 of 9 genomes | — | No papers |
| Can make B vitamins | Not seen | 0 of 9 genomes | — | No papers |
| Can make hydrogen sulfide | Not seen | 0 of 9 genomes | — | No papers |
| Can make methane | Not seen | 0 of 9 genomes | — | No papers |
AGORA2 (Heinken et al. 2023) via VMH, CC BY 4.0 · BacDive (DSMZ), CC BY 4.0 · NJC19 (Lim et al., Scientific Data 2020), CC0
In healthy guts
Found in 90% of healthy people.
- largest Segatella copri 6.2%
- 2nd largest Phocaeicola vulgatus 5.0%
- 3rd largest Faecalibacterium prausnitzii 4.7%
- 4th largest Bacteroides uniformis 3.2%
- 5th largest Agathobacter rectalis 2.5%
- 6th largest Alistipes putredinis 2.3%
- 7th largest Bifidobacterium longum 2.1%
- 8th largest Ruminococcus bromii 1.8%
- 2,170 other microbes, each a sliver 56.7%
- 15.6%
On average, 4.7% of the microbes in a healthy gut: the 3rd largest slice.
Every group, drawn the same way. Only some samples record age or sex, so each group says how many people it comes from. Tap one to see it above.
In conditions
Compared with healthy people in the same studies, it’s less common in 10 conditions and more common in none. Only studies that had both are counted.
A difference is an association: it doesn’t mean this microbe causes, prevents or treats any of these.
Strongest first, then the biggest gap · Each figure is 10 people- Colorectal cancer As many carry it in people with it Healthy 97% With it 94%
Carriers have less, in 6 of 8 studies (3.5% → 2.7% of their gut microbes).
In studies of how people live
“Higher” is the study’s measure: on average, a bigger share of gut bacteria across everyone in the group, carriers or not. It isn’t how many people carry it. An association the authors report, measured once per person. It doesn’t mean a diet changes this microbe, or that the microbe affects health.
Recent research
Source: PubMed, U.S. National Library of Medicine · 1,224 linked papers, last 10 years