Marker Guide

Hydrogen sulphide producing microbes

What this marker measures

The gut microbial community’s capacity to produce hydrogen sulphide (H₂S), a gas generated from the microbial metabolism of sulphur-containing compounds. At physiological levels, H₂S may support colonic epithelial cell signalling and energy metabolism¹; however, at excessive levels, it may compromise the mucus layer and gut barrier integrity^.1–3

Clinical associations

Consider this marker when your patient presents with:

Gut barrier or inflammatory concerns

Suspected increased intestinal permeability, mucus layer disruption, or chronic intestinal inflammation.

Clinical consideration

Also consider when low butyrate-producing potential co-occurs with high H₂S-producing potential, as excess H₂S may inhibit colonocyte butyrate oxidation and compound barrier stress^4,5

Gas and bowel habit symptoms

Bloating, malodorous gas or diarrhoea-predominant

Interpreting the result

All results are compared to Microba's healthy cohort to determine whether they fall within or outside the expected range.

LOW

Hydrogen sulphide-producing potential is lower than expected

This result does not suggest excess H₂S production. No marker-specific intervention needed.

Within Range

Hydrogen sulphide-producing potential is within expected parameters

Suggests physiological H₂S levels may support epithelial signalling and mucosal homeostasis.

HIGH

Hydrogen sulphide-producing potential is higher than expected

May indicate increased  potential mucus layer disruption, impaired colonocyte energy metabolism, and reduced gut barrier integrity. Action: see patient management insights

Patient management insights

Excess hydrogen sulphide-producing potential and support mucus layer and gut barrier integrity.

Dietary strategies

A diet rich in plant foods may reduce levels of sulphate- and taurine-reducing bacteria⁶⁹
GRADE C

Limiting excess intake of sulphur-rich animal proteins, particularly red and processed meats, may reduce microbial H2S production^9,10.
GRADE D

Supplementation Prebiotics

GOS (galacto-oligosaccharides) supplementation may reduce levels of sulphate-reducing bacteria¹¹GRADE D

Inulin supplementation may reduce levels of sulphate-reducing bacteria^12,13GRADE D

Tips for patients discussion

Your report shows elevated levels of gut microbes that produce hydrogen sulphide, a gas with a 'rotten egg' smell. In excess, it can compromise the protective mucus layer and gut barrier. Gradually increasing tolerated fibre and diverse plant foods, while moderating sulphur-rich animal proteins like red and processed meats, can help.

The community

Hydrogen sulphide is not produced by a single species, it's a community-level function. Below are some of the most common, though this list is not exhaustive.

Clostridium saudiense
Blautia_A MIC9206
Gordonibacter urolithinfaciens
Flavonifractor plautii
Clostridium_M bolteae
Erysipelatoclostridium ramosum
Mailhella MIC8103
Romboutsia timonensis
Clostridium sp000435835
Desulfovibrio piger
Gordonibacter pamelaeae
Mailhella sp003150275
UBA7182 MIC8275
Blautia_A MIC8343
Desulfovibrio fairfieldensis
Clostridium_M MIC9612
Blautia_A hydrogenotrophica
Desulfovibrio fairfieldensis
Turicibacter sanguinis
Blautia_A obeum
Turicibacter sp001543345
Lawsonibacter sp000177015
Bilophila wadsworthia

How results are calculated

All microbiome marker results are compared against the Microba Healthy Cohort — a purpose-built reference group of more than 450 healthy individuals, collected and analysed using the same workflow as patient samples.

Each marker is scored by comparing the patient's relative abundance against the cohort average. The distance from this average is expressed as standard deviations, and determines whether a result is classified as Low, Borderline, or High.

How the result scale works

▲ AVG (Healthy Cohort average)

The patient's relative abundance is compared to the Healthy Cohort average. A negative distance from average means the microbial group is less abundant than the Healthy Cohort. A positive distance means it is more abundant. Results falling outside the expected range are classified as borderline or high/low (borderline high/low:+/-0.68,andhigh/low:+/-1.28).

Evidence grading for patient management insights

The letter grades shown next to each patient management insight show the quality of the research behind it. Every insight provided has been through a rigorous review of the scientific literature and graded using the NHMRC Levels of Evidence, so you can see exactly how strong the evidence is before applying it in practice.

Source references for all clinical associations, interpretation definitions, and patient management insights on this card.

1. Blachier, F. et al. Production of hydrogen sulfide by the intestinal microbiota and epithelial cells and consequences for the colonic and rectal mucosa. American Journal of Physiology-Gastrointestinal and Liver Physiology 320, G125–G135 (2021).
2. Singh, S. B. et al. Intestinal Alkaline Phosphatase Prevents Sulfate Reducing Bacteria-Induced Increased Tight Junction Permeability by Inhibiting Snail Pathway. Front. Cell. Infect. Microbiol. 12, 882498 (2022).
3. Ijssennagger, N. et al. Gut microbiota facilitates dietary heme-induced epithelial hyperproliferation by opening the mucus barrier in colon. Proc. Natl. Acad. Sci. U.S.A. 112, 10038–10043 (2015).
4. Beaumont, M. et al. Detrimental effects for colonocytes of an increased exposure to luminal hydrogen sulfide: The adaptive response. Free Radical Biology and Medicine 93, 155–164 (2016).
5. Babidge, W., Millard, S. & Roediger, W. Sulfides impair short chain fatty acid β-oxidation at acyl-CoA dehydrogenase level in colonocytes: Implications for ulcerative colitis. Mol Cell Biochem 181, 117–124 (1998).
6. Teigen, L. et al. Differential hydrogen sulfide production by a human cohort in response to animal- and plant-based diet interventions. Clin Nutr 41, 1153–1162 (2022).
7. Kellingray, L. et al. Consumption of a diet rich in Brassica vegetables is associated with a reduced abundance of sulphate-reducing bacteria: A randomised crossover study. Molecular Nutrition & Food Research 61, 1600992 (2017).
8. Koponen, K. K. et al. Associations of healthy food choices with gut microbiota profiles. The American Journal of Clinical Nutrition 114, 605–616 (2021).
9. David, L. A. et al. Diet rapidly and reproducibly alters the human gut microbiome. Nature 505, 559–563 (2014).
10. Magee, E. A., Richardson, C. J., Hughes, R. & Cummings, J. H. Contribution of dietary protein to sulfide production in the large intestine: an in vitro and a controlled feeding study in humans123. The American Journal of Clinical Nutrition 72, 1488–1494 (2000).
11. Vulevic, J., Drakoularakou, A., Yaqoob, P., Tzortzis, G. & Gibson, G. R. Modulation of the fecal microflora profile and immune function by a novel trans-galactooligosaccharide mixture (B-GOS) in healthy elderly volunteers. The American Journal of Clinical Nutrition 88, 1438–1446 (2008).
12. Hiel, S. et al. Link between gut microbiota and health outcomes in inulin -treated obese patients: Lessons from the Food4Gut multicenter randomized placebo-controlled trial. Clinical Nutrition 39, 3618–3628 (2020)
.13. Holscher, H. D. Dietary fiber and prebiotics and the gastrointestinal microbiota. Gut microbes 8, 172–184 (2017).