Streptococcus thermophilus makes folate that feeds certain gut bacteria
What it found
In lab tests, Streptococcus thermophilus IDCC 2201 produced folate, and three gut bacteria grew better when folate or this bacterium was present.
The work was done in culture dishes, not in people.
What they found
Animal and lab studies
Folate production
Among the 16 probiotic strains tested, only Limosilactobacillus fermentum and Streptococcus thermophilus produced significant amounts of folate (vitamin B9) compared to the control medium. Streptococcus thermophilus was identified as a major folate producer.
Folate-dependent growth
When folate was present, Bacteroides thetaiotaomicron, Veillonella parvula, and Ruminococcus faecis grew 2.8, 3.6, and 3.9 times more, respectively, than when folate was absent. These bacteria also grew better when co-cultured with Streptococcus thermophilus than with other bacteria, with increases of 1.2, 1.3, and 1.9 times.
Co-culture effects
In co-culture with Streptococcus thermophilus in folate-free medium, many bacterial strains grew less, but B. thetaiotaomicron, V. parvula, and R. faecis were not affected. These same bacteria showed the greatest dependence on folate, suggesting they may benefit from the folate made by Streptococcus thermophilus.
Nutrient competition
When B. thetaiotaomicron was grown with supernatant from Streptococcus thermophilus, its growth increased in a dose-dependent way, while B. ovatus growth decreased. This suggests that nutrient competition alone does not explain the growth changes.
Metabolite profiles
The 16 probiotic strains had different profiles of short-chain fatty acids and B vitamins. For example, Lactobacillaceae produced more lactic and propionic acid, while Bacillus and Clostridium produced more acetate and butyrate.
What the authors conclude
“Our results indicate that the interaction between probiotics and the human gut microbiota can influence changes in ecological balance through nutrient cross-feeding, and understanding this interaction can be applied to precision probiotic therapies.”
Also in their conclusions
- They say that the interaction between probiotics and gut bacteria can influence the balance of the gut community through nutrient cross-feeding.
- They suggest that understanding these interactions could be used to develop precision probiotic therapies.
- They note that more research is needed to fully understand how Streptococcus thermophilus affects gut bacteria in living animals or people.
How it was done
The authors wanted to understand how probiotics affect gut bacteria through the nutrients they make, especially B vitamins like folate, because this could lead to more precise probiotic treatments.
They measured the metabolites, including short-chain fatty acids and B vitamins, made by 16 commercial probiotic strains. They then grew Streptococcus thermophilus IDCC 2201 together with 17 common human gut bacteria in a medium that mimics the human gut, with and without folate, and tracked bacterial growth.
What it can’t tell you
- These were lab experiments with bacterial cultures, so they cannot show what happens in the human gut.
- The study used a simplified pairwise co-culture system, which does not capture the complexity of the whole gut microbiome.
- The authors note that excessive folate production might have drawbacks, but this study did not test that.
Who paid
- Conflicts
- Conflict of Interest . The authors have no financial conflicts of interest to declare.
- Authors work at
- Inha University, Republic of Korea; Kyungpook National University, Republic of Korea; Dongguk University, Republic of Korea
The paper
- Title
- Folate Production by Streptococcus thermophilus IDCC 2201 and Its Impact on Human Gut Microbiota
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Nam EH, Lee M, Kim D, Jung YH, Yang J, Shin M (2025). Folate Production by Streptococcus thermophilus IDCC 2201 and Its Impact on Human Gut Microbiota. Journal of microbiology and biotechnology. doi:10.4014/jmb.2502.02045Free full textPubMed 40443239DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error