Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus survive gastrointestinal transit of healthy volunteers consuming yogurt

FEMS Microbiol Lett. 2005 Sep 15;250(2):185-7. doi: 10.1016/j.femsle.2005.07.006.


To date, there is significant controversy as to the survival of yogurt bacteria (namely, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) after passage through the human gastrointestinal tract. Survival of both bacterial species in human feces was investigated by culture on selective media. Out of 39 samples recovered from 13 healthy subjects over a 12-day period of fresh yogurt intake, 32 and 37 samples contained viable S. thermophilus (median value of 6.3 x 10(4) CFU g(-1) of feces) and L. delbrueckii (median value of 7.2 x 10(4)CFU g(-1) of feces), respectively. The results of the present study indicate that substantial numbers of yogurt bacteria can survive human gastrointestinal transit.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Colony Count, Microbial
  • Feces / microbiology
  • Female
  • Gastrointestinal Tract / microbiology*
  • Humans
  • Lactobacillus delbrueckii / physiology*
  • Male
  • Middle Aged
  • Streptococcus thermophilus / physiology*
  • Yogurt / microbiology*