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

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.