The sickness in the tribe

Deep in the Amazonian Forest a tribe is facing an unknown health problem. All of them are having problems with the digestive system, including diarrhea, nausea, and vomiting. All the magical practices implemented by the chief of the tribe are inefficient. Our students as volunteers in the Amazonian area are invited to find a scientific solution of the health crisis. One item from the food supply brought from Bulgaria contains the remedy- the previously stolen yogurt can by one of the tribe members. The latter has felt better after the consumption of the milk. The students have one hour to identify the ingredient relieving the symptoms of the disease. (The ingredient is Lactobacillus Bulgaricus).