© Miloslav Kalab, Agriculture and Agri-Food Canada, Ottawa
The yeast transform the lactose into carbon dioxide, and, to a lesser extent, ethyl alcohol.
Each gram of kefir contains five hundred million lactococci and leuconostocs, more than fifty million lactobacillae and five hundred thousand yeast.
Commensalism and symbiosis can be observed in kefir. Here, the diplococci feed on the waste products of yeast. Some bacteria may even die if the yeast are removed!