Which bacteria are commonly used to make fermented milk products?

Fermented milk products are primarily produced using lactic-acid bacteria, which convert lactose into lactic acid to preserve the milk and develop flavor.12

Commonly used bacteria include various species from the genera Streptococcus and Lactobacillus. Specific applications include:12

• Yogurt: Typically produced using a culture of Lactobacillus bulgaricus and Streptococcus thermophilus. Some manufacturers also add Lactobacillus acidophilus for potential health benefits.3
• Cultured Buttermilk: Often utilizes starter cultures such as Streptococcus lactis, S. cremoris, Leuconostoc citrovorum, and L. dextranicum.4
• Kefir: Made using kefir grains, which contain a symbiotic community of bacteria and yeasts. Bacterial species include L. caucasius, L. lactis, L. kefir, L. plantarum, L. kefiranofaciens, and L. delbrueckii, while the yeast component often includes Saccharomyces kefir and Torula kefir.5

These bacteria are essential for suppressing spoilage organisms and creating the distinct textures and flavors characteristic of cultured dairy foods.24