Lactic acid bacteria
The bacteria that turn milk sugar into lactic acid, souring milk and starting every cheese.
Also: LAB, lactic bacteria, Lactococcus, Lactobacillus
Lactic acid bacteria are a large group of harmless bacteria that feed on lactose, the sugar in milk, and turn it into lactic acid. In cheesemaking they are the first workers: their acid helps rennet set the milk, drives whey out of the curd, protects the cheese from spoilage bacteria and, later, their enzymes help build flavour as the cheese ripens. Lactococcus and Leuconostoc species prefer moderate temperatures, while Streptococcus thermophilus and Lactobacillus species cope with the heat of Alpine and Italian cheeses. Raw milk carries its own mix; most dairies add known strains as a starter culture. The same bacteria make dahi, yoghurt and sourdough.