Lactic Acid Bacteria

The bacteria in a sourdough starter that turn sugars from flour into lactic acid and, in many species, acetic acid too. They usually outnumber the wild yeast by a wide margin and are responsible for sourdough's tang, its lower pH, and much of its keeping quality. Their acids also affect gluten and help control enzyme activity, which matters a lot in rye breads.

By Henry Hunter · Updated October 1, 2026

Henry's notes from the bench

• Think of your starter as a partnership. The yeast does the lifting, the bacteria do the flavor. How you feed and where you keep it decides which partner gets the upper hand.