Whether performing a kettle sour with bacteria or souring in the fermenter using lactic acid-producing yeast for sour beers, the choice of souring strain has important implications for fermentation performance and the flavor and character of the beer. Bacteria fermentations require a secondary yeast strain to complete the alcoholic fermentation, whereas lactic acid-producing yeasts perform both functions (but can be co-pitched with other yeast to achieve desired results). View our best practices guide to help choose yeast and bacteria based on your desired resulting flavors and acidity level.