Which bacterium typically provides a lactic tartness to the beer?

Lactobacillus is a genus of bacteria that is widely known for its role in lactic acid fermentation. This bacterium is commonly used in the production of sour beers as it produces lactic acid, which contributes a tart flavor characteristic of many styles, particularly Berliner Weisse, Gose, and some Flanders ales. The lactic tartness adds complexity and depth to the flavor profile of the beer, creating a refreshing and mildly sour experience.

In brewing, the controlled use of Lactobacillus allows brewers to create specific sourness levels without unwanted off-flavors. It contrasts with other bacteria like Acetobacter, which can introduce unpleasant vinegar notes, or Enterobacter and Staphylococcus, which are not typically associated with desirable flavor production in beer. Thus, the characteristic lactic tartness provided by Lactobacillus is essential to the unique taste profiles of certain beer styles, making it the correct choice in this context.