Flour Shapes the Microbes—and Flavor—of Sourdough

A new study reveals that the type of flour used in sourdough starters strongly influences bacterial communities, even though the same yeast dominates all starters. Researchers at North Carolina State University found that Kazachstania yeast consistently led the fermentation, while bacteria varied with flour type, helping explain differences in bread flavor and texture.

The study, published in Microbiology Spectrum, analyzed starters made with all-purpose, bread, or whole wheat flour using genetic metabarcoding. After weeks of feeding, starters showed stable yeast dominance but flour-dependent bacterial diversity: whole wheat promoted Companilactobacillus, while bread flour favored Levilactobacillus.

Senior author Caiti Heil, Ph.D., explained that each flour provides distinct nutrients, shaping microbial growth and competition. The research began as a classroom project teaching fermentation and evolution, highlighting how sourdough serves as a model for studying microbial ecology.

These findings suggest bakers can influence sourdough flavor and texture simply by changing the flour type.

21-01-2026