The diversity and function of sourdough starter microbiomes

Humans have relied on sourdough starter microbial communities to make
leavened bread for thousands of years, but only a small fraction of global
sourdough biodiversity has been characterized. Working with a
citizen-scientist network of bread bakers, we determined the microbial
diversity of 500 sourdough starters from four continents. In sharp
contrast with widespread assumptions, we found little evidence for
biogeographic patterns in starter communities. Strong co-occurrence
patterns observed in situ and recreated in vitro demonstrate that
microbial interactions shape sourdough community structure. Variation in
dough rise rates and aromas were largely explained by acetic acid
bacteria, a mostly overlooked group of sourdough microbes. Our study
reveals the full extent of microbial diversity in an ancient fermented
food across diverse cultural and geographic backgrounds.