The diversity and function of sourdough starter microbiomes

Area of Science:

• Microbiology
• Food Science
• Fermentation Science

Background:

• Sourdough fermentation relies on complex microbial communities, primarily yeasts and lactic acid bacteria.
• Despite thousands of years of use, global sourdough microbial diversity remains largely uncharacterized.
• Previous assumptions often linked sourdough microbial composition to geographic origin.

Purpose of the Study:

• To characterize the microbial diversity of a large, global collection of sourdough starters.
• To investigate the influence of microbial interactions on sourdough community structure.
• To identify key microbes responsible for variations in dough fermentation characteristics.

Main Methods:

• Community-scientist network collected 500 sourdough starters from four continents.
• Microbial diversity was determined using molecular techniques.
• In situ and in vitro experiments assessed microbial co-occurrence and functional impacts.

Main Results:

• Little evidence found for distinct biogeographic patterns in sourdough microbial communities.
• Strong microbial co-occurrence patterns were observed, indicating significant inter-species interactions.
• Acetic acid bacteria were identified as key drivers of dough rise rates and aroma profiles.

Conclusions:

• Sourdough microbial communities exhibit remarkable global uniformity, contrary to common assumptions.
• Microbial interactions play a crucial role in structuring sourdough ecosystems.
• Acetic acid bacteria represent an important, yet often overlooked, component of sourdough fermentation.