Homemade sourdough bread has been around for hundreds of years, growing in popularity during the COVID-19 pandemic. Sourdough baking begins with a starter culture, which is made up of a community of yeast and bacteria. These microbes are then used to ferment the dough, performing the chemical reactions that allow the dough to rise and develop its flavor. Sourdough starters are often shared between home bakers, or they can be bought commercially. It is commonly thought that sourdough starters are unique to specific regions, but little is known about how or why this happens. An international group of researchers set out to study the diverse microbes in sourdough starters across the globe. 

The researchers sampled 500 different sourdough starters from six countries. They used DNA sequencing to characterize the species present in each one, and then compared factors such as  geographic location and how the culture was maintained. The researchers showed that the composition of the microbial communities varied a lot between samples, and looked for patterns to explain this. Surprisingly, they found that this variation could not be explained by location. The researchers also compared aspects of the starter cultures that are important for baking function. They measured the amount of volatile organic compounds produced, which influence the aroma of the sourdough, as well as the leavening time, which influences the dough rising time. The researchers found that a type of bacteria known as acetic acid bacteria plays a large role in these functions. This was surprising because most previous studies of sourdough microbes focused on other species. 

This study was one of the largest and broadest to date to characterize the microbes in sourdough starters. The researchers demonstrated that a tremendously diverse set of microbes can be present in these cultures.  They also connected their studies of specific bacterial species to the functional characteristics of sourdough starters. This research helped shed light on the mysteries of sourdough starters, and has implications for both bakers and biologists. 

Lead authors Elizabeth Landis and Angela Oliviero are graduate students in the Department of Biology at Tufts University and the Department of Ecology and Evolutionary Biology at the University of Colorado at Boulder, respectively. Corresponding author Benjamin Wolfe is an Associate Professor in the Department of Biology at Tufts University.

Managing Correspondent: Jaclyn Long

Original Article: The diversity and function of sourdough starter microbiomes

Additional Press: Intercontinental study sheds light on the microbial life of sourdough

Image Credit: Shutterstock

Leave a Reply

Your email address will not be published. Required fields are marked *