The Global Sourdough Project

Rob Dunn Lab | A Science of Sourdough Project

The Global Sourdough Project started out as an online survey, distributed to the general public, with the hope that it would find it’s way to sourdough bakers who keep their own starters. Over 1000 people, all over the world, filled out the survey – sharing where their sourdough came from, how it is maintained, and sharing stories of their unique flavors and unique origin stories. Five hundred and sixty of those bakers then sent us a sample of their sourdough starter. We are using genetic techniques (metagenomics, in the lingo of our tribe) to determine which species are present in the starter. Once we know which species are living in each starter, we will use statistical approaches to compare the different communities. By doing this comparison we can begin to understand the factors that influence which community lives in one starter relative to another, why your starter is different from that of someone else. Some bakers suggest (swear by, really) that the biggest factor influencing which species of microbes are found in a starter are the microbes that are on the bodies of the people who started it. Some say it is the grain that is used. Others, the climate. Others still, the water. Everyone might be right; it could be that each starter is influenced by many factors. But we don’t actually know. Now that we know the identity of the organisms in each of a hundreds of starters from around the world we are testing the relative influence of each factor using statistical models — the same sort we would use to understand why there are, say, more bird species in the tropics.

Bread and the microbes on which bread depends are at the heart of our agricultural civilization, the ancient marriage between humans and grains. They are also at the heart of the ways in which we come together to break bread and savor the rich flavors of wild microbes and tamed grains. By this same token, we hope that by studying starters together, we might all understand and savor more than any of us could on our own.

The Global Sourdough Project is just one of our various efforts to study sourdough starters.