The Sourdough Project - Rob Dunn Lab


This would be an interesting project to be a part of &/or follow...


The Sourdough Project
Rob Dunn Lab | Public Science Projects

The best sourdough bread is magical. Each bite contains hundreds of different flavors, many of them not yet named by science much less ordinary language. It is this unnamable diversity of aromas and tastes that combines to allow a slice of sourdough bread, simple bread, to be delightful, rich, invigorating, comforting and filling. The trick, of course, is that there is nothing simple about sourdough bread, nothing at all.

[sourdough-ball] Sourdough bread, like many breads, depends upon microorganisms to rise. But whereas most bread relies on a single organism (baker’s yeast, Saccharomyces cerevisiae), sourdough bread depends on many different microorganisms including yeasts, but also bacteria (lactic acid producing species). These microorganisms live in the “starter” used to make sourdough bread. The starter is composed of the sourdough microorganisms and a small allotment of food on which they survive—typically flour and water. If cared for well, a starter can live, essentially, forever. Some starters are young and begin the moment you add flour to water and wait. Some starters are reported to be thousands of years old, as old as the oldest trees in the world.


Sourdough bread has been baked for more than five thousand years, but even after all of those years of caring for starters, generation after generation, moving from one kitchen to the next, huge mysteries remain. We propose to resolve them here. The first mystery is what determines which microbial species are present in a particular starter. The second is which species make the best starter. The third is the question of whether starters, as they age, go through similar trajectories, predictable stages in their history.

Question 1: Where Do Starter Microbes Come From?

Many bakers and chefs, as well as many scientists, will tell you, with great confidence, where the microorganisms found in starters originally come from (or where they will come from if you make your own starter). This confidence is good news. The bad news is that there is great difference of opinion among individuals as to the answer. Some say the microbes come from the bodies of those making bread. Could the Lactobacillus bacterial species in sourdough starters include some of the same Lactobacillus found on and in the bodies of women? Some say the microbes come from the ingredients, the water or the flour. Others say the microbes come from the air of the kitchen in which the sourdough is being made, or maybe from a passing dog. The truth is we don’t fully know. But we can know.

To answer our first question, we will engage people around the world to make sourdough starter in their homes, using identical ingredients, and then sample the microbes in the resulting starter. We will examine whether they best match the microbes on the person who made the starter, the climate in which the starter was made, the location of the home, or something else. We anticipate studying three thousand starters from countries around the world, hopefully this will include variation sufficient to nail down, once and for all, the origin of the organisms on which our best breads depend.

Question 2: Which Starters are the Best?

The question of the best sourdough starters is, of course, subjective and yet it can nonetheless be judged. We propose to do just that by having internationally recognized chefs and bakers taste and judge breads made from each of many of the sourdough starters from around the world. In addition, we will measure flavor profiles of each resulting bread. The sourdough recipes used will be identical, such that the only thing that differs will be the microbes.

Question 3: What Lives in Ancient Starters?

In addition to considering new starters and the factors that shape them, we will also study ancient starters. We will sample some of the oldest starters in the world to understand how different they really are, whether their microbes tell their stories, and how the flavors of ancient starters relate to newer starters (and why). Do you have an ancient starter that you would like us to study? Let us know. We will also be working with historians to record your story and that of the starter in the process.

These questions are, of course, just the starting point. We have much more we want to do, but this will give you a flavor of what we are fermenting in the lab. This project is a partnership between the Natural History Museum of Denmark, Tufts University and North Carolina State University.

What Can You Do Now?

If you would like to be part of this project, you can sign up here:

No cooking experience required! Be sure to indicate whether or not you have an old sourdough starter you would like to share and something about its history. You can participate even if you don’t have an old starter. If you don’t want to participate, but you would like to stay updated about our results, you can sign up as well. As we get organized and ready for the many samples that will come in, we will send out an email inviting participants to get started, participants, that is, and their microbes.



38 users have voted.


VWFeature 2016 November 23

A partial answer:

Appl Environ Microbiol. 2015 Oct;81(19):6736-48. doi: 10.1128/AEM.01852-15. Epub 2015 Jul 17.

Lactic Acid Bacteria in Durum Wheat Flour Are Endophytic Components of the Plant during Its Entire Life Cycle.


So these bacteria are found in the wheat berry.

Different growing methods give different mixes of bacteria & yeasts!

Staff 2017 February 5


Protocol for Submitting Sourdough Samples

The Dunn and Wolfe labs are interested in the diversity of microbes that exists in sourdough starters around the world. If you have a starter and a method for making sourdough that has proven to make a risen loaf, send us a sample of your starter!

Please plan to package and send your sample on the same day. If you can, send your sample on a Monday so that samples arrive before the weekend. We don’t want your sample to sit in a shipping warehouse over the weekend!


More details for submitting your samples can be found here:



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