In what is perhaps the most "2020" study, a group of researchers from the United States and Denmark (with the help of community scientist-bakers across the globe) have studied the biodiversity contained within 500 sourdough starters. Their research was recently published in the journal eLife.
The researchers collected 500 sourdough starters. These came mainly from the United States and Europe, but also included contributions from New Zealand, Thailand, and Australia.
All 500 sourdough samples were DNA-sequenced to determine their microbial makeup. They then took 40 samples that represented the range of diversity and tested them for aroma profiling, chemical analysis, and rising speed. They discovered that an until-now overlooked component of microbial diversity, acetic acid bacteria, play a significant role in sourdough's aroma and rising speed.
As an observational study, the results do not give us a master recipe for exactly which microbes create which bread characteristics. But the study does show that the types of microbes in a sourdough started affects how it rises, smells, and bakes. If you are still pandemic-baking, rest assured that there is plenty more fun to be had in determining the exact role of the microbes found in sourdough.