Another good read/listen is this gastropod episode (
https://gastropod.com/secrets-of-sourdough/) which features cool projects like a global sourdough sequencing project (
http://robdunnlab.com/projects/sourdough/), a sourdough library (
https://www.puratos.com/campaigns/the-lab---18th-of-october), and it's caretaker (
https://www.instagram.com/sourdough_librarian/)/They did an experiment with bakers from around the world making starters with the same flour, bringing them together and looking at what was in them. From the transcript:
DUNN: When we looked at the bakers’ hands, their skin bacteria on their hands was about half sourdough bacteria. And so they, like, have sourdough paws.
DUNN: We’ve looked at zillions of hands. We’ve never seen anything like this. And so the first result is that the bakers themselves have changed in response to their occupation.
TWILLEY: Normal hands like mine and Cynthia’s and Rob’s—they are something like 2 to 4 percent Lactobacillus.
DUNN: On the hands of the bakers, it is like it’s the star of the show. It’s wild. I mean, if it’s right, you should be able to put flour and water on a baker’s hand and it should start to ferment immediately and become acidic.
GRABER: Working with sourdough has entirely changed the microbial environment on the bakers’ skin. They’ve been colonized by their pets! Rob wonders if the bakers spend so much time with their hands in acidic dough that the sourdough Lactobacillus microbes end up with a competitive advantage over normal skin microbes.