I made it through four weeks of Los Angeles’ COVID-19 shelter in place order before I climbed aboard the isolation sourdough bandwagon. It took more effort than expected just to stay on.
I followed a protocol provided on the King Arthur Flour website to ferment my own starter from flour mixed with water. Twice a day, from March into April, I transferred a bit of starter to a fresh jar, and added fresh flour and water, with no apparent progress. I moved the starter around my little kitchen, searching for a sufficiently warm nook. I restarted the whole process from scratch. I ran through two five-pound bags of all-purpose flour I scrounged at a neighborhood grocery store (everyone else in Los Angeles had taken up baking, too), and when, visiting Costco on a friend’s membership, I lucked into a 25-pound sack, I didn’t pause to wonder where I’d find space for it in the pantry.
And then, finally, one afternoon, I checked the jar in the oven (heat off, light on, a nice steady 70°F) and saw that the starter had surged above the rubber band I put around the jar to mark its beginning volume. I baked bread the next day.
I am no manner of microbiologist, but I knew in a general way that sourdough starter is a microbial culture, and the rising is, of course, due to the metabolism of those microbes — carbohydrates in, carbon dioxide out. I also knew enough to recognize the process of establishing a starter as something like a serial passage protocol: sample the microbes in a batch of flour, give them periodic infusions of fresh growth medium, and let them duke it out for supremacy until the population growth rate was enough to leaven a batch of bread. What I am, though, is a molecular ecologist — and so I naturally started wondering what was known about the population and community genetics bubbling in that blue glass jar.