A good example of having the right yeast is sourdough bread from San Francisco. Boudin Bakery was founded in San Francisco, and used a french baking process wi

A good example of having the right yeast is sourdough bread from San Francisco. Boudin Bakery was founded in San Francisco, and used a french baking process with fermented dough. All of their bread has continued to be made with the same starter dough and yeast from 1849. It even survived the great SF earthquake and fires of 1906, as Louise Boudin threw some starter dough in a bucket and got the hell out of town. The particular yeast and lactobacilli they use interacts with the environment of the SF bay and produces a bread unique to that starter and that area. Making beer is a bit like baking bread in this way, but has more complex steps to achieve different results, so controlling the brewing environment is necessary for consistent results.