Originally Posted by choosybeggar
So bread yeast breaks down starch but brewer's yeast cannot? Or perhaps brewer's yeast can but does so inefficiently?
pretty much the same thing is happening in both processes. With bread it happens at the same time, in brewing we split the process. You can brew beer with baking yeast, and you can bake bread with brewers yeast, but neither is optimal in the other's shoes. It's not uncommon to add diastatic malt powder (basically DME) to bread formulas. The enzymes break down the starch quicker, and you get a very different crust.
Take sourdough for an example. You can leave your beer wort out, and it will start to ferment relatively quickly from naturally occurring yeast and bacteria in the air. You can also leave flour out, and over a much greater time, it will take on the characteristics of the natural yeast and bacteria in the air. This is why you can't keep a "San Francisco" sour dough indefinitely. Eventually it will become a local variant. In this case, worlds collide, and your wild beer and sourdough bread share some common elements.