I've done this on and off over the years, with mixed success. Recently I had really good luck, though, with Wyeast 3278 Lambic. It is a mixed culture that includes several "wild" yeast, two Brett. spp., a sherry flor, and a lactobacillus, as I recall. I skimmed the thick frothy yeast head (barm) from the active fermentation on the third day and added probably three tablespoons of the thick, pasty yeast (consistency of soft-serve ice dream) to 4-1/2 cups of water, added 1/8 cup of dry malt extract stirred dry into 4 cups of flour (this avoids malt extract lumps), and beat it with an electric mixer for a minute or so. I had bubbles in 20 minutes.
After an hour, I added 1-1/2 tablespoon of salt and enough flour to make a moderately stiff dough (but not too stiff), probably another 6-1/2 cups, and a few tablespoons of olive oil, and kneaded it well. (It helps that I am a commercial baker and have a 20 qt. Hobart mixer, but I was just doing a home-scale batch).
I let it rise until at least doubled, punched down, doubled again, divided in two and shaped into two oblong loaves, then let them rise upside down in a floured basket, then when doubled, inverted them onto baker's parchment, slashed the tops, and slid them into the oven. I have a pizza oven, but a pizza stone will work well for free-form loaves like this.
The bread rose about as well as with bread yeast, and had good texture and had a bit of fruity aroma. It was quite good.
Ale barm was the traditional way of leavening bread before commercial bread yeast was available, as well as using a starter or old dough.