wild yeast

I'm relatively new to the sourdough thing myself, but from the bit that I believe I know, I would call your item a starter, used as your sponge, and consider it a poolish.  To my understanding, a biga is a firmer mass.  Have I confused you?  To me, a starter is the mother, the item we use to build off of and to make our sponge, and that sponge is the item we use to bake our daily loaf.  We retain a bit of our starter to build our next baking day's sponge, whether it be a poolish or a bit of biga.  Trust me on this lungalux, there are, and will be others that can better explain this, but all that you need to remember at this point is this:  You've captured the essence of all things sourdough by having mastered the makings of your starter.  Keep that friend alive and everything else will fall into place.

I can't offer an explanation for the yeast to wild yeast ratio, but will tell you this:

Yesterday, I baked two beautiful loaves of whole wheat bread using the recipe from The Bread Baker's Apprentice, by Peter Reinhart.  I knew that I had all day to work with this dough, and therefore, I omitted the yeast and simply used the called for amount of poolish. The loaves proofed for about six hours in a mid 70's temp kitchen, and rose beautifully without the addition of that yeast.  (I didn't adjust the recipe a bit other than not using that one item; it wasn't used in the poolish or in the final dough mix). 

Welcome to TFL, and yes, I agree with you, this site is a tremendous help and an invaluable resource.  I'd hate to think where I'd be without it.  :)

Happy baking! 

Just some quick thoughts. First, I suggest you read through Floyd's Beginning Sourdough Lesson. He also has links to more advanced sourdough info here. As always Floyd leads you through the process step-by-step in a very understandable way.

There is no consistent terminology in the United States for the steps in the sourdough process. Most people would call what you have in your jar and feed regularly a starter, and what you make from the starter to put in the dough a levain or build. But there are many other sets of terms and every one has fierce advocates. The only terms I would avoid adopting are Peter Reinhart's; his recipes are wonderful but somehow he got off track in terminology and was quite stubborn about acknowledging that mistake for several book.

In modern usage poolish and biga refer to preferments made with baker's yeast. I have not seen them applied to sourdough builds. Perhaps when commerical bakers yeast was less available these preferments were made with sour starters, but then again bakers yeast has been available in one form or another for 3000 years so maybe not.

Floyds descriptions are much better, but basically when your starter is working nicely you feed it, wait for it to grow, then take out the normal amount but instead of discarding that you use it to build 100-300 grams of levain. The levain then goes in the dough and takes the place of the commerical yeast (in the meantime don't forget to feed the lonely starter left in the jar!).

If your starter has both yeast and bacteria you don't have to add commercial yeast. Many getting started guides (including King Arthur's) recommend that you start by adding 1/2 tsp of commercial yeast to the final dough mix until you have good success with the receipe, then move on to making with no commercial yeast. This will upset the purists but seems like good advice to me. Some rye sourdough recipes, particularly from Germany, do call for yeast as part of the base recipe.

I recommend that you start out using well-tested recipes from here, RLB's _Bread Bible_, or Hamelman. Bakers yeast (straight) doughs are very forgiving and you can mess around with the recipe and get good results. Sourdough recipes, at least to start, are less forgiving. Start with a tested one until you have more experience.

sPh

I can't add anything new to what the others have said. I can just say, welcome, and little by little what seems extremely complicated to you now will become clearer as you try different recipes. I am a book person and find that taking a good book and reading the definitions, etc, makes it all seem a lot clearer. But do know that there are many different ways of doing things and you'll find that each person has their way. I recomment taking a fairly simple recipe for basic sourdough bread and mastering it. From there you can try different, more complicated techniques.

What you have is a liquid starter to me. You'll see that from that one base you can make all sorts of things and not only bread!

Jane 

Congratulations! You have a liquid starter. The terminology is confusing to most everyone including the experts. The interesting thing about a starter is that it is occurs as a natural ferment from the yeast, lactobacillus and acetobacillus that is present on the wheat berries. This is one reason why organic whole wheat works so well in starters. Another fact is that your starter will change over time as best suits the type of flour and conditons that you're providing it with. You can experiment by making firmer starters which will ferment in the refreigerator into a sponge. There is no mistaking why it's named "sponge" once you've done it. Dryer conditions in the sponge produce a different bread from that produced from a liquid starter. I'll repeat what the others have said in that the best way to proceed is to use one of the starter recipes and to get your bearings on how it's done. After several sessions you'll get the hang of the process after which you can begin to test corners of the envelope.

Wild-Yeast

Sounds like you have successfully made your own wild yeast starter.   I agree with several others that the terminolgy has gotten a little out of hand . . . really have to wonder what the Amerian Cowboys would have  to say  . . . poolish or biga??????   It's just plain old sourdough starter . . . the building block of sourdough baking!   I'm a bit of purest when it comes to sourdough so my recommendation is DO NOT add commercial yeast!   Enjoy!

Galley Wench