Instant Yeast in Levain
I've been having trouble working out a schedule that allows me to bake sourdough with my Levain, so I've been feeding it a few days at a time and then resigning it to the fridge for months at a time for around 9 months now. I remember once using leftover poolish started with instant yeast and treating it like a Levain with feedings and discardings of just flour and water (no more instant yeast ever added) I can't remember if that's still this tub or I tossed that and restarted.
My question is, if you start a Levain with instant yeast and continually take it far enough that it smells deeply of vinegar/alcohol, then let it stagnate in the fridge, and repeat this process, is the yeast culture that survives a monoculture descendent of the instant yeast, or will wild yeasts have taken over? Can instant yeast survive those conditions like the proper sourdough strains can?
I'm happy to clarify the question and conditions I've been working with if it helps. Thanks.
In his free Kindle ebook, Dennis Weaver says it can develop into a wild yeast and bacteria starter.
https://www.amzn.com/B0086W53ZQ?tag=froglallabout-20
Chapter 3, Part 3, location 2642.
The wild yeast don't literally descend from commercial yeast, as they are different species. But whatever wild yeast are in the flour you feed it eventually take over, or become predominant.
In their first edition of "Healthy Bread in Five Minutes a Day, pages 39 and 51, Hertzberg and Francois say basically the same thing, regarding their method of leaving the dough in the container in the fridge for a week. When they make the next batch, they leave scrapings from the previous batch, and mix them in, and it takes on the characteristics of sourdough. In the second edition, they go further into sourdough and pâte fermentée.