My local sour dough tastes like dirty socks -  but concentrated.  It will leaven a loaf, make nice big holes as you expect but the taste is hard to overcome.  It is a far cry from San Francisco sour dough.  Perhaps I'm doing something wrong?  I've tried in two occasions - once 5 years ago and once when covid hype was full blast.  Same results both times - a good rise but a VERY sour taste.

I store blocks of powdered yeast in my deep freezer from costco.  Since we bake regularly we rotate through them - probably the oldest being 5 years. Even at this age it is still robust.  With a sustained grid down situation this will eventually run out.  I thought of trying to cultivate the commercial yeast in the same sour dough method but I eventually discovered it would turn into my local sour dough. Perhaps leaving it out to cross bread with the world is not a good idea.

Has anyone tried the James Towsend method? It is not unique to him and was used for ages.  I suppose you would need to go through a few loaves  to determine if it reverts back to the local strain. He takes a piece dough off the loaf and, if not to be used recently, stores it in salt.  This is your yeast starter for the next loaf.

https://www.youtube.com/watch?v=leC_cCs4i5w

There are some people in town that have sourdough starter that is over 100 years old. They keep it in glass jars.

Makes amazing bread products.

Try a new starter with a dab of commercial yeast and some active yogurt.
Perhaps that will keep the sour bugs out.
I have used that method for starters in the past with good results.

I just got my very first sour dough starter, trying to get it growing, think the high heat in travel killed it. I have absolutely zero idea of what I am doing but am going full speed ahead regardless.

How often you feed it and what's the temp it's maintained in?

starter does not stay unique for ages.  The microbes change with every change of location, with every change of environment, with every change of ingredients.  The microbiology of a starter is always in a state of flux.

If you have sourdough starter, why the mention yeast?

There's no shortage of videos on sourdough.  Wife has been developing and feeding hers for a year now.  It's a freaking science.

We don't use that method, just store in a glass jar in fridge and use 1x per week or so. Going on 3 years now, no issues.