Yeast mutation?

I cultured some wild yeast a while back but I haven't used it for awhile until now. I used it in a new batch. I used two half-full bottles of the old beer I had under the counter and a bottle of dregs I was keeping in the fridge, they are about 2 or 3 months old.

It started just really going today and I smell a lot of really strange smells comming from the airlock, they are not what I remember from using it, but it's been awhile. Could the yeast have mutated or is it more likely that is the yeast acting differently from a different wort?

Culturing yeast requires a lot of sanitation procedures, so if the smell is REALLY off it could be an infection. I study biochemistry and although yeast mutations certainly do happen, getting such a large change is somewhat unlikely unless you have some very different strains of yeast conjugating together (think of it as yeast sex)--especially if you kept them cold so their activity was low. Hope this helps!!! Wait it out and taste it

Yeast sex? I thought yeast reproduce asexually through budding? The strain worked fine before and the two bottles stored at room temp. were fine but the one from the fridge smelled a little funny but I figured it was just stressed.

The budding is indeed true but there is still an exchange of genetic info. I have a feeling your beer will turn out fine, my recent ale had a funny smell from the airlock during fermentation but upon sampling it tasted a-okay

Yeah, ok, I'll just wait and see I guess. I had a beer that started growing mold once and I still drank it, so this'll be ok too probably.