Culturing kefir substitute from sourdough

For a while I tried to keep kefir, and was enamored with it--I liked the idea of the health benefits, but it also tasted amazing. But after some busy periods where the grains ended up neglected, and then the final defeat when the jar that held the kefir grains at the bottom was mistaken for an empty, dirty bottle...and from that point there was no recovering the culture. But a few days ago, I decided to experiment, adding a small amount of sourdough starter to a cup of milk. And today it curdled! And it tastes like kefir. We'll see how it goes from here...

Have you done this before?

I cultured another batch from the last, and it seems to have lost some of the complexity of flavor, tasting more like a mild buttermilk culture--probably, the diversity of microbes decreased because of the change in medium. I'll keep it going though because it's still good. The change could also have been temperature related, as the first batch was on a cold countertop and the second on a warm heat mat, so I'll try culturing it on a cold surface once more.

i was reading about this, as i sort of miss my milk kefir but not enough to go hunting for new starter. apparently you can do the same thing with a kombucha scoby, but it's hit and miss and eventually peters out (according to the internet). Hopefully yours keeps going!