What is the best way to sustain yeast/souring bacteria alive that are cultured up from bottle dregs? I have grown up a fair amount of yeast and presumably souring bacteria in a series of small flasks by combining bottle dregs and low gravity starter wort with the intention of adding it to a series of beers down the road. I have already done this with one batch but am wondering how I can keep the culture I grew up from bottle dregs alive over several months. The cultures were grown up from 2 Russian River and one Wicked Weed bottle. The Russian River I cannot easily obtain so looking to keep it going if possible.
I have been feeding it every 1-2 months with fresh low gravity wort after decanting off the spent wort (which tastes pretty good). Is this ok to leave at room temp and just keep feeding it or should I be leaving them out a few weeks then cold storing in the fridge after each feeding?
Growth/fermentation is obviously happening as activity is seen in the airlock, the wort changes sour, and the yeast/bug cake seems to be increasing with each feeding. However, are the majority of these cells dying over time? Would it be better to plan ahead better and pour off some fresh slurry from a storage flask, add fresh wort, and dump that whole new flask in the beer after allowing for 1-2 weeks of growth?
I know to expect the ratios of yeast (brett and whatever sacc may be alive) as well as bacteria to change over time so results won't be consistent but still a fun side project.