Alcohol Dehydrogenase
Alcohol dehydrogenase actually catalyzes more reactions than the name implies. The enzyme can reduce ketones INTO alcohols, as they do in yeast which already contain this enzyme. These enzymes work optimally at a very high pH ~9, and if the yeast could find a way to save itself from their byproducts of fermentation in DIY reactors they probably would. Sorry to rain on your party, but it's probablly best to stick with the old way of maintaining your DIY reactor but it's nice to hear new ideas.