Are you sure the enzyme would need to operate in an acidic environment? Intact yeast cell membranes would be pretty capable of keeping ions out (thus some pH i

Are you sure the enzyme would need to operate in an acidic environment? Intact yeast cell membranes would be pretty capable of keeping ions out (thus some pH isolation), but I imagine they would be more permeable to small relatively uncharged substances as ethanol. I see no immediate reason why not many of the yeast cell might act tiny bioreactors, keeping a somewhat controlled internal environment, where ethanol might diffuse in and be degraded. Can someone here think of any reason for why this would not be plausible?