The sugar is first decomposed by the anærobiotic yeast plant, and the residues which it leaves behind are consumed in their turn by the ærobiotic mycodermata. There are many other ways in which the sugar can be resolved into carbonic dioxide and water, but everywhere there is the same mixture of anærobiotic and ærobiotic organisms. But it is unnecessary to insist. Enough has already been said to show how the different hydrocarbons of a quantity of wort disappear.
Source: wiktionary