The new gene scientists added to Caldicellulosiruptor bescii that is transcribed and translated to produce an enzyme named bifunctional acetaldehyde and alcohol dehydrogenase. What role does this enzyme play in the production of ethanol? It acts as a catalyst, releasing energy that makes an unfavorable reaction become favorable. It acts as an energy source in a coupled reaction, releasing energy that makes that makes an unfavorable reaction become favorable. It acts as a catalyst, lowing the activation energy and speeding up a reaction. It acts as an energy source in a coupled reaction, lowing the activation energy and speeding up a reaction.