Minor mitochondrial aldehyde dehydrogenase isoform. Plays a role in regulation or biosynthesis of electron transport chain components. Involved in the biosynthesis of acetate during anaerobic growth on glucose. acetaldehyde + H2O + NADP(+) = acetate + 2 H(+) + NADPH H2O + NADP(+) + propanal = 2 H(+) + NADPH + propanoate H2O + NAD(+) + propanal = 2 H(+) + NADH + propanoate The activity increases in the presence of K(+) ions: 15-fold with NADP and 40-fold with NAD, respectively. Alcohol metabolism; ethanol degradation; acetate from ethanol: step 2/2. Present with 23300 molecules/cell in log phase SD medium. Belongs to the aldehyde dehydrogenase family.