Catalyzes the conversion of acetaldehyde or propanal to acetyl-CoA or propanoyl-CoA, respectively, using NAD(+) and coenzyme A. Displays broad specificity since it can utilize aliphatic aldehydes from two to five carbons in length as substrates; the aldehyde substrates can be directly channeled from the aldolase BphI to the dehydrogenase BphJ. Is the final enzyme in the meta-cleavage pathway for the degradation of polychlorinated biphenyls (PCBs). Is also able to utilize NADP(+) instead of NAD(+). Is not active with succinic semialdehyde or picolinaldehyde as substrates. Can also catalyze the reverse reaction, i.e. the reductive deacylation of acetyl-CoA to acetaldehyde, which is then channeled to the BphI active site. The BphI-BphJ enzyme complex exhibits unique bidirectionality in substrate channeling and allosteric activation. acetaldehyde + CoA + NAD(+) = acetyl-CoA + H(+) + NADH CoA + NAD(+) + propanal = H(+) + NADH + propanoyl-CoA Bound pyruvate or other intermediates in the aldol addition reaction catalyzed by BphI allosterically activates BphJ reductive deacylation activity. kcat is 17.2 and 16.3 sec(-1) with acetaldehyde and propanaldehyde as substrate, respectively (at pH 8 and 25 degrees Celsius). Xenobiotic degradation; polychlorinated biphenyl degradation. Heterotetramer composed of two BphI (aldolase) and two BphJ (dehydrogenase). Belongs to the acetaldehyde dehydrogenase family.