Acts as the second step in ethanolamine degradation by converting acetaldehyde into acetyl-CoA (Probable) (PubMed:21803884). May play a role in bacterial microcompartment (BMC) assembly or maintenance (Probable). Directly targeted to the BMC (PubMed:27450681). Expression of the eut operon allows this bacteria to use ethanolamine (EA) as a carbon, nitrogen and energy source. It relies on cobalamin (vitamin B12) both as a cofactor for the ethanolamine ammonia-lyase (EAL) activity and to induce the operon (PubMed:3045078). EA enhances bacterial survival in macrophages in a concentration-dependent manner, suggesting it is an important nutrient during infection (PubMed:29531136). acetaldehyde + CoA + NAD(+) = acetyl-CoA + H(+) + NADH Has a very strong preference for NAD(+) over NADP(+) in both catalytic directions. Optimum pH is 6.5 for acetyl-CoA reductase and 7.5 for acetaldehyde dehydrogenase activities. Amine and polyamine degradation; ethanolamine degradation. Interacts with EutS, which targets it to the interior of the BMC. Probably located inside the BMC. Part of the 17-gene eut operon transcribed from a single promoter, induced by ethanolamine and adenosylcobalamin (AdoCbl, vitamin B12). The first 21 residues target foreign proteins (tested with eGFP) to the BMC in E.coli. The cargo is only detected by Western blot in broken shells, strongly suggesting this protein is normally found inside the BMC and not on its exterior. Can use ethanolamine (EA) as a nitrogen source but not as a carbon source. Slightly attenuated in a mouse model of infection (PubMed:7868611, PubMed:2656649). No aerobic growth on EA supplemented with cobalamin (vitamin B12) (PubMed:10464203, PubMed:16272400). A non-polar deletion mutant does not grow on EA between pH 5.5 and pH 8.5, releases increased amounts of acetaldehyde on EA plus vitamin B12 (PubMed:16585748). A deletion allows growth on acetate, suggesting BMC assembly or maintenance is impaired (PubMed:23585538). Has been used to coproduce acetaldehyde and hydrogen in E.coli. Artificial BMCs can be made in E.coli by expressing eutK, eutL, eutM, eutN, eutS (eutSMNLK) or eutS alone. Cargo proteins can be targeted to them using the first 21 residues of this protein. This can lead to the development of tailored BMCs for specific metabolic reactions. Belongs to the EutE/PduP family.