Acts as the second step in ethanolamine degradation by converting acetaldehyde into acetyl-CoA. May play a role in bacterial microcompartment (BMC) assembly or maintenance. Directly targeted to the BMC (By similarity). Its heterologous expression in S.cerevisiae increases the level of acetylating acetaldehyde dehydrogenase activity (PubMed:26384570). acetaldehyde + CoA + NAD(+) = acetyl-CoA + H(+) + NADH Has a very strong preference for NAD(+) over NADP(+). Amine and polyamine degradation; ethanolamine degradation. Interacts with EutS, which targets it to the interior of the BMC. Probably located inside the BMC. Belongs to the EutE/PduP family. In strain MG1655 the eut operon is interrupted by the CPZ-55 prophage, encoding 9 genes situated between eutA and eutB, which are translated in the other direction. CPZ-55 may prevent expression of the eut operon in strain MG1655. Strain W3110 does not have this prophage element and should be able to express the operon.