Reactivates suicidally inhibited ethanolamine ammonia-lyase (EAL), cyanocobalamin-inactivated EAL and O(2)-inactivated EAL; requires Mg(2+), ATP and adenosylcobalamin. Reactivation probably occurs by the ATP-dependent exchange of cobalamin (By similarity). Protects EAL from inhibition by CN-B12, does not have adenosylation activity (PubMed:15516577) (Probable). Expression of the eut operon allows this bacteria to use ethanolamine 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). Amine and polyamine degradation; ethanolamine degradation. Part of the 17-gene eut operon transcribed from a single promoter, induced by ethanolamine and adenosylcobalamin (AdoCbl, vitamin B12). Can use ethanolamine (EA) as a nitrogen source when AdoCbl but not cyano-B12 or hydroxy-B12 is provided; cannot use EA as a carbon source (PubMed:2656649, PubMed:15516577). Required for aerobic growth on ethanolamine supplemented with cobalamin (vitamin B12) (PubMed:10464203). A non-polar deletion mutant does not grow on EA between pH 5.5 and pH 8.5 (PubMed:16585748). Belongs to the EutA family.