ASPA and Crohn ileitis: We discovered a multifaceted interaction between EA metabolism and amino acids, highlighted by the ability of ileitis-associated amino acids to augment the growth of AIEC on EA, which may reflect reduced glucose catabolism and enhanced secretion of acetate (46), a metabolite of the eut MCP (20); protection against oxidative and acid stress; and use of fumarate (via aspA, frdA-D, dcuC; Figure 4F) as an electron acceptor (55).