MSX1 and colitis: We assessed the fitness advantage provided by Hyd-1 and Hyd-2 in the presence (wild-type strain vs. a Δhya Δhyb mutant) and absence of a specific reductase (e.g., Δfrd mutant vs. Δfrd Δhya Δhyb mutant) in the DSS colitis model (Figure 7B–C).