FrdA is a fumarate reductase encoded by Salmonella, an enzyme belonging to the TCA cycle, this enzyme catalyzes the conversion of fumarate to succinate, and it has been reported to greatly increase expression in Salmonella typhimurium (Steinsiek et al., 2011; Noster et al., 2019b; Westerman et al., 2021), but its exact role in Salmonella-caused infection is still unclear. The gene discussed is FXN; the disease is infection.