The Gfr uptake system provides a context-dependent fitness advantage toSalmonellaTyphimurium SL1344 during the initial gut colonization phase

Salmonella entericaserovar Typhimurium (S. Tm) is a major cause of foodborne diarrhea. However, in healthy individuals, the microbiota typically restricts the growth of incoming pathogens, a protective mechanism termed colonization resistance (CR). To circumvent CR,Salmonellastrains can utilize private nutrients that remain untapped by the resident microbiota. However, the metabolic pathways and environmental niches promoting pathogen growth are still not completely understood. Here, we investigate the significance of thegfroperon in gut colonization ofS. Tm, which is essential for the utilization of fructoselysine (FL) and glucoselysine (GL). These Amadori compounds are present in heated foods with high protein and carbohydrate contents, particularly in Western-type diets. We detected FL in both mouse chow and the intestinal tract of mice and showed thatgfrmutants are attenuated during the initial phase of colonization in the murine model. Experiments in gnotobiotic mice and competition experiments withEscherichia colisuggest thatgfr-dependent fitness advantage is context-dependent. We conclude that dietary Amadori products like FL can supportS. Tm gut colonization, depending on the metabolic capacities of the microbiota.