One model organism that we use to study the intestinal ecosystem during infectious inflammatory diarrhea is the enteroinvasive bacterial pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium). The inflammatory response elicited by S. Typhimurium is aimed at clearing the invading bacteria from the tissue, however a concomitant bloom of S. Typhimurium in the gut lumen (outside the tissue) is observed.
We have shown that reactive oxygen species generated by transmigrating neutrophils oxidize endogenous thiosulfate S2O32-, which originates from the detoxification of intestinal hydrogen sulfide H2S by enterocytes. The oxidation product of thiosulfate generated during intestinal inflammation is tetrathionate S4O62-, which can be utilized as a respiratory electron acceptor by S. Typhimurium (see central model). Anaerobic tetrathionate respiration, one of the hallmark property of the genus Salmonella, provides a significant growth benefit over members of the microbiota that rely solely on a fermentative metabolism to generate energy for growth, thus fueling a bloom of the pathogen.