<i>Salmonella</i> Uses Energy Taxis to Benefit from Intestinal Inflammation

<div><p>Chemotaxis enhances the fitness of <i>Salmonella enterica</i> serotype Typhimurium (<i>S.</i> Typhimurium) during colitis. However, the chemotaxis receptors conferring this fitness advantage and their cognate signals generated during inflammation remain unknown. Here we identify respiratory electron acceptors that are generated in the intestinal lumen as by-products of the host inflammatory response as <i>in vivo</i> signals for methyl-accepting chemotaxis proteins (MCPs). Three MCPs, including Trg, Tsr and Aer, enhanced the fitness of <i>S</i>. Typhimurium in a mouse colitis model. Aer mediated chemotaxis towards electron acceptors (energy taxis) <i>in vitro</i> and required tetrathionate respiration to confer a fitness advantage <i>in vivo</i>. Tsr mediated energy taxis towards nitrate but not towards tetrathionate <i>in vitro</i> and required nitrate respiration to confer a fitness advantage <i>in vivo</i>. These data suggest that the energy taxis receptors Tsr and Aer respond to distinct <i>in vivo</i> signals to confer a fitness advantage upon <i>S</i>. Typhimurium during inflammation by enabling this facultative anaerobic pathogen to seek out favorable spatial niches containing host-derived electron acceptors that boost its luminal growth.</p>