Abstract
Bacterial swarming is a conserved and distinct form of bacterial motility that allows for rapid migration over a surface. Swarming motility is often oppositely regulated and antagonistic to biofilm formation1. To-date, while bacterial biofilms have been associated with pathogenesis and pathobiology of human diseases (e.g., infections, inflammation and cancer)2–4, there are very few examples of swarming behaviors that uniquely define or align with human pathophysiology (e.g., antibiotic resistance)5, 6, 7. Here we report that bacterial swarming is highly predictive of the presence of intestinal stress in mice, pigs and humans. Using a modified agar plate assay, we isolated from murine feces a novel Enterobacter hyperswarming strain, SM3 that demonstrated significant protection from intestinal inflammation and promoted restitution in a mouse model of colitis. As opposed to bacterial biofilms8, we report that the swarming phenotype protects against intestinal inflammation in mice. Mechanistically, commensal swarming strains rapidly consume oxygen in vitro and in vivo, leading to a favorable anaerobic environment conducive to the growth of beneficial anaerobes. The swarming property of bacteria rather than the individual strains themselves, independently lends the ability to protect and heal from intestinal inflammation. This work identifies a new paradigm in which intestinal stress, specifically inflammation, allows for emergence of swarming bacteria, which in turn act to suppress inflammation via mechanisms that are associated in part with oxygen depletion and bloom of beneficial anaerobes.