The Vibrio cholerae type VI secretion system can modulate host intestinal mechanics to displace gut bacterial symbionts

Significance Vibrio cholerae , the causative agent of the diarrheal disease cholera, uses the syringe-like type VI secretion system (T6SS) to pierce adjacent cells. To investigate the role of the T6SS in invasion of intestines already occupied by symbiotic microbes, we genetically engineered V. cholerae strains and performed live 3D imaging in zebrafish to find that V. cholerae can expel a resident bacterial species in a T6SS-dependent manner. Surprisingly, the T6SS acts primarily to increase the strength of gut contractions, rather than directly killing the bacterial competitor. Deletion of an actin cross-linking domain from the T6SS returned gut activity to normal and eliminated V. cholerae ’ s competitive advantage. These findings reveal a strategy by which pathogens can manipulate host biomechanics to redefine gut communities.