Vibrio cholerae requires oxidative respiration through the bd-I and cbb3 oxidases for intestinal proliferation

Vibrio cholerae respires both aerobically and anaerobically and, while oxygen may be available to it during infection, other terminal electron acceptors are proposed for population expansion during infection. Unlike gastrointestinal pathogens that stimulate significant inflammation leading to elevated levels of oxygen or alternative terminal electron acceptors, V. cholerae infections are not understood to induce a notable inflammatory response. To ascertain the respiration requirements of V. cholerae during infection, we used Multiplex Genome Editing by Natural Transformation (MuGENT) to create V. cholerae strains lacking aerobic or anaerobic respiration. V. cholerae strains lacking aerobic respiration were attenuated in infant mice 10⁵-fold relative to wild type, while strains lacking anaerobic respiration had no colonization defect, contrary to earlier work suggesting a role for anaerobic respiration during infection. Using several approaches, including one we developed for this work termed Comparative Multiplex PCR Amplicon Sequencing (CoMPAS), we determined that the bd-I and cbb₃ oxidases are essential for small intestinal colonization of V. cholerae in the infant mouse. The bd-I oxidase was also determined as the primary oxidase during growth outside the host, making V. cholerae the only example of a Gram-negative bacterial pathogen in which a bd-type oxidase is the primary oxidase for energy acquisition inside and outside of a host.