Impact of a human gut microbe on <i>Vibrio cholerae</i> host colonization through biofilm enhancement.

Abstract

Recent studies indicate that the human intestinal microbiota could impact the outcome of infection by <i>Vibrio cholerae,</i> the etiological agent of the diarrheal disease cholera. A commensal bacterium, <i>Paracoccus aminovorans,</i> was previously identified in high abundance in stool collected from individuals infected with <i>V. cholerae</i> when compared to stool from uninfected persons. However, if and how <i>P. aminovorans</i> interacts with <i>V. cholerae</i> has not been experimentally determined; moreover, whether any association between this bacterium alters the behaviors of <i>V. cholerae</i> to affect the disease outcome is unclear. Here, we show that <i>P. aminovorans</i> and <i>V. cholerae</i> together form dual-species biofilm structure at the air-liquid interface, with previously uncharacterized novel features. Importantly, the presence of <i>P. aminovorans</i> within the murine small intestine enhances <i>V. cholerae</i> colonization in the same niche that is dependent on the <i>Vibrio</i> exopolysaccharide and other major components of mature <i>V. cholerae</i> biofilm. These studies illustrate that multispecies biofilm formation is a plausible mechanism used by a gut microbe to increase the virulence of the pathogen, and this interaction may alter outcomes in enteric infections.