Impact of a human gut microbe onVibrio choleraehost colonization through biofilm enhancement

AbstractRecent studies indicate that the human intestinal microbiota could impact the outcome of infection byVibrio cholerae, the etiological agent of the diarrheal disease cholera. A commensal bacterium,Paracoccus aminovorans, was previously identified in high abundance in stool collected from individuals infected withV. choleraewhen compared to stool from uninfected persons. However, if and howP. aminovoransinteracts withV. choleraehas not been experimentally determined; moreover, whether any association between this bacterium alters the behaviors ofV. choleraeto affect the disease outcome is unclear. Here we show thatP. aminovoransandV. choleraetogether form dual-species biofilm structures at the air-liquid interface, with previously uncharacterized novel features. Importantly, the presence ofP. aminovoranswithin the murine small intestine enhancesV. choleraecolonization in the same niche that is dependent on theVibrioexopolysaccharide (VPS) and other major components of matureV. choleraebiofilm. These studies illustrate that dual-species 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.Significance StatementWhile ample evidence suggests that the outcome of some enteric infections can be affected by the intestinal microbiota, how specific gut microbes change the behaviors of a pathogen is unclear. Here we characterize the interaction betweenVibrio choleraeandParacoccus aminovorans, a gut microbe known to increase in abundance in the intestines during activeV. choleraeinfection in humans. These two bacteria form a dual-species biofilm structure at the air-liquid interface, and the gut microbe increases the host colonization efficiency ofV. cholerae. Importantly, our study identifies a previously unknown mechanism of gut microbe-pathogen interaction that has the potential to alter the disease outcome.