Marine biofilms on submerged surfaces are a reservoir for Escherichia coli and Vibrio cholerae.

The enteric bacterium and potential human pathogen, Escherichia coli, is known to persist in tropical soils and coastal waters. Vibrio cholerae causes the disease cholera and inhabits marine environments including microbial films on submerged surfaces. The abundances of E. coli and V. cholerae were quantified in biofilm and water-column samples from three harbors in Honolulu, Hawai'i, which differ in their local and international ship traffic. E. coli and, in some cases V. cholerae, occurred in relatively high abundances in marine biofilms formed on abiotic surfaces, including the exterior hulls of ships. The community fingerprints of the biofilms and the water harboring these pathogens were further analyzed. The community compositions of biofilms from different locations were more similar to each other than to water-column communities from the same locations. These results suggest that biofilms are an overlooked reservoir and a source of dissemination for E. coli and V. cholerae.