Exopolysaccharide protects Vibrio cholerae from exogenous attacks by the type 6 secretion system
Significance This work demonstrates that exopolysaccharide (EPS) produced by Vibrio cholerae can protect against exogenous type 6 secretion system (T6SS) attacks from different bacterial species. This protection does not affect the ability of the EPS-producing cell to use their own T6SS to attack other bacteria, indicating that EPS does not simply increase the physical distance between cells to afford protection. Furthermore, this protective effect does not depend on other genes involved in biofilm biogenesis, suggesting that EPSs can determine the outcomes of antagonistic bacterial–bacterial interactions independent of their typical function in biofilm formation. Thus, extracellular biopolymers of bacteria may play a role in modulating resistance to exogenous attacks by other bacteria as well as providing potential resistance to host innate immune mechanisms.