**4. Biofilms and flagella**

Most of the bacteria, including pathogens, form biofilm to survive and persist in different environments*.* Biofilms are organized bacterial communities attached to a surface and producing a matrix. *V. cholerae* form biofilms at different stages of its life cycle. An increasing number of evidences suggest that *V. cholerae* forms biofilm during the gut infection and biofilm-like aggregates display a hyper-infective phenotype [162]. To persist in the environment, *V. cholerae* forms biofilm on different biotic and abiotic substrates such as floating aggregates, ship hulls, microalgae and copepods [163]. The transition between planktonic motile and non-motile biofilm states is highly regulated [162, 164]. The composition and abundance of the secreted factors involved in biofilm formation, maturation and dispersion largely depend on environmental conditions and on surface composition. In this section, we will review the current knowledge about the biofilm secretome in *V. cholerae* at different stages of the biofilm formation and the interplay between biofilm and motility.
