## 4 Conclusions  
In this study, we described a relevant protocol to characterize the biofilm components of two _Vibrio_ species, both in total biofilm and in several aqueous or organic solvent extracts. The chemical composition, as well as QS signaling and antimicrobial activities of the extracts, were analyzed. In the future, the procedure should be further improved to better eliminate salts before the hydrolysis steps for colorimetric and GC analyses. The global composition (carbohydrate, protein, lipid, and nucleic acid) of the biofilm matrix showed that carbohydrate was the main component. The carbohydrates chemical composition and molecular weight may be slightly different in the biofilm cell supernatants and cell surface. Interestingly, in one case, a biofilm-specific carbohydrate, consisting only in glucose, was identified. The biofilm appeared thus as a specific bacterial phenotype. Therefore, it is potentially a source of biologically active compounds, such as polymers endowed with better biological and functional properties than those already known. Depending on their nature, chemical composition, and structure, the biotechnological potential of the biofilm polymer can be considered in a wide range of uses, such as cryoprotectants, emulsifiers, heavy metal chelators, bioactives for human health and well-being, and as a source of high-value sugar monomers or enzymes [18; 19; 20; 82].  
Antimicrobial resistance is a global public health issue affecting both human and animal health. At the same time, the presence of bacterial contaminants in foodstuffs is causing important economic losses. Therefore, it is urgent to market new antimicrobial molecules targeting, in particular, multi-resistant pathogenic strains, and thus presenting new mechanisms of action. Furthermore, while bacterial genome sequencing shows the existence of numerous genetic clusters that encode the biosynthesis of bioactive metabolites, a large majority of them remain inactive under the planktonic growth mode commonly used in lab experiments [83]. By investigating the underlying regulation pathways of biofilms, such as QS signaling, we will pave the way toward the future production of innovative metabolites.  
The following are available online at [[http://www.mdpi.com/2076-3417/9/22/4971/s1](http://www.mdpi.com/2076-3417/9/22/4971/s1)]([http://www.mdpi.com/2076-3417/9/22/4971/s1](http://www.mdpi.com/2076-3417/9/22/4971/s1)), Figure S1: 165 rDNA sequence of the MS969 strain, Table S1: 165 rDNA sequences of reference strains used in the phylogeny investigation, Table S2: Indicator strains used for antimicrobial activities screening.  
Conceptualization, D.P., D.H.-H., and C.D.-L.; methodology, D.P., F.F., and C.D.-L.; investigation and result analysis, D.P., F.F., L.M., L.K., S.B., C.S., V.V.-B., and C.D.-L.; writing--original draft preparation, D.P., V.V.-B., and C.D.L.; writing--review and editing, C.S., D.H.-H., S.C.-J., and C.D.-L.; supervision, C.D.-L.; project administration, C.D.-L.; funding acquisition, D.P., D.H.-H., and C.D.-L.  
This research received Ifremer internal funding through the Vi-LAB project.  
The authors are greatly indebted to other contributors to the Vi-LAB project from [PERSON] and [PERSON].  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.