Effect of biocidal coatings on microfouling In vitro and in situ results

Coatings containing booster biocide (diuron and tolylfluanid) and copper thiocyanate were exposed to marine bacteria and diatoms. The effect of biocides included in coatings on cells adhesion and biofilm formation was studied in different conditions of immersion. In vitro, two marine bacterial strains (Pseudoalteromonas sp. and Bacillus sp.) and two diatom strains (Cytlndrotheca closterium and Amphora sp.) were used in mono-species culture. In situ (French Atlantic Ocean, Lorient Harbour), the colonization process of natural microfouling onto coatings were evaluated. Confocal laser scanning microscopy was used to observe and quantify cells adhesion on the coatings. The results demonstrated that biocidal coatings are more active against diatom attachment (inhibition) than against bacterial adhesion (no effect). Microalgae were more sensitive to coating. The results between in vitro and in situ assays showed a difference in behaviour according to the mode of presentation of biocide (biocidal solution or coating) or the environment (mono-species culture or marine consortium)