Influence of biocides and algal extracts on adhesion and biofilm formation of marine bacteria

International audienceAny surface immersed in aqueous environment is rapidly colonized by micro and macroscopic organisms [1]. This phenomenon is known as biofouling, which is the origin of complex and recurring point in the global economy and environmental problems. The recent ban of ecotoxic products, used to counteract this phenomenon, generates the interest for research of new antifouling molecules, more environmentally friendly. The objective of this study is to evaluate the potential fouling of microalgae extracts compared to commercial biocides. In this study, the effectiveness of antifouling molecules are evaluated by the adhesion and primary biofilm formation of three pioneering marine bacterial strains. Bacteria were grown at 20 °C. The anti-adhesive activity is evaluated in a static system, by microplates [2] and in a dynamic system, by flow cell. Culture was performed on glass slides in the chambers of the flow cell, adhesion was allowed for 3 hours and a flow of culture environment was applied for up to 48 hours to obtain a biofilm formation. Bacteria are dyed by Syto61 and were observed with a confocal microscopy laser scanning. The effective concentration of commercial biocides, which allows attachment of 50% of bacteria, is between 5 and 18 µM, depending on the bacteria and the biocide. Concerning the extracts of H2O-MeOH (1:1) and MeOH100% of microalgae revealed an inhibition of adhesion and biofilm formation. The microalgal extracts with antifouling activity is analyzed by Hr-MAS to identify the molecules responsible for this activity. The perspectives of this work are to target microalgal strains which can be qualitative sources of biocides withhigh efficiency.This will serve as a basis for developing new antifouling coatings that can be used in temperate and tropical ecosystems