A new method for evaluation of antifouling activity of molecules against microalgal biofilms using confocal laser scanning microscopy-microfluidic flow-cells

WOS:000464485900007Regulatory developments regarding antifouling molecules encourage the search for non-toxic substances. Evaluation tools must evolve to highlight anti-adhesion effects rather than growth inhibition. The work presented here aimed at developing a method based on confocal laser scanning microscopy-microfluidic flow-cells in order to characterize microalgal biofilms. The first part of the work was dedicated to the setting-up of experimental parameters allowing the production of microalgal biofilms. The results obtained showed that it was indeed possible to produce reproducibly biofilms. The size of microalgal strains appeared to be a key-parameter in the adhesion rate and cells adhesion strength. Cylindrotheca closterium cells adhered in lower amount but formed denser biofilms than Porphyridium purpureum. The second part of the work focused on the evaluation of a known antifouling molecule, dibromohemibastadin-1 (DBHB). A comparison with the conventionally used method, multi-well plates experiments, was established. The multi-well plates experiments allowed the determination of minimum inhibitory concentration (MIC) for growth and adhesion inhibition (around 80 mu M). The flow-cells combined with confocal laser scanning microscopy (CLSM) enabled the observation of biofilm, the determination of kinetics parameters of adhesion and an estimation of the adhesion strength