Poster.-- Close Encounters IIM (3rd Kind), Vigo, 23 June 2022Macroalgae, like Ulva genus, provides an important niche for epiphytic biofilm-forming bacteria, including those of the genus Phaeobacter with the ability to antagonize fish pathogens such as Vibrio anguillarum, through the production of tropodithietic acid (TDA) [1–3]. P. gallaeciensis has previously demonstrated its effectiveness as a probiotic in aquaculture by reducing mortality in fish larvae experimentally infected with this pathogen as well as its colonization of U. ohnoi surface [1]. This colonization can be used as apathogen control strategy in multitrophic fish-algae cultures in recirculatingwater systems (IMTA-RAS), improving the health of the fish (Fig. 1).However, the optimal conditions for the culture of U. ohnoi could have a determining influence both on the maintenance of these biofilms and on the production of TDA, especially the intensity of lightN
