There is a growing demand for the efficient treatment of seaweed biomass and the production of seaweeddegrading enzymes. Fifteen algicolous fungi were isolated from the Red Sea macroalgae in Egypt and were studied for their capability of utilizing Sargassum and Palisada biomass and subsequent production of different thallus-degrading enzymes. Most of the fungi efficiently saccharified the macroalgal extracts that amounted to more than 70 % of the sugars in the unfermented macroalgal extract. Algicolous fungi fermented Sargassum through extracellular fucoidanases and alginases that were negatively correlated as revealed by principal component analysis (PCA), suggesting an antagonistic degradation of Sargassum polysaccharides. Extracellular agarases resulted in efficient fermentation of Palisada biomass. Fungi expressed also amylase and protease activities that were low or nonexistent and biomass-dependent.Amylase showed positive correlation with agarase as indicated by PCA, which suggests that the two enzymes synergistically degrade Palisada biomass. The enzymatic cocktails were also able to release reducing sugars from the powdered macroalgal thalli, indicating the importance of enzymes in the saprophytic growth of fungi. Generally, enzymatic activities and specific activities of fucoidanase, alginase, and agarase in algicolous fungi were higher than reported previously for non-algicolous fungi. Enzymatic activities of the marine brown algal pathogen Lindra thalassiae indicated that infection by this pathogen might occur through alginases. The results shed light into production of less expensive enzymatic mixtures from an understudied group of microorganisms targeting seaweeddegradation. These enzymes have many biotechnological and industrial applications as thallus maceration and protoplast isolation despite bioactivity of obtained oligosaccharides

The study of fungal species diversity from marine algae is in its infancy; as now no studies have been carried out on the distribution and diversity of fungi on the surfaces of marine macroalgae where all fungal–algal interactions tend to begin. The aim of this study was to isolate and describe the culturable part of mycobiota associated with the surface of benthic marine macroalgae (epiphytic or epibiotic fungi). This is an important step in understanding their abundance, diversity and factors influencing their variability and composition. The fungal community was dominated by Ascomycetes (89%) with Eurotiales as the most abundant fungal order followed by Capnodiales, Pleosporales, and Hypocreales, while Zygomycetes was less frequent. The nature of occurrence of fungal genera on different macroalgal hosts suggests that a mix of generalists’ framework applies to fungal epiphytes of seaweeds, but the abundance of fungal taxa varied among ecological functional groups of algae, as well as macroalgal taxonomic groups, which imply host filtering. The fungal assemblages were also characterized by temporal variation with variation in temperature, pH, and salinity as the most important abiotic factors. The structure of fungal assemblages showed high beta diversity and low similarity between hosts.