The importance of rearing time on secondary metabolite production: The case study of Sarcotragus spinosulus (Porifera, Demospongiae) cultured in a Mediterranean IMTA system

Marine sponges represent one of the major sources of bioactive compounds of marine origin. However, harvesting the biomass for extraction or artificially synthesizing the compounds to this day remain unsustainable and challenging processes. In this context, integrated cultivation systems such as IMTAs promote an increase in biomass that can subsequently be sustainably exploited for the extraction of secondary metabolites. In the present work, the survival and growth capacity of the sponge Sarcotragus spinosulus was evaluated in the REMEDIA Life IMTA system over 2 and 10 months and the metabolic fingerprints of its extracts were analyzed. When compared between different tissues (i.e. mesohyl and pinacoderm) no significant differences in their chemical composition were found. However, it has been shown that the time of culture significantly affects the sponge metabolome: explants cultured longer (10 months) differ from natural sponges and from those cultured for two months. This difference is caused by polyprenyl hydroquinones, which show a significant reduction of almost 50 % in the longer explants. The findings suggest that shorter culturing periods may be more productive for large-scale polyprenyl hydroquinone production as they yield proportionally higher biomass and metabolite content.