Sargassum biomass as a nutrient source for Kluyveromyces marxianus: effects of hydrothermal treatment and fermentation on antioxidant activity

Since 2011, the coasts of Mexico have experienced massive Sargassum invasions, resulting in substantial economic losses in tourism and fisheries. Circular economy approaches provide an opportunity to valorize this abundant biomass by extracting bioactive compounds for pharmaceutical, food, and feed applications. In this study, Sargassum collected in Cancún was subjected to hydrothermal treatment at 100–200°C, producing carbohydrate rich solid and aqueous fractions. These fractions were subsequently fermented with Kluyveromyces marxianus to evaluate their antioxidant potential. Fermentation conducted over 24–72 h showed that the aqueous fraction fermented for 48 h exhibited the highest radical scavenging activity (~26%), significantly exceeding that of the control (~11%). The results indicate that hydrothermally pretreated Sargassum is a promising substrate for K. marxianus , capable of generating bioactive compounds with antioxidant properties. Importantly, this study is the first to report the use of Sargassum as a substrate for K. marxianus . These findings suggest potential applications for incorporating fermented Sargassum into livestock and aquaculture diets to enhance animal health and growth, while indirectly improving the nutritional quality and safety of animal derived products for human consumption.