Fish waste valorization: protein hydrolysate as sustainable nitrogen and nutrients for production of carotenogenic yeasts biomass.

Global fisheries and aquaculture production reached a record of 178 Mt in 2020. It is forecast that production will rise to 200 Mt by 2029, representing an increase of 25 Mt (14%). However, challenges arise with this increase like fish waste that comprising about two-thirds of total fish production and leading to economic and environmental concerns. The emergence of the bio-based circular economy is explored as a solution to manage fish wastes sustainably and biorefinery approach plays a central role in transforming industrial by-products into value-added products. An alternative to managing fish wastes is the production of fish protein hydrolysates, which contain proteins, oligopeptides and free amino acid, among other nutritional and functional compounds, with many technological applications. The species utilized in this study to produce fish protein hydrolysates was the chondrichthyan Mustelus schmitti , a specie caught by both artisanal and commercial fisheries in Argentina and Uruguay but in vulnerable exploitation due to its life cycle which compromised its fishery sustainability. In this scenario, complete biomass utilization of the already harvested individuals has been proposed encouraging maximal and sustainable use of M. schmitti fishing resources. Fish protein hydrolysates supplemented with dextrose was used as the sole nutrition source for the growth of a carotenogenic red yeast Rhodotorula glutinis capable of producing carotenoids tolurene and torularhodin. Our results indicate that fish protein hydrolysates from M. schmitti is able to support the growth of R. glutinis as the sole nutritional source and enhance carotenoid production compared with laboratory reference culture media.