β-Glucans bioproduction to minimize the ecological impact of effluents derived from the mussel processing industry

Abstract

In the NW of Spain, the annual production of mussel is 2×106 tons (35% of the world). The thermal treatment in the industrial process generates between 300-400 L/t of mussel processing wastewaters (MPW) which have been continuously dumped into the sea without depuration. These effluents, relatively rich in organic matter (7 g glycogen/L and 25 g COD/L), contribute to the progressive deterioration of the marine ecosystem. Based on a laboratory optimization and industrial pre-scale trials, a biotechnological process has been developed, in which the effluents of MPW are transformed into a culture medium (acidification, clarification, ultrafiltration) and used for the production of biomass. Afterwards, the obtained biomass is isolated, fractionated and purified through different processes producing several bioproducts applicable in different sectors: 1) single cell protein (SCP); 2) an extracted cell wall material with a high content in glucans and glycoproteins and 3) purified fractions of 1,3-β-glucans and mannoproteins were obtained after several steps of alkali and acid fractionation of the yeast cell walls. The process was re-scaled and dimensioned for industrial application. In consequence, this paper provides an environmentally friendly, eco-designed and profitable solution that allows integrating the mussel industry into the ecosystem in a sustainable way