Production of Free Sugars by Enzymatic Hydrolysis of Dictyota dichotoma

Abstract

It is well-known that brown macroalgae can be used as a source of valuable sugars with different biological activities, but its polymeric macrostructures should be hydrolyzed for obtaining an acceptable yield. This study deals with the production of free sugars by the enzymatic hydrolysis of optimized biologically pretreated brown seaweed. The biological pretreatment was carried out using solid-state fermentation (SSF) with a white root fungus species (Aspergillus awamori). For this purpose, different temperature growth conditions (30ºC and 50ºC) and inoculum concentrations (106; 107 and 108 spores/g of dried solid) were tested for 20 days of the SSF process. In addition, different dosages of commercial hydrolytic enzyme cocktail Cellic® Ctec2 were tested for enzymatic hydrolysis (EH) of D. dichotoma at a solid/liquid ratio of 2.2% w/v. Finally, biologically pretreated samples at optimum conditions (30ºC and inoculum size of 108 cel/mL) were hydrolyzed with commercial Cellic®Ctec2 at the optimum dosage (112FPU/g). The maximum reducing sugars concentration measured in the hydrolysates was 80 g/kg biomass. Further investigations increasing the solid-liquid ratio and reducing the enzyme dosage are necessary for the complete optimization of sugar production from D. dichotoma.