Production and characterization of enzymatic cocktail produced by Aspergillus niger using green macroalgae as nitrogen source and its application in the pre-treatment for biogas production from Ulva rigida

Abstract Marine macroalgae are gaining more and more importance as a renewable feedstock for durable bioenergy production, but polysaccharides of this macroalgae are structurally complex in its chemical composition. The use of enzymatic hydrolysis may provide new pathways in the conversion of complex polysaccharides to fermentable sugars. In this study, an enzymatic cocktail with high specificity was first isolated from Aspergillus niger using the green macroalgae Ulva rigida as nitrogen source. The cocktail is rich on β-glucosidase, pectinase and carboxy-methyl-cellulase (CMCase). The highest activity was obtained with β-glucosidase (109 IU mL −1 ) and pectinase (76 IU mL −1 ), while CMCase present the lowest activity 4.6 IU mL −1 . The U. rigida pre-treatment with this enzymatic cocktail showed high rate of reduced sugar release, and could bring promising prospects for enzymatic pre-treatment of the biogas production from U. rigida biomass which reached 1175 mL g COD int −1 .