Efficient Biocatalytic Conversion of Stranded Green Macroalgal Biomass Using a Specific Cellulases-Based Cocktail

A specific macroalgal biomass decomposing fungus SL1 newly isolated and identified as Aspergillus fumigatus was found to be an efficient cellulases producer. This strain when cultivated on the whole green macroalgae as sole carbon source permitted the production of specific cellulases (specific activities of 30 and 33 U/mg of proteins for endoglucanase and β-glucosidase, respectively) different from commercial ones as shown by zymography. The application of the produced cellulases-based enzymatic cocktail for the saccharification of alkali pretreated Ulva sp. biomass yielded of 58%. This saccharification rate was optimized using response surface methodology (RSM). An increase of 36% in saccharification yield was obtained under optimized conditions (13 U CMCase, 4% substrate and 135 rpm agitation) which agreed with model predictions. The biocatalytic conversion using specific fungal cellulases may be a promising approach for the biodegradation of stranded macroalgae and its valorization mostly for bioethanol production.