Abstract

Production of bioethanol from macroalgal feedstock involves pretreatment and hydrolysis of biomolecules for release of sugar followed by the fermentation of the sugar. The most commonly used pretreatment method for macroalgal biomass is dilute acid hydrolysis using mineral acids H₂SO₄ and HCl. Optimization of dilute acid hydrolysis of Ulva lactuca yielded 214.67mg g^-1 using 0.5 N H₂SO_4, 5% w/w substrate concentration at 121^oC for 45 min and hydrolysis of Enteromorpha intestinalis yielded 239.94 mg g^-1 of reducing sugar using 0.7 N H₂SO_{4 ,} 5% w/w substrate concentration at 120^oC for 45 min. Crude enzyme extracted from marine bacteria Vibrio parahaemolyticus and purified by the two-step purification produced 61.82% yield with 2.97-fold purification. Enzymatic hydrolysis of pretreated macroalgal biomass produced one-fold higher reducing sugar than acid hydrolysis for Ulva lactuca (261.76±0.9 mg g^-1) and Enteromorpha intestinalis (289.89±2.4 mg g^-1).

Keywords: Pretreatment, Dilute acid, Enzyme, Optimization, Macroalgae, Reducing sugar