Inulinase Production by Agro-Industrial Residues: Optimization of Pretreatment of Substrates and Production Medium

In this work, production of inulinase was studied. Media formulation was optimized by experimental design and response surface techniques, as well as the pretreatment of the agro-industry residues used in the formulation of fermentation medium. Two agro-industry residues were investigated: sugarcane molasses (SCM) and corn steep liquor (CSL). Pretreatment with sulfuric acid was the most effective for clarification of SCM (pH 5.0, 24 h of resting time and final pH 4.0). Clarification of CSL was accomplished with phosphoric acid (pH 3.0, 24 h of resting time and final pH 5.5). A color reduction of approximately 70% was achieved for both substrates. The highest production of inulinase was obtained in a medium containing 100 g l⁻¹ of pretreated SCM, 100 g l⁻¹ of pretreated CSL and 6 g l⁻¹ of Prodex Lac (yeast hydrolysate), yielding 1,139 U ml⁻¹.