Comparative study of the enzymatic convertibility of glycerol- and dilute acid-pretreated sugarcane bagasse using Penicillium- and Trichoderma-based cellulase preparations

Abstract

Three enzyme preparations based on the cellulase complex of Penicillium verruculosum and three Trichoderma reesei-based enzyme cocktails were used for evaluating the enzymatic convertibility of cellulose contained in glycerol- and sulfuric acid-pretreated bagasse. The hydrolysis was initially monitored with a micro-scale method using 2mL of reaction mixture containing 50g/L of pretreated solids, and at an enzyme load of 10mg protein/g cellulose. The results were further validated at a higher scale in a setup consisting of 20mL of reaction mixture with a substrate concentration of 100g/L. For all the cellulase preparations, and regardless of the experiment scale, glycerol-pretreated bagasse displayed better enzymatic convertibility than acid-pretreated bagasse. It was observed that when the enzyme load is increased from 2 to 10mg/g, the cellulose conversion is improved but the specific hydrolysis rate is only marginally affected. Although the Trichoderma-based commercial cocktail CC-3 led to higher hydrolysis rates and conversions than all the other enzyme preparations, the Penicillium-based cellulases, especially PV-Xyl PCA and PV-Hist BGL, also showed good potential. PV-Xyl PCA was relatively effective for hydrolysing acid-pretreated bagasse, and PV-Hist BGL displayed reasonable performance in the hydrolysis in absence of exogenous β-glucosidase.