Preparation of a novel soluble inducer by cellobiase-release microcapsules and its application in cellulase production

Abstract

Effective and low-cost inducer is a prerequisite for efficiency improvement in cellulase production by Trichoderma reesei. In this study, spores of Aspergillus niger enriched with cellobiase were embedded in Ca-alginate microcapsules, attaining a sustained cellobiase-release system (named CRMA) which was then used to catalyze the conversion of glucose into glucose-sophorose sugar mixture via transglycosylation. Further, the process and optimal parameters of transglycosylation reaction were studied in a 5 L reactor and the sophorose concentration reached 70.55 g/L at 50 °C, pH 4.0 with CRMA loading of 200 mL after 72 h of reaction. The obtained sugar mixture was subsequently used as both carbon source and inducer in cellulase production by Trichoderma reesei under fed-batch process. The filter paper activity (FPA) reached 90.28 IU/mL at 144 h fermentation time, 1.85-fold higher than that induced by lactose. These results indicate that the newly established strategy for soluble inducer synthesis has the potential for efficiency improvement and cost reduction in cellulase production.