Current perspective on improved fermentative production and purification of fungal cellulases for successful biorefinery applications: a brief review

Cellulolytic enzymes play the most indispensable and centralized role in the hydrolysis of cellulosic material. Effective enzymatic hydrolysis is one of the major prerequisites in the development of a successful lignocellulosic biorefinery. However, the high cost of cellulase production yet remains to be the major bottleneck for large-scale commercial realization of lignocellusic bio-refinery. In addition, the lack of specificity and inconsistent bioconversion efficiencies of enzymes have restricted their applications towards bioconversion of narrow range of substrates. In view of addressing such bottlenecks associated with cellulase applications and further to improve the applicability of cellulase enzyme in various industrial processes, the current review essentially captures up-to-date information of various strategies adopted for the prospective production and purification of cellulase enzymes. Some holistic strategies deliberated in this review, which evolved over time and have brought about notable improvements in the final titer, yield, specificity, and productivity of the cellulolytic enzymes. It includes utilization of low-cost industrial or agricultural wastes for onsite production, application of enzyme, strain improvement through mutagenic, metabolic engineering and genetic engineering approaches, application of suitable bioprocess optimization techniques, development of ideal bioreactor configuration based on mode of fermentation process, and adaptation of the most intensive purification schemes. Additionally, to address the present existing challenges, more emphasizes have been concentrated towards economically sustainable and comprehensive production strategies of the enzyme.