How to break through the mass transfer barrier between insoluble cellulose and immobilized cellulase

Abstract

The development and utilization of cellulose are of great significance to energy, the economy, and the environment. Given this significance, green enzymatic conversion technology has attracted considerable research interest. Within this field, cellulase immobilization is a key technique that stabilizes the enzyme's structure and allows for its recycling, thereby substantially reducing the cost of cellulose conversion. However, mass transfer barriers between the immobilized enzyme and insoluble substrates often hinder the efficiency of cellulose hydrolysis. Overcoming this obstacle has the revolutionary potential to improve the economic viability of lignocellulosic biorefineries and lead to new cellulosic energy production models. Addressing these mass transfer limitations between immobilized cellulase and insoluble cellulose substrates remains a central challenge in this field. Most reviews on immobilized cellulase have focused primarily on immobilization carriers and methods, but lack a systematic classification and comprehensive analysis of mass transfer issues. This study examines the mass transfer processes involved in the catalysis of insoluble cellulose by cellulase, providing a summary of the strengths and limitations of existing immobilized cellulase research from the perspectives of internal and external mass transfer. This work offers insights relevant to the development of future biorefinery systems that may increase global cellulosic-based ethanol production within a decade, thereby contributing to the transition from a fossil-based to a sustainable circular bioeconomy.