Emerging role of additives in lignocellulose enzymatic saccharification: A review

Enzymatic saccharification is crucial in harvesting clean bioenergy and renewable biomaterials from lignocellulosic biomass. Due to the non-productive adsorption between residual lignin and cellulase, improving the efficiency of enzymatic hydrolysis is challenging. The mild pretreatment methods hinder further lignin removal. According to reports, a wide range of additives are applied to boost the substrate enzymatic digestibility by averting non-productive adsorption between substrate lignin and cellulases. There is a lack of comprehensive classification and summary of these additives, though, resulting in their working mechanisms still being a subject of debate. This mini-review firstly addresses the complexity of the enzymatic hydrolysis system, examining the interactions among its key components (substrate cellulose, residual lignin, and cellulases) involved in enzymatic hydrolysis. Based on, the mechanisms by which these additives operate within the pretreatment process and the enzymatic hydrolysis system are critically reviewed from the perspective of acting as carbon scavengers, lignin blockers, protectors of cellulase, and enhancers of cellulose's accessibility. This review serves as a valuable resource for identifying novel and effective additives to enhance the understanding of lignocellulosic enzymatic saccharification. Moreover, constructive suggestions were put forward for the development of enzymatic saccharification platform.