Engineering cellulases for conversion of lignocellulosic biomass

Abstract

Lignocellulosic biomass is a renewable source of energy, chemicals, and materials. Many applications of this resource require the depolymerization of one or more of its polymeric constituents. Efficient enzymatic depolymerization of cellulose to glucose by cellulases and accessory enzymes such as lytic polysaccharide monooxygenases (LPMOs) is a prerequisite for economically viable exploitation of this biomass. Microbes produce a remarkably diverse range of cellulases, which consist of glycoside hydrolase (GH) catalytic domains and, although not in all cases, substrate-binding carbohydrate-binding modules (CBMs). Since enzymes are a considerable cost factor, there is great interest in finding or engineering improved and robust cellulases, with higher activity and stability, easy expression, and minimal product inhibition. This review addresses relevant engineering targets for cellulases, discusses a few notable cellulase engineering studies of the past decades, and provides an overview of recent work in the field.

Lignocellulosic Biomass-Derived Biogas: A Review on Sustainable Energy in Malaysia

“…The order of hydrolysed cellulose started with amorphous domains, followed by the crystalline domains, as reported by Ling et al (2017), where the yield of monosaccharides dropped as the crystallinity of the substrate increased. Moreover, each cellulase component has its specific capabilities and activity for the adsorption of different types of cellulose through carbohydrate-binding modules (CBMs) during the breakdown of cellulose (Chaudhari et al, 2023).…”

Engineering Enzymes for Environmental Sustainability

“…Hence, engineering individual lignocellulose deconstructing enzymes has been a topic of intense research. For instance, cellulases have been optimised for improved activity, thermostability and pH tolerance; the details of these efforts are outside the scope of this piece, but many of these efforts are covered in excellent reviews [86–89] . Engineered enzyme cocktails have also been developed, with multiple synergistic biocatalysts working together to deconstruct several biomass components in parallel [90] .…”

“…For instance, cellulases have been optimised for improved activity, thermostability and pH tolerance; the details of these efforts are outside the scope of this piece, but many of these efforts are covered in excellent reviews. [ 86 , 87 , 88 , 89 ] Engineered enzyme cocktails have also been developed, with multiple synergistic biocatalysts working together to deconstruct several biomass components in parallel. [90] These cocktails typically consist of cellulases, cellobiohydrolases, endoglucanases, β‐glucosidases, hemicellulases, and lytic polysaccharide monooxygenases.…”

Nature-inspired Enzyme engineering and sustainable catalysis: biochemical clues from the world of plants and extremophiles

“…Mostly, bacterial and fungal enzymes have been used in the process, but plant enzymes present an equally attractive opportunity as these are naturally involved in cell wall turnover in plants. Whatever the source of enzyme, researchers have noted that natural enzymes may not be sufficiently active to enable economically viable bioprocesses, even at optimal conditions or might be subject to product inhibition ( Chaudhari et al, 2023 ). Therefore, enzyme engineering becomes a necessity.…”