Laccases as a Potential Tool for the Efficient Conversion of Lignocellulosic Biomass: A Review

Abstract

Abstract:The continuous increase in the world energy and chemicals demand requires the development of sustainable alternatives to non-renewable sources of energy. Biomass facilities and biorefineries represent interesting options to gradually replace the present industry based on fossil fuels. Lignocellulose is the most promising feedstock to be used in biorefineries. From a sugar platform perspective, a wide range of fuels and chemicals can be obtained via microbial fermentation processes, being ethanol the most significant lignocellulose-derived fuel. Before fermentation, lignocellulose must be pretreated to overcome its inherent recalcitrant structure and obtain the fermentable sugars. Usually, harsh conditions are required for pretreatment of lignocellulose, producing biomass degradation and releasing different compounds that are inhibitors of the hydrolytic enzymes and fermenting microorganisms. Moreover, the lignin polymer that remains in pretreated materials also affects biomass conversion by limiting the enzymatic hydrolysis. The use of laccases has been considered as a very powerful tool for delignification and detoxification of pretreated lignocellulosic materials, boosting subsequent saccharification and fermentation processes. This review compiles the latest studies about the application of laccases as useful and environmentally friendly delignification and detoxification technology, highlighting the main challenges and possible ways to make possible the integration of these enzymes in future lignocellulose-based industries.

Laccase‐Mediated Grafting on Biopolymers and Synthetic Polymers: A Critical Review

“…[33] The traditional removal of ligninderived chromophores from lignocelluloses to enhance whiteness (bleaching) by chlorine and peroxides is gradually being replaced by enzymatic methods, which includes the use of laccase. [34] The mild way in which laccases generate radicals is employed in lignin polymerisation/oligomerisation, but also in delignification; [35] an essential part of the bleaching process. This topic is beyond the scopeo fthis review ande xcellently reviewed by Meyer and co-workers.…”

Double-emulsion technique applied to laccase immobilization on polymeric nanoparticles

“…released, thus allowing its use as adjuvant in animal feed [23]. The use of ligninolytic enzymes, especially laccases, is an attractive method for detoxification and delignification of feed´s insoluble fiber fraction [24]. Lignin polymer functions as a physical barrier that hampers the accessibility of carbohydrates to hydrolytic enzymes and promotes their non-specific adsorption, lowering the number of enzymes available for hydrolyzing carbohydrates and hence diminishing saccharification yields [24].…”

“…The use of ligninolytic enzymes, especially laccases, is an attractive method for detoxification and delignification of feed´s insoluble fiber fraction [24]. Lignin polymer functions as a physical barrier that hampers the accessibility of carbohydrates to hydrolytic enzymes and promotes their non-specific adsorption, lowering the number of enzymes available for hydrolyzing carbohydrates and hence diminishing saccharification yields [24]. In this work the immobilized enzyme exhibited higher stability than free laccase, moreover immobilized laccase activity increased at the end of the sequential assay involving acidic pHs up to alkaline ones.…”

Production of Bio-Derived Fuels and Chemicals

“…The review articles in this Special Issue provide insights into syngas fermentation [14] and the significance of laccases in the development of LB as an important substrate for the production of renewable fuels and chemicals [15]. The review article contributed by Phillips et al [14] indicates that integration of thermochemical gasification of LB and wastes to syngas (CO, CO 2 and H 2 ) and syngas fermentation by autotrophic bacteria is a robust and potentially economical process for the production of fuels and chemicals.…”

“…Important concepts such as Wood-Ljungdahl biochemical pathway reactions and applications, gas solubility, mass transfer, thermodynamics of enzyme-catalyzed reactions, electrochemistry and cellular electron carriers and fermentation kinetics, were highlighted [14]. The review article contributed by Fillat et al [15] provides important studies and perspectives on the use of laccases as a delignification and detoxification tool for efficient conversion of LB into value-added products, with emphasis on lignocellulosic ethanol production; highlighting major challenges and opportunities, and plausible ways to integrate the enzymes in the future lignocellulose-allied industries.…”