Strategies towards Reduction of Cellulases Consumption: Debottlenecking the Economics of Lignocellulosics Valorization Processes

Abstract

Lignocellulosic residues have been receiving growing interest as a promising source of polysaccharides, which can be converted into a variety of compounds, ranging from biofuels to bioplastics. Most of these can replace equivalent products traditionally originated from petroleum, hence representing an important environmental advantage. Lignocellulosic materials are theoretically unlimited, cheaper and may not compete with food crops. However, the conversion of these materials to simpler sugars usually requires cellulolytic enzymes. Being still associated with a high cost of production, cellulases are commonly considered as one of the main obstacles in the economic valorization of lignocellulosics. This work provides a brief overview of some of the most studied strategies that can allow an important reduction of cellulases consumption, hence improving the economy of lignocellulosics conversion. Cellulases recycling is initially discussed regarding the main processes to recover active enzymes and the most important factors that may affect enzyme recyclability. Similarly, the potential of enzyme immobilization is analyzed with a special focus on the contributions that some elements of the process can offer for prolonged times of operation and improved enzyme stability and robustness. Finally, the emergent concept of consolidated bioprocessing (CBP) is also described in the particular context of a potential reduction of cellulases consumption.

Whole Cell Biocatalysis of 5-Hydroxymethylfurfural for Sustainable Biorefineries

“…Considering these, and aiming at sustainable development, biocatalysis has been receiving increased attention due to its milder conditions, higher selectivity and environmental friendliness [18]. Moreover, considering these factors, the use of whole-cell biocatalysts presents advantages over enzyme biocatalysis, such as regeneration of co-factors and ease of catalyst recycling [19,20].…”

Rational feeding strategies of substrate and enzymes to enzymatic hydrolysis bioreactors

“…In the case of cellulose, they are usually released into the liquid fraction once the cellulose chains are hydrolyzed. In contrast to that, cellulases adsorbed onto lignin do not naturally desorb from it, a mechanism usually designated as nonproductive binding [33].…”

Immobilization and Application of the Recombinant Xylanase GH10 of Malbranchea pulchella in the Production of Xylooligosaccharides from Hydrothermal Liquor of the Eucalyptus (Eucalyptus grandis) Wood Chips

“…Innovative and efficient technologies for lignin, cellulose, and hemicellulose fractionation allow the implementation of integrated processes for the co-production of bioenergy and higher value-added bioproducts, such as cello- and xylooligosaccharides and lignin derivatives [ 1 , 2 , 3 , 4 ]. These strategies are necessary to maximize organic matter, reduce waste generation, and obtain products with high added-value, strengthening the circular bioeconomy in plant biomass biorefineries [ 5 ].…”

“…However, the enzymatic hydrolysis of the xylan present in the LCM is still a great challenge, requiring studies on the composition and pretreatment of LCM besides efficient biocatalysts. Furthermore, obtaining and using these biocatalysts must be cost-effective to be economically viable [ 5 , 22 ]. It is well-established that the immobilization of enzymes is fundamental for the viability of the bioprocess since this technique allows the recovery and reuse of the enzyme through several reaction cycles [ 23 , 24 , 25 , 26 ].…”