Engineering of xylanases for the development of biotechnologically important characteristics

Abstract

Xylanases are the main biocatalysts used for the reduction of the xylan backbone from hemicellulose, randomly splitting off β‐1,4‐glycosidic linkages between xylopyranosyl residues. Xylanase market has been annually estimated at 500 million US Dollars and they are potentially used in broad industrial process ranges such as paper pulp biobleaching, xylo‐oligosaccharide production, and biofuel manufacture from lignocellulose. The highly stable xylanases are preferred in the downstream procedure of industrial processes because they can tolerate severe conditions. Almost all native xylanases can not endure adverse conditions thus they are industrially not proper to be utilized. Protein engineering is a powerful technology for developing xylanases, which can effectively work in adverse conditions and can meet requirements for industrial processes. This study considered state‐of‐the‐art strategies of protein engineering for creating the xylanase gene diversity, high‐throughput screening systems toward upgraded traits of the xylanases, and the prediction and comprehensive analysis of the target mutations in xylanases by in silico methods. Also, key molecular factors have been elucidated for industrial characteristics (alkaliphilic enhancement, thermal stability, and catalytic performance) of GH11 family xylanases. The present review explores industrial characteristics improved by directed evolution, rational design, and semi‐rational design as protein engineering approaches for pulp bleaching process, xylooligosaccharides production, and biorefinery & bioenergy production.

Mid–Long Chain Dicarboxylic Acid Production via Systems Metabolic Engineering: Progress and Prospects

“…Their catalytic mechanism can also be understood based on their structure–function relationship. Mutations can be induced at selected sites (via processes such as error-prone PCR and DNA shuffling), and positive mutants can be screened via high-throughput screening. , Second, new enzymes can be identified and designed. Specifically, computer technology can be applied to identify the unresolved key enzymes from the DCA synthesis pathway, and these enzymes can be fabricated de novo .…”

Engineering of GH11 Xylanases for Optimal pH Shifting for Industrial Applications

“…To engineer the pH-associated features of GH11 enzymes, various strategies, such as site-directed mutagenesis [31,32], RD, modeling/site-directed mutagenesis, structural comparison, redesign of electrostatic potential [33], structure analysis [34,35], and bioinformatics-and biostatistics-based approaches [36], have been used. In a recent review, comprehensive up-to-date strategies for creating a diverse xylanase gene library; implementing high-throughput systems to screen enhanced xylanase mutants derived by DE; and utilizing in silico methods for the prediction based on, for example, Framework for Rapid Enzyme Stabilization by Computational libraries (FRESCO) and in-depth analysis of target mutations were thoroughly examined [37] to obtain desirable industrial characteristics, such as alkaliphilic enhancement, thermal stability, and catalytic performance. Nevertheless, protein engineering studies that involve altering the pH profile and improving pH stability are relatively scarce compared with the efforts put into engineering temperature-related properties, such as improving xylanase thermostability.…”

Computer-Aided Reconstruction and Application of Bacillus halodurans S7 Xylanase with Heat and Alkali Resistance

“…Renewable biomass continues to hold promise as a potential resource for producing high-value biochemicals, such as biofuels. Nonetheless, most of the costs associated with producing these products can be attributed to the utilization of biomass-degrading enzymes, such as cellulase, amylase, and xylanase, which are necessary for biomass hydrolysis. − Particularly, xylanase is a class of enzymes that can degrade xylan, one of the most abundant renewable biomass resources, into xylobiose (X2), oligosaccharides above X2, and small amounts of xylose (X1). , Xylanases consist of β-1,4-endoxylanase, α- l -arabinofuranosidase, α- d -glucuronidase, acetyl xylan esterase, ferulic acid esterase, and β- d -xylosidase, of which β-1,4-endoxylanase is the most important in xylan degradation. − Currently, the enzymatic hydrolysis of xylan has become a research hotspot in the production of xylooligosaccharides (XOS) because of the advantages of mild reaction conditions, high product purity, and yield. − For example, alkaline xylanases from Bacillus mojavensis A21 have been used to release X2 and xylotriose (X3) from corncob cellulose . Agricultural waste materials, such as corncob and viscose fibers (hardwood pulp), are often used as raw materials for XOS production.…”