Thermostable microbial xylanases for pulp and paper industries: trends, applications and further perspectives

Kumar, Vishal; Marín-Navarro, Julia; Shukla, Pratyoosh

doi:10.1007/s11274-015-2005-0

Cited by 123 publications

(63 citation statements)

References 68 publications

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“…Heat-tolerant xylanases are required for optimal bioprocessing in the pulp and paper and biorefinery industries, where the raw materials are initially pre-treated at elevated temperatures. As a result, thermophilic enzyme use eliminates the need for cooling prior to the addition of the biocatalyst, thus saving significant amounts of time and energy (Kumar et al, 2016;Rakotoarivonina et al, 2016). Furthermore, higher operation temperatures, in general, enhance substrate and product solubility, minimize diffusion resistance, reduce pumping costs due to reduced viscosity, and minimize the risk of microbial contaminations.…”

Section: Introductionmentioning

confidence: 99%

XynDZ5: A New Thermostable GH10 Xylanase

et al. 2020

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Xylanolytic enzymes have a broad range of applications in industrial biotechnology as biocatalytic components of various processes and products, such as food additives, bakery products, coffee extraction, agricultural silage and functional foods. An increasing market demand has driven the growing interest for the discovery of xylanases with specific industrially relevant characteristics, such as stability at elevated temperatures and in the presence of other denaturing factors, which will facilitate their incorporation into industrial processes. In this work, we report the discovery and biochemical characterization of a new thermostable GH10 xylanase, termed XynDZ5, exhibiting only 26% amino acid sequence identity to the closest characterized xylanolytic enzyme. This new enzyme was discovered in an Icelandic hot spring enrichment culture of a Thermoanaerobacterium species using a recently developed bioinformatic analysis platform. XynDZ5 was produced recombinantly in Escherichia coli, purified and characterized biochemically. This analysis revealed that it acts as an endo-1,4β-xylanase that performs optimally at 65-75 • C and pH 7.5. The enzyme is capable of retaining high levels of catalytic efficiency after several hours of incubation at high temperatures, as well as in the presence of significant concentrations of a range of metal ions and denaturing agents. Interestingly, the XynDZ5 biochemical profile was found to be atypical, as it also exhibits significant exo-activity. Computational modeling of its three-dimensional structure predicted a (β/α) 8 TIM barrel fold, which is very frequently encountered among family GH10 enzymes. This modeled structure has provided clues about structural features that may explain aspects of its catalytic performance. Our results suggest that XynDZ5 represents a promising new candidate biocatalyst appropriate for several high-temperature biotechnological applications in the pulp, paper, baking, animal-feed and biofuel industries.

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Section: Introductionmentioning

confidence: 99%

XynDZ5: A New Thermostable GH10 Xylanase

et al. 2020

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“…They are also widely employed enzymes in industry, being used in brewing and food processing, animal feed preparation, industrial pulp and paper applications and increasingly in biofuel and bioproduct development [2][3][4][5] . While the use of CAZymes is cost-effective in glycan degradation, glycan assembly generally requires the use of expensive starting materials, such as nucleotide phosphosugars 6 .…”

Section: Introductionmentioning

confidence: 99%

Structural and mechanistic analysis of a β-glycoside phosphorylase identified by screening a metagenomic library

Macdonald

Patel

Larmour

et al. 2018

Journal of Biological Chemistry

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Glycoside phosphorylases have considerable potential as catalysts for the assembly of useful glycans for products ranging from functional foods and prebiotics to novel materials. However, the substrate diversity of currently identified phosphorylases is relatively small, limiting their practical applications. To address this limitation, we developed a high-throughput screening approach using the activated substrate 2,4-dinitrophenyl β-D-glucoside (DNPGlc) and inorganic phosphate for identifying glycoside phosphorylase activity and used it to screen a large insert metagenomic library. The initial screen, based on release of 2,4-dinitrophenol from DNPGlc in the presence of phosphate, identified the gene bglP, encoding a retaining β-glycoside phosphorylase from the CAZy GH3 family. Kinetic and mechanistic analysis of the gene product, BglP, confirmed a double displacement ping-pong mechanism involving a covalent glycosyl-enzyme intermediate. X-ray crystallographic analysis provided insights into the phosphate-binding mode and identified a key glutamine residue in the active site important for substrate recognition. Substituting this glutamine for a serine swapped the substrate specificity from glucoside to Nacetylglucosaminide. In summary, we present a high-throughput screening approach for identifying β-glycoside phosphorylases, which was robust, simple to implement, and useful in identifying active clones within a metagenomics library. GH3 β-glycoside phosphorylase from a metagenomic library 2 Implementation of this screen enabled discovery of a new glycoside phosphorylase class and has paved the way to devising simple ways in which enzyme specificity can be encoded and swapped, which has implications for biotechnological applications.Carbohydrate active enzymes (CAZymes) are the biocatalysts responsible for the assembly, degradation and modification of glycans in biological systems 1 . They are also widely employed enzymes in industry, being used in brewing and food processing, animal feed preparation, industrial pulp and paper applications and increasingly in biofuel and bioproduct development [2][3][4][5] . While the use of CAZymes is cost-effective in glycan degradation, glycan assembly generally requires the use of expensive starting materials, such as nucleotide phosphosugars 6 . The high-cost of these materials makes de novo industrial-scale glycan synthesis difficult and usually non-viable.One class of CAZyme that offers a potential solution to the high costs typically associated with enzymatic glycan synthesis is that of the glycoside phosphorylases (GPs), which are increasingly being recognized and used for the biocatalysis and biotransformation of glycans 7-9 . These enzymes ordinarily carry out phosphorolysis by transferring a glycosyl moiety from the nonreducing end of a di-or polysaccharide substrate onto inorganic phosphate, thereby generating a sugar-1-phosphate 10 ( Figure 1A). GPs distinguish themselves from most CAZymes in that the hydrolytic free energy associated with the glycosidic e...

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“…To limit the scope of this review, we have chosen not to cover the introduction of a small number of targeted mutations but focus instead on approaches requiring the screening of many variants. Additionally, there is a large body of literature relating to directed evolution of enzymes to break down plant biomass (Álvarez et al, 2016;Kumar et al, 2016b), but these will not be covered here.…”

Section: Review Scopementioning

confidence: 99%