Characterization of a highly xylose tolerant β-xylosidase isolated from high temperature horse manure compost
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Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
BMC
Abstract
: There is a continued need for improved enzymes for industry. β-xylosidases are enzymes employed in
a variety of industries and although many wild-type and engineered variants have been described, enzymes that are
highly tolerant of the products produced by catalysis are not readily available and the fundamental mechanisms of
tolerance are not well understood.: Screening of a metagenomic library constructed of mDNA isolated from horse manure compost for
β-xylosidase activity identifed 26 positive hits. The fosmid clones were sequenced and bioinformatic analysis performed to identity putative β-xylosidases. Based on the novelty of its amino acid sequence and potential thermostability one enzyme (XylP81) was selected for expression and further characterization. XylP81 belongs to the family 39
β-xylosidases, a comparatively rarely found and characterized GH family. The enzyme displayed biochemical characteristics (KM—5.3 mM; Vmax—122 U/mg; kcat—107; Topt—50 °C; pHopt—6) comparable to previously characterized glycoside hydrolase family 39 (GH39) β-xylosidases and despite nucleotide identity to thermophilic species, the enzyme
displayed only moderate thermostability with a half-life of 32 min at 60 °C. Apart from acting on substrates predicted
for β-xylosidase (xylobiose and 4-nitrophenyl-β-D-xylopyranoside) the enzyme also displayed measurable α-Larabainofuranosidase, β-galactosidase and β-glucosidase activity. A remarkable feature of this enzyme is its ability to
tolerate high concentrations of xylose with a Ki
of 1.33 M, a feature that is highly desirable for commercial applications.
Description
Keywords
Horse manure, Metagenomics, Glycoside hydrolase, Lignocellulose
Citation
Ndata, K. et al. (2021). Characterization of a highly xylose tolerant β-xylosidase isolated from high temperature horse manure compost. BMC Biotechnology, 21(1),61. https://doi.org/10.1186/s12896-021-00722-6