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Highly thermostable GH39 β-xylosidase from a Geobacillus sp. strain WSUCF1

BACKGROUND: Complete enzymatic hydrolysis of xylan to xylose requires the action of endoxylanase and β-xylosidase. β-xylosidases play an important part in hydrolyzing xylo-oligosaccharides to xylose. Thermostable β-xylosidases have been a focus of attention as industrially important enzymes due to t...

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Autores principales: Bhalla, Aditya, Bischoff, Kenneth M, Sani, Rajesh K
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4300165/
https://www.ncbi.nlm.nih.gov/pubmed/25532585
http://dx.doi.org/10.1186/s12896-014-0106-8
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author Bhalla, Aditya
Bischoff, Kenneth M
Sani, Rajesh K
author_facet Bhalla, Aditya
Bischoff, Kenneth M
Sani, Rajesh K
author_sort Bhalla, Aditya
collection PubMed
description BACKGROUND: Complete enzymatic hydrolysis of xylan to xylose requires the action of endoxylanase and β-xylosidase. β-xylosidases play an important part in hydrolyzing xylo-oligosaccharides to xylose. Thermostable β-xylosidases have been a focus of attention as industrially important enzymes due to their long shelf life and role in the relief of end-product inhibition of xylanases caused by xylo-oligosaccharides. Therefore, a highly thermostable β-xylosidase with high specific activity has significant potential in lignocellulose bioconversion. RESULTS: A gene encoding a highly thermostable GH39 β-xylosidase was cloned from Geobacillus sp. strain WSUCF1 and expressed in Escherichia coli. Recombinant β-xylosidase was active over a wide range of temperatures and pH with optimum temperature of 70°C and pH 6.5. It exhibited very high thermostability, retaining 50% activity at 70°C after 9 days. WSUCF1 β-xylosidase is more thermostable than β-xylosidases reported from other thermophiles (growth temperature ≤ 70°C). Specific activity was 133 U/mg when incubated with p-nitrophenyl xylopyranoside, with K(m) and V(max) values of 2.38 mM and 147 U/mg, respectively. SDS-PAGE analysis indicated that the recombinant enzyme had a mass of 58 kDa, but omitting heating prior to electrophoresis increased the apparent mass to 230 kDa, suggesting the enzyme exists as a tetramer. Enzyme exhibited high tolerance to xylose, retained approximately 70% of relative activity at 210 mM xylose concentration. Thin layer chromatography showed that the enzyme had potential to convert xylo-oligomers (xylobiose, triose, tetraose, and pentaose) into fermentable xylose. WSUCF1 β-xylosidase along with WSUCF1 endo-xylanase synergistically converted the xylan into fermentable xylose with more than 90% conversion. CONCLUSIONS: Properties of the WSUCF1 β-xylosidase i.e. high tolerance to elevated temperatures, high specific activity, conversion of xylo-oligomers to xylose, and resistance to inhibition from xylose, make this enzyme potentially suitable for various biotechnological applications.
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spelling pubmed-43001652015-01-21 Highly thermostable GH39 β-xylosidase from a Geobacillus sp. strain WSUCF1 Bhalla, Aditya Bischoff, Kenneth M Sani, Rajesh K BMC Biotechnol Research Article BACKGROUND: Complete enzymatic hydrolysis of xylan to xylose requires the action of endoxylanase and β-xylosidase. β-xylosidases play an important part in hydrolyzing xylo-oligosaccharides to xylose. Thermostable β-xylosidases have been a focus of attention as industrially important enzymes due to their long shelf life and role in the relief of end-product inhibition of xylanases caused by xylo-oligosaccharides. Therefore, a highly thermostable β-xylosidase with high specific activity has significant potential in lignocellulose bioconversion. RESULTS: A gene encoding a highly thermostable GH39 β-xylosidase was cloned from Geobacillus sp. strain WSUCF1 and expressed in Escherichia coli. Recombinant β-xylosidase was active over a wide range of temperatures and pH with optimum temperature of 70°C and pH 6.5. It exhibited very high thermostability, retaining 50% activity at 70°C after 9 days. WSUCF1 β-xylosidase is more thermostable than β-xylosidases reported from other thermophiles (growth temperature ≤ 70°C). Specific activity was 133 U/mg when incubated with p-nitrophenyl xylopyranoside, with K(m) and V(max) values of 2.38 mM and 147 U/mg, respectively. SDS-PAGE analysis indicated that the recombinant enzyme had a mass of 58 kDa, but omitting heating prior to electrophoresis increased the apparent mass to 230 kDa, suggesting the enzyme exists as a tetramer. Enzyme exhibited high tolerance to xylose, retained approximately 70% of relative activity at 210 mM xylose concentration. Thin layer chromatography showed that the enzyme had potential to convert xylo-oligomers (xylobiose, triose, tetraose, and pentaose) into fermentable xylose. WSUCF1 β-xylosidase along with WSUCF1 endo-xylanase synergistically converted the xylan into fermentable xylose with more than 90% conversion. CONCLUSIONS: Properties of the WSUCF1 β-xylosidase i.e. high tolerance to elevated temperatures, high specific activity, conversion of xylo-oligomers to xylose, and resistance to inhibition from xylose, make this enzyme potentially suitable for various biotechnological applications. BioMed Central 2014-12-23 /pmc/articles/PMC4300165/ /pubmed/25532585 http://dx.doi.org/10.1186/s12896-014-0106-8 Text en © Bhalla et al.; licencee BioMed Central. 2014 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Bhalla, Aditya
Bischoff, Kenneth M
Sani, Rajesh K
Highly thermostable GH39 β-xylosidase from a Geobacillus sp. strain WSUCF1
title Highly thermostable GH39 β-xylosidase from a Geobacillus sp. strain WSUCF1
title_full Highly thermostable GH39 β-xylosidase from a Geobacillus sp. strain WSUCF1
title_fullStr Highly thermostable GH39 β-xylosidase from a Geobacillus sp. strain WSUCF1
title_full_unstemmed Highly thermostable GH39 β-xylosidase from a Geobacillus sp. strain WSUCF1
title_short Highly thermostable GH39 β-xylosidase from a Geobacillus sp. strain WSUCF1
title_sort highly thermostable gh39 β-xylosidase from a geobacillus sp. strain wsucf1
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4300165/
https://www.ncbi.nlm.nih.gov/pubmed/25532585
http://dx.doi.org/10.1186/s12896-014-0106-8
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