Bacterial xylan utilization regulons: systems for coupling depolymerization of methylglucuronoxylans with assimilation and metabolism

Bacterial xylan utilization regulons: systems for coupling depolymerization of methylglucuronoxylans with assimilation and metabolism

Bioconversion of lignocellulosic resources offers an economically promising path to renewable energy. Technological challenges to achieving bioconversion include the development of cost-effective processes that render the cellulose and hemicellulose components of these resources to fermentable hexos...

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Bibliographic Details
Published in:Journal of industrial microbiology & biotechnology Vol. 49; no. 2; p. 1
Main Authors: Chow, Virgina, Nong, Guang, St John, Franz J, Sawhney, Neha, Rice, John D, Preston, James F
Format: Journal Article
Language:English
Published: Germany Oxford University Press 14-04-2022
Springer
Subjects:
Amino acids
Bacteria
Biocatalysis
Biotechnology & Applied Microbiology
Cellulose
Endo-1,4-beta Xylanases - metabolism
Enzymes
Genes
Hydrolysis
Monosaccharides
Multigene Family
Paenibacillus
Physiological aspects
Regulon
Review
Sugars
Xylans
Assimilation
Endoxylanase
Paenibacillus
Methylglucuronoxylans
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Summary:Bioconversion of lignocellulosic resources offers an economically promising path to renewable energy. Technological challenges to achieving bioconversion include the development of cost-effective processes that render the cellulose and hemicellulose components of these resources to fermentable hexoses and pentoses. Natural bioprocessing of the hemicellulose fraction of lignocellulosic biomass requires depolymerization of methylglucuronoxylans. This requires secretion of endoxylanases that release xylooligosaccharides and aldouronates. Physiological, biochemical, and genetic studies with selected bacteria support a process in which a cell-anchored multimodular GH10 endoxylanase catalyzes release of the hydrolysis products, aldotetrauronate, xylotriose, and xylobiose, which are directly assimilated and metabolized. Gene clusters encoding intracellular enzymes, including α-glucuronidase, endoxylanase, β-xylosidase, ABC transporter proteins, and transcriptional regulators, are coordinately responsive to substrate induction or repression. The rapid rates of glucuronoxylan utilization and microbial growth, along with the absence of detectable products of depolymerization in the medium, indicate that assimilation and depolymerization are coupled processes. Genomic comparisons provide evidence that such systems occur in xylanolytic species in several genera, including Clostridium, Geobacillus, Paenibacillus, and Thermotoga. These systems offer promise, either in their native configurations or through gene transfer to other organisms, to develop biocatalysts for efficient production of fuels and chemicals from the hemicellulose fractions of lignocellulosic resources.
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USDOE Office of Energy Efficiency and Renewable Energy (EERE)
FG36-02GO12026; FC36-00GO10594; FC36-99GO10476
ISSN:1367-5435
1476-5535
DOI:10.1093/jimb/kuab080