Metabolite labelling reveals hierarchies in Clostridium acetobutylicum that selectively channel carbons from sugar mixtures towards biofuel precursors.

Authors:
Dr. Ludmilla Aristilde, PhD
Dr. Ludmilla Aristilde, PhD
Cornell University
Associate Professor
Environmental Chemistry; Environmental Biochemistry; Environmental Engineering.
Ithaca, NY | United States

Microb Biotechnol 2017 01 22;10(1):162-174. Epub 2016 Nov 22.

Department of Biological and Environmental Engineering, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, 14853, USA.

Clostridial fermentation of cellulose and hemicellulose relies on the cellular physiology controlling the metabolism of the cellulosic hexose sugar (glucose) with respect to the hemicellulosic pentose sugars (xylose and arabinose) and the hemicellulosic hexose sugars (galactose and mannose). Here, liquid chromatography-mass spectrometry and stable isotope tracers in Clostridium acetobutylicum were applied to investigate the metabolic hierarchy of glucose relative to the different hemicellulosic sugars towards two important biofuel precursors, acetyl-coenzyme A and butyryl-coenzyme A. The findings revealed constitutive metabolic hierarchies in C. acetobutylicum that facilitate (i) selective investment of hemicellulosic pentoses towards ribonucleotide biosynthesis without substantial investment into biofuel production and (ii) selective contribution of hemicellulosic hexoses through the glycolytic pathway towards biofuel precursors. Long-term isotopic enrichment demonstrated incorporation of both pentose sugars into pentose-phosphates and ribonucleotides in the presence of glucose. Kinetic labelling data, however, showed that xylose was not routed towards the biofuel precursors but there was minor contribution from arabinose. Glucose hierarchy over the hemicellulosic hexoses was substrate-dependent. Kinetic labelling of hexose-phosphates and triose-phosphates indicated that mannose was assimilated but not galactose. Labelling of both biofuel precursors confirmed this metabolic preference. These results highlight important metabolic considerations in the accounting of clostridial mixed-sugar utilization.

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http://dx.doi.org/10.1111/1751-7915.12459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5270725PMC
January 2017
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References

(Supplied by CrossRef)
LC-MS data processing with MAVEN: a metabolomic analysis and visualization engine
Clasquin et al.
Curr Protoc Bioinformatics 2012

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