Isotope-Assisted Metabolite Analysis Sheds Light on Central Carbon Metabolism of a Model Cellulolytic Bacterium Clostridium thermocellum

Wei Xiong, Jonathan Lo, Katherine Chou, Chao Wu, Lauren Magnusson, Tao Dong, Pin-Ching Maness

Research output: Contribution to journalArticlepeer-review

17 Scopus Citations


Cellulolytic bacteria have the potential to perform lignocellulose hydrolysis and fermentation simultaneously. The metabolic pathways of these bacteria, therefore, require more comprehensive and quantitative understanding. Using isotope tracer, gas chromatography-mass spectrometry, and metabolic flux modeling, we decipher the metabolic network of Clostridium thermocellum, a model cellulolytic bacterium which represents as an attractive platform for conversion of lignocellulose to dedicated products. We uncover that the Embden-Meyerhof-Parnas (EMP) pathway is the predominant glycolytic route whereas the Entner-Doudoroff (ED) pathway and oxidative pentose phosphate pathway are inactive. We also observe that C. thermocellum's TCA cycle is initiated by both Si- and Re-citrate synthase, and it is disconnected between 2-oxoglutarate and oxaloacetate in the oxidative direction; C. thermocellum uses a citramalate shunt to synthesize isoleucine; and both the one-carbon pathway and the malate shunt are highly active in this bacterium. To gain a quantitative understanding, we further formulate a fluxome map to quantify the metabolic fluxes through central metabolic pathways. This work represents the first global in vivo investigation of the principal carbon metabolism of C. thermocellum. Our results elucidate the unique structure of metabolic network in this cellulolytic bacterium and demonstrate the capability of isotope-assisted metabolite studies in understanding microbial metabolism of industrial interests.

Original languageAmerican English
Article number1947
Number of pages11
JournalFrontiers in Microbiology
Issue numberAUG
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 Xiong, Lo, Chou, Wu, Magnusson, Dong and Maness.

NREL Publication Number

  • NREL/JA-2700-72400


  • C-isotope tracer
  • Cellulolytic bacteria
  • Citrate synthase
  • Glycolytic pathways
  • Isoleucine biosynthesis
  • Metabolic flux analysis
  • Tricarboxylic acid cycle


Dive into the research topics of 'Isotope-Assisted Metabolite Analysis Sheds Light on Central Carbon Metabolism of a Model Cellulolytic Bacterium Clostridium thermocellum'. Together they form a unique fingerprint.

Cite this