(94d) Metabolic Reconstruction and Analysis of Butanol Producing Strain Clostridium Beijerinckii NCIMB 8052
Butanol is a higher carbon alcohol with lower water affinity and vapor pressure than ethanol, and hence holds great promise as a liquid fuel alternative. Clostridium beijerinckii has the potential to make butanol economically competitive because it naturally produces butanol as a byproduct of its metabolism and co-ferments pentoses and hexoses (primary components of lignocellulosic hydrolysate). We reconstructed the metabolic network of C. beijerinckii NCIMB 8052 using a combination of novel automation tools and publically available network curation algorithms (GapFill, GapFind). This semi-automated approach to building a computable genome scale model iteratively makes use of published in silico models to supplement network information from more traditional genome annotation databases. The reconstructed network comprises 641 enzymatic genes that catalyze 703 reactions and is further supported by metabolomics measurement data and literature evidence. Constraint-based analysis on the metabolic model reveals potential strategies to rationally align the natural objectives of the organism (selection pressure for growth) with the industrial objectives of the engineer (butanol production). We performed simulated gene knockout experiments to optimize C. beijerinckii's stoichiometric ability to produce butanol from minimal media. The model therefore serves as a guide to experimentally engineer network states in C. beijerinckii to produce an economically competitive fermentation organism.