Development of Klebsiella Oxytoca Genome-Scale Metabolic Model and in silico Analyses for 2,3-Butanediol Production

Authors: 
Park, J. M., GS Caltex
Song, H., GS Caltex
Seung, D., GS Caltex
Rathnasingh, C., GS Caltex

Klebsiella oxytoca is known as one of the most promising 2,3-butanediol (2,3-BD) producers and its whole genome sequences have been reported recently. In order to assess its metabolic characteristics and to optimize its metabolic pathways for 2,3-BD production with a system-wide scope, we constructed a genome-scale metabolic model of K. oxytoca (KoxGSC145) based on genome annotation information, metabolic pathway databases, and various experimental data. The model contains 1,457 stoichiometric reactions and 1,099 metabolites. The model was thoroughly refined and verified by comparing in silico results with experimental data based on constraints-based flux analyses. Then, we applied the model to predict its physiological responses of K. oxytoca according to environmental and genetic perturbations and also to design metabolic engineering strategies to improve its metabolic performance for 2,3-BD production. Firstly, in silico analysis, which tested the effect of augmenting the metabolic flux pool of 2,3-BD precursors, elucidated that increasing the pyruvate pool is primarily important for 2,3-BD synthesis. Secondly, we performed in silico single gene knockout simulation for 2,3-BD overproduction, and investigated the changes of the in silico flux solution space of a ldhA gene knockout mutant in comparison with that of the wild-type strain. Finally, the KoxGSC1457 model was used to optimize the oxygen levels during fermentation for 2,3-BD production. The KoxGSC1457 model successfully investigated metabolic characteristics of K. oxytoca at systems level. [This work was supported by the Industrial Strategic Technology Development Program (No. 10050407) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).]