Rational improvement of the engineered isobutanol-producing Bacillus subtilis by elementary mode analysis

Microbial Cell Factories

Research

Di Huang¹  Yong Li¹  Shanshan Li¹  Jianping Wen²  Xiaoqiang Jia² 

[1] Department of Biological Engineering, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China;Department of Biological Engineering, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China;Key Laboratory of Systems Bioengineering, Ministry of Education, 300072, Tianjin, China;

关键词: Rational strain improvement;    Metabolic network;    Elementary mode analysis;    Target prediction;    Bacillus subtilis;    Isobutanol;   

DOI  :  10.1186/1475-2859-11-101

 received in 2012-03-23, accepted in 2012-07-13,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundIsobutanol is considered as a leading candidate for the replacement of current fossil fuels, and expected to be produced biotechnologically. Owing to the valuable features, Bacillus subtilis has been engineered as an isobutanol producer, whereas it needs to be further optimized for more efficient production. Since elementary mode analysis (EMA) is a powerful tool for systematical analysis of metabolic network structures and cell metabolism, it might be of great importance in the rational strain improvement.ResultsMetabolic network of the isobutanol-producing B. subtilis BSUL03 was first constructed for EMA. Considering the actual cellular physiological state, 239 elementary modes (EMs) were screened from total 11,342 EMs for potential target prediction. On this basis, lactate dehydrogenase (LDH) and pyruvate dehydrogenase complex (PDHC) were predicted as the most promising inactivation candidates according to flux flexibility analysis and intracellular flux distribution simulation. Then, the in silico designed mutants were experimentally constructed. The maximal isobutanol yield of the LDH- and PDHC-deficient strain BSUL05 reached 61% of the theoretical value to 0.36 ± 0.02 C-mol isobutanol/C-mol glucose, which was 2.3-fold of BSUL03. Moreover, this mutant produced approximately 70 % more isobutanol to the maximal titer of 5.5 ± 0.3 g/L in fed-batch fermentations.ConclusionsEMA was employed as a guiding tool to direct rational improvement of the engineered isobutanol-producing B. subtilis. The consistency between model prediction and experimental results demonstrates the rationality and accuracy of this EMA-based approach for target identification. This network-based rational strain improvement strategy could serve as a promising concept to engineer efficient B. subtilis hosts for isobutanol, as well as other valuable products.

【 授权许可】

Unknown   
© Li et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.