期刊
MICROBIAL CELL FACTORIES
卷 14, 期 -, 页码 -出版社
BMC
DOI: 10.1186/s12934-015-0240-6
关键词
Isobutanol; Isoleucine; Gene deletion; Competitive pathway; ILV1; Saccharomyces cerevisiae
资金
- Industrial Technology Research Grant Program from the New Energy and Industrial Technology Development Organization (NEDO) of Japan
- Special Coordination Funds for Promoting Science and Technology, Creation of Innovation Centers for Advanced Interdisciplinary Research Areas
- Grants-in-Aid for Scientific Research [15K06579] Funding Source: KAKEN
Background: Isobutanol is an important biorefinery target alcohol that can be used as a fuel, fuel additive, or commodity chemical. Baker's yeast, Saccharomyces cerevisiae, is a promising organism for the industrial manufacture of isobutanol because of its tolerance for low pH and resistance to autolysis. It has been reported that gene deletion of the pyruvate dehydrogenase complex, which is directly involved in pyruvate metabolism, improved isobutanol production by S. cerevisiae. However, the engineering strategies available for S. cerevisiae are immature compared to those available for bacterial hosts such as Escherichia coli, and several pathways in addition to pyruvate metabolism compete with isobutanol production. Results: The isobutyrate, pantothenate or isoleucine biosynthetic pathways were deleted to reduce the outflow of carbon competing with isobutanol biosynthesis in S. cerevisiae. The judicious elimination of these competing pathways increased isobutanol production. ILV1 encodes threonine ammonia-lyase, the enzyme that converts threonine to 2-ketobutanoate, a precursor for isoleucine biosynthesis. S. cerevisiae mutants in which ILV1 had been deleted displayed 3.5-fold increased isobutanol productivity. The Delta ILV1 strategy was further combined with two previously established engineering strategies (activation of two steps of the Ehrlich pathway and the transhydrogenase-like shunt), providing 11-fold higher isobutanol productivity as compared to the parent strain. The titer and yield of this engineered strain was 224 +/- 5 mg/L and 12.04 +/- 0.23 mg/g glucose, respectively. Conclusions: The deletion of competitive pathways to reduce the outflow of carbon, including ILV1 deletion, is an important strategy for increasing isobutanol production by S. cerevisiae.
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