Increased isobutanol production in Saccharomyces cerevisiae by eliminating competing pathways and resolving cofactor imbalance

Microbial Cell Factories

Research

Fumio Matsuda¹  Kengo Ida²  Hironori Tezuka²  Jun Ishii³  Takashi Kondo⁴  Akihiko Kondo⁵ 

[1] Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, 565-0871, Suita, Osaka, Japan;Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodaicho, 657-8501, Nada, Kobe, Japan;RIKEN Center for Sustainable Resource Science, 1-7-22 Suehirocho, Kanagawa, Turumi-ku, 230-0045, Yokohama, Japan;Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, 657-8501, Kobe, Japan;Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodaicho, 657-8501, Nada, Kobe, Japan;Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodaicho, 657-8501, Nada, Kobe, Japan;Division of Natural Environment and Information, Faculty of Environment and Information Sciences, Yokohama National University, 79-7, Tokiwadai, 240-8501, Hodogaya, Yokohama, Japan;RIKEN Center for Sustainable Resource Science, 1-7-22 Suehirocho, Kanagawa, Turumi-ku, 230-0045, Yokohama, Japan;Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, 657-8501, Kobe, Japan;

关键词: Isobutanol;    Ehrlich pathway;    Single-gene deletion;    Transhydrogenase-like shunt;    Saccharomyces cerevisiae;   

DOI  :  10.1186/1475-2859-12-119

 received in 2013-07-08, accepted in 2013-11-05,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundIsobutanol is an important target for biorefinery research as a next-generation biofuel and a building block for commodity chemical production. Metabolically engineered microbial strains to produce isobutanol have been successfully developed by introducing the Ehrlich pathway into bacterial hosts. Isobutanol-producing baker’s yeast (Saccharomyces cerevisiae) strains have been developed following the strategy with respect to its advantageous characteristics for cost-effective isobutanol production. However, the isobutanol yields and titers attained by the developed strains need to be further improved through engineering of S. cerevisiae metabolism.ResultsTwo strategies including eliminating competing pathways and resolving the cofactor imbalance were applied to improve isobutanol production in S. cerevisiae. Isobutanol production levels were increased in strains lacking genes encoding members of the pyruvate dehydrogenase complex such as LPD1, indicating that the pyruvate supply for isobutanol biosynthesis is competing with acetyl-CoA biosynthesis in mitochondria. Isobutanol production was increased by overexpression of enzymes responsible for transhydrogenase-like shunts such as pyruvate carboxylase, malate dehydrogenase, and malic enzyme. The integration of a single gene deletion lpd1 Δ and the activation of the transhydrogenase-like shunt further increased isobutanol levels. In a batch fermentation test at the 50-mL scale from 100 g/L glucose using the two integrated strains, the isobutanol titer reached 1.62 ± 0.11 g/L and 1.61 ± 0.03 g/L at 24 h after the start of fermentation, which corresponds to the yield at 0.016 ± 0.001 g/g glucose consumed and 0.016 ± 0.0003 g/g glucose consumed, respectively.ConclusionsThese results demonstrate that downregulation of competing pathways and metabolic functions for resolving the cofactor imbalance are promising strategies to construct S. cerevisiae strains that effectively produce isobutanol.

【 授权许可】

Unknown   
© Matsuda et al.; licensee BioMed Central Ltd. 2013. 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.