Increasing Galactose Utilized Ability of Saccharomyces cerevisiae Through Gene Engineering
Saccharomyces cerevisiae is capable of fermenting galactose into ethanol, but the productivity from galactose is much lower than those from glucose. An effective approach is undertaken to improve galactose utilized ability and ethanol productivity through
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Increasing Galactose Utilized Ability of Saccharomyces cerevisiae Through Gene Engineering Tong Shen, Xuewu Guo, Jing Zou, Yueqiang Li, Jun Ma and Dongguang Xiao
Abstract Saccharomyces cerevisiae is capable of fermenting galactose into ethanol, but the productivity from galactose is much lower than those from glucose. An effective approach is undertaken to improve galactose utilized ability and ethanol productivity through gene engineering of the regulatory network controlling the expression of the GAL genes. The GAL gene regulatory network of S. cerevisiae is a tightly regulated system. Gal6, Gal80, and Mig1 are three known negative regulators of the GAL system. In this paper, Gal6, Gal80, and Mig1 were knockout by the way of homologous recombination. This led to a 76 % increase in specific galactose uptake rate compared with the wild-type strain. And the ethanol yield has advanced greatly. Further study showed that GAL80 and MIG1 played more important roles in galactose fermentation of S. cerevisiae than GAL6 did. Keywords Galactose
MIG1 GAL80 GAL6 Saccharomyces cerevisiae
22.1 Introduction Because of increasing oil shortage, fuel ethanol fermentation from different renewable resource has attracted considerable attention. Galactose is widely present in the molasses and ethanol bio-fermentation raw materials. Unfortunately, ethanol yield and productivity from galactose are significantly lower than those from glucose [1]. An effective approach improved galactose utilized ability and ethanol productivity through engineering of the regulatory network controlling the expression of the GAL genes [2–4]. Previous studies reported that the GAL genes are tightly T. Shen X. Guo J. Zou Y. Li J. Ma D. Xiao (&) Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education; Tianjin Industrial Microbiology Key Lab, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, People’s Republic of China e-mail: [email protected]
T.-C. Zhang et al. (eds.), Proceedings of the 2012 International Conference on Applied Biotechnology (ICAB 2012), Lecture Notes in Electrical Engineering 249, DOI: 10.1007/978-3-642-37916-1_22, Ó Springer-Verlag Berlin Heidelberg 2014
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regulated [5, 6]. GAL gene expression requires the well-studied transcriptional activator protein Gal4, which binds to the GAL gene promoters. Gal4 function is inhibited by Gal80 [7, 8], which binds directly to Gal4, and by Mig1, which represses expression of GAL1 and GAL4 in the presence of glucose [9–11]. GAL6, which was recently devoted as member of the GAL regulon [12], also played a negative role in GAL gene expression. In this work, the galactose metabolic flux of saccharomyces cerevisiae was increased by deleting three negative regulatory genes (GAL6, GAL80, and MIG1), this led to a 76 % increase in specific galactose uptake rate compared with the wild-type strain, and the ethanol yield has advanced greatly. Further study showed that GAL80 and MIG1 played more important roles in galacto
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