Regulation in Isobutanol Production in Saccharomyces cerevisiae

Isobutanol has been identified as a good option compared to ethanol because of its lower hygroscopicity, higher energy density and lower volatility, resulting in increased compatibility with current fuel infrastructure. Furthermore, the branched-chain structure of isobutanol provides higher octane number when compared to the n-butano1. Yeast Saccharomyces cerevisiae is a popular host and used as microorganism in biotechnology with successful applications in food, beverage and biofuel production beca use of its facile genetic manipulation, good ability to grow at low pH, tolerance to various types of stress, and ease of separation. The native S. cerevisiae can be producer of isobutanol but only as a by-product in fermentation. Only very small amount of synthesized isobutanol is found in the cytosol of yeast cells through degradation of the amino acid valine via the Ehrlich pathway. Due to isobutanol toxicity to host, the yield product is also limited. In this study, roles of the transcriptional factor Znf1 in the transcriptional regulation of ILV2, ILV3, and ARO10 genes which are involved in valine biosynthesis and Ehrlich pathway, related directly in isobutanol production, was investigated. Moreover, deletion of Znfl significantly deceased cell tolerance to high isobutanol. Thus, the engineered strain overexpressing ZNFI gene could potentially improve productivity of isobutanol as well as enhance isobutanol tolerance.