Tartu TUIT, Estonia
Nowadays society is deeply dependent on non-renewable energy sources, such as oil and gas. These sources are mainly used as fuels, intended to meet the energy and electricity demands of today’s world. However, a wide range of other important chemical compounds are produced from petroleum, most notably hydrocarbon monomers such as ethylene (C2H4). The demand on ethylene has only been increasing during the last decade; the average annual growth from 2007 to 2014 was 2.2%, whereas it is predicted that the growth will increase to 3.6% for the years 2014-2020. This high demand is mainly due to the fact that ethylene is rather multi-purposed, and it is used as an essential building block in many chemical compounds. Its most commonly used polymer product, polyethylene, is a main compound in many plastic materials.
The main aim of our project is to find an alternative and biological way of producing ethylene. That is why we have decided to genetically engineer yeast cells to produce ethylene from sucrose.
In our project, we are going to use two strains of yeast cells with completely dissimilar roles. The subpopulation approach is believed to be more effective than the traditional one, as it does not require genomic integration of several enzymatic steps or a complete pathway in one microorganism. Instead, it will decrease the metabolic burden on the cell and the consumption time needed for metabolic engineering. It will also lower the change or redox unbalance which might take place inside a cell. We will make both of our strains unable to metabolise sucrose. However, in the strain B, the SUC2 gene, responsible for conversion of sucrose to glucose and fructose, will be over-expressed. The protein will be automatically secreted into the sucrose media where it will convert sucrose into glucose and fructose.
Our strain B will not be able to metabolise glucose or fructose, as we are going to delete all the genes responsible for the hexose transport (HXT1-HXT7). In this way, all the glucose or fructose will be used up by strain A. Strain A will naturally convert glucose and fructose into ethanol. The gene (ADH2) responsible for the conversion of ethanol to acetaldehyde will be deleted from strain A, hence, it will to be unable to metabolise ethanol produced and it will just secrete it to the medium. Since strain B is not able to metabolise sucrose, glucose, or fructose, it will use ethanol as its only carbon source. This ethanol will enter the TCA cycle and will eventually be converted into ethylene through EFE, which will be introduced to strain B.
Our team is unique, because it is the first Estonian team to participate in iGEM. Also, most of the participants are students of an innovative program Science & Technology. Furthermore, as the program is international, our team consists of people of different geographical origins, which definitely brings multilateralism and diversity to the team! The team consists of young people interested in biology, genetic engineering, programming, infotechnology, but also marketing and social sciences.