Mentor: Dr. K.T. Shanmugam
College of Agricultural and Life Sciences
"I applied to the USP to have the experience of taking my own independent research project from start to completion. I wish to broaden my knowledge in the fields of applied microbiology and biotechnology research in order to help provide direction for my future graduate school or career plans."
Microbiology and Cell Science
American Society for Microbiology
Microbiology and Cell Science Student Organization
Hobbies and Interests
Cofermentation of glucose and glycerol in E. coli
The goal of my project is to metabolically engineer a strain of Escherichia coli that can coferment glucose and glycerol to ethanol and dihydroxyacetone (DHA) respectively. Ethanol is in great demand as an alternative fuel source and DHA has several industrial applications. Normal ethanol fermentation only yields one molecule of ethanol and a molecule of acetate per molecule of glucose due to the need to balance the overall reaction. However, linking simultaneous fermentation of glucose and glycerol would balance the reaction so that two molecules of ethanol per glucose could be produced without any acetate byproduct. This would theoretically double the efficiency of ethanol fermentation in E. coli. Also, DHA would be produced as a useful side product. The problem is many microbes, including E. coli, prefer glucose as an energy and carbon source and will not ferment glycerol in the presence of glucose. To circumvent this, several genes involved in directing glycerol fermentation will need to be deleted using various genetic techniques such as electroporation and transduction. A gene deletion will also have to be made to halt the fermentation of glycerol at the intermediate DHA, as will deletions for any competing fermentation product pathways. In addition a gene for an active glycerol dehydrogenase, an enzyme that converts glycerol to DHA, from a strain of Bacillus coagulans will need to be introduced into the E. coli strain. Following the genetic engineering, the metabolic flux of the pathways involved will need to be assayed to determine the success of these changes and the need for further tweaks.