Identification and optimization of ethanol tolerance mechanisms in Escherichia coli by means of experimental evolution

Promovendus/a: Toon Swings

Promotor(en): Prof. dr. ir. Jan Michiels, Dr. Natalie Verstraeten

Bio-ethanol is an environmentally friendly alternative for the use of fossil fuels. This form of energy is obtained using microbial fermentation, in which sugar is converted to ethanol. Usually yeast is used as the production-organism, but in the last few years, however, researchers focused more and more on the potential of genetically modified bacteria in the production of bio-ethanol. Although its intrinsic level of ethanol tolerance is rather low, the use of the model organism Escherichia coli in bio-ethanol production seems promising. Yet, in order to achieve anoptimal, efficient production-organism, the level of ethanol tolerance must increase. The mechanisms behind ethanol tolerance are still poorly understood. Previous studies showed that ethanol tolerance depends on deinteractions between multiple genes, so called epistatic interactions. Classic genetic studies, which only explore the effect of single genes are inadequate to identify such complex interactions. Here, the genetic mechanisms underlying ethanol tolerance in E. coli will be studied using experimental evolution. During evolution in the presence of ethanol, the population of E. coli will adapt and evolve to higher levels of ethanol tolerance through fixation of genetic changes. By the study of these genetic changes we will be able to identify the important genetic determinants of ethanol tolerance in E. coli. Ultimately the influence of these determinants will be tested under industrial conditions, so this research can play an important role in bio-ethanol productionin the future.