Carolin Zilske

Project
Metabolic modelling of Clostridium acetobutylicum

Clostridium acetobutylicum is an organism of great industrial interest due to its ability to produce the solvents acetone, ethanol and butanol through the ABE-pathway, which consists of two branches: Acidogenesis and Solventogenesis. During Acidogenesis, the bacterium produces mainly the acids acetate and butyrate. This leads to a decrease of the extracellular pH value, forcing the bacterium to produce solvents like butanol. Known as a strong poisonous agent to Clostridium acetobutylicum, butanol causes various alterations in the metabolic pathways.

Although there are already published models describing the metabolism of Clostridium acetobutylicum available, they neglect the specific influence of butanol. The goal of my thesis is to develop a model with the capability to represent the conversions in cellular physiology with respect to environmental changes. In addition, it should be able to incorporate the impact of butanol on cellular metabolism.

To achieve this aim, I use constraint-based modeling. This approach assumes the time-invariance of fluxes and uses specific limitations to restrict the possible behavior of a metabolic network concerning different environmental situations. To represent the metabolic shift, two separate models will be developed: the first one to describe Acidogenesis and the second one to illustrate Solventogenesis. Both models will be constructed by modifying the relevant constraints, such as the choice of involved reactions. Subsequently, the effect of butanol with regard to the production of biomass will be analyzed.