Systems biology of the butanol-producing Clostridium acetobutylicum: new source of biofuel and chemicals/COSMIC2

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By 2030, worldwide energy consumption is projected to grow by 57%. Fossil fuels cannot meet this demand, as their continued use is causing global warming and they are in any case a finite reserve that will be exhausted before the end of this century. Liquid fuels derived from natural plant material (biofuels), are the most promising alternative energy source for use in the transportation sector. In this regard, an alcohol called butanol is currently receiving considerable interest due to its superior properties compared to ethanol and biodiesel. Butanol has a higher energy content than ethanol, can make use of existing petrol supply and distribution channels, can be blended with petrol at higher concentrations without engine modification, offers better fuel economy and has, unlike ethanol, potential as aviation fuel. Traditionally, butanol is produced by a bacterium called Clostridium acetobutylicum when growing on growth media containing sugars. The fermentation process is known as the Acetone-Butanol-Ethanol (ABE) process. In the first half of the last century, the ABE process was second in importance/scale only to ethanol production from yeast. However, with the advent of the petrochemical industry, the process became uneconomic and was abandoned in the western world from the 1960s onwards. The process has recently been re-established in China and Brazil, where lower operating costs make a process based on inefficient 20th century technology economic. For adoption in the western world, a more efficient process is required. Its derivation will be reliant on improvements to the bacterial strains employed. However, the rational creation of such strains will require a more detailed understanding of the complex processes within the cell that catalyse and control the formation of fermentation products. Deriving a better understanding of the process is the overall objective of this proposal. For this, a new holistic approach termed systems biology will be used, which involves iterative cycles of mathematical modelling and experimental testing. It is made possible by developments made in an earlier funding round in which crucial gene tools and methodologies were developed that will allow precise changes to be made to selected genes and the consequences assessed.