Tuesday, August 12, 2008 - 3:30 PM
S89
Enhancing Bacterial Solvent Tolerance by Expression of an Extremophilic Chaperone
Timothy A. Whitehead, Elisa M. Rodriguez Porcel, Harvey W. Blanch, and Douglas S. Clark. Chemical Engineering, University of California, Berkeley, CA 94720
Future biorefineries will rely on microorganisms that are robust and tolerant against the product that they form. It is generally recognized that membranes are freely permeable to relatively hydrophobic metabolites like ethanol. This increased permeability across the membrane disrupts ion gradients and causes leakage of essential small molecules, resulting in the loss of cell viability. The microbial stress response to alcohols or other solvents suggests that toxicity is not simply a membrane-acting phenomenon, as many molecular chaperones are expressed that serve only to protect and repair proteins. However, expression of endogeneous molecular chaperones has not generally conferred tolerance to microbes sufficient to increase metabolite titers with similar yields, and the theory endures that solvent-resistant phenotypes cannot be the result of a single gene. Here we show that induction of a single gene, encoding for the chaperone thermosome from the hyperthermophilic Methanocaldococcus jannaschii, is sufficient to confer greater ethanol tolerance to E. coli. Such tolerance by cytosolic chaperones suggests a greater contribution of protein denaturation or misfolding to solvent toxicity than has generally been assumed. As such, expression of chaperones from hyperthermophiles may be part of a general strategy to increase metabolite titers in industrial important bioprocesses.
See more of Biocatalysis for Bioenergy
See more of Invited Oral Papers
See more of The Annual Meeting and Exhibition 2008 (August 10 - 14, 2008)
See more of Invited Oral Papers
See more of The Annual Meeting and Exhibition 2008 (August 10 - 14, 2008)