Because of the decreasing global supply of petroleum and increasingly stringent emissions restrictions, the need to find an alternative, renewable transportation fuel has become an important concern. Ethanol has been attracting much attention as a possible substitute fuel since it is a renewable resource (produced by microbial fermentations on biomass feedstocks) and allows for cleaner emissions. A significant problem is that high ethanol concentrations are toxic to the microbes that produce the ethanol. Increasing the production of ethanol through increasing the solvent tolerance of such microorganisms would make the process more favorable by decreasing downstream processing costs (e.g., distillation).

We have investigated the effects of heterologous expression of hyperthermophilic molecular chaperones on the survival phenotypes of E. coli TUNER strain. We first demonstrate that individual heterologous expression of three different molecular chaperones (prefoldin, small heat shock protein, or thermosome) can increase the temperature tolerance of E. coli. We demonstrate that chaperone function of these proteins is responsible for the survival phenotype in E. coli. We extend this approach to test for increased survivability against the biofuels ethanol and butanol. We conclude by testing additivity effects of an alternative protein-stabilizing solute (trehalose) with these hyperthermophilic chaperones.