Mechanisms of Industrial Stress Tolerance in Biofuel Producing Microbes
In industrial biofuels production, complex plant biomass is often initially chemically pretreated to reduce the recalcitrance of lignocellulose to degradation. These processes liberate sugars that can be converted to biofuels by fermentative microbes. However, compounds such as acetic acid that inhibit the growth and productivity of these organisms are also produced. Oak Ridge National Laboratory researchers working at the DOE Bioenergy Science Center (BESC) have used a functional genomics approach to examine acetate tolerance in the biofuel producing bacteria Zymomonas mobilis. These studies have identified a new gene in a selectively evolved Z. mobilis strain whose overexpression results in increased tolerance to acetic acid. Structural characterization of the gene’s product suggests that it is membrane protein involved in protecting the interior of the cell from acidic environmental conditions. Similar genes conferring acetic acid tolerance were also identified in the biofuel-producing yeast Saccaromyces cerevisiae. These results provide new targets for continued engineering and improvement of microbes for use in industrial production of cellulosic biofuels.
S. Yang et al. (2010) “Paradigm for Industrial Strain Improvement Identifies Sodium Acetate Tolerance Loci in Zymomonas mobilis and Saccaromyces cerevisiae,” Proceedings of the National Academy of Science (USA) 107 (23) 10395-10400.