Daniel Olson

In large-scale industrial fermentations, it can be expensive to add oxygen, and to cool fermenters to mesophilic temperatures (20-45C). Using anaerobic thermophilic bacteria avoids both problems, however many genetic tools that have been originally developed for model organisms such as Saccharomyces cerevisiae and Escherichia coli do not work in these organisms. My group is working to develop several types of genetic tools necessary for domestication of thermophilic anaerobic bacteria, including:

• Ways to get foreign DNA into cells
• Tightly-controlled inducible promoters for reliable temporal control of gene expression
• Plasmid-based gene expression systems
• Chromosomal editing tools
• Ways to control the mutation rate

Metabolism can be understood at many levels of aggregation from individual enzymes to the whole organism. An important intermediate level of aggregation is the metabolic pathway. Developing pathways that enable rapid production of desired compounds at high yield and titer requires a detailed understanding of both the individual components and the systems-level behavior that results from the interaction of these components, including:

• Identification of constituent enzymes in a pathway and the stoichiometry of the reactions they mediate
• Characterization of enzyme inhibition and regulation
• Development of screens and selections to improve properties of key enzymes.
• Protein engineering to increase activity, decrease inhibition, or change substrate specificity

Currently, most ethanol is produced using various strains of yeast. These organisms are very good at producing ethanol but have no native ability to consume lignocellulose. This has made it difficult to develop cost-effective yeast-based processes for lignocellulosic ethanol production. My group takes an alternative approach of starting with organisms that natively ferment lignocellulosic biomass and engineering them for efficient biofuel formation. To do this, we need to understand key aspects of the physiology of these native biomass-fermenting organisms, including:

• Which substrates they can consume, and how these substrates are used for growth, energy production, and product formation.
• Factors that limit growth and fermentation.
• Genetic adaptation to stresses associated with industrial fermentation