Research Interests
The rate-limiting step in the conversion of cellulosic material from crop plants such as Poplar or Switchgrass to simple sugars used for fermentation to ethanol is the recalcitrance of complex substrates, such as cellulose, xylan and lignin, to simple mono- and polysaccharides. Other wood crops, as well as potato starch and waste paper sludge are also potential substrates. A critical component of the development of bio-based alternative fuels, such as ethanol and hydrogen, is the identification, characterization and manipulation of microorganisms and biocatalysts for biomass conversion. Organisms and enzymes that can function at or above 100 °C are especially useful for this conversion because the biomass material is typically pretreated at high temperature before microbial or enzymatic conversion. Although the pursuit of biological routes to alternative fuels has been ongoing for several decades, recently available genomics-based approaches offer unprecedented access to novel enzymes and pathways for biomass conversions, making rational, genome-wide approaches for biocatalyst discovery and pathway identification that lead to enzyme production and metabolic engineering possible. An essential component of the application of modern technology to microbial and enzymatic biomass conversion is the ability to genetically manipulate extreme thermophilic microbes and the enzymes they produce. The focus of our research is to use functional and structural genomics-based methods, in conjunction with classical genetics and biochemical approaches, to identify novel biocatalytic (purified enzymes) and metabolic strategies (using whole cells) for bioenergy conversion. This research is part of a long-term collaboration between our lab and the laboratory of MWW Adams in the Department of Biochemistry, focusing on the biotechnological potential of hyperthermophilic microorganisms and enzymes. We have developed genetic tools for manipulation of Pyrococcus furiosus, a hyperthermophilic fermentative anaerobic archaean capable of biomass conversion at or above temperatures of 100 °C and Anaerocellum thermophilum a thermophilic, anaerobic Gram-positive bacterium, unique in its ability to efficiently utilize untreated cellulosic biomass. This work fits into the larger intellectual context of using classical (high temperature microbial bioprocessing, large-scale protein purification) and modern (structural genomics, bioinformatics, transcriptional response analysis, gene replacement/mutational analysis) approaches to study extremophile biology and biotechnology as this relates to bioenergy conversion.