Susan B. Leschine
Professor, Department of Veterinary and Animal Sciences, University of Massachusetts
Ph.D.: University of Pittsburgh Postdoctoral Training: University of Massachusetts
The most abundant organic materials on Earth are structural polysaccharides such as cellulose and chitin. Anaerobic microorganisms that ferment insoluble polymers play a central role in carbon cycling on the planet as a source of CO2 and, indirectly, of methane. The primary objective of our research is to advance understanding of fundamental aspects of the biology of polysaccharide-fermenting microbes. For the most part, our research has concerned species of Clostridium isolated from a variety of soils collected around the world. These clostridia produce ethanol as a product of cellulose fermentation, and therefore are potentially useful for producing fuel alcohol from biomass. Currently, we are investigating the physiology, genetics, and ecology of these bacteria and the cellulase enzymes they produce. Also, we are developing tools for their genetic manipulation so that we may improve ethanol production through metabolic engineering. An important aspect of our work concerns studies of the enzyme systems that catalyze the degradation of insoluble polymers. For the most part, anaerobic bacteria produce extracellular high-molecular-weight multiprotein complexes that hydrolyze plant structural polymers such as cellulose and xylan. We have shown that the cellulase-xylanase system of Clostridium papyrosolvens differs from previously described systems in that it is composed of several discrete multiprotein complexes, rather than a single complex. Current research is aimed at understanding how this multicomplex cellulase-xylanase system is constructed.