Enhanced Trehalose Production

of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science ENHANCED TREHALOSE PRODUCTION IMPROVES GROWTH OF Escherichia coli UNDER OSMOTIC STRESS By Jeremy E. Purvis May 2004 Chair: Lonnie O. Ingram Major Department: Microbiology and Cell Science The disaccharide trehalose protects bacterial cells against multiple environmental stresses. Escherichia coli synthesizes trehalose in response to osmotic stress, heat shock, extreme cold, desiccation, and entry of cells into stationary phase. Previous studies have shown that mutants that cannot produce trehalose are sensitive to elevated osmolarity, oxidation, and heat. Here we examined the potential benefit of trehalose for growth in glucose-mineral salts medium containing a series of concentrations of salts and sugars. Strain W3110 (wild type) was compared to an isogenic strain in which all genes for trehalose synthesis and degradation were deleted, and to a derivative in which a single chromosomal copy of the otsA otsB operon was provided under LacI regulation. Modest differences in growth between wild type and mutant strains suggested a direct protective role for trehalose. These differences in growth were increased when trehalose production was elevated above that of wild-type cells. Our results demonstrate that production of high intracellular