Date of Award:

5-2012

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Committee Chair(s)

Dennis L. Welker

Committee

Dennis L. Welker

Committee

Anne J. Anderson

Committee

Jeffrey R. Broadbent

Committee

Jon Takemoto

Committee

Donald J. McMahon

Abstract

Many microorganisms produce capsules of repeating sugar units that surround the cell called exopolysaccharides. The synthesis of these capsules is a complex process that involves numerous protein components. A better understanding of the way these proteins function and interact with one another will benefit many industrial processes by aiding in the construction of bacterial strains with enhanced properties and could also lead to new treatment strategies against microbial pathogens in which capsule production is important in their ability to cause disease. In this study, the function of one of the proteins involved in the regulation of capsule synthesis in the dairy starter culture Streptococcus thermophilus MR-1C is clearly established. The research in this study also provides insight into the protein-protein interactions involved in capsule production and their conservation among Gram-positive bacteria in the family Streptococcaceae using the dairy starter cultures S. thermophilus MR-1C and Lactococcus lactis subsp. cremoris JRF1, and a commensal strain of the fish pathogen Streptococcus iniae 9066. Experimental data obtained on the ability of the proteins involved in capsule synthesis to interact with counterparts from a different species suggest that the transfer of genes between the streptococci species and to some extent between streptococci and lactococci could form functional regulatory complexes. This would be a necessary requirement for efficient capsule production in starter strains that have been genetically modified to improve their functional characteristics for industrial uses or in naturally occurring recombinant strains.

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fc83d557aeeeff95ad6e78aa08293b7c

Comments

This work made publicly available electronically on December 21, 2012.

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