The human colon contains a dense and complex population of bacteria that persists in an individual throughout life. A major carbon source for these bacteria is polysaccharide in the host's diet, but polysaccharide produced by the host itself may also be utilized by colonic bacteria. Bacteroides, a genus of gram negative obligate anaerobes, is one of the numerically predominant genera of colonic bacteria and appear to be major contributors to the colonic fermentation. Bacteroides species have a novel system for utilization of polysaccharide, a polysaccharide import system. They first bind the polysaccharide to their outer membrane, then translocate it into the periplasm where breakdown begins. This strategy not only helps the bacteria to particulate matter in the host's diet. A major long term goal of the proposed work is to used genetic and biochemical techniques to determine the characteristics and function of proteins involved in the binding and internalization of polysaccharides by Bacteroides species. The starch utilization system of Bacteroides thetaiotaomicron will be used as a model system. Some genes in this system have already been cloned and the function of proteins encoded by these genes will be determined. Other essential genes will be cloned and characterized. The hypothesis to be tested is that outer membrane and periplasmic proteins identified in previous studies form a polysaccharide binding/translocation complex that extends through the outer membrane and into the periplasm. A second goal of the proposed research is to understand what contribution host-derived polysaccharide make to the nutrition of colonic bacteria. Further characterization of mutants unable to utilize host polysaccharide will be done, with particular focus on a mutation that decreases the ability of B. thetaiotaomicron to compete for colonization of the intestinal tracts of germfree mice. The activities of the major groups of colonic mucosa and probably have major long term effects on the mucosa. Although there is no satisfactory assay systems for assessing hr effect of bacterial products on colonic cells. A final goal of this proposal is to begin to develop in vitro assay systems for determining the effects of various bacterial products on colonic cells. Such assay systems are needed not only for studies of the possible contribution of bacterial activities to diseases such as colon cancer, but also for assessing the effects of new food additives such as artificial fats and bulking agents that are known to be fermented extensively by colonic bacteria.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI017876-15
Application #
2060572
Study Section
Biological Sciences 2 (BIOL)
Project Start
1981-04-01
Project End
1998-12-31
Budget Start
1995-01-01
Budget End
1995-12-31
Support Year
15
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Illinois Urbana-Champaign
Department
Microbiology/Immun/Virology
Type
Schools of Arts and Sciences
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
Cho, K H; Salyers, A A (2001) Biochemical analysis of interactions between outer membrane proteins that contribute to starch utilization by Bacteroides thetaiotaomicron. J Bacteriol 183:7224-30
Cho, K H; Cho, D; Wang, G R et al. (2001) New regulatory gene that contributes to control of Bacteroides thetaiotaomicron starch utilization genes. J Bacteriol 183:7198-205
Salyers, A A; Bonheyo, G; Shoemaker, N B (2000) Starting a new genetic system: lessons from bacteroides. Methods 20:35-46
Shipman, J A; Cho, K H; Siegel, H A et al. (1999) Physiological characterization of SusG, an outer membrane protein essential for starch utilization by Bacteroides thetaiotaomicron. J Bacteriol 181:7206-11
Reeves, A R; D'Elia, J N; Frias, J et al. (1996) A Bacteroides thetaiotaomicron outer membrane protein that is essential for utilization of maltooligosaccharides and starch. J Bacteriol 178:823-30
D'Elia, J N; Salyers, A A (1996) Contribution of a neopullulanase, a pullulanase, and an alpha-glucosidase to growth of Bacteroides thetaiotaomicron on starch. J Bacteriol 178:7173-9
D'Elia, J N; Salyers, A A (1996) Effect of regulatory protein levels on utilization of starch by Bacteroides thetaiotaomicron. J Bacteriol 178:7180-6
Cheng, Q; Salyers, A A (1995) Use of suppressor analysis to find genes involved in the colonization deficiency of a Bacteroides thetaiotaomicron mutant unable to grow on the host-derived mucopolysaccharides chondroitin sulfate and heparin. Appl Environ Microbiol 61:734-40
Cheng, Q; Yu, M C; Reeves, A R et al. (1995) Identification and characterization of a Bacteroides gene, csuF, which encodes an outer membrane protein that is essential for growth on chondroitin sulfate. J Bacteriol 177:3721-7
Hwa, V; Salyers, A A (1992) Evidence for differential regulation of genes in the chondroitin sulfate utilization pathway of Bacteroides thetaiotaomicron. J Bacteriol 174:342-4

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