IAI Accepts, published online ahead of print on 17 March 2008

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Infect. Immun. doi:10.1128/IAI.00096-08
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Glycogen and Maltose Utilization by Escherichia coli O157:H7 in the Mouse Intestine

Shari A. Jones, Mathias Jorgensen, Fatema Z. Chowdhury, Rosalie Rodgers, James Hartline, Mary P. Leatham, Carsten Struve, Karen A. Krogfelt, Paul S. Cohen, and Tyrrell Conway^*

Advanced Center for Genome Technology, University of Oklahoma, Norman, OK 73019; Statens Serum Institute, 2300 Copenhagen S, Denmark; Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881

^* To whom correspondence should be addressed. Email: tconway{at}ou.edu.

Mutant screens and transcriptome studies led us to consider whether the metabolism of glucose polymers, i.e., maltose, maltodextrin, and glycogen, is important for E. coli colonization of the intestine. By using the streptomycin-treated mouse model, we found that catabolism of the disaccharide maltose provides a competitive advantage in vivo to pathogenic E. coli O157:H7 and commensal E. coli K-12, whereas degradation of exogenous forms of the more complex glucose polymer, maltodextrin, does not. The endogenous glucose polymer, glycogen, appears to play an important role in colonization, as mutants that are unable to synthesize or degrade glycogen have significant colonization defects. In support of the hypothesis that E. coli relies on internal carbon stores to maintain colonization during periods of famine, we found that by providing a constant supply of a readily metabolized sugar, i.e., gluconate, in the animal's drinking water, the competitive disadvantage of E. coli glycogen metabolism mutants is rescued. The results suggest that glycogen storage may be widespread in enteric bacteria because it is necessary for maintaining rapid growth in the intestine, where there is intense competition for resources and occasional famine. An important implication of this study is that the sugars used by E. coli are present in limited quantities in the intestine, making endogenous carbon stores valuable. Thus, there may be merit to combating enteric infections by using probiotics or prebiotics to manipulate the intestinal microbiota in such a way as to limit the availability of sugars preferred by E. coli O157:H7 and perhaps other pathogens.