The Polysaccharides Cellulose

The polysaccharides cellulose, poly-ss-1,6-N-acetyl-D-glucosamine, and colanic acid are required for optimal binding of E. coli O157:H7 strains to alfalfa sprouts and K12 strains to plastic but not for binding to epithelial cells.

Appl Environ Microbiol. 2008 Feb 29 [Epub ahead of print

Matthysse AG, Deora R, Mishra M, Torres AG.

Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280; Department of Microbiology and Immunology, Wake Forest University Health Sciences, Medical Center Blvd. Room 5086, Winston-Salem, NC 27157; Department of Microbiology and Immunology, Department of Pathology, and Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas 77555-1070.

 

When Escherichia coli O157:H7 is added to alfalfa sprouts growing in water, the bacteria bind tightly to the sprouts. In contrast, laboratory K12 strains of E. coli do not bind to sprouts under similar conditions. The roles of E. coli O157:H7 LPS, capsular, and exopolysaccharides in binding to sprouts were examined. An LPS mutant had no effect on binding of the pathogenic strain. Mutations in cellulose synthase showed a significant reduction in binding; colanic acid mutants were more severely reduced; and binding by poly-beta-1,6-N-acetylglucosamine (PGA) mutants was barely detectable. The addition of a plasmid carrying a cellulose synthase gene to K12 strains allowed them to bind to sprouts. A plasmid carrying the Bps biosynthesis genes had only a marginal effect on the binding of K12. However, introduction of the same plasmid allowed Sinorhizobium meliloti and a non-binding mutant of A. tumefaciens to bind to tomato root segments. These results suggest that although multiple redundant protein adhesins are involved in the binding of E. coli O157:H7 to sprouts, the polysaccharides required for binding are not redundant and that each polysaccharide may play a distinct role. PGA, colanic acid, and cellulose were also required for biofilm formation by a K12 strain on plastic but not for binding of E. coli O157:H7 to mammalian cells