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United States Department of Agriculture

Agricultural Research Service

Title: Transposon Mutagenesis Reveals Potential Suppressors of Curli Fibers in Ehec Strain Edl933

Authors
item UHLICH, GAYLEN
item GUNTHER, NEREUS

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 7, 2006
Publication Date: July 30, 2006
Citation: Uhlich, G.A., Gunther, N.W. 2006. Transposon mutagenesis reveals potential suppressors of curli fibers in ehec strain edl933. {Abstract}. Society for Industrial Microbiology. P.82.

Technical Abstract: A mutation in the promoter of the csgD gene of enterohemorrhagic Escherichia coli strain EDL933 is associated with temperature-independent expression of curli fibers, a rdar (red, dry and rough) colony morphology on agar containing the dye Congo red, and an increased ability to form biofilms when compared to the parent strain. However, no growth conditions have been identified which will elicit the rdar phenotype in the parent strain, suggesting that the phenotype is repressed under laboratory culture conditions. To identify genes in strain EDL933 capable of suppressing the rdar phenotype, we used random Tn5 transposome mutagenesis and screened the mutants for binding to Congo red. Twenty colonies with increased binding of Congo red were identified. Six unique insertions mapped to specific genes involved in outer membrane or peptidoglycan synthesis, chaperone/protease functions, or pyrimidine synthesis. An additional five genes formed rearrangements with mobilizable sections of the chromosome during plasmid rescue. Although 11 unique colonies bound the Congo red dye, suggesting curli expression, none of the colonies had a dry, aggregative phenotype or generated biofilms comparable to the mutant strain. While the genes identified in this study affect curli suppression, individually they are not sufficient or essential for complete suppression of the rdar phenotype.

Last Modified: 9/29/2014
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