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J. Bacteriol. doi:10.1128/JB.00516-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Campylobacter jejuni biofilms up-regulated in the absence of the stringent response utilize a calcofluor white-reactive surface polysaccharide

Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada; Division of Infectious Diseases, University of California San Francisco, California, US; Institute for Biological Sciences, National Research Council, Ottawa, Ontario, Canada

^* To whom correspondence should be addressed. Email: egaynor{at}interchange.ubc.ca.

	Abstract

The enteric pathogen Campylobacter jejuni is a highly prevalent yet fastidious bacterium. Biofilms and surface polysaccharides participate in stress survival, transmission, and virulence in C. jejuni, thus the identification and characterization of novel genes involved in each process has important implications for pathogenesis. We found that C. jejuni reacts with calcofluor white (CFW), indicating the presence of surface polysaccharides harboring 1-3 and/or 1-4 linkages. CFW reactivity increased with extended growth, under 42°C anaerobic conditions, and in a spoT mutant defective for the stringent response (SR). Conversely, two newly isolated dim mutants exhibited diminished CFW reactivity as well as growth and serum sensitivity differences from wild-type. Genetic, biochemical, and NMR analyses suggested that differences in CFW reactivity between wild-type, spoT and dim mutant strains were independent of well-characterized LOS, CPS, and and N-linked polysaccharides. Targeted deletion of carB downstream of the dim13 mutation also resulted in CFW hypo-reactivity, implicating a possible role for carbamoylphosphate synthase in biosynthesis of this polysaccharide. Correlations between biofilm formation and production of the CFW-reactive polymer were demonstrated by crystal violet staining, scanning electron microscopy, and confocal microscopy, with C. jejuni spoT being the first SR null mutant in any bacterial species identified as up-regulating biofilms. Together, these results provide new insight into genes and processes important for biofilm formation and polysaccharide production in C. jejuni.