This Article Full Text (PDF) Other Versions of this Article: IAI.00874-07v1 76/1/38    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bernier, S. P. Articles by Sokol, P. A. Search for Related Content PubMed PubMed Citation Articles by Bernier, S. P. Articles by Sokol, P. A.

 Previous Article  |  Next Article 

Infect. Immun. doi:10.1128/IAI.00874-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

A LysR-Type Transcriptional Regulator in Burkholderia cenocepacia Influences Colony Morphology and Virulence

Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, Calgary, Alberta, Canada, T2N 4N1

^* To whom correspondence should be addressed. Email: psokol{at}ucalgary.ca.

	Abstract

Burkholderia cenocepacia strain K56-2 typically has rough colony morphology on agar medium; however, shiny colony variants (shv) can appear spontaneously. These shv all had a minimum of 50% reduction in biomass formation and were generally avirulent in an alfalfa seedling infection model. Three shv, K56-2 S15, K56-2 S76, and K56-2 S86, were analyzed for virulence in the chronic agar bead model of respiratory infection and although all shv were able to establish chronic infection they produced significantly less lung histopathology than the rough K56-2. Transmission electron microscopy revealed that an extracellular-like matrix surrounding bacterial cells was absent or reduced in the shv compared to the rough wild type. Transposon mutagenesis was performed on the rough wild type strain and a mutant with an insertion upstream of ORF BCAS0225, coding for a putative LysR-type regulator, exhibited shiny colony morphology, reduced biofilm production, increased AHL production, and avirulence in alfalfa. The rough parental colony morphotype, biofilm formation, and virulence in alfalfa were restored by providing BCAS0225 in trans in the transposon mutant. Introduction of BCAS0225 restored the rough morphotype in several shv which were determined to have spontaneous mutations in this gene. In this study, we have shown that the conversion from rough to shv in B. cenocepacia correlates with reduced biofilm formation and virulence, and we determined that BCAS0225 is one gene involved in the regulation of these phenotypes.