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Open Access Highly Accessed Research article

Genetic and phenotypic diversity in Burkholderia: contributions by prophage and phage-like elements

Catherine M Ronning14, Liliana Losada1, Lauren Brinkac1, Jason Inman1, Ricky L Ulrich2, Mark Schell3, William C Nierman1 and David DeShazer2*

Author Affiliations

1 J. Craig Venter Institute, 9704 Medical Center Drive, Rockville, MD 20850, USA

2 U.S. Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, MD 21702, USA

3 Department of Microbiology, University of Georgia, Athens, GA 30602, USA

4 U.S. Department of Energy, Office of Biological and Environmental Research, SC-23.2/Germantown Building, 1000 Independence Avenue SW, Washington DC 20585-1290, USA

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BMC Microbiology 2010, 10:202  doi:10.1186/1471-2180-10-202

Published: 28 July 2010

Abstract

Background

Burkholderia species exhibit enormous phenotypic diversity, ranging from the nonpathogenic, soil- and water-inhabiting Burkholderia thailandensis to the virulent, host-adapted mammalian pathogen B. mallei. Genomic diversity is evident within Burkholderia species as well. Individual isolates of Burkholderia pseudomallei and B. thailandensis, for example, carry a variety of strain-specific genomic islands (GIs), including putative pathogenicity and metabolic islands, prophage-like islands, and prophages. These GIs may provide some strains with a competitive advantage in the environment and/or in the host relative to other strains.

Results

Here we present the results of analysis of 37 prophages, putative prophages, and prophage-like elements from six different Burkholderia species. Five of these were spontaneously induced to form bacteriophage particles from B. pseudomallei and B. thailandensis strains and were isolated and fully sequenced; 24 were computationally predicted in sequenced Burkholderia genomes; and eight are previously characterized prophages or prophage-like elements. The results reveal numerous differences in both genome structure and gene content among elements derived from different species as well as from strains within species, due in part to the incorporation of additional DNA, or 'morons' into the prophage genomes. Implications for pathogenicity are also discussed. Lastly, RNAseq analysis of gene expression showed that many of the genes in ϕ1026b that appear to contribute to phage and lysogen fitness were expressed independently of the phage structural and replication genes.

Conclusions

This study provides the first estimate of the relative contribution of prophages to the vast phenotypic diversity found among the Burkholderiae.