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Journal of Bacteriology, October 2009, p. 6281-6291, Vol. 191, No. 20
0021-9193/09/$08.00+0     doi:10.1128/JB.00906-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Characterization of Hydrogen Peroxide-Induced DNA Release by Streptococcus sanguinis and Streptococcus gordonii{triangledown}

Jens Kreth,1* Hung Vu,1 Yongshu Zhang,1 and Mark C. Herzberg1,2

Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, Minnesota 55455,1 Mucosal and Vaccine Research Center, Minneapolis Veterans Affairs Medical Center, Minneapolis, Minnesota 554172

Received 11 July 2009/ Accepted 6 August 2009

Extracellular DNA (eDNA) is produced by several bacterial species and appears to contribute to biofilm development and cell-cell adhesion. We present data showing that the oral commensals Streptococcus sanguinis and Streptococcus gordonii release DNA in a process induced by pyruvate oxidase-dependent production of hydrogen peroxide (H2O2). Surprisingly, S. sanguinis and S. gordonii cell integrity appears unaffected by conditions that cause autolysis in other eDNA-producing bacteria. Exogenous H2O2 causes release of DNA from S. sanguinis and S. gordonii but does not result in obvious lysis of cells. Under DNA-releasing conditions, cell walls appear functionally intact and ribosomes are retained over time. During DNA release, intracellular RNA and ATP are not coreleased. Hence, the release mechanism appears to be highly specific for DNA. Release of DNA without detectable autolysis is suggested to be an adaptation to the competitive oral biofilm environment, where autolysis could create open spaces for competitors to invade. Since eDNA promotes cell-to-cell adhesion, release appears to support oral biofilm formation and facilitates exchange of genetic material among competent strains.

* Corresponding author. Present address: Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104. Phone: (405) 271-1202. Fax: (405) 271-3117. E-mail: JKreth{at}ouhsc.edu

{triangledown} Published ahead of print on 14 August 2009.

Journal of Bacteriology, October 2009, p. 6281-6291, Vol. 191, No. 20
0021-9193/09/$08.00+0     doi:10.1128/JB.00906-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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