Effects of extracellular DNA and DNA-binding protein on the development of a Streptococcus intermedius biofilm
Article first published online: 18 APR 2013
© 2013 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 115, Issue 1, pages 260–270, July 2013
How to Cite
Nur, A., Hirota, K., Yumoto, H., Hirao, K., Liu, D., Takahashi, K., Murakami, K., Matsuo, T., Shu, R. and Miyake, Y. (2013), Effects of extracellular DNA and DNA-binding protein on the development of a Streptococcus intermedius biofilm. Journal of Applied Microbiology, 115: 260–270. doi: 10.1111/jam.12202
- Issue published online: 12 JUN 2013
- Article first published online: 18 APR 2013
- Accepted manuscript online: 29 MAR 2013 08:27AM EST
- Manuscript Accepted: 22 MAR 2013
- Manuscript Revised: 13 MAR 2013
- Manuscript Received: 13 DEC 2012
- Grant-in-Aid for Scientific Research
- Japan Society for the Promotion of Science. Grant Numbers: 21592387, 24592872
- biofilm development;
- DNA concentration;
- extracellular DNA;
- extracellular HLP;
- Streptococcus intermedius
The aim of this study was to clarify the effects of homologous and heterologous extracellular DNAs (eDNAs) and histone-like DNA-binding protein (HLP) on Streptococcus intermedius biofilm development and rigidity.
Methods and Results
Formed biofilm mass was measured with 0·1% crystal violet staining method and observed with a scanning electron microscope. The localizations of eDNA and extracellular HLP (eHLP) in formed biofilm were detected by staining with 7-hydoxyl-9H-(1,3-dichloro-9,9-dimethylacridin-2-one) and anti-HLP antibody without fixation, respectively. DNase I treatment (200 U ml−1) markedly decreased biofilm formation and cell density in biofilms. Colocalization of eHLP and eDNA in biofilm was confirmed. The addition of eDNA (up to 1 μg ml−1) purified from Strep. intermedius, other Gram-positive bacteria, Gram-negative bacteria, or human KB cells into the Strep. intermedius culture increased the biofilm mass of all tested strains of Strep. intermedius, wild-type, HLP-downregulated strain and control strains. In contrast, the addition of eDNA (>1 μg ml−1) decreased the biofilm mass of all Strep. intermedius strains.
These findings demonstrated that eDNA and eHLP play crucial roles in biofilm development and its rigidity.
Significance and Impact of the Study
eDNA- and HLP-targeting strategies may be applicable to novel treatments for bacterial biofilm-related infectious diseases.