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J Appl Microbiol. 2013 Jul;115(1):260-70. doi: 10.1111/jam.12202. Epub 2013 Apr 18.

Effects of extracellular DNA and DNA-binding protein on the development of a Streptococcus intermedius biofilm.

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  • 1Department of Oral Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.

Abstract

AIMS:

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.

CONCLUSIONS:

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.

© 2013 The Society for Applied Microbiology.

PMID:
23551549
[PubMed - indexed for MEDLINE]
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