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

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. Co-localization of eHLP and eDNA in biofilm was confirmed. The addition of eDNA (up to 1 μg ml-1) purified from S. intermedius, other Gram-positive, –negative bacteria, or human KB cells into the S. intermedius culture increased the biofilm mass of all tested strains of S. intermedius, wild-type, HLP down-regulated strain, and control strains. In contrast, the addition of eDNA (> 1 μg ml-1) decreased the biofilm mass of all S. 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.

内容要旨・審査要旨・論文本文の公開:
内容要旨 : LID201409191007.pdf
審査要旨 : LID201409191008.pdf
論文本文 : k2757_fulltext.pdf
本論文は，著者Asikin Nurの学位論文として提出され，学位審査・授与の対象となっている。
著者の申請により要約(2014-09-20公開)に替えて論文全文を公開(2019-10-09)

This is the peer reviewed version of the following article: 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. J Appl Microbiol, 115: 260-270., which has been published in final form at https://doi.org/10.1111/jam.12202. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.