title: Effects of extracellular DNA and DNA-binding protein on the development of a Streptococcus intermedius biofilm.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  eDNA- and HLP-targeting strategies may be applicable to novel treatments for bacterial biofilm-related infectious diseases.
authors.affiliation: Department of Oral Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Nur
authors.forename: K
authors.initials: K
authors.lastname: Hirota
authors.forename: H
authors.initials: H
authors.lastname: Yumoto
authors.forename: K
authors.initials: K
authors.lastname: Hirao
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Murakami
authors.forename: T
authors.initials: T
authors.lastname: Matsuo
authors.forename: R
authors.initials: R
authors.lastname: Shu
authors.forename: Y
authors.initials: Y
authors.lastname: Miyake
mesh_terms: D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D045744:Cell Line, Tumor; D004247:DNA / Q000032:analysis / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D003850:Deoxyribonuclease I; D006801:Humans; D034367:Streptococcus intermedius / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D004247:DNA; D003850:Deoxyribonuclease I