title: Evidence of compositional differences between the extracellular and intracellular DNA of a granular sludge biofilm.
abstract: OBJECTIVE
  Extracellular polymeric substances (EPS) are an important component of microbial biofilms, and it is becoming increasingly apparent that extracellular DNA (eDNA) has a functional role in EPS. This study characterizes the eDNA extracted from the novel activated sludge biofilm process of aerobic granules.
  
  
  RESULTS
  Exposing the sludge to cation exchange resin (CER) was used for the extraction of eDNA and intracellular DNA (iDNA) from aerobic granules. This was optimized for eDNA yield while causing minimal cell lysis. We then compared the DNA composition of these extractions using randomly amplified polymorphic DNA (RAPD) fingerprinting and PCR-based denaturing gradient-gel electrophoresis (DGGE). Upon the analysis of the genomic DNA and the 16S rRNA genes, differences were detected between the sludge biofilm eDNA and iDNA.
  
  
  CONCLUSIONS
  Different bacteria within the biofilm disproportionally release DNA into the EPS matrix of the biofilm.
  
  
  CONCLUSIONS
  The findings further the idea that eDNA has a functional role in the biofilm state, which is an important conceptual information for industrial application of biofilms.
authors.affiliation: Advanced Water Management Centre, The University of Queensland, Qld, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Cheng
authors.forename: A E
authors.initials: AE
authors.lastname: Cook
authors.forename: T
authors.initials: T
authors.lastname: Fukushima
authors.forename: P L
authors.initials: PL
authors.lastname: Bond
mesh_terms: D001419:Bacteria / Q000737:chemistry* / Q000166:cytology / Q000235:genetics*; D018441:Biofilms; D002411:Cation Exchange Resins / Q000737:chemistry; D004269:DNA, Bacterial / Q000032:analysis* / Q000235:genetics; D058645:Denaturing Gradient Gel Electrophoresis; D005110:Extracellular Space / Q000737:chemistry*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique; D012722:Sewage / Q000382:microbiology*; D018508:Water Purification
chemical_list: D002411:Cation Exchange Resins; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012722:Sewage