title: Comparative gene expression analysis of Porphyromonas gingivalis ATCC 33277 in planktonic and biofilms states.
abstract: OBJECTIVE
  Porphyromonas gingivalis is a keystone pathogen in the onset and progression of periodontitis. Its pathogenicity has been related to its presence and survival within the subgingival biofilm. The aim of the present study was to compare the genome-wide transcription activities of P. gingivalis in biofilm and in planktonic growth, using microarray technology.
  
  
  METHODS
  P. gingivalis ATCC 33277 was incubated in multi-well culture plates at 37°C for 96 hours under anaerobic conditions using an in vitro static model to develop both the planktonic and biofilm states (the latter over sterile ceramic calcium hydroxyapatite discs). The biofilm development was monitored by Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscopy (SEM). After incubation, the bacterial cells were harvested and total RNA was extracted and purified. Three biological replicates for each cell state were independently hybridized for transcriptomic comparisons. A linear model was used for determining differentially expressed genes and reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to confirm differential expression. The filtering criteria of ≥ ±2 change in gene expression and significance p-values of <0.05 were selected.
  
  
  RESULTS
  A total of 92 out of 1,909 genes (4.8%) were differentially expressed by P. gingivalis growing in biofilm compared to planktonic. The 54 up-regulated genes in biofilm growth were mainly related to cell envelope, transport, and binding or outer membranes proteins. Thirty-eight showed decreased expression, mainly genes related to transposases or oxidative stress.
  
  
  CONCLUSIONS
  The adaptive response of P. gingivalis in biofilm growth demonstrated a differential gene expression.
authors.affiliation: Laboratory of Dental Research, University Complutense, Madrid, Spain.
authors.forename: P
authors.identifier: http://orcid.org/0000-0003-4421-7845
authors.initials: P
authors.lastname: Romero-Lastra
authors.affiliation: Laboratory of Dental Research, University Complutense, Madrid, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: Sánchez
authors.affiliation: Laboratory of Dental Research, University Complutense, Madrid, Spain.
authors.forename: H
authors.initials: H
authors.lastname: Ribeiro-Vidal
authors.affiliation: Laboratory of Dental Research, University Complutense, Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Llama-Palacios
authors.affiliation: Laboratory of Dental Research, University Complutense, Madrid, Spain.|ETEP (Etiology and Therapy of Periodontal Diseases) Research Group, University Complutense, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Figuero
authors.affiliation: ETEP (Etiology and Therapy of Periodontal Diseases) Research Group, University Complutense, Madrid, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Herrera
authors.affiliation: ETEP (Etiology and Therapy of Periodontal Diseases) Research Group, University Complutense, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Sanz
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D003773:Dental Plaque / Q000382:microbiology; D017886:Durapatite; D020869:Gene Expression Profiling; D006801:Humans; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D010518:Periodontitis / Q000382:microbiology; D010933:Plankton / Q000254:growth & development*; D016966:Porphyromonas gingivalis / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D012329:RNA, Bacterial / Q000235:genetics*
chemical_list: D012329:RNA, Bacterial; D017886:Durapatite