IADR Abstract Archives
Study of Differential Expression of Proteins of Porphyromonas gingivalis Biofilm
Objectives: To analyze the differential expression of proteins of Porphyromonas gingivalis when growing in biofilms, in comparison with planktonic state.
Methods: Monospecies biofilms of P. gingivalis ATCC33277 were formed on sterile hydroxyapatite discs, immersed in the modified brain heart infusion (BHI) medium with bacteria suspension [107 colony forming unit (cfu)/mL], while planktonic cell cultures were obtained by inoculating BHI medium with bacteria suspensions (107 cfu/mL) in sterile plastic tubes. Both were incubated in anaerobic conditions at 37°C during 96 hours. To extract the proteins, biofilm and planktonic cells were disrupted by sonication. Then the samples were cleaned and solubilized. Label-free quantitative (without peptide or protein labeling) proteomics (LC-MS/MS) was applied to identify and quantify the proteins from biofilm and planktonic states. The acceptances criteria for proteins identification were a FDR (False Discovery Rate) <1% and at least one peptide identified with high confidence (confidence interval, CI<95%). In the quantification of proteins, a series of filters were applied to determine if a protein was differentially expressed between both conditions: abundance ratio variability (0-30%), p-value <0.05, q-value <0.05 and fold change (log2(ratio)≥±0.6).
Results: 892 proteins were identified, among them 862 proteins (41 exclusive) were found in the planktonic state and 851 proteins (30 exclusive) were found in the biofilm state. Of these proteins, 614 could be quantified and 73 proteins were differentially expressed. The repressed proteins were mainly involved in metabolism, biosynthesis and the fimbriae synthesis, and over-expressed proteins were involved in translation, oxidative stress, and proteins with unknown function.
Conclusions: P. gingivalis presented differential protein expression in biofilm growth, when compared to planktonic state, and these proteins may be good candidates to be used in both diagnosis and treatment of periodontitis.
Methods: Monospecies biofilms of P. gingivalis ATCC33277 were formed on sterile hydroxyapatite discs, immersed in the modified brain heart infusion (BHI) medium with bacteria suspension [107 colony forming unit (cfu)/mL], while planktonic cell cultures were obtained by inoculating BHI medium with bacteria suspensions (107 cfu/mL) in sterile plastic tubes. Both were incubated in anaerobic conditions at 37°C during 96 hours. To extract the proteins, biofilm and planktonic cells were disrupted by sonication. Then the samples were cleaned and solubilized. Label-free quantitative (without peptide or protein labeling) proteomics (LC-MS/MS) was applied to identify and quantify the proteins from biofilm and planktonic states. The acceptances criteria for proteins identification were a FDR (False Discovery Rate) <1% and at least one peptide identified with high confidence (confidence interval, CI<95%). In the quantification of proteins, a series of filters were applied to determine if a protein was differentially expressed between both conditions: abundance ratio variability (0-30%), p-value <0.05, q-value <0.05 and fold change (log2(ratio)≥±0.6).
Results: 892 proteins were identified, among them 862 proteins (41 exclusive) were found in the planktonic state and 851 proteins (30 exclusive) were found in the biofilm state. Of these proteins, 614 could be quantified and 73 proteins were differentially expressed. The repressed proteins were mainly involved in metabolism, biosynthesis and the fimbriae synthesis, and over-expressed proteins were involved in translation, oxidative stress, and proteins with unknown function.
Conclusions: P. gingivalis presented differential protein expression in biofilm growth, when compared to planktonic state, and these proteins may be good candidates to be used in both diagnosis and treatment of periodontitis.