In vitro antibacterial activity of the peptide PsVP-10 against Streptococcus mutans and Streptococcus sobrinus with and without glycocalyx

The antibacterial activity of the peptide PsVP-10 obtained from Pseudomonas sp. R10 against Streptococcus mutans and Streptococcus sobrinus was investigated. One hundred and twenty strains of S. mutans and 120 strains of S. sobrinus with and without glycocalyx were isolated from saliva samples in trypticase-yeast-cysteine-sucrose-bacitracin (TYCSB) agar. Bacterial identification was made by polymerase chain reaction. Glycocalyx production was observed in modified TYCSB agar and confirmed with a modified version of the microplate adherence assay. The minimum inhibitory concentration (MIC) of PsVP-10 bacteriocin was determined by means of the agar dilution method, and the time of bacterial death was calculated by means of colony-forming unit counts. The MIC of the bacteriocin PsVP-10 for both bacterial species with and without glycocalyx was < 2 mg/L and the time of bacterial death was less than 240 s for all the studied bacterial strains. Thus, bacteriocin PsVP-10 could be an interesting possibility to combat these cariogenic bacterial species.