Aim: Search for diffusible elements with antimicrobial activity produced by bacteria from the normal flora against the oral pathogen Porphyromonas gingivalis.
Materials and methods: The inhibitory capacity of different clinical isolates of P. gingivalis was evaluated by the appearance of an inhibition zone using the agar diffusion method. The inhibitory substance was purified from supernatants of overnight cultures of bacteria using an hydrophobic resin (Sep-Pak C8 Waters Company). The resin was eluted with increasing concentrations of methanol (10% -100%), where the fraction with inhibitory activity was called the active fraction. This fraction was characterized by chemical and physical properties such as resistance to heat, pH and enzyme treatments.
Results: Of the tested bacteria Staphylococcus epidermidis showed an inhibitory effect on P. gingivalis. The purified fractions from a supernatant from S. epidermidis that showed activity against the indicator strain P. gingivalis fractions were eluted with 70% -100% methanol. This diffusible factor was resistant to different pH, temperature tolerant and enzymatic degradation by proteinases, DNase and RNase.
Conclusion: The results suggest that S. epidermidis produces a diffusible factor with bacteriocin characteristics capable to inhibit the growth of P. gingivalis.
This work was funded by projects from DI 48-09R (MB), DI 24-09/1 (MC-R) of the Universidad Andrés Bello and CONICYT Grant MC-R.