[Effect of A.viscosus on growth of P. gingivalis in vitro]

To investigate the effect of A. viscosus on growth of P. gingivalis in vitro.

Groups as single-species(A.viscosus or P.gingivalis) and dual-species (A.viscosus and P.gingivalis) were incubated in BHI broth anaerobically at 37 degrees C, and growth curve of each group was monitored for 48 hours; Meanwhile the dual-species cultures of 2-hour interval were taken and the dilution was inoculated on BHI blood agar plates for 72 hours. The percentage of P. gingivalis was detected. BHI blood agar plates inoculated with P. gingivalis were prepared, and different concentrations of A. viscosus and its degerming supernatant were inoculated on the above plates in dropping method and incubated anaerobically for 72 hours. Zones of inhibition were measured and the data were analysed with SPSS 10.0 software package for one-way ANOVA.

A. viscosus was in logarithmic phase of growth at 2-hour and reached plateau at 8-hour. P. gingivalis entered logarithmic phase at 12-hour and reached plateau at 32-hour. Co-culture group was in logarithmic phase of growth at 2-hour and reached plateau at 12-hour. The percentage of P.gingivalis decreased gradually on BHI plates (P<0.05) and at 8-hour no P. gingivalis colony was found. The average diameters (mm) of inhibition zones were 19.3, 17.4, 13.2, 9.8 when the concentration of A. viscosus applied was 1 x 10(9), 10(8), 10(7), 10(6) CFU/ml, respectively. There was significance difference among the four groups (P<0.05). The supernatant of A. viscosus didn't show restrain on plates with P. gingivalis.

The study suggests that A. viscosus could inhibit the growth of P. gingivalis by nutrition competition in vitro.