Methods: Antibacterial property of propolis extracted was tested by using the agar-well diffusion method. Each bacteria at 106 - 108 CFU /ml was mixed with Mitis Salivarius Bacitracin Agar (MSBA). Each agar plate was punched out using a cork borer into 7 wells. The concentration of propolis extracts each at 600 mg/ml and 2- folded serial dilution with Dimethyl Sulfoxide (DMSO) were 300, 150, 75, 37.25, 18.75, 9.375 mg/ml respectively were filled in twelve wells with 20 µl per well, using DMSO as control group. The samples were incubated at 37o C under 5% CO2 environment for 24 hrs. Inhibition zone were measured.
Results: Propolis extract at concentration of 600 mg/ml possessed highest antibacterial property against Streptococcus mutans with inhibition zone of 12.10±0.46 mm., followed by Streptococcus gordonii and Enterococcus faecalis with inhibition zone of 11.80±0.42 mm. and 10.69±0.61 mm respectively. The minimum inhibition concentrations of propolis extract showing inhibition zones on Streptococcus mutans, Streptococcus gordonii and Enterococcus faecalis were 18.75, 9.375 and 4.688 mg/ml respectively.
Conclusions: Propolis extract from Australia possesses antimicrobial activity against Streptococcus mutans, Streptococcus gordonii and Enterococcus faecalis. However, further study should be established prior to practical application.