Inhibitory Activity of Propolis from Philippine Stingless Bees (Tetragonula biroi Friese) against Select Microorganisms

The antimicrobial activity of the ethanol extract of propolis (EEP) from the stingless bee, Tetragonula biroi Friese, was screened for activity against Escherichia coli, Pseudomonas aeruginosa,Bacillus cereus,Candida krusei, Staphylococcus aureus, and Penicillium chrysogenum using the disk diffusion method and agar-well assay. The highest inhibitory activities of EEP was observed at 30% (w/v) against Bacillus cereus (12.78 ± 1.92 mm), followed by Staphylococcus aureus (10.22 ± 0.83 mm), Penicillium chrysogenum (13.33 ± 2.40 mm), and Candida krusei (6.00 ± 0.00 mm) compared to the other concentrations – 10% (v/v) and 20% (v/v) of EEP. The antimicrobial activity of 30% w/v EEP against P. chrysogenum and C. krusei was comparable to mycostatin at 13.67 ± 0.58 and 6.33 ± 0.58 mm, respectively. The EEP was found to have no effect on Escherichia coli and Pseudomonas aeruginosa. Considered as a natural product, propolis has the potential to be a substitute for synthetic antimicrobial compounds commonly used in commercial products such as soaps.