Antibacterial and Sporicidal Activities of Methanolic Sygygium polyanthum L. Leaf Extract against Vegetative Cells and Spores of Bacillus pumilus and Bacillus megaterium

The Sygygium polyantum L. leaf has been used as spice as well as traditional herbal medicine. The methanolic extracts of S. polyanthum L. was tested for antibacterial and sporicidal activities against vegetative cells and spores of Bacillus pumilus ATCC14884 and B. megaterium ATCC14581. The disc diffusion assay (DDA), minimum inhibition concentration (MIC), minimal bacterial concentration (MBC) and sporicidal activities of the extract on Bacillus sp. were analyzed using Clinical and Laboratory Standard Institutes (CLSI) methods. The effect of the extract on spores was visualized using scanning electron microscope (SEM). The results show that the inhibition zone of the extract on B. pumilus and B. megaterium was 12.16 ± 0.57 mm. The extract has been able to inhibit the growth of B. pumilus and B. megaterium vegetative cells with MICs of 0.08- and 0.04 mg/ml, respectively. Moreover, the B. pumilus and B. megaterium can be killed by MBCs of 1.25- and 0.64 mg/ml, respectively. One presence of extract can kill 100% of all Bacillus sp. spores during 1 h exposure time. SEM observation showed that the spores were destroyed by the extract. These results suggested that S. polyanthum L. extract can be developed as antibacterial and antispore against Bacillus sp.