Antibacterial activity of methanol extract from Wedelia biflora (L.) DC. growing in the Can Gio Mangrove Biosphere Reserve, Vietnam

The study investigated antibacterial activity of methanol extract of Wedelia biflora (L.) DC. (Wollastonia biflora or Melanthera biflora) growing in the Can Gio Mangrove Biosphere Reserve, Vietnam by using agar well diffusion method. Antimicrobial activity strength of Wedelia biflora (L.) DC. was depended on diameter of antibacterial zone causing by the methanol extract. The findings showed that methanol extract of whole plants, Wedelia biflora (L.) DC. exhibited antibacterial activity against Gram (+) bacteria: Bacillus cereus and Staphylococcus aureus but negative effects on Gram (-) bacteria: Pseudomonas aeruginosa and Escherichia coli. Its antibacterial activity increased with increase in extract concentration. Only extract with concentration of 1000 mg mL-1 had moderately antibacterial strength against B. cereus but the extract with other tested concentrations had antibacterial activity at weak level according to Manuanza’s rating scale of antibacterial zones.