Abstract

Betel plant, Piper betle has excellent potential to be used as an alternative antimicrobial agent to replace the use of commercial antibiotic in aquaculture. The present study evaluates the in vitro antimicrobial activity of betel leaf extract against Vibrio alginolyticus isolated from Asian sea bass, Lates calcarifer. Disc diffusion method was used to evaluate the antimicrobial activity of different concentrations of betel leaf extract and to compare the antimicrobial activity with commercial antibiotics. Broth dilution method was used to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the extract against V. alginolyticus. It was found that 100 mg/mL of the extract produced significantly (P < 0.05) largest inhibition zone (19 mm) compared to other concentrations. Concentrations between 10 and 80 mg/mL of the extract produced inhibition zone similar (P > 0.05) as the commercial antibiotics. The MIC and MBC for the extract at 100 mg/mL were 0.2 mg/mL and 0.39 mg/mL, respectively. The results show that ethanolic crude extract of betel leaves at 100 mg/mL is a potential alternative to antibiotic against V. alginolyticus infection.

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