Antibacterial activity of some herbal extracts against shrimp pathogenic bacteria

Abstract

This study was carried out to determine the antibacterial activity of some herbal extracts from different medicine plants obtained in the Mekong Delta (Psidium guajava, Cleistocalyx operculatus, Syzygium samarangense, Melaleuca leucadendra, Eucalyptus camaldulensis Dehn., Combretum quadrangulare) against shrimp pathogenic bacteria (Vibrio parahaemolyticus, Vibrio harveyi). The antibacterial activity of herbal extracts was detected by standard disc diffusion method (Kirby-Bauer), minimum inhibitory concentration (MIC) was conducted by using the dilution method and minimum bactericidal concentration (MBC) was also determined. The results indicated that (i) The antibacterial activity of tested herbal extracts with V. parahaemolyticus was different from V. harveyi, specifically, V. parahaemolyticus was considered more sensitive with the tested herbal extracts with the larger inhibition zone diameter than V. harveyi; (ii) The extracts of C. quadrangulare had the strongest antibacterial activity (inhibition zone of 20.16mm) against V. parahaemolyticus (MIC of 1.56 mg/mL, MBC of 3.125 mg/mL) and E. camaldulensis Dehnhardt (inhibition zone of 16.5 ± 2.18 mm) against V. harveyi (MIC of 0.78 mg/mL, MBC of 3.125 mg/mL), respectively. The result of this study showed that the extracts of C. quadrangulare and E. camaldulensis Dehnhardt are potential herbal plants for further application in shrimp farming