Antimicrobial activity of herbal extracts against Vibrio spp. bacteria isolated from white feces syndrome on white leg shrimp (Litopenaeus vannamei) in some provinces in the mekong delta

Abstract

The study was conducted to determine the antibacterial activity of three herbal extracts: guava (Psidium guajava), leafflower (Phyllanthus urinaria L), beach daisy (Wedelia biflora (L.) DC ) against Vibrio spp. isolated from white feces syndrome infected shrimp in some provinces in the Mekong Delta. The antibacterial activity of the three herbal extracts was evaluated by the well diffusion method, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). The results indicated that there were 102 isolates in total of 378 shrimp samples which were clarified into 7 groups. Among these group, Vibrio alginolyticus group were the most abundant species with the percentage of 50 %, followed by Vibrio cholerae group with the percentage of 17.7%. The herbal extracts of P. guajava and P. urinaria L showed a broad - spectrum antibacterial activity against ten isolates which were selected for MIC and MBC test. The extract of P. urinaria L had the strongest antibacterial activity against V. harveyi CM3HPA2 and V. alginolyticus CM3IB2 (MIC of 0.2 mg/ml, MBC of 0.39 mg/ml). The obtained results indicated that the herbal extract of P. urinaria L will be a good candidate for reducing opportunistic pathogens Vibrio spp. abundant in gastrointestinal tract of shrimp.