Antimicrobial activity of herbal extracts against Vibrio spp. Bacteria isolated from white feces syndrome infected 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 (Psidium guajava, Phyllanthus urinaria L, Wedelia biflora (L.) DC ) against shrimp pathogenic bacteria Vibrio spp. isolated from white leg shrimp (Litopennaeus vannamei) infected white feces syndrome in some provinces in the Mekong Delta. The antibacterial activity was evaluated by well diffusion method, Minium Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). The results indicated that: (i) There were 102 isolated strains in total shrimp samples which were clarified into 7 groups. Among these group, V. alginolyticus group were the most abundant species with the percentage of 50 %, followed by V. cholerae group with the percentage of 17.7%; (ii) The herbal extracts of P. guajava, P. urinaria L showed a broad spectrum antibacterial activity against ten isolated strains in diseased shrimp; (iii) The extract of P. urinaria L had the strongest antibacterial activity against V. harveyi CM3HPA2 and V. alginolyticus CM3IC1 (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 good candidate for futher studies in order to find out an alternative method for antibiotics in preventions and treatments in shrimp diseases.