ISOLATION AND SCREENING OF BACTERIOCIN PRODUCING BACTERIA INHIBITING SHRIMP PATHOGENIC VIBRIO PARAHAEMOLYTICUS

Abstract

Early Mortality Syndrome (EMS) also named Acute Hepatopancreatic Necrosis
Disease (AHPND) should be considered as a dangerous shrimp disease that has affected shrimp farms in Southeast Asia. It was detected in shrimp farms in southern China as first record in 2009 and afterward in Vietnam, Thailand and Malaysia. Lactic acid bacteria and Bacillus isolated from some samples of various fermented vegetables, seafood gastrointestinal tract and pond water were supposed to have capability to antagonize Vibrio parahaemolyticus causing the EMS. 47 strains of lactic acid bacteria and 133 strains of Bacillus were isolated and tested for antibacterial assays with the broth-dilution method and the agar well diffusion method. The results showed that 11 out of 180 strains could inhibit the Vibrio. The Bacillus sp. BV1 strain showed the highest antibacterial activity (antibacterial activity of 85.6%, bacteriocin activity of 4222.820 AU/mL). This strain was selected for the antagonistic experiment to Vibrio parahaemolyticus on white leg shrimp. Survival rates were significantly improved to 85% and 90% (for the treatment with 104 and 106 CFU/mL of Bacillus sp. BV1, respectively), which were much higher than untreated
control after 9 days of challenge.

Keywords: Lactic acid bacteria, Bacillus, bacteriocin, Vibrio parahaemolyticus, EMS/AHPND