Effect of Green Tea Extract on Vibrio Parahaemolyticus Inhibition in Pacific White Shrimp (Litopenaeus Vannamei) Postlarvae

Inhibitory effect of green tea against Vibrio parahaemolyticus was assessed to determine its potential as antibacterial agent for Pacific white shrimp culture. Aqueous extracts obtained by boiling or soaking tea leaves in hot water could inhibit the growth of V. parahaemolyticus. Inhibition zone diameters, carried out by agar well diffusion method with 1x106 CFU.mL-1 of tested bacteria in agar medium, ranged from 14.4 to 16.4 mm. The minimum inhibitory concentration (MIC) determined by broth dilution method during 24-hour incubation was 10% (v/v). G reen tea extract (GTE) was effective on reducing mortality of shrimp postlarvae challenged with V. parahaemolyticus at 104 CFU.mL-1. Survival rate of shrimp reared in water treated with 1 mL.L-1 GTE (80±5.4%) was higher (P<0.05) than that of control (70±2.04%). Total Vibrio counts of whole shrimp, estimated 5 days after the postlarvae were challenged with V. parahaemolyticus at 106 CFU.mL-1, were 6.4x106 and 2.3x106 CFU.g-1 in control and GTE-treated shrimp, respectively. Results of this study suggest that green tea is a promising natural antibacterial agent that can be used for V. parahaemolyticus control during the nursery phase of Pacific white shrimp.