Efficiency of Indigenous <i>Pseudomonas aeruginosa</i> as Biocontrol Agent against <i>Vibrio</i> Infection in Shrimp (<i>Penaeus monodon</i>) Culture

Abstract

The efficacy of Pseudomonas aeruginosa as a biocontrol agent against Vibrio mimicus infection in shrimp ( Penaeus monodon ) culture was evaluated. The antagonistic Pseudomonas sp. Ps2 and Vibrio sp. V1 were previously isolated from healthy and moribund shrimp intestines respectively. The two strains were identified using molecular method. Four-day acute pathogenicity tests were carried out on shrimp ( Penaeus monodon ) postlarvae using different concentrations of the strains. Histopathological examination of the hepatopancreas of the postlarvae was carried out after each pathogenicity test. Probiotic trial of the antagonistic Pseudomonas aeruginosa on culture of shrimp ( Penaeus monodon ) challenged with pathogenic Vibrio mimicus by immersion was carried out for 12 days. Water quality parameters (pH, temperature, ammonia, nitrite, nitrate, salinity and dissolved oxygen) were determined during shrimp culture. Molecular analysis conducted on Pseudomonas sp. Ps2 and Vibrio sp. V1 revealed that they are closely related to Pseudomonas aeruginosa strain XyC5 and Vibrio mimicus strain XQ respectively. The use of Pseudomonas aeruginosa had no pathogenicity effect on shrimp since no shrimp mortality was recorded. The LC 50 of Vibrio mimicus was calculated to be 3.2 x 10 4 cfu/ml. Vibrio mimicus addition resulted in 54% mortality and unhealthy hepatopancreas. No addition of bacteria resulted in 22% mortality and healthy hepatopancreas while Pseudomonas aeruginosa plus Vibrio mimicus addition resulted in zero mortality and healthy hepatopancreas. The water quality parameters were within the optimum ranges throughout the culture period. The results suggest that the indigenous antagonistic Pseudomonas aeruginosa strain XyC5 could be beneficial as biological control agent for management of vibriosis in shrimp aquaculture.