Identification of agents causing vibriosis in litopenaeusvannamei shrimp culture in Kendal, Central Java, Indonesia and application of microalgae dunaliellasalina and tetraselmischui as bio-control agents against vibriosis

Abstract

Aquaculture of Vannamei shrimp at Kendal, Central Java, Indonesia has been using an intensive system, which could provoke the degradation of water quality in the pond. One of the emerging effects due to such degradation becoming threat for shrimp aquaculture is the loss caused by vibriosis disease. This study aimed to identify the presence of vibriosis-causing bacteria in shrimp pond at Kaliwungu, Kendal, Central Java and use the microalgae Dunaliella salina and Tetraselmis chui as bio control agents against Vibriosis. The Vibriosis-causing bacteria were isolated from the hepatopancreas and tails of ten shrimps showing clinical signs of vibriosis infection, cultured on the Thiosulfate Citrate Bile Salt Sucrose media. Out of 20 isolates, three isolates were selected for further gene sequence identification of 16rRNA using the Repetitive Sequence-based Polymerase Chain Reaction (rep-PCR) and were analyzed with BLAST. Universal primer 27F (5’AGAGTTTGATCMTGGCTCAG-3’) and 1492R (5’TACGGTTAACCTTGTTACGACTT-3’) were selected as the primers to identify the isolated bacteria. Results demonstrated that the three isolated bacteria were positive as vibriosis-causing agent in shrimp, which were U1H1 AND U4H1, identified as Vibrio alginolyticus, and U1E1 as V. harveyi. The use of microalgae as biocontrols was performed. Forty-five shrimps infected by vibrio reared during 21 days and feed with D. salina and T. chui showed a decreased of bacteria amount, which were counted by Total Plate Count method. The result indicated that the microalgae was capable to produce an antibacterial compounds against vibrio. Key Words: aquaculture, disease, pond water quality, bacteriosis, clinical symptom.