THE EFFECT OF Halomonas aquamarina N-acyl-Homoserine-Lactone (AHL) DEGRADING BACTERIA ISOLATED FROM MICROALGAE Chaetoceros muelleri ON SURVIVAL AND HEPATOPANCREAS INTEGRITY OF WHITE SHRIMP (Litopenaeus vannamei) LARVAE AFTER CHALLENGED WITH Vibrio sp.

• Main Author: MANDASARI (NIM : 20616004), SHABRINA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30904
• Institution: Institut Teknologi Bandung

Shrimp vibriosis syndrome that occurred when Vibrio sp. express its virulence factor through quorum sensing mechanism can cause high shrimp mortality in shrimp industry. One alternative to overcome this syndrome is by controlling quorum sensing through bacterial enzimatic biodegradation of Vibrio sp. autoinducer (AHL). This research aimed to determine the effect of use of AHL–degrading bacteria Halomonas aquamarina culture isolated from microalgae Chaetoceros muelleri on shrimp survival and hepatopancreas integrity after Vibrio challenge. The research was done in four steps: (i) isolation and identification of bacteria from C. muelleri culture, (ii) HHL (N–hexanoyl–homoserine–lactone) degradation assay by H. aquamarina using HPLC method, (iii) shrimp larvae challenge test in six treatments : (1) addition of H. aquamarina 24 hours before Vibrio sp. (‘P1’), (2) addition of H. aquamarina with Vibrio sp. simultaneously (‘P2’), (3) addition of Vibrio sp. 24 hours before H. aquamarina (‘P3’), (4) no bacteria addition (‘P4’), (5) only H. aquamarina addition (‘P5’), (6) only Vibrio sp. addition (‘P6’), and (iv) shrimp hepatopancreas histological analysis. During 48 h incubation it was observed that H. aquamarina was able to degrade HHL at the rate of 0.18 mg L-1h-1. Furthermore, H. aquamarina was able to decrease Vibrio sp. bioluminescence up to 28.9%. The highest shrimp survival after Vibrio challenge was obtained in P5 treatment of 76.2% (p<0.05) followed by P4, P1, P2 and P3 of 66.4%, 64.7%, 62.9% and 62.0% respectively, which all significantly higher than P6 (22.7%) (p<0.05). Hepatopancreas histological analysis showed that the addition of H. aquamarina was also able to improve the epithelial cells integrity and minimize the cell damage and necrosis caused by Vibrio sp. The overall result suggested that H. aquamarina can decrease Vibrio sp. bioluminescence, increase shrimp survival and integrity of epithelial cells of shrimp hepatopancreas after Vibrio challenge.