Effect of AHL-Degrading Bacteria Halomonas sp. Isolated from Micro-Algal Cultures Chaetoceros muelleri on Virulence of Vibrio sp. and Survival of White Shrimp Larvae (Litopennaeus vannamei) Against Vibrio sp.
Virulence of Vibrio has been known regulated by quorum sensing, which is regulated by secretion and sensing signal molecule N-Acyl-Homoserine Lactone (AHL). Degradation of AHL enzymatically by bacteria might be an alternative method to inhibit virulence of Vibrio sp. In the previous study, AHL-degra...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/22174 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Virulence of Vibrio has been known regulated by quorum sensing, which is regulated by secretion and sensing signal molecule N-Acyl-Homoserine Lactone (AHL). Degradation of AHL enzymatically by bacteria might be an alternative method to inhibit virulence of Vibrio sp. In the previous study, AHL-degrading bacteria Halomonas sp. has been isolated from Chaetoceros muelleri. This study was aimed to determine the effect of Halomonas sp. to virulence of Vibrio sp. and survival of white shrimp larvae (Litopenaeus vannamei) when challenged by Vibrio sp. This study was divided into three steps: (1) N-hexanoyl-homoserine lactone (HHL) degradation assay by Halomonas sp. using HPLC (2) impact of Halomonas sp. on quorum sensing-regulated bioluminescence of Vibrio sp. detected by tecan multireader and (3) white shrimp larvae challenge test against Vibrio sp. with six different treatments which are addition of isolate only (P1), addition of Vibrio sp. only (P2), addition of isolate 24 hours before addition of Vibrio sp. (P3), addition isolate and Vibrio sp. at the same time (P4), addition of isolate 24 hours after addition of Vibrio sp. (P5) and no isolate were added into the tank (P6). The result showed that Halomonas sp. was able to decrease HHL concentration with degradation rate 0.19 ppm/h. Furthermore, Halomonas sp. was able to inactivate AHL produced by Vibrio sp. shown by decreasing of bioluminescence after 24 hours. Finally, addition of Halomonas sp. significantly increased the survival of white shrimp larvae when challenged by Vibrio sp. (p<0.05). P4 gave highest survival (68.1%) followed by P1 (61.8%) and P5 (55.7%). These results were significantly different with P2 (22.7%). It can be concluded that Halomonas sp. was able to decrease virulence of Vibrio sp. and increase the survival of white shrimp larvae against Vibrio sp. through disruption of quorum sensing mechanism. |
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