Molecular Identification of Vibrio alginolyticus Causing Vibriosis in Shrimp and Its Herbal Remedy
M D Abdul Hannan1, M D Mahbubur Rahman2, M D Nurunnabi Mondal3
1Department of Aquatic Animal Health Management, Sher-e-Bangla Agricultural University , Dhaka , Bangladesh.
Abstract:
Penaeus monodon is highly susceptible to vibriosis disease. Aims of the study were to identify the pathogen causing vibriosis in P. monodon through molecular techniques and develop a biocontrol method of the disease by application of herbal extracts. Shrimp samples were collected aseptically from the infected farm and the bacteria were isolated from the infected region of those samples. Based on phenotypic identification, several isolates were identified as Vibrio sp. 16S rRNA gene sequences of the selected isolates exhibited 100% homology with V. alginolyticus strain ATCC 17749. An in vivo infection challenge test was performed by immersion method with V. alginolyticus where these isolates caused high mortality in juvenile shrimp with prominent symptoms of hepatopancreatic necrosis. Antibiogram profile of the isolates was determined against eleven commercial antibiotic discs whereas the isolates were found resistant to multiple antibiotics. A total of twenty-one herbal extracts were screened where Emblica officinalis, Allium sativum, and Syzygium aromaticum strongly inhibited the growth of V. alginolyticus in in vitro conditions. In in vivo conditions, the ethyl acetate extracts of E. officinalis and A. sativum successfully controlled the vibriosis disease in shrimp at a dose of 10 mg/g feed. This is the first report on molecular identification and biocontrol of V. alginolyticus in shrimp in Bangladesh.
Abstract:
Penaeus monodon is highly susceptible to vibriosis disease. Aims of the study were to identify the pathogen causing vibriosis in P. monodon through molecular techniques and develop a biocontrol method of the disease by application of herbal extracts. Shrimp samples were collected aseptically from the infected farm and the bacteria were isolated from the infected region of those samples. Based on phenotypic identification, several isolates were identified as Vibrio sp. 16S rRNA gene sequences of the selected isolates exhibited 100% homology with V. alginolyticus strain ATCC 17749. An in vivo infection challenge test was performed by immersion method with V. alginolyticus where these isolates caused high mortality in juvenile shrimp with prominent symptoms of hepatopancreatic necrosis. Antibiogram profile of the isolates was determined against eleven commercial antibiotic discs whereas the isolates were found resistant to multiple antibiotics. A total of twenty-one herbal extracts were screened where Emblica officinalis, Allium sativum, and Syzygium aromaticum strongly inhibited the growth of V. alginolyticus in in vitro conditions. In in vivo conditions, the ethyl acetate extracts of E. officinalis and A. sativum successfully controlled the vibriosis disease in shrimp at a dose of 10 mg/g feed. This is the first report on molecular identification and biocontrol of V. alginolyticus in shrimp in Bangladesh.
Insights
This study identifies Vibrio alginolyticus as the cause of vibriosis in Penaeus monodon shrimp. Herbal extracts from Emblica officinalis and Allium sativum effectively controlled the disease, offering a potential biocontrol strategy.
Area of Science:
- Aquatic animal health
- Microbiology
- Natural product chemistry
Background:
- Vibriosis, caused by Vibrio species, is a significant disease affecting Penaeus monodon (black tiger shrimp) aquaculture.
- The pathogen responsible for vibriosis in Penaeus monodon in Bangladesh was not previously identified using molecular methods.
- Antibiotic resistance in Vibrio isolates necessitates the development of alternative disease control strategies.
Purpose of the Study:
- To molecularly identify the Vibrio species causing vibriosis in Penaeus monodon.
- To evaluate the efficacy of various herbal extracts as a biocontrol agent against identified Vibrio pathogens.
- To establish a sustainable and effective treatment for vibriosis in shrimp aquaculture.
Main Methods:
- Bacterial isolation and phenotypic identification from infected Penaeus monodon.
- Molecular identification using 16S rRNA gene sequencing.
- In vitro and in vivo challenge tests to assess pathogenicity and efficacy of herbal extracts (Emblica officinalis, Allium sativum, Syzygium aromaticum).
Main Results:
- Molecular identification confirmed the pathogen as Vibrio alginolyticus, exhibiting 100% homology with reference strain ATCC 17749.
- The identified Vibrio alginolyticus isolates demonstrated resistance to multiple commercial antibiotics.
- Ethyl acetate extracts of Emblica officinalis and Allium sativum demonstrated significant in vitro inhibition and successfully controlled vibriosis in vivo at 10 mg/g feed.
Conclusions:
- Vibrio alginolyticus is identified as the causative agent of vibriosis in Penaeus monodon in Bangladesh.
- Emblica officinalis and Allium sativum extracts show potent antimicrobial activity against Vibrio alginolyticus, presenting a viable biocontrol option.
- This study provides the first report on the molecular identification and herbal biocontrol of Vibrio alginolyticus in shrimp aquaculture in Bangladesh.
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