The Association of Vibrio species and Cyanobacteria in Selected Local Shrimp Farm

Dayang Najwa, Binti Awg Baki (2023) The Association of Vibrio species and Cyanobacteria in Selected Local Shrimp Farm. Masters thesis, Universiti Malaysia Sarawak.

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The discovery of cyanobacteria supporting the persistence of Vibrio species in the environment have bridged the gap for the discovery of Vibrio related association, however, the existing evidence are mixed. Some studies showed that cyanobacteria may be the side-kick to Vibrio species in marine environments, while others have found little or no association between the two groups. In this research, the association between Vibrio species and cyanobacteria in a selected local shrimp farm in Sarawak was examined. Over the course of 5 months starting from August 2021 to December 2021 with 2 weeks intervals between each sampling starting from the stocking of shrimp larvae up to the harvesting time, thirty-two (n=32) samples were collected from two shrimp ponds labelled as Pond A and Pond B, the effluent, and influent water of the shrimp farm from Persatuan Nelayan Kawasan Satang Biru, Telaga Air. Vibrio species and cyanobacteria population density were observed, and canonical Correspondence Analysis (CCA) was used to evaluate their correlation. Molecular method called duplex-Polymerase Chain Reaction (duplex-PCR) was used to identify Vibrio parahaemolyticus and Vibrio cholerae at molecular levels. An inverted microscope with a DIC filter that can produce pseudo-3D images was used for the morphological identification of cyanobacteria. As a result, V. parahaemolyticus showed 78%, 100%, 90%, and 90% prevalence while V. cholerae showed 72%, 61%, 90% and 70% prevalence from Pond A, Pond B, effluent, and influent, respectively. The morphological identification of cyanobacterial species revealed the presence of Pseudanabaena, Chroococcus, Phormidium, Oscillatoria and Lyngbya genus in our local shrimp farm. Results from CCA showed an insignificant correlation between Vibrio species and cyanobacteria with p-values of 0.847, 0.255, 0.288, and 0.304 for Pond A, Pond B, effluent, and influent water, respectively. This lack of association suggests that other factors such as species-specific association, regional factors, and other multidimensional landscapes may play a role in the persistence of Vibrio species in shrimp farms. Additionally, this research also examined the virulence genes and antibiotic susceptibility of V. cholerae and V. parahaemolyticus. Ten (n=10) V. cholerae and ten (n=10) V. parahaemolyticus isolates were selected from the same study. The primers used were tdh, trh for V. parahaemolyticus isolates and ctxB, rtxA and rtxC for V. cholerae isolates. 70% of rtxA and 90% of rtxC virulence genes were present in V. cholerae isolates while tdh and trh were absent in V. parahaemolyticus isolates. Antibiotic susceptibility testing showed that all V. cholerae and V. parahaemolyticus isolates were resistant to at least one antibiotic with the mean MAR indices of 0.34 for V. cholerae and 0.24 for V. parahaemolyticus. The MAR index of 0.20 and greater indicates that antibiotics are heavily contaminating the shrimp farm water. V. cholerae isolates showed resistance towards 25 µg sulfamethoxazole (100%), 30 µg cephalothin (80%), 30 µg neomycin (70%), 10 µg streptomycin (70%) and 30 µg ceftriaxone (60%). On the other hand, V. parahaemolyticus showed resistance towards is 30 µg cephalothin (100%), 10 µg streptomycin (100%), 25 µg sulfamethoxazole (100%) and 300 µg compound sulphonamides (80%). With no evidence of resistance from V. cholerae isolates, 10 µg imipenem, 30 µg tetracycline, 10 µg norfloxacin appeared to be the most potent antibiotics. All of V. parahaemolyticus isolates were susceptible with 30 µg ceftazidime, 30 µg ceftriaxone, 30 µg amikacin, 30 µg neomycin, 30 µg nalidixic acid, 5 µg ciprofloxacin, 25 µg sulfamethoxazole-trimethoprim and 30 µg chloramphenicol. For the treatment against V. cholerae and V. parahaemolyticus, 5 µg ciprofloxacin was found to be the best with the exception of banned antibiotics in food animals. This study contributes to the better understanding of Vibrio species’ distribution level in shrimp farm, and the possibility of them in causing diseases. The need for proper antibiotic administration and water treatment in shrimp farming environments is recommended to reduce the risk of antibiotic-resistant infections caused by V. cholerae and V. parahaemolyticus and minimize negative impact on the environment.

Item Type: Thesis (Masters)
Subjects: A General Works
Q Science > QR Microbiology
Z Bibliography. Library Science. Information Resources
Z Bibliography. Library Science. Information Resources
Divisions: Academic Faculties, Institutes and Centres > Faculty of Resource Science and Technology
Faculties, Institutes, Centres > Faculty of Resource Science and Technology
Date Deposited: 06 Sep 2023 06:58
Last Modified: 04 Mar 2024 03:36

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