Evaluation of microalgae as quorum-sensing inhibitors to protect gnotobiotic Aartemia franciscana (Kellogg, 1906) against Vibrio campbellii
Diseases remain as one of the major constraints in aquaculture industry. The use of microalgae as quorum sensing inhibitor (QSI) to disrupt communication in pathogenic bacteria could be another disease control alternative as regulation of virulence factors in bacterial pathogens are regulated by...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/104398/1/NURUL%20AINI%20BINTI%20ABDUL%20HALIM%20-%20IR.pdf |
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| Summary: | Diseases remain as one of the major constraints in aquaculture industry. The use of
microalgae as quorum sensing inhibitor (QSI) to disrupt communication in pathogenic
bacteria could be another disease control alternative as regulation of virulence factors
in bacterial pathogens are regulated by quorum sensing (QS). Thus, the present study
evaluated different microalgae isolated from shrimp pond as quorum sensing inhibitors
in in vitro and in in vivo settings. In this study, the effects of nine microalgae species on
acyl-homoserine lactone-regulated phenotypes of two QS reporter strains
(Chromabacterium violaceum CV026 and Escherichia coli JB523) and anti-Acute
Hepatopancretic Necrosis Disease (anti-AHPND) were investigated. Five microalgae
pellet extracts; Picochlorum eucaryotum, Monoraphidium sp., Amphora coffeiformis,
Desertifilum tharense and Bulboplastis apyrenoidosa inhibited violacein production of
quorum sensing reporter strain CV026 with the largest inhibition zone of P.
eucaryotum (6.85 ± 0.15 mm). Further tests showed that the supernatant of algae
extracts also inhibited quorum sensing using the QS reporter strain JB523. In JB523
reporter strain, a significant decrease in QS-regulated GFP production (p < 0.05) were
observed in all microalgae species except for Spirulina platensis. The highest
percentage of inhibition of JB523 were demonstrated by P. eucaryotum (1 ± 0.02 %)
respectively, Monoraphidium sp. (1 ± 0.04 %) and Chlorella sp. (1 ± 0.02 %). The
growth of all reporter strains was found to be unaffected by the microalgal samples.
The most promising micro-algal strains as bacterial disease control agents were found
to be P. eucaryotum, A. coffeiformis and D. tharense. Meanwhile, screening of anti-
AHPND activities revealed that three green algae P. eucaryotum, Monoraphidium sp.
and Chlorella sp. were able to inhibit two AHPND strains of Vibrio parahaemolyticus.
The best three microalgae species with QSI activities; A. coffeiformis, D. tharense and
P. eucaryotum were selected for Artemia challenge assay. A significant (p < 0.05)
survival were observed in Artemia bioencapsulated with A. coffeiformis (95 ± 0 %), D.
tharense (85 ± 10 %), and P. eucaryotum (60 ± 0 %) even after challenged with Vibrio
campbellii, BB120 (12.5 ± 5 %). The results in this study indicated that quorum
quenching microalgae has the potential to be used as biocontrol tool to manage disease
outbreak particularly vibriosis in aquaculture farms. |
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