Water-soluble natural products from seaweed have limited potential in controlling bacterial pathogens in fish aquaculture

Mata, Leonardo, Wright, Emily, Owens, Leigh, Paul, Nicholas, and de Nys, Rocky (2013) Water-soluble natural products from seaweed have limited potential in controlling bacterial pathogens in fish aquaculture. Journal of Applied Phycology, 25 (6). pp. 1963-1973.

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Abstract

Seaweeds producing natural products with in vitro efficacy against bacterial pathogens offer the opportunity for therapeutic services in fish aquaculture, for example inhibiting the growth of pathogens through the direct release of bioactive metabolites into the culture environment. The red alga Asparagopsis taxiformis was used to test this hypothesis because of its effective natural products and mechanisms to release these metabolites into the surrounding environment and because it can be cultivated intensively in land-based systems. Here we quantify the release, accumulation and residence time of the major halogenated metabolites from A. taxiformis in the cultivation medium and subsequently test the in vitro bioactivity of these water-soluble metabolites against multiple strains of the pathogenic bacterium Streptococcus iniae. The two major halogenated metabolites in A. taxiformis (bromoform and dibromoacetic acid) were released into the water and reaching steady-state concentrations of 27.7 ± 1.5 μg L⁻¹ and 4.8 ± 1.3 μg L⁻¹, respectively, under standard cultivation conditions. This water delayed the in vitro growth of the pathogenic bacteria S. iniae but did not prevent it. Increasing the levels of A. taxiformis metabolites in the water by three orders of magnitude with aqueous extracts of biomass inhibited the growth of S. iniae, but it was also toxic to fish. In an immersion challenge experiment, intermediate non-ichthyotoxic levels of A. taxiformis metabolites were ineffective as a treatment for barramundi infected by S. iniae. The evidence suggests that there is little potential for A. taxiformis bioactive metabolites to provide therapy services to fish infected with S. iniae.

Item ID: 26848
Item Type: Article (Research - C1)
ISSN: 1573-5176
Keywords: Asparagopsis taxiformis, bacteria, barramundi, disease, halogenated metabolites, natural therapy
Funders: Fundação para a Ciência e Tecnologia (FCT), Portugal, Advanced Manufacturing Cooperative Research Centre (AMCRC), Australian Government Cooperative Research Centre Scheme
Projects and Grants: FCT project PTDC/MAR/112792/2009, FCT post-doctoral scholarship SFRH/BPD/46999/2008
Date Deposited: 08 May 2013 06:21
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070401 Aquaculture @ 50%
07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070404 Fish Pests and Diseases @ 50%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8301 Fisheries - Aquaculture > 830102 Aquaculture Fin Fish (excl. Tuna) @ 50%
83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8398 Environmentally Sustainable Animal Production > 839899 Environmentally Sustainable Animal Production not elsewhere classified @ 50%
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