Event Abstract

Back to Event

The use of macro- and microalgae as functional ingredients in diets for meagre (Argyrosomus regius, Asso 1801)

Marta Monteiro1, 2, Rafaela A. Santos1, 2, 3*, Ana Couto2, Claudia R. Serra2, 3, Irene Gouvinhas3, Ana I. Barros3, Aires Oliva-Teles1, 2, Paula Enes2 and Patricia Díaz-Rosales2, 4
  • 1 Faculdade de Ciências, Universidade do Porto, Biologia, Portugal
  • 2 Centro Interdisciplinar de Pesquisa Marine e Ambiental (CIIMAR), Portugal
  • 3 Centro de Investigação e Tecnologias Agroambientais e Biológicas, Universidade de Trás-os-Montes e Alto Douro (CITAB-UTAD), Portugal
  • 4 Inmunología y Patología de Peces, Centro de Investigación en Sanidad Animal (CISA, INIA), Spain

Meagre (Argyrosomus regius, Asso 1801) has become an attractive candidate for aquaculture diversification, due to its excellent growth and biological characteristics (Quéméner, 2002). However, the expansion of meagre culture is at risk due to a range of common diseases. Enhancing host defense mechanisms with natural immunotherapeutic agents has become increasingly important for the prevention and prophylaxis of farmed fish diseases (Harikrishnan et al., 2011). During the last years, attention has been focused on marine organisms as a source of substances of therapeutic interest. Thus, the present research intends to explore novel immunotherapeutics produced by macro- and microalgae and use such bioactive compounds as functional ingredients in diets. Microalgae are natural sources of amino acids and long-chain polyunsaturated fatty acids, essential for fish health, and macroalgae present high levels of well-known bioactive compounds such as polysaccharides. Moreover, both macro- and microalgae are natural sources of bioactive carotenoids and peptides with potential health-promoting and disease-preventing properties (Holdt and Kraan, 2011;Yaakob et al., 2015). The final goal of the present work is characterizing micro- and macroalgae extracts in terms of bioactivity, and explore their effects on fish growth and health in order to evaluate their adequacy as fish feed ingredients and serve as a basis for further research on the use of selected algae biomass as functional ingredients and ultimately for product commercial development. Firstly, evaluation of possible potential bioactivities (such as anti-oxidant, anti-inflammatory, antibacterial and antiviral) of algal extracts has to be accomplished. Thus, the potential antioxidant activity of methanol:water extracts from two microalgae (Nannochloropsis sp. and Chlorella sp.) and three macroalgae (Gracilaria sp., Fucus vesiculosus and Ulva rigida) was evaluated. The free radical scavenging activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) spectrophotometric methods, as described by Queiroz et al. (2017). Total phenols content was determined, according to Folin-Ciocalteu spectrophotometric method, using gallic acid (GAE) as standard (Machado and Domínguez-Perles, 2017). Total phenolic content ranged from 1.11 mg GAE/g dw in Ulva rigida extract to 9.35 mg GAE/g dw in F. vesiculosus extract. The microalga Chlorella sp. and the macroalga F. vesiculosus were the most effective extracts at scavenging ABTS and DPPH radicals. Overall, results suggested that crude methanol extracts of Fucus vesiculosus and Chlorella sp. are the most effective in terms of antioxidant activity. Next, antibacterial, antiviral and anti-inflammatory activities will be evaluated in vitro for selection of the most promising algae after analysis of the antioxidant capability. The antimicrobial capacity of the dried biomass will be assessed against the most common and problematic bacteria in fish aquaculture Gram negative (Vibrio spp., Aeromonas veronii, Aeromonas hydrophyla subsp. hydrophila, Tenacibaculum maritimum, Photobacterium damselae subsp. piscicida and Photobacterium damselae subsp. damselae) as well as Gram positive (Bacillus subtilis), using the standard disk diffusion method. To determine the anti-inflammatory, the dried biomass will be used to evaluate changes in prostaglandin E2 (PGE2) expression in vitro, as well as cytokines involved in inflammation process such as cyclooxygenase 1 (COX-1), interleukin-1β (IL-1β), tumor-necrosis factor (TNF- α) and interleukin-6 (IL-6). Moreover, antiviral activity of the algal extracts will be tested both in cells lines (rainbow trout gonad, RTG-2; epithelioma papulosum cyprinid, EPC; zebrafish fibroblasts, ZF4; zebrafish hepatocytes, ZFL) and primary cell cultures from meagre infected with viral haemorrhagic septicaemia virus (VHSV), infectious pancreatic necrosis virus (IPNV) and European sheatfish virus (ESV) after incubation with the algal extracts, using viral titer determination. Taking advantages of zebrafish as experimental animal model, once the potential bioactivities have been characterized, the cytotoxicity of the most promising algal extracts will be analyzed in the cell lines already described and primary cell cultures as well as on zebrafish embryos. Furthermore, immune modulation of the previously selected algal extracts, will be evaluated in the embryos (wild type and neutrophil-specific transgenic line) and studied at two levels: potential protection against a bacterial infection and potential role in resolution of the inflammation process. The use of zebrafish as experimental model is a recent approach in the nutritional research field (Ulloa et al., 2014). Using zebrafish reduces time consuming, labor and cost, inclusion percentages of algal extracts inclusion in diets for further experiments in meagre. Thus, formulation of feeds supplemented with algae will be made for zebrafish, embryos and adults. Feed chemical composition will be analyzed and their effects will be analyzed from different approaches: evaluating the possible negative effect on larvae intestine by histological analysis, immunohistochemistry, and expression of genes involved in the inflammation process; and growth performance in adults and quantification of growth-related genes. Finally, the optimal algae at the best tested concentrations will be included in formulated diets for meagre. Meagre will be fed with selected algae and their effects on growth performance, digestibility, gut microbiota profile and immune response will be evaluated. At the end of the trial, a bacterial challenge will be performed. The potential immunomodulatory ability of algae dietary supplementation in meagre, following stimulation with the pathogen Photobacterium damselae subsp. piscicida will be studied. Humoral, cellular and molecular immune parameters will be determined in plasma, primary cell cultures and tissues. In conclusion, preliminary results suggest that methanol:water extracts of Chlorella, microalga, and F. vesiculosus, macroalga, showed the greatest antioxidant activity. Further analysis, described above, will be carried out in the near future. Thus, the whole project will contribute to the development of meagre aquaculture, by providing information on zootechnical performance and digestibility, as well as by contributing to the formulation of better feeds, not only nutritionally efficient, but with immune-boosting properties, using zebrafish as experimental animal model.

Acknowledgements

M. Monteiro, RA. Santos, A. Couto, CR. Serra P. Enes, were supported by grants SFRH/BD/114995/2016, SFRH/BD/131069/2017,SFRH/BPD/101354/2014, SFRH/BPD/101038/2014 and SFRH/BPD/101012/2014 respectively, from FCT under the POCI program. This work was funded by the FCT, Portugal [PTDC/CVT-WEL/5207/2014 and UID/AGR/04033/2013], and co-financed by the European Investment and Structural Funds (FEEI) through the COMPETE2020 - Operational Competitiveness Program [POCI-01-0145-FEDER-016797 and POCI-01-01

References

Harikrishnan, R., Balasundaram, C. and Heo, M.S. (2011). Impact of plant products on innate and adaptive immune system of cultured finfish and shellfish. Aquaculture 317, 1–15. doi:10.1016/J.AQUACULTURE.2011.03.039.
Holdt, S. L. and Kraan, S. (2011). Bioactive compounds in seaweed: functional food applications and legislation. J. Appl. Phycol. 23, 543–597. doi:10.1007/s10811-010-9632-5.
Machado, N. F. L. and Domínguez-Perles, R. (2017). Addressing facts and gaps in the phenolics chemistry of winery by-products. Molecules, 22(2), 1–48. doi: 10.3390/molecules22020286.
Queiroz, M., Oppolzer, D., Gouvinhas, I., Silva, A. M., Barros, A. I. R. N. A., and Domínguez-Perles, R. (2017). New grape stems’ isolated phenolic compounds modulate reactive oxygen species, glutathione, and lipid peroxidation in vitro: Combined formulations with vitamins C and E. Fitoterapia, 120(May), 146–157. https://doi.org/10.1016/j.fitote.2017.06.010
Quéméner, L. (2002). Le maigre commun (Argyrosomus regius): biologie, pêche, marché et potentiel aquacole. Ed. Quae.
Ulloa, P.E., Medrano J.F. and Feijoo, C.G. (2014). Zebrafish as animal model for aquaculture nutrition research. Front. in Genet. 5, 313. doi: 10.3389/fgene.2014.00313.
Yaakob, Z., Ali, E., Zainal, A., Mohamad, M. and Takriff, M. (2014). An overview: biomolecules from microalgae for animal feed and aquaculture. J. Biol. Res. 21, 6. doi:10.1186/2241-5793-21-6.

Keywords: meagre, Zebrafish, macroalgae, Microalgae, Fish Diseases, Aquafeeds, antioxidant activity

Conference: IMMR'18 | International Meeting on Marine Research 2018, Peniche, Portugal, 5 Jul - 6 Jul, 2018.

Presentation Type: Poster Presentation

Topic: Aquaculture

Citation: Monteiro M, Santos RA, Couto A, Serra CR, Gouvinhas I, Barros AI, Oliva-Teles A, Enes P and Díaz-Rosales P (2019). The use of macro- and microalgae as functional ingredients in diets for meagre (Argyrosomus regius, Asso 1801). Front. Mar. Sci. Conference Abstract: IMMR'18 | International Meeting on Marine Research 2018. doi: 10.3389/conf.FMARS.2018.06.00117

Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.

The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.

Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.

For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.

Received: 05 May 2018; Published Online: 07 Jan 2019.

* Correspondence: Miss. Rafaela A Santos, Faculdade de Ciências, Universidade do Porto, Biologia, Porto, 4169-007, Portugal, rafaela.santos@ciimar.up.pt