In conclusion, the study showed that there were differences in the amount of yeast in gut linked to diets that were evaluated, with a significantly higher yeast load in fish feed the diet including S. cerevisiae (Y). No differences were found in yeast composition between diets or between gut segments. Debaryomyces hansenii was the dominant yeast species found in gut regardless of diet type. Differences of amount of yeast could also be linked to time (i.e., before and after). No differences were found on growth performance in fish between diets. Further research on the effect of yeast in feed is necessary for continued understanding of the impact on the yeast flora of Arctic charr.
Agboola, J.O., Øverland, M., Skrede, A. & Hansen Øvrum, J. (2021). Yeast as major protein-rich ingredient in aquafeeds: a review of the implications for aquaculture production. Reviews in Aquaculture, 13, 949–970.
https://doi.org/10.1111/raq.12507
Andlid, T., Juárez, R-V. & Gustafsson, L. (1995). Yeast Colonizing the Intestine of Rainbow Trout (Salmo gairdneri) and Turbot (Scophtalmus maximus). Microbial Ecology, 30, 321–334. https://doi.org/10.1007/BF00171938
Aubin J., Gatesoupe, F-J., Labbé, L. & Lebrun, L. (2005). Trial of probiotics to prevent the vertebral column compression syndrome in rainbow trout (Oncorhynchus mykiss Walbaum). Aquaculture research, 36, 758-767.
https://doi.org/10.1111/j.1365-2109.2005.01280.x
Balcázar, J.L., de Blas, I., Ruiz-Zarzuela, I., Vendrell, D., Gironés O. & Muzquiz J.L.
(2007). Enhancement of the immune response and protection induced by probiotic lactic acid bacteria against furunculosis in rainbow trout
(Oncorhynchus mykiss). Federation of European Microbiological Societies (FEMS) Immunol Med Microbiol, 51, 185–193. https://doi.org/10.1111/j.1574-695X.2007.00294.x
Barnes, E. M. & Durben, J. D. (2010). An evaluation of DVAqua ®, a fully-fermented yeast culture, during long-term hatchery rearing of McConaughy strain rainbow trout. Aquaculture nutrition, 16, 299–304. https://doi.org/10.1111/j.1365-2095.2009.00665.x
Belda, I., Ruiz, J., Santos, A., Van Wyk, N & Pretorius I.S. (2019). Saccharomyces cerevisiae. Trends in genetics, 35 (12), 256–257.
https://doi.org/10.1016/j.tig.2019.08.009
Berg, R.D. (1996). The indigenous gastrointestinal microflora. Trends in microbiology, 4 (11), 430–435. https://doi.org/10.1016/0966-842X(96)10057-3
Berge, G.M. & Austreng E. (1989). Blue Mussel in Feed for Rainbow Trout.
Aquaculture, 81, 79–90. https://doi.org/10.1016/0044-8486(89)90232-9 Brännäs, E., Nilsson, J. & Eriksson, L.-O. (2011). Rödingavel. En summering av det
svenska avelsprogrammet från 1982-2011. Report 9. Uppsala: Department of wildlife, fish and environment, Swedish University of Agricultural Sciences.
https://pub.epsilon.slu.se/8389/1/Brannas_E_etal_111018.pdf
Carlberg, H., Brännäs E., Lundh, T., Pickova J., Cheng, K., Trattner, S. & Kiessling, A.
(2014). Performance of Arctic charr fed with Baltic Sea-sourced ingredients.
(Reports of Aquabest project 10/2014). Helsinki: Aquabest.
References
Carlberg, H., Lundh, T., Cheng, K., Pickova, J., Langton, M., Gutiérrez Vázguez, J.L., Kiessling, A. & Brännäs, E. (2018) In search for protein sources: Evaluating an alternative to the traditional fish feed for Arctic charr (Salvelinus alpinus L.).
Aquaculture, 486, 253–260. https://doi.org/10.1016/j.aquaculture.2017.12.027 Chikwati, E.M., Venold, F.F., Penn, M.H., Rohloff, J., Refstie, S., Guttvik, A., Hillestad,
M. & Krogdahl, Å. (2012). Interaction of soyasaponins with plant ingredients in diets for Atlantic salmon, Salmo salar L. British Journal of Nutrition, 107, 1570–1590. 10.1017/S0007114511004892
FAO (1995). Code of Conduct for Responsible Fisheries. FAO, Rome, Italy., In:
http://www.fao.org/docrep/005/v9878e/v9878e00.HTM.
FAO (2011). Demand and supply of feed ingredients for farmed fish and crustaceans:
trends and prospects. FAO Fisheries and Aquaculture Technical Paper No. 564.
FAO, 2011. 87 pp.
(http://www.fao.org/3/ba0002e/ba0002e.pdf)
FAO (2012). The State of World Fisheries and Aquaculture 2012. Rome. 209 pp.
(http://www.fao.org/3/i2727e/i2727e.pdf)
FAO (2022). The State of World Fisheries and Aquaculture 2022. Towards Blue Transformation. Rome, FAO.
(https://doi.org/10.4060/cc0461en)
Gatesoupe, F.J. (2007). Live yeasts in the gut: Natural occurrence, dietary introduction, and their effects on fish health and development. Aquaculture, 267, 20–30.
https://doi.org/10.1016/j.aquaculture.2007.01.005
Hajra, A., Mazumder, A., Verma, A., Ganguly Prasad, D., Mohanty, B.P & Sharma, A.P.
(2013). Antinutritional factors in plant origin fish feed ingredients: the problems and probable remedies. Advances in Fish Research, vol. V, 193–202.
Hardy, R.W. (2010). Utilization of plant proteins in fish diets: effects of global demand and supplies of fishmeal. Aquaculture research, 41, 770–776.
https://doi.org/10.1111/j.1365-2109.2009.02349.x
Hauptman, B.S., Barrows, F.T., Block, S.S., Gaylord, G.T., Paterson, J.A., Rawles, S.D., Sealey, W.M. (2014). Evaluation of grain distillers dried yeast as a fish meal substitute in practical-type diets of juvenile rainbow trout, Oncorhynchus mykiss.
Aquaculture, 432, 7–14. https://doi.org/10.1016/j.aquaculture.2014.03.026 Hines, I.S., Ferguson, C. S., Bushman, T. J., Gatlin III, D. M., Jensen, Smith, S. A.,
Kuhn, D. D., Stevens, A. M. (2021). Impact of a yeast-based dietary supplement on the intestinal microbiome of rainbow trout, Oncorhynchus mykiss.
Aquaculture research, 52, 1594–1604. https://doi.org/10.1111/are.15011
Hoseinifar S.H., Mirvaghefi, A. & Merrifield, D.L. (2011). The effects of dietary inactive brewer's yeast Saccharomyces cerevisiae var. ellipsoideus on the growth,
physiological responses and gut microbiota of juvenile beluga (Huso huso).
Aquaculture, 318, 90–94. https://doi.org/10.1016/j.aquaculture.2011.04.043 Huyben, D., Nyman, A., Vidakovic, A., Passoth, V., Moccia, R., Kiessling, A., Dicksved,
J. & Lundh, T. (2017a). Effects of dietary inclusion of the yeasts Saccharomyces cerevisiae and Wickerhamomyces anomalus on gut microbiota of rainbow trout.
Aquaculture, 473, 528–537. https://doi.org/10.1016/j.aquaculture.2017.03.024
Huyben, D., Sun, L., Moccia, R., Kiessling, A., Dicksved. J. & Lundh, T. (2017b).
Dietary live yeast and increased water temperature influence the gut microbiota of rainbow trout. Journal of Applied Microbiology, 124, 1377–1392.
https://doi.org/10.1111/jam.13738
Jobling, M., Tveiten, H. & Hatlen, B. (1998). Cultivation of Arctic charr: an update.
Aquaculture International, 6, 181–196.
https://doi.org/10.1023/A:1009246509657
Jordbruksverket (2020). Vattenbruk 2020 (JO1201, Publicised 2021-08-31). Swedish Board of Agriculture.
https://jordbruksverket.se/om- jordbruksverket/jordbruksverkets-officiella-statistik/jordbruksverkets-statistikrapporter/statistik/2021-08-31-vattenbruk-2020 [2021-09-24]
Jorgensen, H. E., Christiansen, S. J. & Jobling, M. (1993). Effects of stocking density on food intake, growth performance and oxygen consumption in Arctic charr (Salvelinus alpinus). Aquaculture, 110 (2), 191–204.
https://doi.org/10.1016/0044-8486(93)90272-Z
Kiessling, A. (2009). Feed-the key to sustainable fish farming. In: Ackerfors, H.,
Cullberg, M. & Wrammer, P. (eds.). Fisheries, Sustainability and Development.
Stockholm, Royal Swedish Academy of Agriculture and Forestry. 303–322.
Langeland, M., Vidakovic, A., Vielma, J., Lindberg, J.E., Kiessling, A. & Lundh, T.
(2016). Digestibility of microbial and mussel meal for Artctic charr (Salvelinus alppinus) and Eurasian perch (Perca fluviatilis). Aquaculture nutrition, 22, 485–
495. https://doi.org/10.1111/anu.12268
Larsson, S. & Berglund, I. (1998). Growth and food consumption of 0+ Arctic charr fed pelleted or natural food at six different temperatures. Journal of Fish Biology, 52, 230–242. https://doi.org/10.1111/j.1095-8649.1998.tb00795.x
Lundh, T., Langeland, M., Vidakovic, A., Vielma, J. & Kiessling, A. (2014). Nutrient digestibility and growth in Arctic charr fed microbial and mussel protein meal.
(Reports of Aquabest project 23/2014). Helsinki: Aquabest.
Nilsson, J., Brännäs, E., Eriksson, L.-O. (2010). The Swedish Arctic charr breeding programme. Hydrobiologia, 650, 275–282. https://doi.org/10.1007/s10750-010-0232-9
NRC. (2011). Nutrient Requirements of Fish and Shrimp. Washington, DC: The National Academies Press.
Nyman, A., Huyben, D., Lundh, T. & Dicksved, J. (2017). Effects of microbe- and mussel-based diets on the gut microbiota in Arctic charr (Salvelinus alpinus).
Aquaculture reports, 5, 34–40. https://doi.org/10.1016/j.aqrep.2016.12.003 Olstorpe, M., Vidakovic, A., Huyben, D. & Kiessling, A. (2014). A technical report on
the production of microbial protein. (Reports of Aquabest project 13/2014).
Helsinki: Aquabest.
Pitcher, T., Kalikoski, D., Pramod, G. & Short, K. (2009). Not honouring the code.
Nature, 457 (5), 658–659. https://www.nature.com/articles/457658a [2022-12-05]
Ringø, E. & Gatesoupe, F.J. (1998). Lactic acid bacteria in fish: a review. Aquaculture, 160, 177–203. https://doi.org/10.1016/S0044-8486(97)00299-8
Ringø, E., Schillinger, U. & Holzapfel, W. (2005). Antimicrobial activity of lactic acid bacteria isolated from aquatic animals and the use of lactic acid bacteria in aquaculture. Biology of growing animals, 2, 418–453.
https://doi.org/10.1016/S1877-1823(09)70051-7
Romero, J., Ringø, E., Merrifield, D. (2014). The Gut Microbiota of Fish. In: Merrifield D. & Ringø, E. (red). Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics. West Sussex: John Wiley & Sons, Ltd. 75–100.
Rumsey, G.L., Hughes, S.G., Smith R.R, Kinsella, J.L. and Shetty K.J. (1991)
Digestibility and energy values of intact, disrupted and extracts from brewer's dried yeast fed to rainbow trout (Oncorhynchus mykiss). Animal Feed Science and Technology, 33, 185–193. https://doi.org/10.1016/0377-8401(91)90059-2 Smith, A.A., Dumas, A., Yossa, R., Overturf, K.E. & Bureau, D.P. (2018). Effects of
soybean meal and high-protein sunflower meal on growth performance, feed utilization, gut health and gene expression in Arctic charr (Salvelinus alpinus) at the grow-out stage. Aquaculture Nutrition, 24, 1540–1552.
https://doi.org/10.1111/anu.12691
SOU 2009:26. Det växande vattenbrukslandet. https://www.regeringen.se/rattsliga-dokument/statens-offentliga-utredningar/2009/03/sou-200926/
Stewart, G.G. (2014). Saccharomyces cerevisiae. Encyclopedia of Food Microbiology (Second Edition), 2014, 309–315. https://doi.org/10.1016/B978-0-12-384730-0.00292-5
Tabachek. L. J-A. (1988). The effect of feed particle size on the growth and feed efficiency of Arctic charr [Salvelinus alpinus (L.)]. Aquaculture, 71 (4), 319–
330. https://doi.org/10.1016/0044-8486(88)90201-3
Tacon, J. G. A. & Metian, M. (2008). Global overview on the use of fishmeal and fish oil in industrially compounded aquafeeds: Trends and future prospects.
Aquaculture, 285, 146–158. https://doi.org/10.1016/j.aquaculture.2008.08.015 Tedengren, M. & Kautsky. N. (1986). Comparative study of the psychology and its
probable effect on size in blue mussels (Mytilus Edulis L.) from the North Sea and the northern Baltic proper. Ophelia, 25 (3), 147–155.
https://doi.org/10.1080/00785326.1986.10429746
Vidakovic, A., Langeland, M., Sundh, H., Sundell, K., Olstorpe, M., Vielma, J., Kiessling, A. & Lundh, T. (2016). Evaluation of growth performance and intestinal barrier function in Arctic Charr (Salvelinus alpinus) fed yeast (Saccharomyces cerevisiae), fungi (Rhizopus oryzae) and blue mussel (Mytilus edulis). Aquaculture Nutrition, 22, 1348–1360.
https://doi.org/10.1111/anu.12344
Waché, Y., Auffray, F., Gatesoupe, F-J., Zambonino, J., Gayet, V., Labbé, L. & Quentel, C. (2006). Cross effects of the strain of dietary Saccharomyces cerevisiae and rearing conditions on the onset of intestinal microbiota and digestive enzymes in rainbow trout, Onchorhynchus mykiss, fry. Aquaculture, 258, 470–478.
https://doi.org/10.1016/j.aquaculture.2006.04.002
Wallace, C. J., Kolbeinhavn G. A. & Reinsnes, G. T. (1988). The Effects of Stocking Density on Early Growth in Arctic Charr, Salvelinus alpinus (L.). Aquaculture, 73, 101–110. https://doi.org/10.1016/0044-8486(88)90045-2
Ytrestøyl, T., Synnøve Aas, T. & Åsgård, T. (2015). Utilisation of feed resources in production of Atlantic salmon (Salmo salar) in Norway. Aquaculture, 448, 365–
374. http://dx.doi.org/10.1016/j.aquaculture.2015.06.023
Øverland, M., Karlsson, A., Mydland, T. L., Romarheim, H. O., Skrede, A. (2013).
Evaluation of Candida utilis, Kluyveromyces marxianus and Saccharomyces cerevisiae yeasts as protein sources in diets for Atlantic salmon (Salmo salar).
Aquaculture, 402–403, 1–7. https://doi.org/10.1016/j.aquaculture.2013.03.016
Aquaculture is a rapid growing sector and an important contributor to the world food supply. Historically, the aquaculture industry has been dependent on marine resources as fishmeal and fish oil for protein sources in feed for farmed fish. Due to unreliable catches, the threat of overfishing and fluctuations in price, the industry itself has started to look for alternatives to fishmeal and fish oil to enhance sustainability within aquaculture. When looking for replacements for these marine resources, it is of great importance to consider a suitable amino acid profile and protein content for fish. From a sustainability perspective, the most favourable option would be to use feed ingredients not suitable for direct human consumption to avoid competition of feed resources. The protein rich blue mussel has been discussed as a substitute to fishmeal for a long time, where mussels below marketing size would be ideal to use for this purpose. Plant protein is commonly used as an alternative to marine resources in aquaculture, however plant protein can many times be directly consumed by humans. Instead, it might be necessary to look further down the food chain. Microorganisms, such as yeast and fungi, has been of interest as a protein replacer in fish feed, where the baker’s yeast (Saccharomyces cerevisiae) has been suggested as a suitable option with desirable traits.
All feed intake by the fish need to pass through the gut. In the fish gut, there is a complex system of microorganisms inhabiting the surfaces, referred to as the microbiota. The microbiota affects various important processes of the host. Yeast, as being one of the types of microorganisms present in fish gut, can exist in large number and in various composition. The normal microbiota is a dynamic system but can be seen as a base of the microorganisms inhabiting the gut in normal conditions. What happens to the yeast flora when fish are feed yeast compared to other diets? Will the diet alter the number of, or the diversity of yeast species found in the gut? Will different gut sections respond differently to the feed? These were all questions that were addressed in the present study. Four different diets were fed to Arctic charr for two weeks. A reference diet resembled to a commercial diet, containing fishmeal as a protein source was used. In two of the experimental diets, 40 percent of the fishmeal was replaced by baker’s yeast or by blue mussel meal.
The third experimental diet contained ingredients originated from the Baltic Sea, with a protein content of 1/3 fishmeal and 1/3 blue mussel meal combined with 1/3 baker’s yeast. Four different parts of the gut were analysed to see if the response
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differed between these sections in the gastrointestinal tract. Differences in the yeast flora composition and yeast loads from before and after two weeks of dietary treatment was investigated together with fish growth performance. Also, bacterial and fungi growth was estimated when analysing the samples. The yeast load and yeast composition in the feeds were also analysed. No differences in growth performance were found between the different groups at the end of the study.
Regarding the yeast flora, there were no differences between the yeast species found in the gut between the different diets. Debaryomyces hansenii was the dominate yeast species throughout all samples in the experiment i.e., not the same yeast species that was added in the feeds. The gut sections did not have an effect on the number of, or the diversity of yeast species in this experiment. However, when looking at the number of yeasts found in gut, there were indications pointing towards that the fish fed the diet containing 40 percent of baker’s yeast, had a higher number of yeast present in the gut than the other diets. However, the study design was not optimally designed for this type of analysis and therefore the results need to be looked at as just indications. Further research needs to investigate whether feeding baker’s yeast to Arctic charr results in higher yeast amounts in gut.
I would like to thank my supervisor Johan Dicksved for great assistance and guidance with this thesis. Also, I am thankful for everyone who has been involved in the practical part of the study for helping me in the lab. I would like to thank my husband, family and friends for always cheering me on and for helping me with the life puzzle, which enabled me to finish this report. And a thanks to my kids Haldo and Hildur, just for being the best.