Microbial interactions in aquaculture - Probiotic roseobacters as a sustainable means to control fish pathogens
Aquaculture is the fastest growing protein production sector in the world. A major bottleneck in aquaculture is bacterial infections, which can lead to great losses. Fish larvae of several commercially important finfish are fed live feed due to the lack of appropriate artificial feed formulations. L...
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| Format: | Book |
| Language: | English |
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Technical University of Denmark
2019
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| Online Access: | https://orbit.dtu.dk/en/publications/904c04c0-7810-4cd5-9a73-7d7f22495ba1 https://backend.orbit.dtu.dk/ws/files/197458610/PhD_Thesis_Bastian_Barker_Rasmussen.pdf |
| Summary: | Aquaculture is the fastest growing protein production sector in the world. A major bottleneck in aquaculture is bacterial infections, which can lead to great losses. Fish larvae of several commercially important finfish are fed live feed due to the lack of appropriate artificial feed formulations. Live feed cultures are high in nutrition, which promote growth of bacteria including fast growing opportunistic pathogens. Live feed can function as infection vectors for pathogenic bacteria. Thus, fish larvae are especially susceptible to bacterial infections. Antibiotics are still used to combat bacterial infections in fish larvae cultures as the larvae cannot be efficiently vaccinated, however, the risk of resistance development and the associated health risk have led to the search for sustainable alternatives. Two types of promising alternative biocontrol are the use of probiotic bacteria and bacteriophages (virus that infect bacteria) the socalled phage therapy. The probiotic Phaeobacter spp. are able to inhibit the growth of a range of pathogens including Vibrio spp. due to the production of the antimicrobial compound tropodithietic acid (TDA). Phaeobacter spp. have successfully been shown to inhibit Vibrio spp. in axenic, i.e., without background microbiota, as well as few non-axenic live feed systems. Furthermore, Phaeobacter spp. are able to protect the live feed Artemia as well as fish larvae of cod and turbot against the Vibrio spp. induce disease vibriosis. The purpose of this PhD project was to investigate if probiotic Phaeobacter spp. were able to inhibit fish pathogenic bacteria in non-axenic live feed cultures either alone or in combination with bacteriophages (the latter in collaboration with researchers from aquaculture and in the area of phage therapy). Furthermore, this PhD sought to examine the possible practical application of Phaeobacter based probiotics in commercial aquaculture via upscaling in live feed microalgae. The present PhD study has shown that Phaeobacter spp. are able to antagonise ... |
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