Développement de nouvelles stratégies de prévention et de résistance aux infections opportunistes chez l'Omble de fontaine (Salvelinus fontinalis)

Authors: Boutin, Sébastien
Advisor: Audet, CélineDerome, Nicolas
Abstract: Bacteria can colonize every ecological niche including multicellular organisms, due to their fast growth and their biochemical abilities, . Host-bacteria relationships are complex and range from parasitism to mutualism. Under this framework, my theoretical objective is to study the relationship complexity between brook charr and its microbial partners. This fish species is targeted by opportunistic infections from bacterial pathogens belonging to the Flavobacterium genus. My applied objective focuse on the development of alternative strategies to prevent and treat these infections without antibiotics. The first result of this project highlight that hypoxic stress induce a diminution of the potentially beneficial bacteria leading to a dysbiosis, which in turn triggers opportunistic infections. Then, we isolated bacteria from the microbiome to test their antagonistic effects on two pathogens Flavobacterium columnare and F. psychrophilum. We identify seven potential candidates in vitro, one tested in vivo and being effective to prevent cold-water disease via interference competition. The last objective is to test the existence of host genetic regions associated with the recruitment capacity of beneficial genera in the microbiome. To this end, we analyze the skin microbiome of 86 progenies issued from a dihybrid cross. A strong inter-individual variability is observed and we identify three genetic regions involved in the recruitment of three bacterial genera including Methylobacterium, which is very important to maintain microbiome homeostasis. Overall, the results demonstrate the role of skin microbiota in brook charr resistance against opportunistic infections.
Document Type: Thèse de doctorat
Issue Date: 2013
Open Access Date: 19 April 2018
Permalink: http://hdl.handle.net/20.500.11794/24346
Grantor: Université Laval
Collection:Thèses et mémoires

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