Genetic and phenotypic study of Bisifusarium domesticum ; Etude génétique et phénotypique de Bisifusarium domesticum

Bisifusarium domesticum is a cheese associated mold used for its organoleptic properties during Saint-Nectaire and Reblochon production and/or for its “anticollanti” property to prevent cheese stickiness. Despite this frequent use during cheese-making and its prevalence on various cheeses, there is a major lack of scientific knowledge about this species. This PhD project aimed at filling this gap. To do so, a B. domesticum collection (n=25) was created and an unexpected diversity of Fusarium sensu lato isolates was observed which led to the description of four new fungal species (B.allantoides, B. penicilloides, Longinectria lagenoides and L. verticilliforme), including two belonging to a new genus. Low intraspecific genetic diversity among B. domesticum isolates was noted. Then, the adaptation of B. domesticum as well as the novel species to cheese was studied and growth characteristics compatible with cheese-making conditions (temperature, aw, NaCl, growth on cheese), lipolytic and proteolytic abilities of some isolates were favored by temperatures similar to those of ripening cellars. Also, volatile compound productions of interest were highlighted as well as several genes (e.g. siderophore, sodium transporter, sugar transported) potentially linked to adaptation to a cheese environment although further in-depth studies are needed.Finally, no known mycotoxins production or mycotoxin gene clusters were identified, reinforcing the safety status of B. domesticum. ; Bisifusarium domesticum est une moisissure associée uniquement aux fromages. Elle est utilisée pour un apport organoleptique dans les Saint-Nectaire et Reblochon et/ou pour sa propriété “anticollanti”, pour prévenir l’apparition de morges collantes. Malgré une utilisation fréquente en production et sa mise en évidence sur divers fromages, il n’y avait, jusqu’à ce jour, que très peu de connaissances scientifiques sur cette espèce. L’objectif de cette thèse était donc de combler ce déficit. Pour ce faire, une collection d’isolats de B. domesticum (n=25) ...