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Dernière mise à jour : Mai 2018

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PhD thesis of Nassima Illikoud (2014-2017)

Nassima Illikoud
Characterization of the genes involved in spoilage potential of Brochothrix thermosphacta (M. Zagorec, E. Jaffrès, M.F. Pilet)

Abstract:

The microbiological spoilage of food leads to considerable economic losses. It results from the development and metabolism of microorganisms producing undesirable odors, flavors, textures or colors. Brochothrix thermosphacta, is one of the main spoilage bacteria in meat and seafood products. It produces metabolites responsible for unpleasant odors, varying according to the strains, foods and bacterial communities that surround it. We evaluated its genetic and phenotypic diversity within a collection of strains from various ecological origins. Different methods discriminated the strains into distinct groups, revealing significant diversity. However, this is not related to the environment from which the strains were isolated. Four strains representative of this diversity were analyzed by comparative genomics. The genomic content is similar, the differences residing in the content of phages and / or plasmids and surface components which may contribute to their ecological adaptation. Point mutations may be responsible for the different capacities to produce spoilng molecules. A transcriptomic study has shown that genes differentially expressed during growth on a meat or seafood matrix encode important functions for growth and survival in these specific niches. Analysis of the volatiloma showed that B. thermosphacta produces different molecules responsible for unpleasant odors which vary depending on the matrix. Therefore, we have shown a matrix effect rather than a strain effect on the spoilage potential of B. thermosphacta.

Valorisation:

  • Illikoud, N., C. Klopp, A. Roulet, O. Bouchez, N. Marsaud, E. Jaffres and M. Zagorec 2018. One complete and three draft genome sequences of four Brochothrix thermosphacta strains, CD 337, TAP 175, BSAS1 3 and EBP 3070. Standards in Genomic Science 13: 22. Ranking du JCR: Q4. https://doi.org/10.1186/s40793-018-0333-z.
  • Illikoud, N., A. Rossero, R. Chauvet, P. Courcoux, M.-F. Pilet, T. Charrier, E. Jaffrès and M. Zagorec 2019. Genotypic and phenotypic characterization of the food spoilage bacterium Brochothrix thermosphacta. Food Microbiology 81: 22-31. Ranking du JCR: Q1. https://doi.org/10.1016/j.fm.2018.01.015.
  • Illikoud, N., R. Gohier, D. Werner, C. Barrachina, D. Roche, E. Jaffres and M. Zagorec 2019. Transcriptome and volatilome analysis during growth of Brochothrix thermosphacta in food: Role of food substrate and strain specificity for the expression of spoilage functions. Frontiers in Microbiology 10: 2527. Ranking du JCR: Q2. https://doi.org/10.3389/fmicb.2019.02527.