Exploration de la diversité de Carnobacterium maltaromaticum en vue d'identifier des souches protectrices anti-Listeria monocytogenes à robustesse élevée

Abstract : The food industry is constantly seeking to improve food preservation processes. Biopreservation imposes itself as an alternative to the use of chemical preservatives and involves micro-organisms selected as protective cultures for their natural antimicrobial properties. The aim of this study was to benefit from the diversity of Carnobacterium maltaromaticum in order to identify strains capable of inhibiting the growth of Listeria monocytogenes, a food-borne pathogen. For this purpose, a molecular typing method that enables fine strain identification has been established, then a method of screening of antibacterial activities with high robustness has been developed. The molecular typing method is a MLVA (Multiple-locus variable-number tandem repeat (VNTR) analysis) with 3 VNTR loci (VNTR-A, VNTR-B, VNTR-C). It allowed to discriminate 15 different genotypes among a collection of 24 C. maltaromaticum strains. These results confirmed the high strain diversity within this species and showed the high performance of this method. The screening method is based on high throughput competition assays where each member of a collection of C. maltaromaticum strains was co-cultivated with a bioluminescent strain of L. monocytogenes. It was established that the bioluminescence of this strains is highly correlated to bacterial growth in micro-cultures, indicating that it is possible to investigate the stability of antagonistic properties of each collection member under multiple different culture conditions. The use of this method allowed to identify C. maltaromaticum strains with bioprotection properties that are poorly influenced by culture conditions. Besides the fundamental interest of this method for investigations of competitive interactions in food, it allowed to identify strains with high potential for bioprotection applications
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https://hal.univ-lorraine.fr/tel-01963724
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Submitted on : Friday, December 21, 2018 - 3:09:48 PM
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Sara El Kheir. Exploration de la diversité de Carnobacterium maltaromaticum en vue d'identifier des souches protectrices anti-Listeria monocytogenes à robustesse élevée. Ingénierie des aliments. Université de Lorraine; Université libanaise, 2016. Français. ⟨NNT : 2016LORR0230⟩. ⟨tel-01963724⟩

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