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Recherche de molécules antibactériennes chez des bactéries du sol (Bacillus spp.) pour une nouvelle génération de désinfectants biologiques.: Search for new antibacterials from soil bacteria (Bacillus spp.) for the development of a new generation of biological disinfectants.

par Bajaj, Omar
Président du jury George, Isabelle
Promoteur Bouhajja, Emna
Co-Promoteur Dechamps, Etienne ;Andric, Sofija
Publication Non publié, 2023-06-12

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Résumé :

The wide diversity of soil bacteria has led to the emergence of numerous applications. Themost studied soil bacteria are members of the Bacillus genus, because of their interesting properties. Bacillus are widely used in industry because of their ability to produce highly stablespores. Among its applications, Bacillus spores are used to create probiotic-based hygieneand cleaning products. Bacillus has also been widely studied for their ability to produce secondary metabolism. The production of secondary metabolism helps the bacteria to defend themselves against pathogens and competitors present in the soil. The search for these secondarymetabolisms is important today, with the growing number of antibiotic-resistant pathogens.In this context, the objective of this work was to search for antibacterial molecules in Bacillusin view of the developent of a a biological disinfectant. Different protocols were used to identifypotential antibacterial activities against four pathogens: S. aureus, E. coli, P. aeruginosa, andE. hirae. Initially, Bacillus strains on solid media were tested. The most active strains werefound against S. aureus and E. coli. Some antibacterial activity was also identified against E.coli and P. aeruginosa. The bacterial supernatant was then tested against pathogens in solid andliquid media. The solid media test identified two supernatants active against three pathogens:S. aureus, E. coli, and E. hirae. The liquid culture protocol was used to quantitatively measurepathogen inhibition by the supernatant. This highlighted and revealed the inhibitory activity oftwo strains at different volumes of supernatant. The final step was to measure the activity of thesupernatant for two strains, this time following European Standards for disinfectants. The resultswere not conclusive, and the two supernatants did not meet the minimum criteria required bythe standards.Despite this, the tests used in this work revealed numerous antibacterial activities. A deeperunderstanding of the mechanism of action, concentration, and persistence of the molecules produced would offer a wide range of applications, including the creation of new biological hygiene products or disinfectants.