New approaches are being studied intensively to control Campylobacter jejuni in the food industry. Plant extracts represent promising alternative antimicrobial agents for biofilm control. In this doctoral thesis, we prepared and tested different preparations of Lavandula angustifolia and L. x intermedia against biofilm formation of C. jejuni on abiotic surfaces. Biofilm formation was challenged through targets such as motility, attachment and intercellular communication of C. jejuni. We optimized the method of culturing and studying the biofilm of C. jejuni on an abiotic surface, specifically at the solid/liquid interface, using confocal laser scanning microscopy. We developed, optimized and upgraded a method for studying the intercellular communication of C. jejuni with the V. harveyi MM30 biosensor strain, which proved to be accurate and more sensitive compared to the high pressure liquid chromatography with fluorescence detector (HPLC-FLD) method. All lavender preparations successfully removed the mature biofilm of C. jejuni from the abiotic surface. Likewise, all lavender preparations successfully inhibited the motility, attachment of C. jejuni to abiotic surfaces and biofilm formation of C. jejuni. Lavander preparations did not lower significantly the concentration of autoinducer-2 (AI-2) signalling molecules in the spent medium of C. jejuni. The rt-PCR did not show the significant effect of lavender essential oil on the expression of the luxS gene in C. jejuni. Transcriptomic analysis of the planktonic culture of C. jejuni after exposure to lavender essential oil showed that the expression of many genes important for motility, biofilm formation, iron metabolism and stress response of C. jejuni has been changed. These traits represent new, promising targets for C. jejuni biofilm control.
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