Résumé
AbstractThe threat of bacterial resistance to antibiotics has created an urgent need todevelop new antimicrobials. The aim of this study was to characterize thechemical diversity of Litsea cubeba leaf essential oil (EO) and its impacts onthe antibacterial activity against pathogenic bacteria. Essential oils collectedfrom seven provinces in North Vietnam (n = 25) were characterized by theirhigh content in either 1,8-cineole or linalool. Linalool-type EOs were moreeffective against the eight bacterial strains tested than 1,8-cineole-type. Oilsamples, LC19 (50% 1,8-cineole) and BV27 (94% linalool), were selected toinvestigate their antibacterial mechanisms against Escherichia coli. A strongbactericidal effect was observed after 4 and 2 h of exposure respectively.Microscopic analysis of treated E. coli cultures clearly showed that EOs causedchanges in cell morphology, loss of integrity and permeability of the cellmembrane, as well as DNA loss. However, the effects of both EOs weredistinct. LC19 mostly affected cell membrane, led to a significant cellfilamentation rate and altered cell width, whereas BV27 damaged cellmembrane integrity leading to cell permeabilization and altered nucleoidmorphology with the appearance of spot and visibly altered compaction.