Composition of four essential oils obtained from plants from Cameroon, and their bactericidal and bacteriostatic activity against Listeria monocytogenes, Salmonella enteritidis and Staphylococcus aureus

The composition of four essential oils (EOs) extracted by hydrodistillation from plants of common use in Cameroon (Curcuma longa, Xylopia aethiopica, Zanthoxylum leprieurii L., Zanthoxylum xanthoxyloides) was assessed by gas chromatography-mass. Their bactericidal and bacteriostatic activity was tested in vitro against three food borne pathogenic bacteria: Listeria monocytogenes, Salmonella enteritidis and Staphylococcus aureus. The bacteriostatic activities of this EOs on food borne bacteria were assessed in vitro through optical density measurements. The minimal bactericidal concentrations (MBC) were determined in broth combined with a spot plating method. Z. xanthoxyloides and Z. leprieurii showed a similar composition, with a prevalence of oxygenated monoterpenes (about 58%). The EO of Z. xanthoxyloides was the most effective against the microorganisms tested. Its higher concentration of geraniol could be linked to this higher activity. In almost all cases, the MBC was higher than the maximum concentration tested (3000 ppm). Notwithstanding their low bactericidal effect, the EOs studied showed interesting inhibiting activities against the tested food borne pathogens. S. enteritidis was the most resistant to the bacteriostatic effect of the four EOs. The knowledge of the antimicrobial potential of local plant EOs used in developing countries could help in their choice and their use to improve food safety and shelf-life.