Antimicrobial activity of the essential oil of mastic gum (Pistacia lentiscus var. chia) on Gram positive and Gram negative bacteria in broth and in Model Food System

The addition of mastic gum in broth culture inoculated with Staphylococcus aureus, Lactobacillus plantarum, Pseudomonas fragi and Salmonella enteritidis inhibited the growth of these organisms as monitored with the Malthus Instrument (in microsiemens). The rate of inhibition was greater on Gram positive bacteria than that observed on Gram negative bacteria. In most cases the size of inoculum and the concentration of mastic gum affected the growth/survival of the organisms. The addition of EDTA in coliform broth increased the inhibitory activity of mastic gum against Salmonella enteritidis, but did not affect significantly the inhibition of this organism in Model Food System (skim milk) at 37°C.