ANTIMICROBIAL EFFECT OF MEXICAN OREGANO (LIPPIA BERLANDIERI Schauer) AND ITS ESSENTIAL OIL AGAINST FIVE VIBRIO SPECIES

Abstract

New consumer trends towards consumption of natural products have driven research and development of novel forms of food preservation, in order to prevent poisoning due to chemical additives. The aim of this work was to assess the antimicrobial effect of Mexican oregano (Lippia berlandieri Schauer) and its essential oil against Vibrio alginolyticus, V. cholerae no-01, V. mimicus, V. parahaemolyticus and V. vulnificus. The antimicrobial effect was determined by the minimal inhibitory concentration and minimal bactericidal concentration (MIC and MBC) for oregano and its essential oil, with different concentrations of thymol and carvacrol. Death kinetics for V. cholerae no-01 were also carried out at 5 and 35 °C for two of the essential oils. Data show a favorable antimicrobial effect of oregano on all five species of Vibrio, which did not show significant differences for MIC and MBC values, at concentrations of 1.5 to 2.5 % of oregano, and of 100-200 mg L^-1 of the essential oil. Regarding death kinetics, 35 °C produced the fastest inactivation time observed for V. cholerae no-01. At this temperature, addition of oregano essential oil diminished up to 7 logarithmic cycles in only 30 minutes; this effect was also obtained at 5 °C, but over a 24 to 144 h period.