Antibacterial potential of essential oils extracted from three medicinal plants against some foodborne bacteria

Abstract

This study aims to evaluate the antibacterial activity of essential oils extracted from the green leaves of three medicinal plants, namely Cupressus macrocarpa, Schinus terebinthifolius, and Eucalyptus citriodora, against selected foodborne bacteria. Gas chromatography/mass spectrometry (GC/MS) analysis was employed to identify the chemical composition of the extracted essential oils. The two main chemical components of C. macrocarpa essential oils (EO) were terpinene-4-ol (32.37%) and citronellol (29.29%). The primary components of S. terebinthifolius EO were α-phellandrene (44.35%) and o-cymene (10.42%). Meanwhile, αphellandrene (13.5%) and sabinene (24.24%) constitute the majority of E. citriodora EO. The antibacterial activity of the essential oils was assessed against Gram-positive bacteria including Bacillus cereus, Staphylococcus saprophyticus, Lysinibacillus fusiformis, and Kocuria rhizophila, as well as the Gram-negative bacterium Serratia liquefaciens. Standard antibiotics like Penicillin, Amoxicillin, and Ampicillin were used for comparison. The results revealed varying degrees of antibacterial activity against each pathogenic isolate used. C. macrocarpa essential oil exhibited the strongest antibacterial action, with a 55.7 mm inhibition zone diameter against Bacillus cereus, which displayed resistance to the tested standard antibiotics. Meanwhile, essential oils of the choosed plants also inhibited the growth of S. liquefaciens despite its tolerance to the tested antibiotics. The minimum inhibitory concentrations (MIC) of C. macrocarpa, S. terebinthifolius, and E. citriodora essential oils ranged from 0.06 to 1.5 mg/ml, 0.68 to 2.0 mg/ml, and 0.2 to 1.77 mg/ml, respectively. These findings highlight the potential of the tested essential oils as antibacterial agents for preserving food materials in a safe, sustainable, cost-effective, and ecofriendly manner.