ANTIMICROBIAL ACTIVITIES AND INTERACTION EFFECTS OF VIETNAMESE LITSEA CUBEBA (LOUR.) PERS ESSENTIAL OIL AND ITS ENDOPHYTIC ACTINOBACTERIA

Abstract

The aim of this study was to evaluate the antimicrobial activity of Litsea cubeba (Lour.) Pers (L. cubeba) essential oil and its endophytic actinobacterial crude extracts (EACE) against pathogenic bacteria in individual and in combination. Using the broth micro-dilution assay, the results indicated that both L. cubeba essential oil and its EACE showed inhibition effect against Aeromonas hydrophila ATCC 35654, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 13061, and drug resistant strains such as: Methicillin-resistant Staphylococcus epidermidis (MRSE) ATCC 35984 and Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 33591. The minimal inhibitory concentration (MIC) of L. cubeba essential oil and its AECE were from 3.13 to 6.25 µl ml-1 and 50.0 to 333.3 µl ml-1 respectively. From the indices of fractional inhibitory concentration (FIC) of the combination of L. cubeba essential oil and its EACE, the synergistic effects were found against E. coli, S. aureus, B. cereus and MRSE. The combination treatment of L. cubeba essential oil and its EACE enhance the inhibition effect against food-borne bacteria 16 times comparing with individual treatment.