Assessment of the Antibacterial Activity of Lavender cultivated in Tasmania and identifying its geographical and botanical origins

Abstract

Objectives: This study compared the antimicrobial activity of lavender honey manufactured in Tasmania Australia with Manuka honey as a control. Methods: Lavender essential oil also examined for antimicrobial activity. The volatile compounds were identified to find the bioactive compounds responsible for the antibacterial activity. Next, the volatile data of the Lavender honey and essential oil from Lavandula angustifolia cultivated in Tasmania, were used to indicate the geographical and botanical origins of the using head space solid-phase micro extraction (HS SPME) and Gas Chromatography Mass Spectrometry (GC-MS).  The antimicrobial activity of Lavender Honey and essential oil from Tasmania were examined using the broth micro-dilution method to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Bacteriostatic end points were determined spectrophotometrically, then bactericidal end points were determined by plating. Methicillin-sensitive and methicillin-resistant strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were used in this study. Results: Lavender honey showed similar, and in some bacterial species, slightly higher activity than Manuka honey. The MICs and MBCs for lavender honey ranged from 6.25% to 25% v/v compared to MICs of Manuka honey which ranged between 12.5% and 25% v/v. The MIC and MBC values of lavender honey and Manuka honey against P. aeruginosa were 12.5% v/v and 25% v/v respectively. The corresponding values for a methicillin-sensitive strain of S. aureus were 6.25% v/v and 12.5% v/v respectively. The MIC and MBC were the same for both honey for E. coli equal to 12.5 % v/v and for MRSA equal to 6.25 % v/v. The growth of S. aureus, including MRSA and E. coli completely inhibited by Lavender E. oil at concentrations of 2.25%. Whereas, the growth of P. aeruginosa partly inhibited by the same concentrations. Use of a spectrophotometer facilitated reading of MIC values. Conclusion: These results suggest that lavender honey and essential oil could be used as an antimicrobial agent for infections caused by S. aureus including MRSA, E. coli and P. aeruginosa.