Chemical composition and antimicrobial potency of locally grown lemon essential oil against selected bacterial strains

The hydro distillation method was used to isolate and identify essential oils from locally available lemon samples and determine their antimicrobial potency against selected gram positive and negative bacterial strains using the disk diffusion method. Two locally available and highly consumed lemon fruit samples were used for the isolation of essential oils by hydro distillation using Clevenger type apparatus. The obtained essential oils were analyzed and identified by gas chromatography-mass spectrometry (GC-MS). The essential oils at different concentrations were used to determine antimicrobial potency using one gram (+) Staphylococcus aureus (S. aureus) and three gram (-) bacteria, Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Proteus vulgaris (P. vulgaris), through the disk diffusion method. Both the essential oils contain twenty-two active compounds with a variation of percentage identified based on GC retention. The main bioactive compounds with high content in Omani sweet lemon essential oil were limonene (84.73%), a-pinene (1.06%), alpha-terpineol (2.80%), beta-myrcene (2.16%), beta-pinene (3.36%), terpinen-4-ol (1.16%) and alpha-terpinolene (2.33%) and several other minor compounds. Similarly, Omani sour lemon essential oil was composed of limonene (53.57%), alpha-terpineol (14.69%), beta-pinene (8.23%), alpha-pinene (1.84%), beta-myrcene (1.51%), alpha-terpinolene (4.33%), terpinen-4-ol (3.38%), cymene (1.80%), beta-bisabolene (1.43%), beta-linalool (0.85%) and E-citral (1.08%) with several other minor chemical compounds. Antimicrobial results showed that most concentrations of both essential oils did not give any potential antimicrobial against employing bacterial strains. Therefore, the obtained results show that both essential oils could be needed for further extensive biological study and their mechanism of action. (C) 2016 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.