In vitro antibacterial activity of some plant essential oils

BACKGROUND: To evaluate the antibacterial activity of 21 plant essential oils against six bacterial species. METHODS: The selected essential oils were screened against four gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris) and two gram-positive bacteria Bacillus subtilis and Staphylococcus aureus at four different concentrations (1:1, 1:5, 1:10 and 1:20) using disc diffusion method. The MIC of the active essential oils were tested using two fold agar dilution method at concentrations ranging from 0.2 to 25.6 mg/ml. RESULTS: Out of 21 essential oils tested, 19 oils showed antibacterial activity against one or more strains. Cinnamon, clove, geranium, lemon, lime, orange and rosemary oils exhibited significant inhibitory effect. Cinnamon oil showed promising inhibitory activity even at low concentration, whereas aniseed, eucalyptus and camphor oils were least active against the tested bacteria. In general, B. subtilis was the most susceptible. On the other hand, K. pneumoniae exhibited low degree of sensitivity. CONCLUSION: Majority of the oils showed antibacterial activity against the tested strains. However Cinnamon, clove and lime oils were found to be inhibiting both gram-positive and gram-negative bacteria. Cinnamon oil can be a good source of antibacterial agents

Biological hardening and genetic fidelity testing of micro-cloned progeny of Chlorophytum borivilianum Sant. et Fernand.

The micro-cloned plantlets of Chlorophytum borivilianum registered more than 95% establishment in soil following treatment with various bio-inoculants namely; Glomus aggregatum, Trichoderma harazianum and Piriformospora indica whereas Azospirullum sp. (CIM-azo) and Actinomycetes sp. (CIM-actin) showed only up to 85% plantlet establishment. The un-rooted shoots were also treated withthese bio-inoculants, for in vivo root induction and increased survival rate/establishment frequency when transferred to soil. The un-rooted shoots also showed in vivo rooting (50%) when treated withmycorrhiza Glomus aggregatum (VAM) and Trichoderma harazianum. The genetic fidelity testing of micro-cloned, bio-hardened progeny based on a RAPD analysis using 40 random decamer DNA primers indicated a strong uniformity in relation to the parent genotype