Antimicrobial activity of essential oils in environment animals

Aim of the study: To evaluate the antimicrobial effects of essential oils in vitro for a possible application to reduce the content of microorganisms in the air of animal farms. Goals: 1. To evaluate the sensitivity in profile of microorganism strains in vitro to some essential oils by using the disk diffusion method. 2. To evaluate the sensitivity in profile of microorganism strains in vitro to some essential oils by using the broth dilution method. 3. Determine the antimicrobial activity in vitro of some combinations of different essential oils by using the broth dilution method. 4. To quantify the antibacterial properties of essential oils on a strain of Escherichia coli in the presence of an emulsifier. The complex investigations of essential oils in vitro was performed for the first time in Lithuania. Essential oils were selected by their antimicrobial activity against Gram-positive (Staphylococcus aureus, Enterococcus faecium) and Gram-negative (Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis) bacteria, moulds: Paecilomyces variotii, Cladosporium herbarum, Fusarium moniliforme, Aspergillus versicolor, Aspergillus fumigatus, Aspergillus niger, Aspergillus oryzae and yeast Candida albicans. The assays determine the concentrations required to inhibit growth and reduce microorganisms cells. The antimicrobial activity in vitro of some combinations of essential oils were determined. Interactions among essential oil, bacteria and lecithin were evaluated. Lecithin diminished antibacterial properties. Practical value of the research – in the experiments of this thesis the most effective essential oils were found, i.e., Thymus vulgaris L., Mentha piperita, Malaleuca alternifolia and Cymbopogon citrarus, which possess antimicrobial activity and can be used as a natural biocide for application to reduce the content of microorganisms in the air of animal farms, without emulsifier lecithin