[ antimicrobial activity of thyme, sweet marjoram, savory and eucalyptus oils on escherichia coli, salmonella typhimurium, aspergillus niger and aspergillus flavus]

ABSTRACT

The presence of pathogenic microorganisms in aviculture threatens the health of fowl and humans. Thyme [Zataria multiflora Boiss], sweet marjoram [Origanum majorana], savory [Satureja hortensis] and eucalyptus [Eucalyptus globules] are Iranian herbal medicines that are used in folk medicines. The aims of this study were to evaluate the antimicrobial activity of these oils separately and in combination against Escherichia coli, Salmonella typhimurium, Aspergillus niger and Aspergillus flavus in vitro condition. The antimicrobial activity of essential oils against different isolates of microorganisms was evaluated by disc diffusion and macro broth dilution assays. The results showed that the antimicrobial activity of thyme, sweet marjoram and savory oils against different bacteria and fungi were more than the eucalyptus oil. When ethanol was used as a solvent in comparison with dimethyl sulfoxide, the antimicrobial activity of oils was increased. The type of solvent creates meaningful discrepancy on effectiveness of oils [p<0.001]. In disc diffusion method, the fungi were sensitive than bacteria and A. niger was more sensitive than A. flavus. The sensitivity of bacteria was dependent to the type of bacteria and essential oil and the oils showed inhibitory effect against fungi and the fungicidal effect of oils were weaker than bactericidal effect. The antimicrobial activities of effective oils were related to thymol and carvacrol components in respect. Due to limitations in usage of chemical compounds in poultry and food industries, the essential oils look to be appropriate alternatives for some disinfectants to control the human and animal diseases in the future