ABSTRACT
Vibrio parahaemolyticus causes acute gastroenteritis associated with the consumption of contaminated raw or under cooked seafood. The virulence of vibrio parahaemolyticus is initially attributed to the production of a thermostable direct hemolysin [TDH]. The survey of different concentrations of garlic essential oil [Allium sativum] on MIC, MBC, growth curve and production of TDH toxin of vibrio parahaemolyticus. The effects of garlic essential oil at concentrations of 0, 0.005, 0.015, 0.03 and 0.045% on the MIC, MBC, growth curve and production of TDH toxin of vibrio parahaemolyticus were studied in BHI model. MIC and MBC of garlic essential oil was estimated 0.03%. The essential oil showed significant effect on toxin production, Titers of TDH production in 0 and 0.005% were 1/256 comparing to 1.64 in 0.015% concentration of EO. Concentrations of 0.005 and 0.015% of garlic essential oil reduced the bacterial growth rate significantly [p<0.05] compared to the control group. Garlic essential oil showed to be effective against bacterial growth and production of TDH toxin. Its potential application in food systems may be suggested
ABSTRACT
Increasing human knowledge about adverse effects of chemical preservatives has increased public interest to consume products with natural preservatives such as plant extract and their essential oils. In this study chemical composition of essential oil of Afsantine and antibacterial effect of its essential oil and aqueous, ethanolic and methanolic extracts against the most important food borne pathogens, Salmonella typhimurium, Listeria monocytogenes, E. coli O157:H7, Bacillus cereus and Staphylococcus aureus were evaluated. Gas Chromatography-Mass Spectrometry [GC-MS] method was used for chemical composition analysis of the essential oil. Disk diffusion method was done to screen bacterial sensitivity. The Minimum Inhibitory Concentrations [MIC] of extracts were evaluated by broth micro-dilution method. The essential oil components were identified and the major constituents of the oil were Beta Thujone [29.75%] and Phellandrene [20.20%]. In disk diffusion method the most sensitive strain to the essential oil and the extracts was S. typhimurium and E.coli O157:H7. MICs of Afsantine essential oil against S. aureus and L. monocytogenes were estimated 3000 ppm. The methanolic extract showed antimicrobial activity against L. monocytogenes, E.coli O157:H7, B. cereus and S. aureus were estimated 10, 10, 8 and 4 mg ml-1, respectively. The results of this study revealed that the essential oil and methanlic extract of Afsantine have greater antimicrobial effects on given strains and might be used as a natural preservative in food system.