In-vitro study of inhibitory effect of garlic extract on Aeromonas sobria

BACKGROUND: Garlic (Allium sativum) is known for its anti-bacterial properties, but information on its effects against bacteria species that are important in fish diseases is scarce. OBJECTIVES: The aim of this research was to use garlic as a natural product to improve the aquatic animal health status so as to compensate the demand for environment-friendly products for sustainable aquaculture. METHODS: For this purpose thee methods of extraction including: row garlic extract, water, ethanol and methanol extract were used for in-vitro toxicity tests on Aeromonas sobria by disk diffusion and tube test. RESULTS: According to results in 200 and 400 mg/mL concentrations of ethanol extract of garlic, the inhibition zone of bacterial growth was 7 and 10 mm respectively. There was no inhibition zone for all concentrations of methanol extract of garlic. In water garlic extract the inhibition zone for concentrations of 100, 200 and 400 mg/mL were 8, 10 and 14 mm respectively. For 100% and 50% raw garlic the inhibition zone was 27 and 8 mm respectively. MIC for Aeromonas sobria in ethanol extract, water extract and raw garlic were estimated as 200, 100 mg/mL and 10% respectively. MBC for these extracts was also estimat-ed as 300, 100 mg/mL and 25% respectively. CONCLUSIONS: Our data indicate that raw and water extract of garlic have the highest antibacterial effect. Ethanol extract had a lower effect and methanol showed no bacteriostatic effect. Therefore, garlic extract can inhibit the growth of Aeromonas sobria, an important fish pathogen, and may have therapeutic value, particularly for carp.