AMB Volume 41, Issue 4, 2025 Pages 564-573 https://doi.org/10.59393/amb25410416
The potential use of garlic (Allium sativum) as an alternative to antibiotics in aquaculture: GC-MS analysis and in vitro antimicrobial activity
Derdachi R.
The current study aims to evaluate the chemical composition of garlic aqueous extract and its antimicrobial efficacy against the microbial flora of Nile tilapia. Microbial flora was isolated from gills, intestines, skin, and tank water and identified by biochemical tests. After that, their antibiotic resistance was tested to five commonly used antibiotics: ampicillin (10 μg), erythromycin (15 μg), tetracycline (30 μg), ciprofloxacin (10 μg), and gentamicin (10 μg). The antibacterial activity of garlic aqueous extract was tested using the diffusion method, and its chemical composition was tested by gas chromatography-mass spectrometry (GC-MS). The results indicate the presence of Escherichia coli, coagulase-negative Staphylococci, Citrobacter freundii, Salmonella spp., and Pseudomonas spp. All bacterial strains were sensitive to ciprofloxacin, 92.30% sensitive to gentamicin, 69.23% susceptible to tetracycline, 38.46% susceptible to erythromycin, and 30.76% sensitive to ampicillin. 38.46% of the isolates were multidrug-resistant bacteria. The antibacterial activity test showed that 83.33% of the strains were extremely sensitive to garlic extract. MIC values varied between 3.23 mg/mL and 12.93 mg/mL, and MBC values ranged between 3.23 mg/mL and 103.5 mg/mL. Thus, the GC-MS analysis revealed the presence of several sulfur compounds, including diallyl disulfide (31.34%) and diallyl sulfide (15.00%), which have antimicrobial activity and other beneficial biological functions. Garlic aqueous extract demonstrated strong antibacterial activity and potential use in preventing and curing bacterial diseases in fish.
Keywords: Allium sativum, Antibacterial activity, Antibiotic resistance, Aqueous extract, Oreochromis niloticus
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