Antibacterial activity of ethanolic and aqueous extract of Ajwain (Trachyspermum ammi) and Mountain tea (Stachys lavandulifolia) against Lactococcus garvieae strains

The widespread use of antibiotics in agriculture, aquaculture, and medicine has led to the environmental dispersion of these compounds and the rise of drug-resistant bacterial pathogens. To prevent antibiotic resistance, employing herbal extracts and essential oils against pathogenic bacteria is a promising strategy. This study evaluated the antimicrobial efficacy of plant extracts from Trachyspermum ammi (T. ammi) and Stachys lavandulifolia (S. lavandulifolia) against Lactococcus garvieae (L. garvieae) using the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and disc diffusion test. Results showd that the ethanolic extract of T. ammi showed inhibition zones ranging from ۲۲.۰۶ mm to ۰ mm, with an MBC of ۱۸.۷۵ mg/mL, while the aqueous extract ranged from ۱۸.۲ mm to ۰ mm, with an MBC of ۷۵ mg/mL. For comparison, the inhibition zones for streptomycin, erythromycin, and gentamicin were ۲۱.۷۵, ۲۰.۷, and ۱۸ mm for the ethanolic extract and ۲۱.۳۲, ۱۹.۹, and ۱۸.۵ mm for the aqueous extract, respectively. In the case of S. lavandulifolia, the ethanolic extract exhibited inhibition zones ranging from ۱۷.۲ mm to ۰ mm, with an MBC of ۷۵ mg/mL, while the aqueous extract ranged from ۱۶.۶ mm to ۰ mm, also with an MBC of ۷۵ mg/mL. The inhibition zones for streptomycin, erythromycin, and gentamicin were ۲۲.۳, ۱۸.۹, and ۱۸.۱ mm for the ethanolic extract and ۲۱.۸, ۲۰.۲, and ۱۷.۹ mm for the aqueous extract, respectively. In conclusion, both T. ammi and S. lavandulifolia possess significant antimicrobial activity against L. garvieae, particularly at higher concentrations. Ethanolic extracts generally demonstrated greater efficacy compared to aqueous extracts, suggesting ethanol as a more effective solvent for extracting antimicrobial compounds. These findings support the potential use of these plant extracts as alternative treatments in aquaculture to combat bacterial infections and reduce reliance on traditional antibiotics, thereby mitigating the risk of antibiotic resistance

کلیدواژه ها:

Antibacterial activity ، Lactococcus garvieae ، Stachys lavandulifolia ، Trachyspermum ammi