Antimicrobial potencies of Ephedra alata extracts against marine pathogens

Abstract

Aquaculture is a fast-growing food sector but is plagued by a plethora of bacterial pathogens that infect water and fish. The current work aims to scrutinize the antibacterial and the antibiofilm potencies of aqueous and methanolic extracts of Ephedra alata aerial parts against predominant fish pathogens including Vibrio alginolyticus, Vibrio parahaemolyticus, Aeromonas trota, Aeromonas salmonocida and Aeromonas hydrophila. Disk diffusion and microdilution methods were used to test the antibacterial activity. Biofilm inhibition was tested using XTT (2,3-bis (2-methyloxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay. The toxicity of extracts was evaluated in vivo on Brine shrimp (Artemia salina).

Results show that both extracts displayed antibacterial activity against all tested strains. Aqueous extract expressed the great activity against A. hydrophila with Minimal Inhibitory Concentration (MIC) value of 3.12 mg/mL and Minimal Bactericidal Concentration (MBC) value of 6.25 mg/mL. While A. trota was the most sensitive bacteria towards the methanolic extract with MIC and MBC values of 6.25 mg/mL. The tested extracts were able to inhibit biofilm formation with concentration-dependent manner. Moreover, no cytotoxic effect on Brine shrimp was registered for the extracts. Overall, Ephedra alata extracts can be considered as good potentials sources of anti-fish pathogens and safety in an aquatic ecosystem.