Assessment of antibacterial activity of leaf extracts of Crinum asiaticum L. against five gram negative fish pathogenic bacterial strains

Crinum asiaticum L., an evergreen ethnomedicinal herb known for its diverse pharmacological properties, has been extensively studied for its antimicrobial effects against fungi, human, and plant pathogenic bacteria. However, its potential has not previously been investigated in the context of aquaculture. This pioneering study evaluates the antibacterial activity of various solvent extract fractions (Petroleum ether, Chloroform, Ethyl acetate, and N-butanol) from C. asiaticum leaves against key fish pathogenic bacterial strains, including Aeromonas hydrophila, Aeromonas veronii, Aeromonas salmonicida, Pseudomonas putida , and Pseudomonas fluorescens . Utilizing agar well-diffusion, microdilution methods, and growth kinetics analysis, complemented by Scanning Electron Microscopy (SEM) to observe bacterial morphological changes, the study reveals that the Petroleum ether extract demonstrates remarkable antibacterial activity across all tested strains. With a notably low Minimum Inhibitory Concentration (MIC) of 0.250 mg mL⁻¹, the extract shows significant promise as a natural alternative to synthetic antibiotics in aquaculture. This is especially critical given the rising concerns over antibiotic resistance and environmental impacts in fish farming. Notably, this is the first study to report the antibacterial effects of C. asiaticum L. leaf extracts against fish pathogenic bacteria, highlighting its potential role in promoting sustainable disease management practices in the aquaculture industry. • The study focused on the antibacterial potential of the different solvent extract fractions of leaves of C. asiaticum L., an evergreen ethnomedicinal herb known for its various pharmacological properties. • The investigation targets fish pathogenic bacterial strains, including Aeromonas hydrophila, Aeromonas veronii, Aeromonas salmonicida, Pseudomonas putida, and Pseudomonas fluorescens. • The Petroleum ether extract stands out for its significant activity against all tested pathogenic strains, with a low Minimum Inhibitory Concentration (MIC) value of 0.250 mg mL -1 . • This study marks the first instance of C. asiaticum L. leaf extracts being reported for their antibacterial effect against fish pathogenic bacterial strains, suggesting potential applications in the aquaculture industry.