Vol. 9, Special Issue 6, Part G (2025)

Antibiotic resistance is the global researchable issue to be addressed to avoid excess antibiotic residues in the food web. Antibacterial property of seaweed extract against bacterial pathogen was well studied. Even though, the research reports on antibacterial property of seaweed extract against important bacterial pathogens in animals in India, are very much limited. There is an essential need for novel antibiotics and other secondary metabolites that prevent the spread of infections in human as well as in animals who are developing resistance for microbes to the most of existing antibiotics. Therefore, to study the antibacterial property of methanolic extracts of six marine macroalgae viz, U. lactuca, C. aerea, S. tenerrimum, K. alvarezii, G. edulis and G. acerosa in well diffusion assay and broth dilution assay against S. aureus, E. coli, K. pneumoniae and P. putida by using three varying concentrations viz., 25, 50, 75 µg/mL. The standard drug of antibiotic, Ampicillin was utilized. Gelidiella acerosa (75 µg/mL) showed a highest antibacterial activity against S. aurues (20 mm) by well diffusion assay. It is observed that G. acerosa against S. aurues revealed a highest activity against 50 µg/mL concentration (80.56%) in broth dilution assay. Hence, methanolic extracts of Gelidiella acerosa and Chetomorpha aerea seaweed extracts have the capability to prevent the growth of Staphylococcus aureus. This bactericidal property of seaweeds can be utilized as alternate to conventional antibiotic utility in economically important diseases of livestock especially the mastitis.