EFFECT OF POSTBIOTICS OF LACTICASEIBACILLUS PARACASEI SD1AND LACTICASEIBACILLUS RHAMNOSUS SD4 AGAINST METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS SUBSP. AUREUS (ATCC 43300)

Abstract

This study investigated the antimicrobial activity of Lacticaseibacillus paracasei SD1 (SD1) and Lacticaseibacillus rhamnosus SD4 (SD4), as well as their postbiotics, against methicillin-resistant Staphylococcus aureus ATCC 43300. Antimicrobial activity was performed using the agar overlay method for probiotics and the agar well diffusion method for postbiotics, with inhibition zones measured in millimeters (mm). The mean inhibition zones of probiotic cells were 12.60±1.64 mm for SD1 and 16.07±1.98 mm for SD4, whereas postbiotics exhibited significantly larger inhibition zones of 14.27±0.55 mm for SD1 and 17.08±0.65 mm for SD4. Minimum inhibitory concentration (MIC) values for postbiotics were 62.50±0.00 µg/ml for SD1 and 31.25±0.00 µg/ml for SD4, while both demonstrated the same minimum bactericidal concentration (MBC) of 250±0.00 µg/ml. These findings indicated that postbiotics of both strains exhibit stronger antimicrobial potency against methicillin-resistant S. aureus compared with live probiotic cells.