Anti-microbial activity of potential probiotic lactic acid bacteria against Methicillin-Resistant Staphylococcus Aureus (MRSA)

Abstract

Lactic acid bacteria (LAB)are the essential ingredients in probiotic foods, intestinal microflora, and dairy products able to cope up and exist in diverse environmental ranges. Samples were collected using sterile test tubes and transported to a laboratory in the icebox for further biochemical characterization. Gram test and catalase activity were examined after microscopically distinct colonies were sub-cultured to pure colonies based on standard gram and catalase test protocols. Subsequently, these bacteria were characterized for their ability to grow at various salt concentrations (5%,10%, and15%) and temperature gradients (15{degrees}C, 30{degrees}C, 45{degrees}C). Acid-tolerance was analyzed by growing the colonies in MRS broth adjusted to acidic pH (pH 3) and pH 7.2 (control). Bile tolerance of LAB isolates was assayed by growing in 0.3% bile-supplemented MRS agar. Bile salt hydrolase (BSH) activity was studied by growing 10 l of the prepared overnight culture on BSH screening media containing MRS agar plate supplemented with bile salts. The LAB isolates were checked for antimicrobial activity by agar well diffusion assay. All isolates found gram-positive, catalase-negative and non-motile, convex elevation and entire margin. All LAB isolates were able to grow at 5-10% Nacl concentration, whereas moderately grow at 10% concentration but rarely grow at 15% Nacl concentration. BCM2, BBM3 and BGM1 record the highest acidic resistance viability percentage 94.9%, 92.7%, and 91.8% respectively. BCM3 has the lowest acidic resistance with a viable percentage of 87.4%. BBM1 records the highest bile tolerance activity whereas BCM2 has the lowest bile tolerance. All isolates were found BSH positive. The study reveals LAB isolates showed a putative probiotic potential. Article highlightsLAB are the main ingredients of probiotic products commercially available in the market nowadays. To effectively functioning the host gastrointestinal tract probiotics, need to have certain criteria like acid and bile tolerance this study reveals O_LIAcid tolerance activity of LAB isolated from bovine milk C_LIO_LIBile tolerance activity of LAB isolated from bovine milk C_LIO_LIBile salt hydrolase (BSH) activity of LAB isolates C_LIO_LIAntimicrobial activity of LAB against MRSA C_LI