Human health awareness is increasing day by day and the preference for drugs without side effects has prompted research on the beneficial properties of bacteriocins from microorganisms. One of the ways by which bacteria can destroy the pathogens is via bacteriocin production that displays antimicrobial activity against bacteria closely related to the producer strain. This study was aimed to isolate Staphylococcus aureus from skin samples for the production of bacteriocin.The crude bacteriocin was produced from isolated strain by the production of cell-free supernatant using 10, 000 rpm, at 4 0 C for 40 min. Agar well diffusion method indicated the antimicrobial activity of cell-free supernatant against the strain of E. coli. The proteinaceous nature of the inhibitory substance was confirmed by SDS- PAGE as well as enzymatic degradation method. Further, high-performance liquid chromatography was used for the purification of bacteriocin. Large-scale production of bacteriocin was done using the adsorption-desorption method. The effect of bacteriocin isolated from the strains on the cancer cell line was also explored by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and Annexin-V apoptosis assay. Five isolates obtained from 93 samples showed significant antimicrobial activity against different indicator strains. Cell-free supernatant of Isolates 4 displayed maximum zone of inhibition 28+0.5 mm against E. coli. This isolate was used for further optimization and purification process. HPLC indicated the presence of a large aggregate of a protein as resulted in one absorbance peak. The maximum bacteriocin production of isolated Staphylococcus aureus strains was achieved when they were cultivated in BHI broth with 1% NaCl, Glucose as carbon source, Yeast extract Nitrogen source at pH 6, and temperature at 32 0 C incubated for 48 hours. The 2 Bradford method was used for the quantification of produced bacteriocin and measured concentration of bacteriocin was 0.7 mg/ml. The result of the MTT assay (IC50 = 18.026 ± 0.067(µg/ml)) and Annexin V (apoptosis index = 0.50) displayed that the produced bacteriocin has significant antitumor activity against MDA MB 231 cell lines.The research conducted indicates antimicrobial and anticancer activity of produced bacteriocin.
Keywords: Bacteriocin, Staphylococcus aureus, Supernatent, Cancer cell, Antimicrobial activity