Inhibition of Methicillin Resistant Staphylococcus aureus by Bacteriocin Producing Pseudomonas aeruginosa

Bacteriocins are natural antimicrobial peptides with attractive possible applications in food preservation and health care. In the present study, bacteriocin producing bacterial strain Pseudomonas aeruginosa were isolated from soil which exhibited antagonistic activity against Methicillin Resistant Staphylococcus aureus (MRSA) bacteria. The bacteriocin producing strain TA6 was confirmed as P. aeruginosa by biochemical tests and 16S rRNA gene sequence analysis. Maximum bacteriocin activity (100AUml(-1)) was observed at 37 degrees C with pH 6.0 in 24h time duration. SDS-PAGE analysis of the extracellular protein of P. aeruginosa TA6 revealed a bacteriocin-like protein with a molecular mass of similar to 10kDa. MRSA cells were treated with culture supernatant of P. aeruginosa TA6 and analyzed by FT-IR. The treated and untreated MRSA showed band variations at 671 and 3460cm(-1) corresponding to alkyl and amide group respectively. Mixed proportions of dead and live control populations were analyzed by flow cytometry to determine detection limits of the Dead/Live cells. The flow cytometry detection of defined proportions of dead (p2) and live (p1) cells at 3h were p2=60.5%; p1=39.5% and 6h p2=66.5%; p1=33.5% respectively. The scanning electron microscopy observation showed the main changes in the cell membrane structural integrity of S. aureus after exposure to the bacteriocin from P. aeruginosa TA6 at 12h incubation. Together, the results suggested that bacteriocin from P. aeruginosa TA6 was effective against MRSA.