Bacteriocinogenic potential of newly isolated strains of Enterococcus faecium and Enterococcus faecalis from dairy products of Pakistan.

Present study was carried for the isolation of bacteriocin producing Enterococci from indigenous sources. Gram positive enterococci are known for having the ability to produce enterocins with good antimicrobial potential. A total of 34 strains were isolated from processed dairy products of Pakistan and seven out of them were found to be member of genus enterococci on selective enumeration. Biochemical and molecular characterization revealed that four of these isolates (IJ-03, IJ-07, IJ-11 and IJ-12) were Enterococcus faecalis while three (IJ-06, IJ-21 and IJ-31) were Enterococcus faecium. Local processed cheese was the source of all enterococcal isolates, except E. faecium IJ-21 and IJ-31 which were isolated from indigenous yoghurt and butter samples respectively. Bacterial isolates were sensitive to commonly used antibiotics except methicillin and kanamycin. They also lack critical virulence determinants mainly cytolysin (cyl), gelatinase (gel), enterococcal surface protein (esp) and vancomycin resistance (vanA and vanB). Polymerase chain reaction amplification identified that enterocin A and P genes were present in the genome of E. faecium IJ-06 and IJ-21 while E. faecium IJ-31 genome showed only enterocin P genes. No amplification was observed for genes that corresponded with the enterocins 31, AS-48, L50A, L50B and ent 1071A and 1071 B. Also there were no signals of amplification found for E. faecalis IJ-11 indicating that the antimicrobial activity was because of an enterocin different from those checked by PCR. So the indigenous bacterial isolates have great potential for bacteriocin production and they had antibacterial activity against a variety of closely related species.