ISOLATION, SCREENING AND PARTIAL CHARACTERIZATION OF A BACTERIOCIN FROM LACTIC ACID BACTERIAL ISOLATE

摘要

In the present study food source were screened for bacteriocin producing lactic acid bacteria using the deferred antogonism technique, disc diffusion and horizontal agar diffusion technique. The lactic acid bacterium, producing bacteriocins, very active against a range of Grampositive organisms was selected for further studies. A partial purification of the bacteriocin was attempted by gel-filtration using sephadex G-25. An antimicrobial assay was carried out with the different peaks. The peak with antimicrobial activity was concentrated by lyophilization and subjected to reverse phase HPLC on an octadecyl silane column. The HPLC chromatogram did not correspond to that of nisin, a well documented bacteriocin. Antimicrobial activity was not due to the action of hydrogen peroxide. Antimicrobial activity was completely lost upon treatment with trypsin, suggesting that the antimicrobial component is of peptide origin. Further characterization by mass spectra and amino acid analysis needs to be carried out.