Purpose: To purify and partially characterize the bacteriocin produced by L. mesenteroides A11 isolated from chicken breast.
Methods: Previous studies showed L. mesenteroides A11 is bacteriocinogenic and inhibits L. monocytogenes. In this study, the partially purified bacteriocin was obtained from the neutralized filter-sterilized culture supernatant of L. mesenteroides A11 grown in BHI broth at 25 °C for 24 h. For that, purification with Amberlite® XAD-16 resin, followed by solid phase extraction – SPE were employed. Fractions were obtained with a 2-propanol gradient and collected in each step of purification assay. The organic solvent was removed in a rotatory evaporator and the titre of the bacteriocin in the remaining aqueous solution was determined by the critical dilution assay, expressed as arbitrary units per ml (AU/ml), using L. monocytogenes as indicator strain. The final active fraction was concentrated by freeze-drying and partially purified bacteriocin was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to estimate molecular weight by means of silver staining and biological revelation of gel.
Results: Bacteriocin titre in initial L. mesenteroides A11 culture supernatant was 3,200 AU/ml. High recovery of bacteriocin was obtained with XAD-SPE since no loss was detected in bacteriocin quantification in fractions collected during purification steps. By SDS-PAGE, molecular weight of L. mesenteroides A11 bacteriocin was estimated as 3.5 to 8.5kDa.
Significance: Purification of antimicrobial peptides from L. mesenteroides A11 provided information that may be useful to design food biopreservation applications.