Characterization of purified antimicrobial peptide produced by Pediococcus pentosaceus LJR1, and its application in preservation of white leg shrimp

The bacteriocinogenic lactic acid bacterium Pediococcus pentosaceus LJR1 isolated from rumen liquor of goat had strong anti-bacterial activity toward Listeria monocytogenes in vitro. This antibacterial activity was lost on treatment with protease indicating that the bacteriocin is proteinaceous in nature. The bacteriocin LJR1 produced by P. pentosaceus was purified following a three step procedure consisting of ammonium sulphate precipitation, gel filtration chromatography and reverse phase-high performance liquid chromatography. The molecular weight of purified bacteriocin was determined to be 4.6 kDa using Tricine SDS-PAGE. Further, we found that the proteinaceous bacteriocin was stable at 100 degrees C as well as 121 degrees C for 30 min and 15 min respectively and also at different pH ranging from 4 to 10 when stored for 15 min at 37 degrees C. Its minimum inhibitory concentration for S. typhi MTCC134 and L. monocytogenes MTCC 1143 was 7.81 mu g/ml and 15.63 mu g/ml respectively. Scanning electron microscopy analysis of the surface of S. typhi treated with the bacteriocin showed the presence of craters; while in the case of treated L. monocytogenes blebs were observed. The addition of the bacteriocin to shrimp (white leg shrimp) has led to reduction of about 1 log units of L. monocytogenes on day 1 and maintained for 7 days on storage at 4 degrees C. It is clear that the purified bacteriocin has good potential as a bio preservative for application in food industry.