The Purification And Partial Characteriaztion Of Bacteriocin Produced By Lactobacillus Rhamnosus LS-8

The hurdle technology used for low, micro-processed food preservation, the biologicalpreservative is one of its key points, in which bacteriocins are widely studied as one kinds ofpreservatives. Lactic acid bacteria is generally recognized as safe microorganisms, a lot oflactic acid bacteria can produce one or more antibacterial substances, including proteins orpolypeptides which are called bacteriocins synthesized by ribosome biogenesis. Thesebacteriocins are efficient, non-toxic, non-residual, no drug resistance, etc, which makethemselves become a focal point in food bio-preservation research.This experiment is to obtain a bacteriocin with a strong inhibitory effect andbroad-spectrum through isolation and screening of lactic acid bacteria from China’straditional fermented foods and the bacteriocin was purified, thereafter the physiochemicalcharaterisitics of the bacteriocin was investigated,we draw the following conclusions throughexperiments.1. Strains with inhibitory effect from a variety of traditional fermented foods wereisolated by double plate method, by which LS-8was selected because of its significantinhibitory effect.16S rDNA molecular identification results shown that the LS-8lactic acidbacteria was Lactobacillus rhamnosus (similarity of99.9%).2. The bacteriocin was preliminarily extracted by ethyl acetate, after which it was furtherpurified by polypeptide separation column in AKTA protein purification system, finally itwas purified by preparative liquid chromatography.3. It was shown that the bacteriocin had the highest activity at pH5.0while it wasweaker at pH2.0or13.0. It was stable even heated to120℃for20min. The inhibitoryactivity still existed when stored at4℃for3months. The bacteriocin can inhibit Escherichiacoli, Staphylococcus aureus and Salmonella spp.4. Alternately treatment by acridine orange and high temperature culture was used toeliminate plasmid, in which it was shown that plasmids were eliminated at the24thgeneration and completely disappear at the29th generation. Additionally, the results showedthat the inhibitory effect did not change significantly between the29th and the1th, whichindicated that the bacteriocin was coded by genes in the genome and was notplasmid-encoded.