Study Of Bacteriocin Produced By Lactobacillus Pentosus 31-1

Lactobacillus pentosus 31-1 isolated from Xuan Wei Ham produced antimicrobial substance which was inhibitory to several Lactobacillus plantarum strains. After eliminating organic acid, oxid catalase, and so on, we have confirmed the antimicrobial role is because of bacteriocin.To optimize bacteriocin production researching was done on the respect of incubation condition and the media components. And the optimum incubation time was 24h, the optimum temperature was 30℃, the optimum broth initial pH was 6.5. The optimum media component was: lactose 3%, trypone 1.5%, soybean peptone 2%,meat extract 3%, peptonethe 2%,Tween 80 0.1%, K2HPO40.2%, NaAc 0.5%, Tri-Ammonium citrate 0.2%, MgSO4 0.058%, MnSO4 0.025%, H2O 1000ml. Production of bactericoin under the optimum broth was 640AU/ml, 8 times than MRS media.The bacteriocin was purified by ammonium sulphate precipitation, followed by SP-Sepharose FF cation exchange chromatography. And the bacteriocin was washed with 0.1M NaCl(in acetate buffer,pH5.5), at 1.2ml/min. And the specific activity was 1259.84AU/mg. The molecular size of bacteriocin was estimated to be under 14.2kDa, according to tricine-SDS PAGE.Bacteriocin was inactivated when treated with pepsin, proteinase K, trypsin, papain, neutral proteinase, and part-inactivated by α-amylase.But remained active after incubation at pH 2-8 for 4h at 37℃ and when heated 15min at 80℃. The mechanism of activity of bacteriocin is bactericidal,as shown by a obvious decrease about 2-3 orders of magnitude in the viable cell numbers of L.plantarum over a period of 3-4h. The bacteriocin had a broad spectrum, including several strains from Lactobacillus, Streptococcus, Pediococcus, especially including Staphylococcus aureus, E.coli, Bacillus cereus, B.subtilis, B.megaterium.Lactobacillus pentosu 31-1 was successfully used as starter culture of fermented sausages in He Nan province Shuan hui meat company. It can made sausages acid-producing very fast, finally up to pH 5.2, especially inhibit Escherichia strains growing and finally dispear in product. This indicated that bacteriocin produced from Lactobacillus pentosus 31-1 have great potential application as preservatives in food, and the strain as starter culture of fermented sausages.