Screening And Research Lactic Acid Bacteria Of Antibacterial Property And Their Bacteriocins In Traditional Pickle

The84strains tested of lactic acid bacteria were isolated from the sour cabbage juice prepared by herdsman in the’east Inner Mogolia Region, there are60coccus, while24strains of bacilli. B.y the Plate punch diffusion method, using Escherichia coli AS1.487as the indicator. Then using Escherichia coli, Bacillus cereus, Micrococcus luteus and Partial mould as the indicator for another more screening to carry out bacteriostasis capacities, and initiatory investigate the bionomics and purification of bacteriocin produced by the selective strain of lactic acid bacteria. The results indicated that there are27strains have an evident effect to Escherichia coli AS1.487, which zones of inhibition even to exceed14.0mm. Via multifarious indicator to repeatedly screening, finally the bacteriocin producing strain S1-4which has broad spectrum was screeninged from84lactic acid bacteria. It could inhibit not only typal gram-positive bacteria(such as Bacillus cereus、 Micrococcus aureus etc.) and gram-negative bacteria(Escherichia coli), but also to have a certain inhibition to mould(Penicillium expansum etc.). After obviated the interference of Acids, it was steady and active in acid or weak acid. Its optimum pH was4.0, and had good thermal stability between pH2.0and pH5.5, even though treated at121℃after30min, it has still remaining93.42%activity when pH4.0. The bacteriocins S1-4was sensitive to papain, and the bacteriostatic activity descended18.42%, but have a little sensitive to pepsin and trypsin. Centrifugated fermenting liquor and collected un-cell supernate, purify by ammonium sulfate precipitation, after the fermentation broth was dialysed, some substances which the molecular weight3.5KDa to8KDa had a powerful bacteriostatic effect to Bacillus cereus; then by Sephadex G-15column chromatography, three kinds of composition were obtained, composition of the second summit has certain bacteriostatic activity. The results indicated, the bacteriostatic activity composition would be a kind of small molecular polypeptide, and the molecular weight is about6.7KDa. Composition of the second summit will be studied further. The strain was initial identified as Lactobacillus plantarum by physiological-biochemical and molecular-biological testing.