Studies Of Physical Chemical And Biological Characters Of Three Lactobacilli And Their Bacteriocin

Three strains of the lactobacilli, N8101, N8603 and N9301, isolated from the guts of the Inner Mongolian sheep and cattle, were partially characterized biologically, which showed that they could grow at pH 4.2 and at relatively high alkaline circumstance. The Halo method showed that their significant depression on the growth of the strong toxic salmonella and Escherichia, which indicates that they could be used in the feeds. The further study of the fermentation characterization of the three strains showed that the N8101, N8603 and N9301 could be stable after fermenting for 22h, 20h and 16h respectively, and their supernatant had the highest bacteriostasis among which there was no hydrogen dioxide and there was no effect in the acid products.The purification of the three strains showed that the optimal concentration for the ammonium sulfate precipitation was that it was at 70% of its saturation. The solution of the precipitation of the salt precipitation and the peak value liquid were performed on the SDS-PAGE electrophoresis, the result showed that the molecular weight of the peak value liquid of the N8603 was 35kDa.The characterization of the crude extract of the bacteriocin of the three lactobacilli showed that they were relatively heat tolerable, the bateriocin of the N8603 and the N9301 lost their activities when heated at 121℃. The bacteriocin of the N8101 still stayed active when heated for 30 min at 100℃.The bacteriocins of the three stains were relatively high acid tolerable and kept bioactive at pH 2 to 3. When treated by the Proteinase K, trypsinase and the pepsin, they showed significant declined bacteriostasis, while they still kept the activities when treated with the amylaseа. The trypsinase could completely depress the bateriocin of the N8603 which indicated that they are proteins.