Study On Antibacterial Characterization Stability Of Lactic Acid Bacteria In The Koumiss

Studied on the antibacterial characterization stability of two lactic acid bacteria which had higher inhibitory activity against indicator organism－ Listerial monocytogenes and Bacillus subtilis in all isolated lactic acid bacteria of the koumiss collected from the herdsman′s home in Inner Mongolia-XiLinGuoLe region. The result showed: after isolating their plasmid , one strain had no plasmid and another strain had one plasmid about 21kb.Bacteria growth were harmed by physical factor,chemical factor,physical factor combined with chemical factor respectively, then some colonies could restore the growth were selected out. In all restorative colonies of the strain without plasmid, the mutants that could not ferment carbohydrate or inhibit the growth of indicator organism did not be found. So the antibacterial characterization of this strain was stabile. In all restorative colonies of another strain, only one mutant lost the antibacterial characterization and its fermentation ability became weaker correspondingly. However, this mutant did not lose its plasmid. So the antibacterial characterization of this strain was also stabile.