The Characteristics Of Antibacterial Substance Produced By Enterococcus Faecizum BZ2

In order to obtain the strain with antibacterial activity,lactic acid bacteria(LAB)isolated from traditional koumiss in Inner Mongolia with antibacterial activity screened by double agar diffusion method.While the characteristics of antibacterial substances and methos of purification produced by Lactococcus were analyzed,and the results were as follows:After excluding the interference of organic acids and hydrogen peroxide,the cell-free supernatant(CFS)of BZ2 still has an inhibitory effect on Listeria monocytogenes CMCC54002.It was also sensitive to protease,which indicated that the antibacterial substance produced by strain BZ2 was protein.The strain BZ2 was identified as Enterococcus faecium through the morphology,physiological-biochemical and 16S rRNA sequence analysis method.After treatment at 121℃ for 15 minutes,the antibacterial substance produced by E.faecium BZ2 retained its activities at pH range from 2.0 to 6.0.The antibacterial substance were not sensitive to different organic solvents,surfactants,metal ions and ultraviolet rays.The antibacterial substance produced by E.faecium BZ2 could be against different Gram-positive and Gram-negative bacterias.Antibacterial substances was initially produced after 12h incubation at 37 ℃ and showed the highest inhibitory activity at 30h and remained stable afterwards.It also maintained relatively stable antibacterial activity stored at-20 ℃,4 ℃ and room temperature after 30 days.The effect of antibacterial substance against L.monocytogenes CMCC54002 was killing.The antibacterial substance of E.faecium BZ2 was extracted by acetone precipitation,ethanol precipitation and ethyl acetate.The results showed the extraction with ethyl acetate was the best method and the optimum volume ratio of CFS and ethyl acetate was 1:1.The SDS-PAGE electrophoresis showed that the molecular mass of the bacteriocin was between 60-80KDa.