Study On Antibacterial Mechanism Of Koumiss Fermentation Bacteria Antimicrobial Substances On The Salmonella Enteritidis

The strains with better antibacterial activities were screened from 9 strains of lactic acid bacteria and 5 yeast strains which were isolated from koumiss of Xilin Gol League, Inner Mongolia. The physical and chemical characteristics as well as antibacterial mechanism of their fermentation broth were studied.1. Co fermentation of lactobacillus D6 and E13 with yeast J10A1 were screened by the method of oxford cup agar diffusion and excluding of organic acids and hydrogen peroxide. Antibacterial substances of the two combinations have better antibacterial activities.2. The target strains were identified by morphological features, physiological and biochemical method and 16S rRNA or 26S rDNA gene sequence homology analysis. D6, E13 and J10A1 respectively identified as E.durans, L. plantarum and Pichia manshurica.3. The results of the stability tests of antibacterial substances showed that the antimicrobial substances produced by D6 and E13 had a very high stability against heat and ultraviolet. Antibacterial activity decreased with the increase of pH. Antibacterial ability decreased in different degree after the pepsin and trypsin treatment, relatively insensitive to alkali protease, papaya protease, lysozyme and proteinase K.4. With Salmonella enterica subsp. enterica as indicator bacteria, the study on antibacterial mechanism showed that, the antibacterial substances had a great influence on Salmonella, lag phase of, Salmonella growth curve was delayed, logarithmic phase shortened and logarithmic peak decreased; The total soluble sugars and electrolyte leaked, leaded to the increase of liquid conductivity and the content of total soluble sugars; Sugar absorption capacity decreased, phosphorus metabolism became slow first, then remained stable. Antibacterial substances produced by E13 have stronger inhibitory action.Comprehensive analysis of the above test results, the antibacterial substances produced by lactic acid bacteria not only destroy or make holes on the cell membrane, but also affect the metabolism of bacteria, exert the inhibitory effect by causing the bacteria to be unable to carry on the normal growth and the reproduction.