Study On Characterization Of Antibacterial Substance From Lactobacillus Plantrum

The Lactobacterillus Plantrum can produce broad-spectrum antimicrobialsubstance, which inhibitted strongly gram-positive bacteria such as Bacillus subtilisand Staphylococcus aureus, Gram-negative bacteria such as Escherichia coli andSalmonella pullorum and yeast fungi. In order to maximize the yield of inhibitorymaterial by liquid cultivation of Strain of Lactic Acid bacterium,Single-factor-experiment design and orthogonal experiment design were used tooptimize the culture conditions.The purification and characterization of this substancewere also studied. The results as follows:(1) The optimal conditions for its growth were obtained at culture time of40h,30℃，initial pH6.0, inoculation rate of2%and seed age of12h under anaerobiccondition. Following fermentation conditions for the highest inhibition activity togram-negative bacteria were with culture temperature at28℃, initial pH7.0,2%inoculation quantity,10h seed age and24h culture time under anaerobic conditions,Following fermentation conditions for the highest inhibition activity to gram-positivebacteria were with culture temperature at28℃, initial pH6.5,1%inoculation quantity,6h seed age and40h culture time under anaerobic conditions.(2) Antibacterial activity was studied by well test. The result showed that:antibacterial substance from its super-natant was eliminated the organic acids andhydrogen peroxide. Not only this inhibitory activity were not sensitive to pepsin,papain, trypsin, but also this antibacterial substance was heat-stable even atautoclaving temperature(121℃for20min). The bacteriocin-like activity was kept aslower than pH4.5.(3) The antibacterial substance from Lactobacterillus Plantrum was separated bydialysis (MWCO1000) and purificatied by chromatography with AB-8and DM101macroporous resin. The results showed that: the antimicrobial substance from thisexperimental strain was small polarity molecules with molecular weight less than1000.