Studied Of Antimicrobiol Substance LPX-600 Produced By Lactobacillus Paraplantarum X-600

In this study, 420 LAB (Latic acid bacteria) strains were isolated from twelve kinds of fermented foods. Among them, one LAB strain exhibited strong inhibition to the growth of Salmonella sp., and it was identified as Lactobacillus paraplantarum X-600 according to the characteristics of morphology, physiology and biochemistry tests (API 50 CHB/E system) and the comparison of 16S rDNA sequence. The strain produces a low-molecular-weight antimicrobial substance designated LPX-600, which is bactericidal for many Gram positive and negative pathogen and spoilage bacteria, including Salmonella sp., Escherichia coli, Staphylococcus aureus, Serratia marcescens, Klebsiella pneumoniae, etc.LPX-600 was purified through ammonium sulfate precipitation or n-butyl alcohol extraction, cation-exchange chromatography, gel filtration and reverse-phase HPLC. Molecular weight of LPX-600 ranged from 600 Da to 1,000 Da by the analysis of dialysis and gel filtration and the purity reached 95% by HPLC analysi. The antimicrobial substance was heat-stable and only partly inactivated after treatment at 121℃ for 15min.The LPX-600 was also stable to proteolytic enzymes treatment (protease K, pepsin, papain).Lactobacillus paraplantarum X-600 have potential application in foods. Experiments were conducted to study the activity of fermented solution against Salmonella sp on fresh poak and the influence of fermented solution on surface pH, water content and sensory quality of poak meat. The results indicated that fermented solution can effectively inhibit the growth of Salmonella sp. on poak meat at 4℃ and room temperature. Surface pH of fresh poak decreased after the treatment of fermented solution. Water content of poak meat gradually decreased during storage. Sensory evaluation showed that the addition of fermented solution had no negative effect on sensory quality of fresh poak.