Research And Application Of The Inhibition Activity Of Lactobacillus Plantarum To Cladosporium

As people’s increasing attention to food safety and self health, researches on functions and features of probiotic strains have increasingly become a research highlight of food microbiology field. As a kind of beneficial microorganism, lactic acid bacteria(LAB) are general regarded as safety(GRS). The application history in food industry of LAB is very long. At the same time, LAB have many other functions such as health-care and probiotic function which make them become research priorities in all kinds of probiotic strains. Along with the developing researchers of LAB, their antibacterial effects to spoilage microorganisms and pathogenic microorganisms have been concerned. It will have a great application prospect and huge production value to develop natural microbial preservations which are more safety and efficient than chemical preservative by using LAB and their metabolites.Lactobacillus plantarum JCM1149 was found that it had antifungal activity to several common molds, was chosen to be the object of this study. Oxford cup method was chosen to determinate the antimicrobial activity. Effect of culture conditions including culture temperature, culture time and initial pH value of broth to antifungal ability of Lactobacillus plantarum JCM1149 was explored further. And the optimum culture condition was obtained by response surface analysis methods. At the mean time, proteins from Lactobacillus plantarum metabolites were extracted by method of ammonium sulfate precipitation, and their antifungal abilities were detected in the after analysis. Organic acids from Lactobacillus plantarum metabolites were analyzed by high performance liquid chromatography(HPLC),their antifungal abilities were also measured. Furthermore, this study researched the application of antibacterial activity of Lactobacillus plantarum in food storage. Lactobacillus plantarum JCM1149 was found to have inhibition ability to Staphylococcus aureus and Escherichia coli. Following conclusions could be drawn through this study:(1) Sterile concentrated fermentation liquor with antifungal abilities of Lactobacillus plantarum JCM1149 cultivated in different conditions including culture temperature, culture time and initial pH value of broth were determined by oxford cups methods. It was drawn that when the culture temperature was 37 ℃, culture time was 24 h, and initial pH value of brothwas larger than 6.0 and less than 7.0, the antifungal ability was stronger. The regression model was built by response surface analysis(RSA), then the optimum culture condition was gotten through solving the model equation: culture temperature was 33.6 ℃, culture time was 24.7 h,and initial pH value of broth was 6.4. The reliability of the model was verified by text and the inhibition zone of optimum culture condition was 22.73 mm, having no significant difference to prediction value 22.85 mm. The effect order of activity sequence was culture temperature,culture time and initial pH value of media.(2) Method of ammonium sulfate precipitation was used to collect proteins of Lactobacillus plantarum JCM1149 fermentation liquor and no antifungal abilities were detected. HPLC was used to analyze organic acids in the fermentation liquor. 4 organic acids were found and their concentrations respectively were: oxalic acid 1.59 mg/mL, L-malic acid1.17 mg/mL, L-lactic acid 15.21 mg/mL andacetic acid 5.42 mg/mL. Further text results showed that these 4 organic acids with the same concentration of Lactobacillus plantarum fermentation liquor had weaker antifungal abilities. It could be told that antifungal metabolites generated by Lactobacillus plantarum including constituents more than organic acids.(3) Both of two treatment groups which were adding sodium benzoate solution(final concentration 0.001 g/mL) and bacterium suspension of Lactobacillus plantarum JCM1149 showed antibacterial abilities in the storage of pickle materials. Lactobacillus plantarum JCM1149 was not inhibited by sodium benzoate solution. In the aspect of inhibiting bacteria in samples, sodium benzoate and JCM1149 had synergetic enhancement. But in the antifungal ability, sodium benzoate did not showed efficient activity yet Lactobacillus plantarum JCM1149 still showed better. As for the antibacterial function to Staphylococcus aureus and Escherichia coli., Lactobacillus plantarum fermentation liquor had stronger inhibition ability than organic acids which indicated that other effective bacteriostatic constituents were generated by Lactobacillus plantarum.