Isolation And Purification Of L. Paracasei And Its Application In Meat Of,

One strain which can produce antimicrobial substance was isolated from the L-LAB sauerkraut broth fermentation by our lab. After optimizing and identifying this strain, it was identified as Lactobacillus paracasei, and it was named as Lactobacillus paracasei HD1.7. Through the research on the strain, we knowed that the antimicrobial substance produced by Lactobacillus paracasei HD1.7 had strong antimicrobial activity and very broad antimicrobial range, so it has great foreground in application. Isolation and purification of the bacteriocin produced by Lactobacillus paracasei HD1.7 were mainly studied in this paper; the comparative molecular weight of the bacteriocin was ascertained; some elementary research about its application in cooked meat food was done. Theory elements about mass-production of this kind of bacteriocin and the academic elements of extensive application of this bacteriocin in food antisepsis were established in this paper.An effective experiment protocol was researched to isolate and purify the bacteriocin produced by Lactobacillus paracasei HD1.7, and the conditiaon of isolation and purification was ascertained. Ultrafiltration was conducted by using ultrafiltration membranes which comparative molecular weight was 5,000 and 10,000. It was confirmed that through ammonium sulphate precipitation (30-60%), SP-Sepharose Fast Flow ion exchange chromatography and Sephadex G-50 gel chromatography, the bacteriocin could be isolated and purified effectively. Determination of protein content and titer was operated during the process of isolation and purification. After isolation and purification, the specific activity of bacteriocin was 1725.3AU/mg, 37.09 fold than the initial culture and a recovery of 10.46% of the initial activity was obtained. The comparative molecular weight of the antimicrobial bacteriocin was determined to be 7,800 by Urea-SDS-PAGE. Elementary research was done to make the bacteriocin which was produced by Lactobacillus paracasei HD1.7 be applied in braised ham and bacon. The results showed that the bacteriocin and some chemical preservatives all had certain antisepsis role when used singly. When the bacteriocin and chemical preservatives were mixed together, new preservatives would enhance the antisepsis effect, and the adding dose of chemical preservatives would be reduced. So side effect of chemical preservatives to human beings would be decreased. The experiment results demonstrated that the mixture of bacteriocin and 1% NaL had better antisepsis effect than other preservative combinations.