Using Nisin To Improve The Antibacterial Of Bio-plastic And Optimization Of Nisin Gene Cluster

Traditional plastics bring the convenience, but also cause a number of troubles to human. So emerge in large numbers bioplastic to our daily life, it has been successfully used in food and beverage packaging. In food production, the customer is highly demanding in safety and health. So looking for new ways to inhibit microbial growth to maintain food fresh, safety, high quality become the primary task. Polyhydroxyalkanoates (PHAs), as a novel class of biopolymer, are attracting more attention due to their diverse material properties and environment-independent biodegradability. In order to meet the needs of the community to improve the function of this newly bioplastic using Nisin, a recognized safe natural food preservative, prepare a highly efficient, long-lasting antimicrobial effect of PHA plastics. Here, this study report the preparation of PHA exhibiting efficient antibacterial activity by embedding Nisin, a food additive generally recognized as safe, into poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), a type of PHA with high biocompatibility. The study first prepared Nisin-containing PHBHHx films using solvent casting method. Then, confocal laser scanning microscopy analysis showed that well-mixed integrated structure of the films with an even distribution of the Nisin particles in the PHBHHx matrices. Last, the antimicrobial activity of PHBHHx/Nisin films against Micrococcus luteus was quantified on agar plate by measuring the size of inhibition zone. Cultivation in liquid media further confirmed the releasing of Nisin from the films and the long-time antibacterial activity. Results showed that the threshold of Nisin concentration for long-time and effective inhibition against bacteria growth is 25ug/g.With the increasing of Nisin consumption, how to improve its yield has become the focus of researchers. So this study based on Nisin signal character, and T7RNA polymerase effective drive activity designed the new pathway of Nisin biosynthetic. Methods:1) Used CATCH biotechnology clones the nisin cluster from the wile type lactococcus lactis SO to the shuttle plasmid pMG36e.2) Measuring their growth curve.3) Using the agar diffusion method to detect Nisin activity. Result:1) Succeeds building the new Nisin expression plasmids; 2) From the growth curve, identified new strains have a normal growth, that is to say, Nisin expression plasmids didn’t influence their growth. But the wile type strain has a fast growth phage that they get their stationary phage earlier; 3) The Nisin activity detecting revealed that the new designed plasmids have expression the antimicrobial Nisin in the heterologous strain. But the Nisin yield 10 folds lower than the wile type strain. Although this study didn’t break the yield of the wile type strain, this new design could expression in Lactococcus lactis MG1363. That providing a new strategy to improve Nisin yield.This research by using a solution casting method, the environmental health of Nisin applied to plastics, prepared a highly efficient and durable antibacterial PHA. Providing a safty and health anti-palstic. Established an important technology for industry produce antimicrobial PHA. Also expanding Nisin applied in material. Additional, the new design of Nisin gene cluster is fresh ideas as refer to improve Nisin output.