"Fish-in-net" Immobilization Studies On Antibacterial And Lactose Hydrolysis Bifunctional Enzyme Preparation

Milk is a kind of natural drink which is rich in nutrients, however, the high lactose content (5%) in milk makes people feel bad after drinking it. Lactase can dissolve lactose so that people can digest and absorb the low-lactose product. But due to the high cost (156rmb/kilo) and low rate of recycling of lactase, it is very inconvenient to produce in mass.Among large amount of technology in enzyme engineering, enzyme immobilization possess an essential possition. Nevertheless, he existing technology has its own fixed strengths and weaknesses, therefore looking for universal technology of enzyme immobilization becomes the focus of concern in the field. In 2006, our group built a "Fish-in-net" immobilization technique, the silica-based matrix structure which is used in this method fits for comparatively many types of enzyme immobilization. To this end, we combined "Fish-in-net" immobilization and molecular imprinting technology to prepare immobilized lactase with high activity and ratio of reuse. But Milk is a nutrient-rich medium, it is easy to be contaminated. The enzyme which is mentioned above does not prepare a good solution to the proliferation of bacteria in milk. In order to discover the enzyme which possess both functions of lactose hydrolysis and anti-bacteria, we conducted the research of "Fish-in-net "bifunctional enzyme immobilization.The results show that:the specific activity of the produced immobilized latase which utilizes lactose molecule as imprinting moleclule is obviously higher than the specific activity of traditional "Fish-in-net" immobilized latase. Immobilized lactase markedly improved in thermal stability, but the optimum temperature, pH did not change. The ratio of reuse of the immobilized lactase is of good performance, after nine times'repeated use, the activity is still more than 80%.Immobilization of lactase after cross-linking of lysozyme has a high antimicrobial activity of lysozyme.In summary, through using this biological material with dual activity, we overcame the common bacterial contamination problems in production. Peripheral lysozymes which are covalently connected are not easy to fall off, and do not interfere with the massing between the substrates and products of lactase in the channels. The technology which combines Molecular imprinting and "Fish-in-net" to imobilize lactase and cross-link lysozyme is expected to improve the process of producing low-lactose production, and is of potential applications.