Food Safety Assessment Of The New Type Of Lactase Expressed By Pichia Yeast

Lactase called β-galactosidase, has a great potential for application in food, medicine, health care products industry. Application of lactase in the field of medicine can be as enzyme drugs, which treat symptoms of lactose indigestion, industrial field by lactose enzyme preparation of low lactose or no lactase lactose dairy products, used in the processing of fermented dairy products, dried whey and emissions, low production poly galactose. The rapid development of genetic engineering technology, especially the development of the eukaryotic expression system, make excellent enzymology properties of different sources of lactase heterologous expression and can make use of genetic engineering technology of lactose enzyme modification processing, at the molecular level, can make the lactose enzymes for the large-scale production and application. But due to the existence of people of genetically modified foods food safety concerns. It is necessary to provide the scientific basis of food safety through the enzyme lactase biotechnology to application. Therefore, the microbial expression of lactase edible safety research for the protection of the transgenic food security of our country, promote the popularization and application of recombinant lactase is of great significance.The research of object in this topic was the recombinant Pichia pastoris expression of lactase, developed by Biotechnology Research Institure, CAAS(China Academy of agricultural science). In this study, by reference to the existing plant transgenic food edible safety evaluation method, researched the expression of recombinant Pichia lactase the edible security of the system of comprehensive study. The main expression of recombinant Pichia lactase gastrointestinal digestion simulation test was adopted to improve the allergenic research; By Ames test, mouse bone marrow micronucleus test and mouse sperm malformation test mutagenic study; Teratogenic toxicity studies for SD rats; 90 days old rat feeding trials for the chronic toxicity research.The results show that:1. Digestion gastrointestinal simulation experiments showed that recombinant Pichia expression in gastric juice to digest lactose enzyme, extremely difficult to digest in intestinal juice, lactase Iwas a lower risk of potential toxicity。2. Recombinant Pichia expression lactase samples of TA97, TA98, TA100, TA102 strains of the number of colonies are in the normal range, there was no dose-response relationship. Each dose group of micronucleus rate, sperm deformity rate compared with normal control group, were no significant differences.3. Teratogenic index of SD rat was less than 10, the number of teratogenic hazard was more than 300, and there was lower teratogenic effect;4. By adding recombinant Pichia expression of the enzyme lactase diet fed rats after 90 days, the rats’ growth index and toxicology index was no significant difference with control group, and did not find the chronic toxic effect;The results of this study showed that use of recombinant Pichia expression lactase was a lower risk of potential toxicity and irritability within the scope of the normal.The aim of this study was to the recombinant Pichia pastoris expression of lactase edible safety evaluation on the basis, for the perfection of genetically modified food in China’s food safety evaluation standard system to provide some theoretical basis and also for the yeast expression of lactase for commercial production to provide a scientific basis and provide a scientific guidance for producers and consumers, to promote the standardization of the market of genetically modified food.