Study On The Technology Of Selenium-rich Culture And Agent's Producing Of Lactobacillus Plantarum NCU116

Selenium is an essential trace element of human body, which is of great significance to health. It is a safe and effective method to convert inorganic selenium into organic selenium by using microorganisms as the carrier. In a large number of microbial carriers, Lactobacillus plantarum as probiotics show advantages when compared with other microorganisms. Therefore, it has become a hot spot to enrich selenium by using Lactobacillus plantarum. In this paper, we mainly study on the technology of selenium-riched culture and produce of L. plantarum NCU116 agent by spray drying. The main conclusions are as follows:1. Study on the formula of L. plantarum NCU116 selenium enrichment culture medium. Method of the single factor experiment was used and ingredient of selenium enrichment culture medium was determined by carbon source,nitrogen source, buffer salt and selenium concentration. On the basis of single factor experiment, optimized medium formula was obtained by orthogonal test.The optimized formula of medium is: 2 % glucose, 1 % beef powder and 2 %yeast powder, 0.6 % dipotassium phosphate, 0.01 % magnesium sulfate, 0.004 %hydrated manganese sulfate, 0.1 % Tween-80, and 4 ug/mL Se4+, In the optimum medium, the number of viable bacteria at the end of fermentation could reach 4.89×109 CFU/mL, and the enrichment rate of selenium was 52.47 %.2. Study on the selenium enrichment culture conditions of L. plantarum NCU116. Selenium enrichment culture conditions were determined: sodium selenite was added at the 4th and 6th hour, 5 % inoculum concentration, cultured at 37 ? for 20 h. At the end of fermentation, the enrichment rate of selenium was 66 % and the number of viable bacteria could reach 6.5×109 CFU/mL. In the process of cultivation, after 2 h delay of the lag phase, the log phase lasted for14 h,followed by 8-h stationary phase, and started to decline after 24 h.. L. plantarum NCU116 belongs to homofermenter. In the process of the Se4+ enrichment culture,L. plantarum NCU116 consumed a lot of glucose and experienced a normalphysiological process, and lactic acid was produced during selenium enrichment culture.3. Study on the preparation technology of highly active agent made of L.plantarum NCU116. The formula of freeze-dried protective agent determined by orthogonal design experiments was: 7.5 % monosodium glutamate, 10 %trehalose and 2.5 % glycine. Optimized condition of vacuum freeze-drying was:selenium-enriched fermentation borth was centrifugated at 4000 rpm for 15 min,material thickness within 4 mm, The viable bacteria count in the agent reached6.2×1011 CFU/mL. After storage for 60 days at-20 ?, the amount of viable bacteria was up to 5.8×1011 CFU/mL.