Preparation Of Selenium Compounds And Its Genotoxicity

Selenium has several extraordinary physiological functions for humans and animals, which can improve the level of immune, anti-aging, antioxidant, anti-cancer, anti-tumor, anti-cardiovascular disease and so on. Nevertheless, selenium deficiency in China is serious, which has caused widespread recognition and attention. Selenium-additives research has become a hot topic of research at home and abroad. Currently, there are inorganic selenium (sodium selenite) and organic selenium (selenomethionine) on the market, but to some extent, these agents have side effects. People who are becoming more and more attention to their health are looking forward to more safe and efficient selenium supplements. The selenium compounds metabolism by microbial synthesis, synthesis of selenoproteins, selenium amino acids, selenium and other biological macromolecules polysaccharide, these compounds are safe, more easily absorbed by the body. Its research and commercialization must be fill the gospel of people’s health.Saccharomyces cerevisiae D254 was the best strains screened from Geotrichum candidum, Rhodotorula glutinis, Candida Albicans, S.cerevisiae by gradient plate method, the enrichment of domestication and liquid culture. Initially identified selenium concentration in liquid culture of S.cerevisiae D254 as the most suitable for the production of 70 mg/L-90 mg/L.We studied the effects of selenium concentration on antioxidant enzymes activity of S. cerevisiae D254 by adding different concentrations of selenium in culture medium, fermentation of S. cerevisiae, superoxide dismutase, glutathione peroxidase and catalase in the activities of three antioxidant enzymes were determinated. Results showed that with the selenium concentration increased in medium, three antioxidant enzymes activity were increased first and then decreased, when the selenium concentration was 90 mg/L, the enzyme activity reached maximum. In conclusion, selenium concentration can improve cell antioxidant enzyme activity within a certain range.Response Surface Technology and Plackett-Burman test were used to study the effects of the selenium concentration, culture temperature, incubation time, initial pH, inoculating quantity of cells and culturing volume on the selenium compounds production. The level of each factors was determined by a single factor test and steepest ascent test; the fermentation conditions of selenium compounds production by S. cerevisiae D254 cells were established by a three-factor and three-level Box-Behnken test. The results showed that:concentration of selenium content, initial pH and incubation temperature were the main factors affecting the selenium compounds, there was a significant interaction between selenium concentration and culture temperature. The optimal culture conditions for selenium compounds production were as follows:selenium concentration 81.3 mg/L, initial pH 6.3, and incubation temperature 28.6℃. The predicted selenium compounds production is 1550.994p.g/L. The actual selenium compounds measured was 1544.165 μg/L, which is similar to the predicted production.Genetic toxicology were studied between selenium compounds and selenomethionine. TA97, TA98, TA100 and TA102 strains were seleted for Ames test. The mouse bone marrow micronucleus test and sperm aberration test were used to evaluate the genotoxicity of selenium compounds and selenomethionine. The experimental group were 0.015 mg/mL,0.03 mg/mL,0.06 mg/mL seperately, one negative control and one positive control were set at the same time. The Ames test results for selenium compounds production and selenomethionine to TA97, TA98, TA100 and TA102 showed no mutagenic activity in experimental range. Selenium compounds and selenomethionine have no gene inducted-degeneration. Mouse bone marrow micronucleus test and sperm aberration test results showed that selenomethionine concentration greater than or equal 0.06 mg/ml were positive. Selenium compounds were negative in the test range. Collectively, selenium compounds as a food additive are more safe than selenomethionine.