啤酒酵母菌对无机硒的有机转化

Bioconversion of Inorganic Selenium into Organic Selenium by Beer Yeast(Saccharomyces cerevisiae)

利用啤酒酵母菌对无机硒(亚硒酸钠)进行有机转化。通过在培养基中加入不同浓度的无机硒溶液和不同时间加入无机硒溶液,于28℃、220 r/min摇床条件下培养5 d,离心得菌细胞,测定前样品预处理:破碎菌细胞,显微镜下计数,计算破碎率,破碎后的菌体装入透析袋于蒸馏水中透析除去无机硒。准确测定无机硒,用浓硫酸-高氯酸的消化体系消化样品后,紫外分光光度法于335 nm处测量吸光度,在标准曲线上查出硒含量,计算无机硒的转化率。啤酒酵母菌的最佳加硒时间为24 h,亚硒酸钠浓度大于12μg/mL对啤酒酵母菌转化无机硒有明显抑制作用,啤酒酵母菌对无机硒的摄入率约为62%,转化率约为53%;超生波细胞粉碎仪破碎细胞的破碎率为55%左右。结果表明,啤酒酵母菌可以转化无机硒。

Beer yeast （Saccharomyces cerevisiae） was used to convert inorganic selenium （sodium selenite） into organic selenium by fermentation. The fermentation was adding different concentration of inorganic selenium into the medium in different time cultured in 28℃ at 220 r/min on a shaker bed for five days, then centrifuge to harvest the cells. Before testing, the cells were pretreated by crushing, count under a microscope, and calculate the broken rate of the cell, and then put the post-broken cells into a dialysis bag in distilled water to eliminate inorganic selenium. The sample was digested with concentrated sulfuric acid-perchloric acid digestion system to accurately measure the inorganic selenium with ultraviolet spectrophotometer at 335 nm for their light absorbance and consult on standard curve for the selenium content to calculate the conversion rate of inorganic selenium. The best selenium-adding time was at 24 hours. When the concentration of sodium selenite was over 12 pLg/mL it obviously inhibit the conversion of inorganic selenium by yeast. The assimilation rate of selenium by yeast was 62% and the conversion rate was 53%. The cell broken rate with ultrasonic cell pulverizer was about 55%. The results indicated that beer yeast could convert inorganic selenium.