Study On Submerged Cultivation And Nutrition Analysis Of Se-enriched Ganoderma Lucidum

Ganoderma Lucidum(GL) is one of the most precious Chinese medicinal Fungi.Selenium is an essential trace element for human being. There are very few reports about the studies on the bio-transform of selenium using GL as biological carrier and activated selenium ore solution (ASOS) as selenium source all over the world. Therefore, the research in this paper has important significance in probing new ways of selenium accumulation and in providing new resources of organic selenium. The main research contents and the results gotten are as follows.Firstly, the components of culture medium were optimized by the steepest ascent path experiments and Response Surface Method (RSM) when using ASOS only as selenium resource:glucose2.13%,bran juice3.96%,KH2PO40.3%,MgSO4·7H2O0.09%.Under the optimized cultivation conditions,the biomass reached 18g·L-1,the total selenium content exceeded 150μg·g-1 and the selenium accumulation rate could reach 55%.Secondly,the processing technology of ASOS was studied by orthogonal experimental methodology as follows: Adding 300g powder of selenium mine to 600mL rotated NH3·H2O of 0.6mol·L-1 and lasted for 72h, then dried it out and repeated for twice. Then phosphate butter of pH8.0 was added to the treated powder for ultrasonic extraction for 0.5h. The final selenium content in the solution could be 50μg·mL-1.Different concentrations of ASOS and Na2SeO3 could be added to culture medium and when the content of ASOS was 5μg·mL-1 and Na2SeO3 was 10μg·mL-1 in the culture medium,the biomass reached 18g·L-1,the total selenium content could reach about 260μg·g-1 and the selenium accumulation rate exceeded 30%.In the amplification cultivation in 5L bioreactor based on the shaken flask experiments,the bioreactor parameters were investigated. The optimized conditions gained through single-factor method,orthogonal experimental methodology and the on-line control methods of bioreactor were as follows: cultivation temperature 28℃,air flow rate1.2 L·min-1,initial pH 6.5,stirring speed 120 r·min-1,grading control of pH 5.0,Dissolved oxygen(DO,in series with stirring speed)6%.Under the optimized fermentation conditions,the biomass reached 14.91g·L-1,the total selenium content exceeded 354μg·g-1 and the selenium accumulation rate could get to 35.2%.Finally, the nutrition components and the existence form of selenium in Se-GL were analyzed. The protein content of Se-GL was 16.28%, while that of normal GL was only 12.31%. The content of trace elements in Se-GL were determined by Atom-absorption spectrometry and the results showed the contents of Ca, Fe, Zn and Se are 398.1μg·g-1, 338.7μg·g-1, 45.6μg·g-1 and 318.5μg·g-1 respectively. It is also found that the organic selenium was 79.1% to the total selenium. The costing results of materials showed that it's more economical to use ASOS as selenium resources instead of Na2SeO3.