Research On The Selenium-Rich Mycelium Of Pleurotus Ostreatus By Liquid Fermentation

Selenium is the essential element of human body widely applicated in medicine. At present, the main organic selenium medicines, such as tablet of sodium selenite and sodium selenite-rich salt ect. were difficult to be absorbed and had harmful effects. Research indicated that organic selenium from biological sources functions superior to inorganic selenium in aspects of physiology and pharmacology without any harmful effects. It is an effective way to explore natural organic products to supply selenium to strengthen the constitution and enhance illness resistance. The objectives of the project are to produce selenium-rich mycelium of Pleurotus ostreatus by liquid fermentation of selenium carrier - strain of Pleurotus ostreatus which is widely adaptable and rapidly reproduced in sodium selenite Na₂SeO₃ medium.Strains, medium and its pH, and Se concentration were screened according to the response of mycelium of Pleurotus ostreatus (dry matter wight) of 9 strains with wide temperature variation in 10 kinds of medium in liquid fermentation to enenly increased pH from 4. 5⁸. 0 and sodium selenite Na₂SeO₃ concentration from 0-12. 0mg. L^-1. The results were: Dry matter weight of strains P13, HP3 and Xiangwei were obviously higher in medium No. 1, 5, and 10 under neutral condition in pH 6. 5, 7. 0, 7. 5. Dry matter weight and Se content were higher at 6. 0 7. 5, 9. 0 mg. L^-1 sodium selenite in liquid medium.The optimization fermentation condition to culture selenium-rich mycelium of Pleurotus ostreatus were futher carried out using the orthogonal design of four factors (strains, medium, pH, and Se concentration) with three levels L9 (3⁴) . The results showed that dry matter weight of mycelium of Pleurotus ostreatus in No. 2 (Strain 13, PDA medium, pH 7. 0, and 7. 5mg. L^-1 sodium selenite) was the highest and defined to be the optimization fermentation condition. Content of Se was determined by o-phenylenediamine spectrophotometry in purified and dried (60 ℃) mycelium after 8 d liquid fermentation at 28℃ and shaker rate 200 r/min in the optimization fermentation condition. The concentration of Se in mycelium of Pleurotus ostreatus was 625 ug/g and 95% in organic form. It indicated thatmycelium of Pleurotus ostreatus was extremely strong in Se enrichment. Thus demonstrated that powder of mycelium of Pleurotus ostreatus could be processed into Se medicine and nutrients to function as a simple but effective way of Se complementarity.