Solid Fermentation Production Of Ergosterol With Aspergillus Niger

Ergosterol is an important component of the fungal cell membrane.It is important raw materials to medicine and chemical industry and the main raw material to production of vitamin D₂.In this paper,solid fermentation production of ergosterol with Aspergillus niger was studied.Qualitative and identification was analysised by Thin-layer Chromatograph(TLC), Ultraviolet Spectrameter(UV)and HPLC.The results show that ultraviolet scans of the separation and purification sample consistents with ultraviolet scans of ergosterol standard.Both have characteristic absorption peak at the wavelength of 271 nm,282nm, 293nm.HPLC of Aspergillus niger crude extractive,HPLC of the separated and purificated sample and HPLC of ergosterol standard have the peak of about same retention time which is 9.7min.It had been established that a relatively accurate determination of ergosterol quantitative method which is TLC - UV.It was studied that the conditions of extracting ergosterol from Aspergillus niger by ultrasonic-assisted alcohol-base saponification.The alcohol-base saponification experiment results show that the extraction effect of ethanol is better than that of methanol.And the better conditions are obtained that for one bottle of fermentation products(6.5g dry fermentation products),when 10ml of ethanol,20mL of NaOH concentration 20 percent,extract 2 times with Petroleum ether,the extraction effect is better.The conditions of ultrasonic were optimized by orthogonal test.The results show that the better Ultrasonic conditions are temperature is 40℃,time is 45 min, power is 280W.The solid fermentation of Aspergillus niger was studied.The optimum culture medium are abtained as follows:m(wheat bran):m(bean bran)is 8.5:1.5,water rate of culture medium is 1.05 ml·g^-1,the original pH is 7.0,(NH4)₂SO₄ is 0.02 g /(g dry culture medium),fermentation time is 66 h,fermentation temperature is 28℃.And factors which impact greater on the fermentation were optimized by orthogonal test. The results show that the order of impact fermentation is the water rate of culture medium＞original pH＞fermentation time＞the ratio of raw materials.And the fermentation conditions are that the water rate of culture medium is 1.0,original pH is 7.5,fermentation time is 66 hours,the ratio of raw materials is 8(wheat bran):2(soybean bran).Under the optimum condition,the yield of ergosterol reach 0.858 g /(g dry culture medium).Silica-gel column chromatography was applied for the isolation and purification primary studies of ergosterol from the Aspergillus niger crude extract.Qualitative analysis was made by UV and HPLC.The result is satisfactory.The purity of ergosterol is 81.5%.