Induction And Expression Of β-glucosidase Gene In Pichia Pastoris

In order to obtain high activityβ-glucosidase and development and utilization of residues yeast of fermentation liquid,this research took a strain of genetic engineering GS115 bgll as the fermentation strain.The appropriate conditions of induction and expressionβ-glucosidase and its enzymatic properties were studied;on this basis,a 5L fermentor enlarge fermentation experiment were carried out;on how to use yeast of fermentation liquid were exploratory studied.The results indicated that the appropriate conditions of induction and expressionβ-glucosidase were initial pH6.0 of FM21,adding 0.1%histidine and 0.4%PTM1 respectively, inoculumed 6%with additive amount of methanol 1%,24h.In addition,add the ammonium sulfate,potassium dihydrogen phosphate,Tween80,oleic acid can enhanceβ-glucosidase activity.The high-density fermentation in the fermentor indicated that,after 72h induction of methanol,theβ-glucosidase activity was 145 IU/mL and the expression of protein reached 7500mg/L.The highest enzyme activity and expression of extracellular protein was 1.87 and 1.79 times of that in the shake flask respectively,its enzyme production capacity increased by 33.6 times of the primitive Aspergillus niger strain,was achieved a high-level expression ofβ-glucosidase.When use high-concentration salt extract nucleic acid of residues yeast of fermentation liquid,yield of nucleic acid material was 1.56%,extraction rate was 2.71%,purity of 97.2%. Molecular weight around in 19392bp.Use Alkali extract polysaccharides of residues yeast of fermentation liquid can gain double polysaccharides.The comprehensive utilization of yeast of fermentation liquid reduce a large number of the environmental pollution caused by yeast emissions.