该研究以BS120作为出发菌株,通过常压室温等离子体诱变(atmospheric and room temperature plasma,ARTP)技术进行诱变处理,第一轮以40 mg/L 8-氮鸟嘌呤为筛选拮抗物进行筛选,得到核黄素产量和得率分别提升61.60%和58.12%的菌株BSG1。第...该研究以BS120作为出发菌株,通过常压室温等离子体诱变(atmospheric and room temperature plasma,ARTP)技术进行诱变处理,第一轮以40 mg/L 8-氮鸟嘌呤为筛选拮抗物进行筛选,得到核黄素产量和得率分别提升61.60%和58.12%的菌株BSG1。第二轮诱变以300 mg/L寡霉素为筛选拮抗物进行筛选,筛选获得菌株BSG3,核黄素产量和得率较BS120分别提升83.59%和78.76%。将核黄素操纵子表达质粒pMX45转入BSG3中,得到菌株BSG5,核黄素产量达到(4467.08±99.47)mg/L,得率为(42.56±1.25)mg/g葡萄糖,较BS120分别提高140.94%和120.52%,展现了良好的核黄素发酵性能和遗传稳定性。展开更多
Squalene and oxidosqualene cyclizations are regarded as the most complex chemical reactions in the nature,which can achieve protonation,deprotonation,a sequence of hydride and methyl migration. Dammarenediol-Ⅱ synth...Squalene and oxidosqualene cyclizations are regarded as the most complex chemical reactions in the nature,which can achieve protonation,deprotonation,a sequence of hydride and methyl migration. Dammarenediol-Ⅱ synthase（ DS）,as a kind of 2,3-oxidosqualene-triterpene cyclase,catalyses2,3-oxidosqualene to form dammarenediol-Ⅱ. To assess the three-dimensional（ 3 D） structure and catalytic active sites of dammarenediol-Ⅱ synthase,utilizing the homology modeling method,3 D models of DS were established in the Modeller9 v14 software and I-TASSER server. With the highest sequence identity with DS,human oxidosqualene cyclase 3 D models（ PDB： 1 W6K and 1 W6J） were chosen as templates. Through further evaluation and optimization,an optimal DS model was obtained consequently. Then several putative catalytic active sites were found through the molecular docking simulation between DS model and product dammarenediol-Ⅱ by using Autodock 4. 2. Finally,site-directed mutants of DS were expressed in Saccharomyces cerevisiae,a significant decrease of the yield of dammarenediol-Ⅱ is achieved,which verified the significance of these putative active sites.展开更多
文摘该研究以BS120作为出发菌株,通过常压室温等离子体诱变(atmospheric and room temperature plasma,ARTP)技术进行诱变处理,第一轮以40 mg/L 8-氮鸟嘌呤为筛选拮抗物进行筛选,得到核黄素产量和得率分别提升61.60%和58.12%的菌株BSG1。第二轮诱变以300 mg/L寡霉素为筛选拮抗物进行筛选,筛选获得菌株BSG3,核黄素产量和得率较BS120分别提升83.59%和78.76%。将核黄素操纵子表达质粒pMX45转入BSG3中,得到菌株BSG5,核黄素产量达到(4467.08±99.47)mg/L,得率为(42.56±1.25)mg/g葡萄糖,较BS120分别提高140.94%和120.52%,展现了良好的核黄素发酵性能和遗传稳定性。
基金Supported by the National Basic Research Program of China(2012CB721105)the Major Research Plan of Tianjin(16YFXTSF00460)
文摘Squalene and oxidosqualene cyclizations are regarded as the most complex chemical reactions in the nature,which can achieve protonation,deprotonation,a sequence of hydride and methyl migration. Dammarenediol-Ⅱ synthase（ DS）,as a kind of 2,3-oxidosqualene-triterpene cyclase,catalyses2,3-oxidosqualene to form dammarenediol-Ⅱ. To assess the three-dimensional（ 3 D） structure and catalytic active sites of dammarenediol-Ⅱ synthase,utilizing the homology modeling method,3 D models of DS were established in the Modeller9 v14 software and I-TASSER server. With the highest sequence identity with DS,human oxidosqualene cyclase 3 D models（ PDB： 1 W6K and 1 W6J） were chosen as templates. Through further evaluation and optimization,an optimal DS model was obtained consequently. Then several putative catalytic active sites were found through the molecular docking simulation between DS model and product dammarenediol-Ⅱ by using Autodock 4. 2. Finally,site-directed mutants of DS were expressed in Saccharomyces cerevisiae,a significant decrease of the yield of dammarenediol-Ⅱ is achieved,which verified the significance of these putative active sites.
