微生物方法生产麻黄碱和伪麻黄碱的研究

麻黄碱和伪麻黄碱是药用植物麻黄的主要生物碱类次生代谢产物,具有重要的药用价值.中国是世界上惟一通过天然植物提取麻黄碱的国家,该文简述了近年来利用微生物半转化、微生物直接转化和重组微生物制备麻黄碱的研究进展,对各自存在的问题进行了讨论,展望了微生物在麻黄碱和伪麻黄碱生物合成中的应用前景.     

氩离子注入介导麻黄基因组DNA转化获得产麻黄碱重组酵母菌

通过氩离子(Ar )注入介导蓝麻黄基因组DNA在异常汉逊酵母(Hansenula anomala)中随机转化,转化后的酵母菌经BTB指示性辅助筛选、斜面传代、液体培养、铜铬盐定性检识和RP-HPLC定量检测,获得了遗传稳定的以葡萄糖为碳源、NaNO3为氮源生物合成麻黄碱和(或)伪麻黄碱的重组酵母菌3株。液体培养72h,RP-HPLC测试胞外麻黄碱和伪麻黄碱的最高产量分别为11.87mg/L和4.11mg/L;胞内伪麻黄碱最高含量为294.86mg/g干细胞,胞内麻黄碱未检出。分析了Ar 注入介导蓝麻黄基因组DNA在酵母菌中的遗传转化效率,探讨了麻黄基因组DNA大分子的完整性对其在酵母菌中遗传转化的影响。     

重组酵母菌的高密度发酵表达

酵母作为一类外源基因的表达系统具有很多优点 ,有许多外源基因在工程酵母菌表达生产重要的外源蛋白[1] 。从生理学角度看 ,作为外源基因的受体细胞 ,酵母的生理和遗传特性影响着外源基因的表达。同时 ,外源基因的表达 ,特别是高表达的外源蛋白对宿主细胞有抑制作用甚至会导致细胞中毒或死亡。再加上工程菌的培养过程中的不稳定性问题的存在 ,因此 ,菌体细胞的高浓度和目的基因的高表达是一对矛盾 ,它们互相制约 ,构成生物工程研究的重要工作之一。1 .工程酵母菌的高密度发酵酵母的高密度发酵是一个相对概念 ,一般指发酵液中酵母浓度在 30 …     

利用三阶段葡萄糖添加策略减少乙酸合成并促进重组大肠杆菌生产L-苯丙氨酸

为了降低副产物乙酸的积累和提高L-苯丙氨酸的产量,分别优化了L-苯丙氨酸发酵的初始葡萄糖浓度和葡萄糖的指数流加策略.结果表明,20 g/L的初始葡萄糖浓度可以控制细胞的比生长速率低于临界值0.3 h-1,显著地降低了乙酸的积累,提高了L-苯丙氨酸的产量.采用预设比生长速率μ3* =0.4(h-1)进行葡萄糖的指数流加取得了实际最大比生长速率0.29 h-1,使细胞的比生长速率低于临界值,促进了L-苯丙氨酸的合成,最终获得L-苯丙氨酸的产量达48.45 g/L,比本实验室原有水平提高了37％.     

重组酵母菌乙醇脱氢酶基因的克隆及序列分析

目的:克隆产麻黄碱重组酵母菌乙醇脱氢酶基因片段,并对其进行序列分析,为研究该基因在重组酵母中与麻黄碱生物合成途径的关系提供参考.方法:根据一段利用抑制差减杂交技术获得的来源于重组酵母乙醇脱氢酶基因片段,采用RACE的方法扩增Adh基因,使用分子生物学软件对该基因进行生物信息学分析.结果:获得一段大小为1 245 bp的基因片段,编码375个氨基酸,含有两个催化域和两个锌结合域,与来源于Gandida boidinii ADH3基因的同源性为85％.结论:克隆的基因为乙醇脱氢酶基因,并在GenBank注册,登录号为JF293468.     

日本育成葡糖淀粉酶重组酵母菌

1986年在大阪召开的大阪发酵工程学年会上,三得利啤酒公司应用微生物研究所和酒类研究所发表了一项研究成果。用DNA组入染色体的方法选育成功稳定的基因重组酵母菌。将根霉的葡糖淀粉酶基因组入乙醇发酵能力接近于生产菌的酵母菌中,使其分泌产生葡糖淀粉酶,而无需加热处理(无蒸煮)就能由淀粉产生13％以上的乙醇。特别在用木薯淀粉为原料时分解率很高。转化为乙醇的产率与现行工业生产法相同。为使染色体中重组性能稳定,从小瓶到大容器重组体经数十代仍可稳定产生葡糖淀粉酶。 此重组体有可能在良好的通用发酵罐中实现工业化。该公司已实现用根霉的葡糖淀粉酶进行淀粉的无蒸煮乙醇生产,这种方法由淀粉产乙醇的能耗量约减少了三成。     

酪氨酸流加方式对重组大肠杆菌发酵生产L-苯丙氨酸的影响

研究了流加浓度对酪氨酸重组大肠杆菌Escherichia coli BR-165(pAP-B03)发酵生产L-苯丙氨酸的影响.结果表明,诱导后L-酪氨酸流加加速了菌体的生长,提高了生产强度,缩短了发酵周期.在流加浓度为75 mg/h时,最大菌体干重达到了40.13 g/L(对照11.48 g/L),生产周期缩短到30 h(对照48 h),生产强度达到1.409 g/h/L(对照0.876 g/h/L).但是L-酪氨酸的流加对L-苯丙氨酸的最终产量没有明显的影响,因此可认为流加酪氨酸是减少发酵时间并提高生产强度的有效方法.本研究获得的酪氨酸流加方式对L-苯丙氨酸的工业化生产具有一定的指导意义.     

压力对酵母菌及其海藻糖生成的影响

酵母菌海藻糖是其在培养条件发生“恶劣”变化时生成的一种应激代谢产物。当压力在0．5．1．0MPa时,酵母菌海藻糖含量为6．5mg／g,较对照提高27％。确定压力提高酵母海藻糖的最适条件为：采用复合培养基,菌体前培养时间20h,压力1．0MPa、加压温度34℃,pH6．0,升降压速度为0．10MPa/min,加压培养3h,此时,酵母海藻糖含量达到11mg／g。     

忽地笑愈伤组织培养条件对加兰他敏合成的影响

研究了忽地笑次生代谢产物加兰他敏的合成以及各种理化因子对加兰他敏合成的影响。结果表明,蔗糖是忽地笑愈伤组织培养的最佳碳源,而且在90 g/L浓度培养下加兰他敏含量最高,达到0.068%;附加500 mg/L苯丙氨酸前体物也可提高加兰他敏产量。酪氨酸和水杨酸不利于加兰他敏的积累。此外,2,4-D和浓度高于0.5 mg/L的NAA、IBA抑制加兰他敏的合成,但高浓度的6-BA却对加兰他敏的合成起促进作用。     

氮源对重组大肠杆菌发酵产L-精氨酸的影响

考察有机氮源种类、蛋白胨用量以及(NH4)2SO4用量对重组E.coli发酵产L-精氨酸的影响.结果表明:以蛋白胨作为有机氮源且用量在10 g/L,( NH4 )2SO4用量在15 g/L时,摇瓶发酵产L-精氨酸产量最高,达到9.4g/L.在5L发酵罐进行补料分批培养,通过补加(NH4)2 SO4,L-精氨酸产量可以达到18.8 g/L,比未补加提高了108.9％.     

酵母菌磷脂酰肌醇(PI)的生物合成及其重要的生理学功能

本文对近年来在酵母菌磷脂酰肌醇 (PI)生物合成 ,PI与酵母菌信号传导的相互关系 ,PI在酵母菌耐浓度酒精中的作用和PI在酵母菌胞外酶分泌解阻遏中的作用等方面最新研究进展进行了较为全面的讨论。     

Biosynthesis of Purine Alkaloids in Camellia Plants

The metabolism of [8-¹⁴C]adenine and [8-¹⁴C]hypoxanthine infour species of Camellia plants was investigated in relationto the synthesis of purine alkaloids, caffeine and theobromine.Young leaves of C. sinensis had the ability to synthesize caffeine,but in C. irrawadiensis, these labelled precursors were incorporatedinto theobromine, not caffeine. No synthesis of purine alkaloidscould be detected in C. japonica and C. sasanqua leaves. Conventional"salvage" and degradation pathways of purines were present inall species of Camellia plants examined. ¹ Present address: Research Center, Mitsubishi Chemical IndustriesLtd., 1000 Kamisida-cho, Midori-ku, Yokohama, 227 Japan. (Received September 29, 1986; Accepted January 22, 1987)     

Marine Pyridoacridine Alkaloids: Biosynthesis and Biological Activities

Pyridoacridines are a class of strictly marine‐derived alkaloids that constitute one of the largest chemical families of marine alkaloids. During the last few years, both natural pyridoacridines and their analogues have constituted excellent targets for synthetic works. They have been the subject of intense study due to their significant biological activities; cytotoxic, antibacterial, antifungal, antiviral, insecticidal, anti‐HIV, and anti‐parasitic activities. In the present review, 95 pyridoacridine alkaloids isolated from marine organisms are discussed in term of their occurrence, biosynthesis, biological activities, and structural assignment.     

Principal-Component Analysis of the Characteristics Desirable in Baker's Yeasts

Twenty-seven properties considered to be required for good bakery products were examined in 56 industrial and 2 laboratory yeast strains. The data obtained were applied to principal-component analysis, one of the multivariate statistical analyses. The first and second principal components together were extracted, and these accounted for 77.7% of the variance. The first principal component was interpreted as the glycolytic activity of yeast in dough, and the second one was interpreted as the balance of leavening abilities in sweet and flour doughs from the factor loadings. The scattergram on the two principal components was effective in grouping the 58 yeast strains used.     

Principal-Component Analysis of the Characteristics Desirable in Baker's Yeasts

Twenty-seven properties considered to be required for good bakery products were examined in 56 industrial and 2 laboratory yeast strains. The data obtained were applied to principal-component analysis, one of the multivariate statistical analyses. The first and second principal components together were extracted, and these accounted for 77.7% of the variance. The first principal component was interpreted as the glycolytic activity of yeast in dough, and the second one was interpreted as the balance of leavening abilities in sweet and flour doughs from the factor loadings. The scattergram on the two principal components was effective in grouping the 58 yeast strains used.