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1.
粪产碱杆菌青霉素酰化酶在枯草芽孢杆菌中的表达优化   总被引:1,自引:0,他引:1  
在5L发酵罐中进行了表达粪产碱杆菌青霉素G酰化酶的重组枯草杆菌WB600(pMA5)的发酵研究。实验表明,发酵液中的葡萄糖浓度和菌体产酶能力密切相关,维持低葡萄糖水平,可以提高枯草杆菌WB600(pMA5)青霉素G酰化酶的合成能力。采用混合碳源进行发酵,在生长阶段流加葡萄糖,并维持低浓度,在发酵12h菌体浓度达到约13.8g/L时停止流加葡萄糖,使茵体利用发酵液中的可溶性淀粉作为碳源,避免葡萄糖的代谢副产物对茵体产酶能力的抑制,青霉素G酰化酶的表达水平从原来的55u/L提高到582u/L。  相似文献   

2.
对大肠杆菌 L- 天冬酰胺酶的摇瓶发酵进行了研究。在最适条件下发酵 12h,可使产酶达到60u/m l。在培养基中添加 001% 硫酸亚铁和 2% 的 W 试剂可分别提高产酶能力 15% 和28% 。该发酵过程是一个耗氧很大的过程。  相似文献   

3.
嗜热芽孢杆菌β-半乳糖苷酶发酵条件研究   总被引:1,自引:0,他引:1  
以嗜热芽孢杆菌为菌种,研究发酵生产β-半乳糖苷酶的条件。应用均匀设计法优化发酵培养基组成,结果为(g/L):乳糖0.5、蛋白胨2.0、牛肉浸膏2.0、K2HPO4 0.01。在温度55℃、初始pH7.0、摇床转速200r/m in 和10% 接种量条件下,发酵24h,β-半乳糖苷酶酶活力达13.2U/m L。在乳糖水解反应中,证实该酶能催化转半乳糖苷反应,合成半乳糖低聚糖。  相似文献   

4.
利用无蒸煮工艺,探讨玉米生粉酒精发酵的最佳工艺条件:原料加水比为1∶2.5,α-淀粉酶用量为10μ/g原料,糖化酶用量为400μ/g原料,青霉素用量为1600μ/L。在30℃,pH4.2条件下,2141菌株发酵120h后,酒精度达9.6%,残还原糖0.22%,淀粉利用率82.54%  相似文献   

5.
从黄石市土壤中分离到一株产碱性蛋白酶的革兰氏阴性杆菌,不产芽抱,具美膜.能在pH9-11条件下生长、产酶.产酶最适pH值为9,最适温度为37℃,适发酵时间为36h.发酵产酶量为45.0U·mL-1根据实验结果,该菌株鉴定为毛状假单抱菌Pseudomonas lasia.  相似文献   

6.
氨基酰化酶产生菌GR1—11菌株的选育和产酶条件的研究   总被引:1,自引:0,他引:1  
采用物理因子诱变剂处理出发菌株米曲霉3.951(Aspergillus 3.951),获得氨基酰化酶(EC3.5.1.4)高产菌株GR1-11,这株经紫外线和γ射线诱变获得的变异株的产酶能力较出发菌株提高了91%,在最佳培养条件下,每克曲含氨基酰化酶达122.4单位,40%至60%饱和度硫酸铵沉淀所得粗酶比活力达210U/mg。  相似文献   

7.
本研究采用木薯粗淀粉原料,双酶法制糖,在过量生物素下添加青霉素的发酵工艺路线,以接种量8%、初糖浓度100~130g/L,在发酵的适当时间添加适量青霉素(约4u/ml),发酵过程流加尿素溶液控制pH7.1~8.0范围,同时流加浓糖液,经40小时摇瓶培养,结界谷氨酸生成量高达101.9g/L,糖酸转化率59.53%。与传统的采用精淀粉控制生物素"亚适量"工艺相比,可大幅降低粮耗、降低成本,提高产酸15~20g/L.  相似文献   

8.
以嗜热芽孢杆菌为菌种,研究发酵生产β-半乳糖苷酸的条件,应用均匀设计优化发酵培养基组成,结果为:服糖0.5、蛋白胨2.0、牛肉浸膏2.0、K2HPO4 0.01。在温度55℃、初始PH7.0、摇床转速200r/min和10%接种量条件下,发酵24h,β-半乳糖苷酸酶活力达13.2U/mL。在乳糖水解反应中,证实该酶能催化转半乳糖苷反应,合成半乳糖低聚糖。  相似文献   

9.
葡萄糖氧化酶发酵动力学的研究   总被引:4,自引:0,他引:4  
利用恒化器研究了葡萄糖氧化酶(GOD)发酵动力学,建立了较为合理的恒化培养系统。对采集的数据用计算机进行回归,求得最大比生长速率μmax=0.225h-1、饱和常数Ks=8.91g/L、基质得率系数YGmax=0.49g/g以及维持系数m=0.02g/g·h。并研究了pH、DO、NH2-N、葡萄糖酸、细胞产率,酶比活及体积产酶速率等参数随比生长速率变化的规律。在D=0.131h-1下体积产酶速率(DE)达最大值,为3.46×16.67μmol/s·L·h,是分批发酵最大体积产酶速率(1.53×16.67μmol/s·L·h)的2.26倍。  相似文献   

10.
对圆弧青霉PG37发酵产酶工艺及脂肪酶提取工艺等进行了系统的研究。实验结果表明,20m3发酵罐在通风量为0.3~0.8V/V/min、搅拌转速为180r/min、发酵温度为28℃、培养过程中流加棉籽油以控制发酵醪pH值为6.5~7.0的条件下,发酵84h左右,成熟发酵醪酶活为4520U/mL。发酵液经过滤、超滤浓缩、硫铵沉淀、造粒等过程制得颗粒碱性脂肪酶成品,酶的提取总收率在70%以上,颗粒酶活力单位为5.0×104U/g。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

14.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

15.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

16.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

17.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

18.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

19.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

20.
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