酶法转化谷氨酰胺

高产谷氨酰胺的谷氨酸棒杆菌经酶解和超声波处理后，释放出高活性的谷氨酰胺合成酶(Glutamine synthetase，简称GS). GS的胞外催化反应受各种反应条件和因素的影响. 通过单因子实验、响应面实验和正交实验发现，反应混合物中最显著的影响是腺三膦(ATP)，当ATP浓度在40~50 mmol/L时，催化作用达到最高；同时酶量对反应也有较大的影响. 研究了粗酶液在细胞外反应时各种因素对谷氨酸棒杆菌GS催化作用的影响，获得了体外酶催化反应的适宜条件，最高转化产生的谷氨酰胺可达7.1 g/L，转化率达到94.8%.     

实验条件对肌酸比色法测定双乙酰的影响

本文对利用肌酸比色法测定双乙酰过程中的若干影响因素进行了研究，进一步完善了此测定方法。     

mp65和sap2真核表达质粒对小鼠系统性白色念珠菌感染的免疫保护作用

目的研究白色念珠菌mp65和sap2基因真核表达质粒对小鼠系统性白色念珠菌感染的免疫保护作用。方法将pcDNA3.1-mp65和pcDNA3.1-sap2质粒分别或联合免疫BALB/c小鼠,ELISA法检测免疫小鼠外周血中抗MP65和抗Sap2蛋白特异性IgG抗体,流式细胞仪检测免疫小鼠脾脏中CD4+、CD8+T淋巴细胞百分含量的变化,并观察白色念珠菌攻击后免疫小鼠的存活率。结果免疫后小鼠血清中可检测出抗两种蛋白的特异性IgG抗体,两种质粒均能诱导脾脏中CD4+T淋巴细胞百分含量增高,并可提高白色念珠菌系统性感染小鼠的存活率。结论pcDNA3.1-mp65和pcDNA3.1-sap2质粒均能诱导小鼠的体液免疫和以CD4+T淋巴细胞为主的细胞免疫,且对白色念珠菌的系统性感染有一定的保护作用。     

利用肺炎克雷伯氏菌以葡萄糖和磷酸铵盐为底物生产2,3-丁二醇

1 INTRODUCTION Interest in microbial production of 2,3-butanediol has been increasing recently due to the extensive indus-trial application of this product. This colorless and odorless liquid with a high boiling point and a low freezing point is a potential valuable fuel additive. Its heating value is 27.198kJ·g-1, which is quite near the value of ethanol (29.055kJ·g-1). Besides, condensation of diol to methyl ethyl ketone (MEK) coupled with subsequent hydrogenation yields octane isom…     

Production of 2,3-Butanediol by Klebsiella Pneumoniae Using Glucose and Ammonium Phosphate

The production of 2,3-butanediol by Klebsiella pneumoniae from glucose supplemented with different salts was studied. A suitable medium composition was defined by response surface experiments. In a medium containing glucose and （NH4）2HPO4, the strain could convert 137.0g of glucose into 52.4g of 2,3-butanediol and 8.4g of acetoin in shaking flasks. The diol yield amounted to 90% of its theoretical value and the productivity was 1-1.5g.L^-1.h^-1. In fed-batch fermentation, the yield and productivity of diol were further enhanced by maintaining the pH at 6.0. Up to 92.4g of 2,3-butanediol and 13.1g of acetoin per liter were obtained from 215.0g of glucose per liter. The diol yield reached 98% of its theoretical value and the productivity was up to 2.1g.L^-1.h^-1.