大肠杆菌葡萄糖脱氢酶基因的克隆与原核表达

克隆出大肠杆菌编码葡萄糖脱氢酶(PQQGDH)的 gcd 基因，构建了诱导型表达载体pET28a-gcd，转化大肠杆菌E. coli BL21后获得阳性克隆菌株BL21/pET28a-gcd。IPTG诱导后，经SDS-PAGE分析表明，该工程菌PQQGDH的表达量约为对照菌的18倍，约为18.2 mg/L，实现了高表达。此外，研究发现添加MgCl₂能提高PQQGDH的表达量。     

葡萄糖对莱茵衣藻生长和产氢的影响

通过在莱茵衣藻的培养基中添加葡萄糖,考察了葡萄糖对莱茵衣藻生长及产氢的影响。结果表明,在Tris Acetate Phosphate (TAP)培养基中添加葡萄糖对莱茵衣藻生长有利,最佳葡萄糖浓度为03g/L,藻细胞数和叶绿素浓度分别提高了12.8％和16.4％。在产氢培养基中,添加葡萄糖对莱茵衣藻产氢也有促进作用,氢气产量提高了27％。     

重组葡萄糖脱氢酶的表达及辅酶再生应用研究

为解决异源表达酮还原酶域EryKR1的重组大肠杆菌Escherichia coli BL21(pET28a-eryKR1)催化环己酮还原时消耗的氢供体NADPH再生的问题,构建了克隆枯草芽孢杆菌葡萄糖脱氢酶基因gdh的重组菌E.coli BL21(pET28a-gdh),其中的gdh基因经Nucleotide BLAST功能分析显示与枯草芽孢杆菌9902的gdh基因序列(登录号为EF626962.1)的一致性达到100%。SDS-PAGE检测显示该重组菌经IPTG诱导后可以高效表达出葡萄糖脱氢酶(GDH),其表达量占全菌可溶性蛋白质的64%。GDH粗酶液的比酶活为137.90U/mg。通过气相色谱检测添加了E.coli BL21(pET28a-gdh)的E.coli BL21(pET28a-eryKR1)环己酮还原反应体系中的环己醇含量,结果显示加入重组GDH的双重组菌耦合反应体系中环己醇的产率为82.21%,是未添加GDH的反应体系对应值的3.23倍,表明重组GDH可以为EryKR1还原环己酮系统解决辅酶再生问题。     

温度对发酵过程中乙醇脱氢酶的活性效应

温度是微生物生命活动中重要的环境因子,文章以活性干酵母为材料,通过实验研究了微生物乙醇发酵过程中温度对乙醇脱氢酶的影响.结果表明,这种酶在29℃～35℃时具有较高的活力.     

Effect of γ-PGA Coated Urea on N-Release Rate and Tomato Growth

The anionic polymer γ-polyglutamic acid(γ-PGA) was used to coat urea and slow its dissolution. Three types of slow release urea(SRU) fertilizers(polymer coated urea with pore constriction, polymer coated urea with enzyme inhibitor and polymer coated urea with pore constriction and enzyme inhibitor) were prepared and tested for the N-release rate. After using SRU, the effect on the tomato growth was analyzed. The extracts of SRU were analyzed for NH3/NH4+-N and NO3--N. The N-release rate was used to determine the optimum ratio of ingredients. The results show that the three types of SRU met the dissolution rate standards recommended by the Committee of European Normalization. γ-PGA SRU increased the chlorophyll content of tomato(flowering stage) by an average of 100% compared with that grew in untreated urea. The results from soil analysis(0-60 cm in tomato pots) indicate that the content of NH3/NH4+-N in SRU-treated pots was 25%-61% higher than that in soil from urea-treated pots during the growing period,while the content of NO3--N was nearly 50% lower after the tomato had been harvested. Newly formulated SRU fertilizer increases nitrogen uptake and reduces loss of applied nitrogen. Plant growth is enhanced, a valuable resource is conserved, and the aquatic environment benefits from decreased level of nitrate in agricultural run-off.