基于细胞性质分析不同有机溶剂对简单节杆菌C1,2脱氢反应的影响

通过对简单节杆菌细胞性质的研究,探讨了不同有机溶剂(乙醇、DMF、DMSO、甲醇)加入后醋酸可的松生物转化反应效率产生差异的原因。采用底物转化法检测生物转化率,采用平板活菌计数法计算细胞存活率,通过糖代谢活力保留值表征细胞的生理代谢活力,用原子力显微镜观察细胞超显微结构,以FDA法表征细胞膜通透性。在体积分数为4%的条件下,4种有机溶剂均能提高简单节杆菌生物转化醋酸可的松的初始转化速率和最终转化率,转化率从高到低依次为乙醇>DMSO>甲醇>DMF;4种溶剂对简单节杆菌存活率和糖代谢活力保留值的影响趋势基本一致,其中DMF最大,DMSO次之,乙醇和甲醇较小;4种溶剂中,甲醇对简单节杆菌细胞完整性的影响最大,乙醇次之,DMF和DMSO差别不明显;4种有机溶剂对简单节杆菌细胞膜通透性的影响大小依次为甲醇>乙醇>DMSO>DMF。上述结果表明,细胞生理代谢活力和细胞膜通透性的差异是造成转化率水平不同的重要原因。其中,细胞膜通透性的增强有利于底物分子更容易进入细胞与生物酶接触,进而提高转化率。

Study on the Effects of Different Kinds of Organic Solvents on C1,2 Dehydrogenation Reaction by the Analysis of Arthrobacter Simplex Cell Characters

The cell characters were studied to analyze the reason for difference of the conversion efficiency of Arthrobacter simplex on cortisoniacetas(CA) in the presence of different kinds of organic solvents(ethanol,DMF,DMSO,methanol).The bioconversion rate was determined by the substrate conversion method,the cell survival ratio was calculated by the counting method on plates,the cell metabolic activity was assessed by the glucose metabolic activity retention,AFM was used to observe the cell ultrastructure,FDA method was adopted to determine the cell membrane permeability.Both of the initial conversion rate and the final conversion rate for the biotransformation process were increased by adding four kinds of organic solvents at the concentration level of 4%(volume fraction).The conversion rate for the four kinds of organic solvents decreased in the following order:ethanol>DMSO>methanol>DMF,the four kinds of organic solvents exerted similar influence upon cell survival ratio and glucose metobolic activity retention,among which DMF was the most influential,DMSO was the secondly,methanol and ethanol was the least.For the integrity of cells,the cell visible change was observed with the addition of methanol and ethanol,and no remarkable change was found with the addition of DMF and DMSO.The cell membrane permeability decreased in the following order:methanol>ethanol>DMSO>DMF.These results indicated that the difference of conversion rate was resulted from the difference in cell physiological metabolic activity and cell membrane permeability.The increase in cell membrane permeability maybe improve the diffusion of substrate molecules into the cell and their contact with the biological enzyme,which lead to the enhancement of biotransformation process.