比浊法在测定发酵液菌体浓度中的应用

Application of Nephelometry on Determining the Cell Concentration in Fermentation Liquid

目前 ,测定发酵液菌体浓度的方法有重量法、平板计数法。重量法操作繁琐、耗时长 ,难以满足控制分析的需要。平板计数法费时且误差较大。采用比浊法测定发酵液菌体浓度 ,根据菌体浓度在一定范围内与吸光度成线性关系 ,通过测菌体浓度和相应吸光度值作工作曲线 ,然后测试样吸光度值 ,在工作曲线上求出菌体浓度。波长和稀释剂的选择是影响准确度的重要因素。根据理论计算和实验 ,选定波长为 62 0nm ,正丁醇、乙醇、氯仿的混合液为稀释剂。实验设备采用光导纤维电极 ,且配有电磁搅拌装置 ,较其它比浊法具有较高的灵敏度和稳定性。光导纤维电极比浊法设备简单、操作方便、快速 ,测量相对误差小于 3 % ,相对标准偏差小于 3 % ,精密度高 ,准确度好 。

At present, determining methods of the cell concentration in fermentation liquid contain gravimetric method and plate counting method. The operation of gravimetric method is too complex and needs too much time. The determinable error in plate counting method is larger. Nephelometry is used to determine the cell concentration in fermentation liquid, according to the linear relationship between the cell concentration and its absorption in some range, we can make the working curve by determining the cell concentration and its corresponding absorption, and then we can obtain the determinable value of the absorption. The wavelength and the diluent have important effect on the accuracy of the method. According to theory and experiment, the selected wavelength is 620 nm, the diluent is the mixed solution of n -butyl alcohol, ethanol and chloroform. The equipment is optical fiber electrode, which is equiped with magnetic stirrer, it has higher sensitivity and stability than other nephelometers. Optical fiber electrode nephelometry has advantages of simple equipment and operation easy and also quick, high accuracy and better property. The method relative error is less than 3% , and relative standard derivation is less than 3% .It is adaptable to the control of practical production in the industry.