中文摘要：

目的：消除菌悬液中无机盐沉淀对比浊法测定生长量的干扰。方法：以嗜有机甲基杆菌ME25为材料，采用比浊法，研究了EDTA对菌悬液中无机沉淀物的清除效应以及对菌体生物量测定的影响。结果：在室温、pH4～11，1．25×10^-2mol／L EDTA与菌悬液样品作用1min，即可去除样品中无机盐沉淀，样品稳定，在lh内不影响样品中菌体吸光度的测定；实际样品和理论样品测定，相对误差小于3．0％，回收率为98％～100％，RSD均小于0．5％。结论：采用螯合剂EDTA可快速去除菌悬液中的无机盐沉淀，有效地消除沉淀物的干扰，明显提高了比浊法测定生长量的准确度，简便易行，具有较高的实用价值。

英文摘要：

Objective： To eliminate the interference of precipitate caused by inorganic salt in liquid medium on bacterial growth determination by turbidimetry. Methods： Using Methylobacterium organophilium ME25 as a model system, the effects of chelator EDTA on optical density determination and precipitate removal with spectrophotometer are investigated. Results ： Chelator EDTA of 1.25×10^-2mol/L could eliminate completely the precipitate in medium within a minute in the pH from 4.0 to 11.0 at room temperature, and the stability of sample is sustained more than an hour and didn＇ t affect the bacterial density determination at 600 nm （ 0D660）. The data of optical density measured with real samples and standard samples showed the relative error of 3.0% , recovery of 98.0% - 100% , relative standard deviation （RSD） of 0.5%. Conclusion： Chelator EDTA was quickly able to remove inorganic salt precipitate in medium and eliminating the interference of precipitate on bacterial growth determination. A relatively reliable, accurate and precise method used to measure bacterial optical density in precipitate-containing liquid medium was proposed.