TURBIDITY MEASUREMENTS OF BACTERIAL CULTURES IN SOME AVAILABLE COMMERCIAL INSTRUMENTS
TURBIDITY MEASUREMENTS OF BACTERIAL CULTURES IN SOME AVAILABLE COMMERCIAL INSTRUMENTS
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DOI：
10.1016/0003-2697(70)90174-0
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发表时间：
1970-01-01
影响因子：
2.9
通讯作者：
KOCH, AL
中科院分区：
文献类型：
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作者：
KOCH, AL
几乎每个细菌生理学和生物化学的学生都通过液体培养物的浊度来评估细菌浓度，浊度是通过主要设计用于测量吸光度的仪器来测量的。每种类型的量热计、分光计、耳计都被用于此目的。实验者通常不测试这些测量的比例性、精密度、准确度和适用范围。我们在这里汇集了细菌光散射的理论和实验研究（l-3）以及由现成的商业仪器施加的实用性的未发表的观察结果。细菌悬浮液散射的大部分光与入射光束的原始传播方向仅偏离几度角（见文献1的图3）。因此，决定浊度测量灵敏度的主要因素是光管所观察到的角度孔径。一个理想的浊度计，具有良好的准直光束和无限小的光管，将不会接收到任何散射光。这意味着在普通分光光度计和量热计中测量的由于光散射引起的主光束损失的表观吸光度小于由于总散射光引起的表观吸光度，因为一部分散射光仍然落在检测器上。前向散射光的高方向性取向也会导致与比尔-朗伯定律模拟的偏差增加，即，在高浓度的细菌细胞中，被一个细菌散射（在检测器的视野之外）的部分光将被另一个细菌二次散射并重新定向，从而落在检测器上。可见，表观吸光度（= A）与细菌干重mg /ml（= w）的标准曲线为
Almost every student of bacterial physiology and biochemistry assesses the bacterial concentration by the turbidity of the liquid cultures as indicated by measurements in instruments primarily design for the measurement of absorbance. Every type of calorimeter or spectroph, otometer has been used for this purpose. Often the experimenter does not test the proportionality, precision, accuracy, and range of applicability of such measurements. We bring together here theoretical and experimental studies of the light scattering of bacteria (l-3) and unpublished observations on the practicalities imposed by readily available commerical apparatus.The majority of light scattered by, a bacterial suspension is scattered at angles th, at deviate only a few degrees from the original direction of propagation of the incident light beam (see Fig. 3 of ref. 1). Thus, the major factor that determines the sensitivity of turbidity measurements is the sangular, aperature viewed by the phototube. An ideal turbidimeter, being one with a well collimated beam and an infinitely small phototube, would receive none of the scattered light. This means that the apparent absorbance which is a measure of loss from the primary beam due to light scattering when measured in ordinary spectrophotometers and calorimeters is less than that due to the total light scattered, since a portion of the scattered light still falls upon the detector. The high directional orientation of forward scattered light also leads to increased deviations from the analog of the Beer-Lambert law, ie, at high concentrations of bacterial cells, part of the light scattered (out of view of the detector) by one bacterium will be secondarily scattered by another and reoriented so that it falls upon the detector. It is therefore evident that the standard curves of the apparent absorbance (= A) versus mg dry weight of bacterial/ml(= w) will