MEASUREMENT OF BACTERIAL RANDOM MOTILITY AND CHEMOTAXIS COEFFICIENTS .1. STOPPED-FLOW DIFFUSION CHAMBER ASSAY
MEASUREMENT OF BACTERIAL RANDOM MOTILITY AND CHEMOTAXIS COEFFICIENTS .1. STOPPED-FLOW DIFFUSION CHAMBER ASSAY
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DOI：
10.1002/bit.260370707
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发表时间：
1991-03-25
影响因子：
3.8
通讯作者：
LAUFFENBURGER, DA
中科院分区：
文献类型：
--
作者：
FORD, RM;PHILLIPS, BR;LAUFFENBURGER, DA
细菌趋化性是指细胞群体响应化学梯度的定向运动，在非混合系统中细菌群体的分布和动态相互作用中起着关键作用。 因此，为了对环境中细菌的迁移行为进行可靠的预测，需要根据细胞的内在特性对趋化反应进行定量表征，停流扩散室（SFDC）的设计提供了一种表征良好的化学梯度和可靠的方法来测量细菌的迁移行为。 在流过腔室期间，化学浓度的阶跃变化施加在细菌的均匀悬浮液上。 一旦流动停止，扩散引起瞬时化学梯度发展，细菌通过形成高细胞密度的带来响应，该带朝向更高浓度的引诱剂移动。 通过光散射观察到的细菌空间分布的变化在10分钟的时间内记录在显微照片上。 计算机辅助图像分析将照相底片的吸光度转换为细菌密度分布的数字表示。 数学模型（第二部分）用于定量表征这些观察的内在细胞参数：趋化敏感性系数chi-0，来自条带中累积的聚集细胞密度，以及随机运动系数μ，来自在没有化学梯度的情况下的群体分散。我们成功地测定了大肠杆菌K12对岩藻糖反应的这两个群体参数的值。 获得的值为mu = 1.1 +/- 0.4 x 10（-5）cm 2/s和chi-0 = 8 +/- 3 x 10（-5）cm 2/s。 我们已经证明了一种方法，能够确定这些参数值，从现在验证的数学模型，这将是有用的预测应用系统中的细菌迁移。
Bacterial chemotaxis, the directed movement of a cell population in response to a chemical gradient, plays a critical role in the distribution and dynamic interaction of bacterial populations in nonmixed systems. Therefore, in order to make reliable predictions about the migratory behavior of bacteria within the environment, a quantitative characterization of the chemotactic response in terms of intrinsic cell properties is needed.The design of the stopped-flow diffusion chamber (SFDC) provides a well-characterized chemical gradient and reliable method for measuring bacterial migration behavior. During flow through the chamber, a step change in chemical concentration is imposed on a uniform suspension of bacteria. Once flow is stopped, diffusion causes a transient chemical gradient to develop, and bacteria respond by forming a band of high cell density which travels toward higher concentrations of the attractant. Changes in bacterial spatial distributions observed through light scattering are recorded on photomicrographs during a 10-min period. Computer-aided image analysis converts absorbance of the photographic negatives to a digital representation of bacterial density profiles. A mathematical model (part II) is used to quantitatively characterize these observations in terms of intrinsic cell parameters: a chemotactic sensitivity coefficient, chi-0, from the aggregate cell density accumulated in the band and a random motility coefficient, mu, from population dispersion in the absence of a chemical gradient.Using the SFDC assay and an individual-cell-based mathematical model, we successfully determined values for both of these population parameters for Escherichia coli K12 responding to fucose. The values obtained were mu = 1.1 +/- 0.4 x 10(-5) cm2/s and chi-0 = 8 +/- 3 x 10(-5) cm2/s. We have demonstrated a method capable of determining these parameter values from the now validated mathematical model which will be useful for predicting bacterial migration in application systems.