Department of Chemical Engineering, Thornton Hall, University of Virginia, Charlottesville, Virginia 22903-2442, USA.
Biotechnol Bioeng. 1997 Mar 5;53(5):487-96. doi: 10.1002/(SICI)1097-0290(19970305)53:5<487::AID-BIT6>3.0.CO;2-D.
The migration of chemotactic bacteria in liquid media has previously been characterized in terms of two fundamental transport coefficients-the random motility coefficient and the chemotactic sensitivity coefficient. For modeling migration in porous media, we have shown that these coefficients which appear in macroscopic balance equations can be replaced by effective values that reflect the impact of the porous media on the swimming behavior of individual bacteria. Explicit relationships between values of the coefficients in porous and liquid media were derived. This type of quantitative analysis of bacterial migration is necessary for predicting bacterial population distributions in subsurface environments for applications such as in situ bioremediation in which bacteria respond chemotactically to the pollutants that they degrade.We analyzed bacterial penetration times through sand columns from two different experimental studies reported in the literature within the context of our mathematical model to evaluate the effective transport coefficients. Our results indicated that the presence of the porous medium reduced the random motility of the bacterial population by a factor comparable to the theoretical prediction. We were unable to determine the effect of the porous medium on the chemotactic sensitivity coefficient because no chemotactic response was observed in the experimental studies. However, the mathematical model was instrumental in developing a plausible explanation for why no chemotactic response was observed. The chemical gradients may have been too shallow over most of the sand core to elicit a measurable response. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 487-496, 1997.
先前，人们已经从两个基本的输运系数（随机游动系数和趋化感应灵敏度系数）的角度来描述液体介质中趋化细菌的迁移。为了对多孔介质中的迁移进行建模，我们已经表明，这些出现在宏观平衡方程中的系数，可以被有效值所替代，这些有效值反映了多孔介质对单个细菌游动行为的影响。还推导出了多孔介质和液体介质中系数值之间的显式关系。这种对细菌迁移的定量分析对于预测地下环境中细菌种群的分布是必要的，例如在原位生物修复中，细菌会对它们降解的污染物产生趋化感应。我们根据我们的数学模型，对文献中报道的两个不同实验研究中的细菌穿透沙柱的时间进行了分析，以评估有效输运系数。结果表明，多孔介质的存在使细菌群体的随机游动性降低，降低的幅度与理论预测相当。由于在实验研究中没有观察到趋化感应，我们无法确定多孔介质对趋化感应灵敏度系数的影响。然而，该数学模型对于解释为什么在实验研究中没有观察到趋化感应是非常有帮助的。在大部分沙芯中，化学梯度可能太浅，无法引起可测量的响应。
