Englert Derek L, Manson Michael D, Jayaraman Arul
McFerrin Department of Chemical Engineering, Texas A&M University, TX, USA.
J Vis Exp. 2010 Apr 19(38):1779. doi: 10.3791/1779.
Chemotaxis allows bacteria to approach sources of attractant chemicals or to avoid sources of repellent chemicals. Bacteria constantly monitor the concentration of specific chemoeffectors by comparing the current concentration to the concentration detected a few seconds earlier. This comparison determines the net direction of movement. Although multiple, competing gradients often coexist in nature, conventional approaches for investigating bacterial chemotaxis are suboptimal for quantifying migration in response to concentration gradients of attractants and repellents. Here, we describe the development of a microfluidic chemotaxis model for presenting precise and stable concentration gradients of chemoeffectors to bacteria and quantitatively investigating their response to the applied gradient. The device is versatile in that concentration gradients of any desired absolute concentration and gradient strength can be easily generated by diffusive mixing. The device is demonstrated using the response of Escherichia coli RP437 to gradients of amino acids and nickel ions.
趋化作用使细菌能够接近吸引性化学物质的来源或避开排斥性化学物质的来源。细菌通过将当前浓度与几秒前检测到的浓度进行比较，不断监测特定化学效应物的浓度。这种比较决定了运动的净方向。尽管自然界中常常同时存在多个相互竞争的梯度，但传统的研究细菌趋化作用的方法在定量研究细菌对吸引剂和排斥剂浓度梯度的迁移反应方面并不理想。在此，我们描述了一种微流控趋化模型的开发，该模型用于向细菌呈现精确且稳定的化学效应物浓度梯度，并定量研究它们对所施加梯度的反应。该装置具有通用性，因为通过扩散混合可以轻松生成任何所需绝对浓度和梯度强度的浓度梯度。利用大肠杆菌RP437对氨基酸和镍离子梯度的反应对该装置进行了演示。
