Many chemotaxis assays allow for the assessment of bacterial chemotaxis by determining the number of cells migrating toward a chemoattractant or away from a chemorepellent. Some of these assays use a capillary filled with a chemoeffector/agarose mixture to allow cells to accumulate at the mouth of the capillary. Subsequently, assumptions about the relative strengths of chemotaxis strength are based on visual comparisons. Here, we describe a modification of this assay that uses a hydrogel matrix to enable quantitative time-course measurements by analyzing image pixel intensities. This approach allows a high-throughput method when coupled with the aid of a motorized microscope stage.
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This study was supported by National Science Foundation grant MCB-1253234. We are indebted to Bahareh Behkam for sharing the Zeiss Axio Observer Research microscope and the Omnicure S1000 UV light source, and to Aziz Mahama Traore for training in hydrogel capillary fabrication.
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