Amplification of chemotactic responses of motile bacterial cells for characterizing preferential chemotaxis toward carbon sources

A novel microfluidic device is described that can detect the chemotactic response of motile bacterial cells (Escherichia coli) that swim toward a preferred nutrient with high resolution by sorting and concentrating them. The device consists of the typical Y-shaped microchannels that have been widely used in chemotaxis studies to attract cells toward a high concentration and a concentrator array integrated with arrow head-shaped ratchet structures beside the main microchannel to trap and accumulate them. Since the number of accumulated cells in the concentrator array continuously increases with time, the device makes it possible to amplify the chemotactic responses of the cells to 10 times greater than that in the typical Y-shaped channels in 60 min. In addition, the device can characterize the chemotactic sensitivity of chemoreceptors to chemoeffectors by comparing the number of cells in the concentrator array at different distances from the channel junction. Since the device allows the analysis of the chemotactic responses and sensitivity of chemoreceptors with high resolution, we believe that not only can the device be broadly used for various microbial chemotaxis assays but it also can further the advancement of microbiology and even synthetic biology.