Separation of Motile Euglena Using Microchannel

Euglena is a unique microorganism that combines characteristics of animals and plants and expected as new biofuel and microbial actuator. When the euglena is used for these purposes, high motility cells must be important. Conventionally, when taking out target microorganism , micropipette was used but it was time-consuming and there was a risk of damaging microorganism. In this study, we propose using microchannel to separate motile euglena efficiently and to avoid damaging. In order to achieve this purpose, first, we investigated the behavior of Euglena in flow. We quantitatively evaluated Euglena’s swimming mode and diffusion coefficient in a straight microchannel（width1000µm，hight100µm） using image analysis. We found that as the flow velocity rises，fraction of Euglena which swims parallel in flow increases. In addition, we found that Euglena has rheotaxis. Rheotaxis fraction increases rapidly around flow rate of 80µm/s and decreases over flow rate of 120µm/s. We analyzed Euglena’s diffusion coefficient with Particle Tracking Velocimetry (PTV) using ImageJ. Euglena’s diffusion coefficient rises as the flow velocity increases, but it decreases at flow rate of 60µm/s. This phenomenon seems to be due to Euglena’s rheotaxis. As a summary so far, we found that Euglena was strongly influenced by flow velocity, and the motion depends on the flow rate. Based on these experimental results, we made separating microchannel by soft lithography that using 3D printed mold. As a result, we succeeded in separating motile Euglena which is 12% higher on average swimming speed.