| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 107 === In this work, we used a microfluidic device to produce various nutrient field from a point source for comparisum, and study the chemotactic behavior of K. veneficum (CCMP426). Planktonic cells are introduced after starving for 6 hours and placed in the culture medium or seawater.The microfluidic device comprised a T channel and a nutrient channel. Nutrient is injected with different volumetric flow rate and concentration so that the distribution of nutrient in the T channel is varied.
The results show that higher density of starving K. Veneficum can be found in the regions of high nutrient concentration and concentration gradient when they are originally introduced in seawater with supplied to the nutrient channel.When the source of nutrient increases to 5X or 10X and is delivered at higher flow rate, planktonic cells start to exhibit negative chemotaxis, beacuase the difference osmotic pressure between inner and outer cell. The results show that starving planktonic cells seek for high concentration of nutrient up to a certain level, but tend to avoid regions with extra-high concentration. The increased volumetric flow rate will effect on the density of the planktonic cells significantly, due to the disturbance of the T channel and the increased concentration in overall space.
When the plankton cells without starvation in the original culture medium (1X), it has higher sensitivity to react environment changing, and the difference of planktonic density at different local concentrations or concentration gradients is more obvious. The density of planknic cells also varies with different concentration of nutrients obviously.
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