(115c) Population Dynamics of Microalgae

One of the distinctive features of cell-division of microalgae is that various single-cells can divide into different numbers although they are from the same species. This has led us to study the population dynamics of the microalgae starting from single and multiple cells. The goal was to see how the population of algae cells changes over time, or if the daughter cells divide into same numbers as do the mother cells, and if it is possible to artificially select a high-growing algae cell colony. We have investigated the population dynamics of Chlorella vulgaris in nano-liter scale static droplet array in PDMS microfluidic chip. Each of the droplets in the chip mimicked a batch bioreactor. The change of number of cells was observed until the growth of the cells reached to a stationary phase. We found that a single Chlorella vulgaris cell can divide into 3, 4, 5, 6, and 16 cells. There is a significant heterogeneity in the population dynamics even if the initial cell numbers are the same. We also have observed that the daughter cells do not divide into same numbers as do the mother cells. Currently, using a dynamic droplet generation method, we are developing a method of isolating algae cells that divide into higher number of cells.