S. elongatus was cultured in test tubes under 5% CO2 until
OD730 = 0.8. To make the 5% CO2 environment, Anaero PackCO2
(Mitsubishi Gas Chemical Company, Inc., Tokyo, Japan) was used.
The culture was diluted in BG11 at 1 cell per 100 nL (104 cells/mL).
Droplets were prepared by laying 1mL cell suspension on a glass
slide printed with highly water-repellent mark (high-density
amino group introduction coat, 570 holes of 1mm in diameter,
480mm spaces between holes; Matsunami Glass, Osaka, Japan).
Due to the patterning of the hydrophobic area (spacing between
holes) and hydrophilic area (holes), droplets were formed. Based
on the number of cells in a droplet and the cell concentration of the
suspension, the volume of one droplet was approximately 100 nL.
After the glass slidewas covered with oil, the cells were cultured in
micro-compartmentalized droplets for four days