Calibration of the ion microsensor
Prior to the flux measurement, the microsensor were calibrated with cultural media having different
concentrations of Ca2+ , 0.1 mM and 0.01 mM① respectively. Only microsensor
with a Nernstian slope >22② mV/decade were used in this study. The same microsensor
were calibrated again according to the same procedure and standards after each test. Data was discarded if the post-test calibrations failed. 说明：
Calibration of oxygen microsensor
The oxygen microsensor was calibrated with nitrogen-saturated and common cultural media.