Fig. 2.

Effect of methanol on fluorescein leakage in droplets. a Histogram of nonfluorescent droplets only containing BMMY medium with 1% methanol. b Histogram of fluorescent droplets generated from 40 h reaction solution of cellulase in BMMY medium with 1% methanol and 20 μM fluorogenic substrate FCB. c Histogram of a binary mixture of nonfluorescent and fluorescent droplets at a 10:1 mixing ratio. d A typical recording of fluorescence signals when detecting the binary droplet mixture. e Fluorescence microscopy image of the binary droplet mixture. Droplets were incubated at 30 °C for 48 h. All histograms show approximately up to 10,000 droplets