Fig. 1
a Fluorescence intensity/OD600 of various B. subtilis strains in microtiter plates. Strains were grown in LB supplemented with 1.0% glucose and 0.1 mM IPTG under the same culture condition (37 °C, 220 rpm). Fluorescence intensity and OD600 were recorded by microplate reader every 15 min, the numbers on the x-axis represent the time points. We calculated the relative value of GFP expression level by using the formula: GFP fluorescence intensity/OD600. Experiments were performed in triplicate, but for clarity, only one representative line of the mean value is shown. b Visualization of green fluorescent protein production in B. subtilis by fluorescence microscopy. The overnight pre-culture was diluted to OD600 of 0.1 in fresh production medium (LB, 1.0% glucose, 0.1 mM IPTG). Subsequently, the mixture was incubated in flasks at 37 °C, 220 rpm for 5 h, and then the culture was immediately taken for fluorescence microscopy