The promoter and RBS combinations were characterised by measuring the expression of fluorescent proteins in B. subtilis. Cultures of B. subtilis transformed with the test constructs and non-transformed B. subtilis (control) were grown to the mid-log phase. Fluorescence and O.D.600 were both measured using a plate reader to generate fluorescence levels of the various samples. To make this data more generic, the fluorescence data were normalized to cell number using the O.D.600 and a calibration curve of O.D.600 vs colony forming units, as explained in the diagram below:
This calibration curve allowed us to produce the final data as shown below. The following graph clearly shows that B. subtilis transformed with GFP and RFP BioBricks are fluorescing at the corresponding excitation and emission wavelengths.