Figure 3. Validation of the dual GFP-luxCDABE reporter system.

(a) Structure of the reporter systems used. In the three cases, the expression of the different reporters is triggered by a lacI^q-Ptrc expression system [28]. Plasmid pGLR2-Ptrc has the dual reporter system, while in pLUX-Ptrc, only the luxCDABE operon is present. Additionally, in the pGFP-Ptrc plasmid, GFP alone is placed under the control of the lacI^q-Ptrc system. (b) and (c) Comparison of reporter performances in response to IPTG. Overnight-grown cells were diluted 1∶20 in fresh M9 minimal media with 1 mM of IPTG. After 4 h of induction, promoter activities were calculated by normalizing the reporter signal (RLU or fluorescence) to the OD₆₀₀. In this sense, promoter activity represents RLU/OD₆₀₀ in (b) and fluorescence/OD₆₀₀ in (c). Vertical bars represent the standard deviation calculated from four technical replicates.