Quantitative measurement of pH influence on SalR regulated gene expression in Acinetobacter baylyi ADP1

The influence of medium pH conditions on regulation of the sal operon was quantitatively measured by using a genetically engineered Acinetobacter baylyi ADP1 strain ADPWH_lux. Live-cell based bioluminescence assays determined that the SalR, a LysR-type transcriptional regulator (LTTR), functioned in a range of medium pH conditions. During exponential growth, SalR regulated bioluminescence production peaked at the neutral pH and tolerated medium pH changes of 5.5–9.0. In the stationary phase, the SalR regulated gene expression reached 20–35% of the maximum productivity during the exponential phase. This report reveals the influence of pH conditions on a LTTR system and demonstrates that the biosensor strain can be a useful tool for understanding transcriptional regulations in different environments.