The pH of the mouth drops several times per day after mealtimes, which results in severe tooth decay over time if not addressed. One way to combat this problem is to engineer the microbiome of the mouth to respond dynamically to changes in pH. To enable this, here we present the development of a novel dual-state promoter for the detection of and response to pH fluctuations in the mouth has been started.

This novel transcription regulation element will be capable of having both constitutive and inducible activity. This is achieved by linking a constitutive promoter downstream a pH-inducible promoter. We plan to characterize our dual-state promoter by first linking single promoters upstream green fluorescent protein (GFP) and assess the transcriptional activity via fluorescence assays. This will be followed by assays on the dual-state promoter.

The hypothesis is that the pH-inducible promoters will have minimal activity at a neutral pH, with an intense activity as the pH nears and crossed the cavity formation threshold. Furthermore, it is hypothesized that the constitutive promoters will have a constant activity, independent of pH. The dual-state promoter construct is hypothesized to have the combined effect of both of the promoters, with a constant basal expression as well as a pH-inducible response. This technology will have future applications in any system requiring pH detection and response.