Biosensors

• CapR
• DmpR
• HbpR
• HcaR
• HpaR
• NahR
• PaaX
• XylR
• XylS

Biosensor

Biosensor in prokaryotes functions as analytical device for detection, consisting of a detector, a central processor and a reporter. Environmental signals activate the recognition component as an input, the central processor then receives the signal and expresses reporter in response as an output. The detection range of a biosensor is limited but specific. The processing procedure concerning transcription and translation is automatic-controlled by bacteria itself, so it is convenient comparing with chemical method. Additionally, as bio-elements, they have the characteristic of being tunable.
Bacteria living in aromatics-rich environment naturally have aromatic sensors. In Pseudomonas putida, there are XylR detecting toluene, XylS detecting benzoate, and DmpR detecting phenol. In Escherichia coli, there are HcaR detecting phenyl propionic acid, MhpR detecting 3-hydroxyl cinnamic acid and PaaX detecting phenyl acetic acid. These natural sensors function as transcriptional factors regulating expression of downstream genes that degrade aromatic compounds as alternative carbon source. Despite numerous previous studies, the performances of these biosensors are not fully characterized and well-tuned.
Deeply concerned about the hazardous environmental condition, we collected information concerning aromatic sensors from previous papers and focused on constructing biosensors with low basal signal, high induction ration and wide detection range to detect aromatic pollutants in environment.

Hello, zheng pu

After obtaining these sensors’ coding sequence via PCR or synthesis, we constructed an expression system composed of two parts: (Fig 1)
(1) A constitutive Pc promoter linked with sensor’s coding sequence that encodes the regulating protein;
(2) The corresponding inducible promoter located in the front of RBS-sfGFP fluorescence reporter
We tested fluorescence intensity to show induction ratio of each expression system when exposed to their inducers through ELIZA and flow cytometry. Naturally, the performances of these transcriptional factors are not well characterized and needs further tuning to be biosensors.