Development of a whole-cell biosensor for detection of pyocyanin based on a transcriptional regulation factor

The infection caused by multidrug-resistant bacteria Pseudomonas aeruginosa is a huge challenge in biomedical treatment, and early identification of pathogen P. aeruginosa has guiding significance for patient treatment. Pyocyanin (PYO) is a virulence factor uniquely secreted by the P. aeruginosa, thus valuable information about the presence of P. aeruginosa and the patient's infection progression status can be revealed through detection of PYO (the biomarker of P. aeruginosa infection) in clinical samples. Herein, we developed a unique and convenient whole-cell biosensor for PYO based on a transcriptional regulator (BrlR) responding to PYO. The input signal of this biosensor is the concentration of PYO, and the output signal is the intensity of fluorescent protein. The characteristic curve of the biosensor fitted well with the hill equation (R2 =0.9911), and the limit of detection (LOD, S/N = 3) of PYO estimated from the whole-cell biosensor calibration curve was 1.3 μM, lower than the concentration range currently used for clinical detection and required only about 1/4 of current detection time. Moreover, this biosensor exhibits good reliability, repeatability, and reproducibility in detecting PYO concentration of biological samples. The biosensor we developed here can be used to detect PYO content in infected patients conveniently, sensitively, and inexpensively, paving the way for early warning of severe P. aeruginosa infections.