Bioengineering, a Cadmium Sensing Green Fluorescent Protein, Based Whole-Cell Biosensor From Pseudomonas aeruginosa

Abstract

Heavy metal toxicity is a significant issue due to an increase in industrial waste production, with cadmium being one of the major pollutants. An approach involving homologous cloning was made to bioengineer a microbial cadmium biosensor from a strain of Pseudomonas aeruginosa. The promoter pCadR from P. aeruginosa was cloned into a vector pEGFP-N2 using Gibson assembly. Escherichia coli DH5 alpha strain was used as the host cell, which on sensing cadmium, produced fluorescence using the reporter gene called green fluorescent protein (GFP). The clone, pEGFP-N2CadR, was subjected to increasing concentrations of cadmium chloride to determine the sensitivity. It was observed that pEGFP-N2CadR responded to micromolar concentrations of cadmium chloride; however, it was determined that the biosensor tested it with lead nitrate and copper sulfate solutions had non-specific interactions with other metals. The interaction of the promoter with the metals was weak compared to previous studies, which was attributed to several reasons mentioned in the paper. As the sensor's fluorescent intensities were dull and indistinguishable, it was not classified as a useful cadmium biosensor. Further studies for determining the promoter interaction and affinity towards various metals at varying concentrations are required to validate the results obtained.