Designing a bacterial biosensor for detection of mercury in water solutions

Authors: AMIR ROOINTAN, NOOSHIN SHABAB, JAMSHID KARIMI, ALIREZA RAHMANI, MOHAMMAD YOUSEF ALIKHANI, MASSOUD SAIDIJAM

Abstract: Due to increasing advances in physical and chemical techniques for the assessment of pollutants in the environment, there is an immediate demand for a bioassay that can report both the presence of an analyte and its biological effects. In accordance with this need, there has been a fast growth in whole-cell biosensor technology. In this study we aimed to design a whole-cell bacterial biosensor to detect mercury in liquid solutions. The Pseudomonas pBS228 merR gene and its related promoter/operator was synthesized by Bioneer. The green fluorescence protein (GFP) gene was used as a reporter. GFP was cloned downstream of the merR gene. The construct, including the merR promoter, gene, and GFP, was cloned in a pUC19 vector and transferred into E. coli BL21 (DE3) bacteria. Transformed bacteria were used as whole-cell biosensors for detecting mercury. Mercury detection was monitored by means of microscopy and fluorometry techniques. Transformed BL21 (DE3) biosensors responded mainly to Hg(II), with the lowest detectable concentration being 10^-8 M during a 3-h exposure induction period. Our results demonstrated that the noninfectious bacterial biosensors developed in the present study could be beneficial and enforceable in detection of mercury in contaminated water samples at concentrations as low as 10^-8 M.

Keywords: merR, mercury, green fluorescent proteins, whole cell biosensors, biosensing techniques

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