MerR‐fluorescent protein chimera biosensor for fast and sensitive detection of Hg²⁺ in drinking water

Abstract

Mercury ion (Hg2+) is a universal pollutant and its detection is crucial for public healthcare. In this study, we developed a novel fluorescent biosensor by construction of a protein fusion between the mercury‐sensing transcription factor MerR and enhanced yellow fluorescent protein (EYFP). Hg2+‐induced conformational change of MerR was transduced into fluorescence signal. Fluorescence intensity of the biosensor protein decreased with increasing concentrations of Hg2+ and a linear response was obtained in the range of 0.5–40 nM. The limit of detection was 0.5 nM, which was much lower than the maximum allowed level in water. The biosensor specificity was highly dependent on type and concentration of metal ion. The biosensor exhibited high specificity in a mixture of metal ions at 0.5 nM concentration. However, the interference effect was more pronounced at 40 nM concentration of metal ions. The measurement was completed in less than 1 Min with no need for sample preparation or preincubation steps. The biosensor achieved accurate and reliable detection in the spiked drinking water sample, as validated by the inductively coupled plasma optical emission spectrometry.

Review of microbial biosensor for the detection of mercury in water

“…Purified protein‐based biosensors: Different types of non‐enzymatic proteins which include engineered and naturally occurring proteins are used in biosensors for detection purposes. Detection of mercury in potable water is done by designing a merR ‐fluorescent protein biosensor that ensures rapid detection having a linear range between 0.5 to 40 nM and a lowest detectable limit of 0.5 nM (Özyurt et al., 2019). Enzyme‐based biosensors: Different types of enzymes are used as sensors to detect the presence of heavy metals in the environment or water depending upon their activation or inhibition properties.…”