A gas reporting whole-cell microbial biosensor system for rapid on-site detection of mercury contamination in soils

As optical reporting elements, fluorescent proteins are extensively used in whole-cell microbial biosensors. However, the use of these optical reporters is limited in opaque media such as soil. This study described a method utilizing gas as a reporting signal that could be used for the rapid on-site detection of mercury in soil. In this biosensor, the MerR protein could capture mercury ions and then bind the promoter of the efe gene to initiate the synthesis of the ethylene (C2H4)-forming enzyme that produced the gas. The research showed that the mercury ion concentrations could be converted into C2H4 gas signals, which were quantified using a handheld C2H4 sensor. By optimizing the biosensor to improve its anti-interference ability in the system, it could detect mercury ion concentrations in the soil ranging from 0.2 to 20 mg/kg within 45 min, effectively reflecting whether the mercury pollution in the soil exceeded the limit standard. This study provides a simple, inexpensive, and portable method for the on-site detection of soil pollutants. [Display omitted] •A novel whole-cell microbial biosensor system was constructed to detect the mercury in soil with gas signal.•The anti-interference ability of mercury detection system was improved by introducing a constitutive gas reporting biosensor.•This method could realize the on-site detection of bioavailable mercury in soil without the need for large instruments.•This method could realize the detection of bioavailable mercury in 45 min without the need for a predigestion procedure.