Functional characterization of Gram-negative bacteria from different genera as multiplex cadmium biosensors

Publication date: 15 August 2017
Source:Biosensors and Bioelectronics, Volume 94
Author(s): Lara Bereza-Malcolm, Sanja Aracic, Ruban Kannan, Gülay Mann, Ashley E. Franks
Widespread presence of cadmium in soil and water systems is a consequence of industrial and agricultural processes. Subsequent accumulation of cadmium in food and drinking water can result in accidental consumption of dangerous concentrations. As such, cadmium environmental contamination poses a significant threat to human health. Development of microbial biosensors, as a novel alternative method for in situ cadmium detection, may reduce human exposure by complementing traditional analytical methods. In this study, a multiplex cadmium biosensing construct was assembled by cloning a single-output cadmium biosensor element, cadRgfp, and a constitutively expressed mrfp1 onto a broad-host range vector. Incorporation of the duplex fluorescent output [green and red fluorescence proteins] allowed measurement of biosensor functionality and viability. The biosensor construct was tested in several Gram-negative bacteria including Pseudomonas, Shewanella and Enterobacter. The multiplex cadmium biosensors were responsive to cadmium concentrations ranging from 0.01 to 10µgml⁻¹, as well as several other heavy metals, including arsenic, mercury and lead at similar concentrations. The biosensors were also responsive within 20–40min following exposure to 3µgml⁻¹ cadmium. This study highlights the importance of testing biosensor constructs, developed using synthetic biology principles, in different bacterial genera.



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