Pyocyanin: the electrical connection between bacteria and microchips

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Lyn Venken, Wolfgang Eberle, Kathleen Marchal, Jos Vanderleyden

Centre of Microbial and Plant Genetics, Belgium

Recent developments demonstrate that the combination of microbiology with micro- and nanoelectronics is a successful approach to develop new miniaturized sensing devices and other biochip technologies. In the last decade, there is a shift from the optimization of the abiotic components, e.g. the chip, to the improvement of the processing capabilities of cells through genetic engineering. The multidisciplinary approach of synthetic biology will not only give rise to systems with new functionalities, but will also improve the robustness and speed of their response towards applied signals. In this project, we aim to illustrate the potential of integrating microbiology with microdevices by the development of a new biological part that allows transfer of information from bacteria to microchips by means of electrical signalling. In order to obtain electrical signalling between bacteria and micro-electronic devices, we exploit the redox cycling behaviour of electron shuttles. In the first stage of this project, pyocyanin, an electron shuttle produced by Pseudomonas aeruginosa, was selected as an appropriate electron signal to establish the electrical connection between bacteria and microchips since it’s possible to detect pyocyanin in bacterial cultures in a quantitative manner with microchip-based detection techniques. By introducing the biosynthesis pathway of pyocyanin in Escherichia coli, bacterial biosensor cells are capable of producing pyocyanin in a dose-response manner when detecting a specific analyte. Although pyocyanin is proven to be an accurate molecule to establish an electrical connection between bacteria and microelectronic devices, the production of pyocyanin by E. coli requires further optimization. Therefore, pyocyanin production is further optimized in this study by tackling the toxicity of pyocyanin through an evolutionary approach. When pyocyanin production by E. coli and pyocyanin detection with the microelectronic system is fully characterized, pyocyanin can be exploited as a new reporter molecule in bacterial biosensors and used to develop novel microchip-based biosensors.