Mediated bioelectrochemical system for biosensing the cell viability of Staphylococcus aureus

Abstract

Staphylococcus aureus is one of the most dangerous human pathogens and is the cause of numerous illnesses ranging from moderate skin infections to life-threatening diseases. Despite advances made in identifying microorganisms, rapid detection methods for the viability of bacteria are still missing. Here, we report a rapid electrochemical assay for cell viability combining the use of double redox mediators and multiwall carbon nanotubes-screen printed electrodes (MWCNTs-SPE), ferricyanide (FCN) and 2,6-dichlorophenolindophenol (DCIP), which served as electron shuttle to enable the bacterial-electrode communications. The current originating from the metabolically active cells was recorded for probing the activity of the intracellular redox centers. Blocking of the respiratory chain pathways with electron transfer inhibitors demonstrated the involvement of the electron transport chain in the reaction. A good correlation between the number of the metabolically active cells and the current was obtained. The proposed assay has been exploited for monitoring cell proliferation of S. aureus during the growth. The sensitivity of the detection method reached 0.1 OD600. Therefore, the technique described is promising for estimating the cell number, measuring the cell viability, and probing intracellular redox center(s).

Bioelectrochemical Systems for Measuring Microbial Cellular Functions

“…As shown in Figure , there are three independent bioelectrochemical approaches (direct detections, mediated detections, or labeling‐based detections) have been established , –, . Applying of biological recognition elements, such as cofactors, antibodies, microbes, organelles, tissues or high organisms cells .…”

“…evaluated the performance of activated sludge as a source of microbial community that provides a direct oxidation of organic substrates with a sustainable current output. In that system, the electrochemical signals were originated only from the metabolically active microbes . Cell viability, cultivation time, type, and concentration of the degradable organic substrates have been identified as major regulators for the electrocatalytic functions.…”

“…For the electrochemically‐inactive organisms, the direct communication with the electrode is not possible. Therefore, exogenous agents (artificial redox mediators) are required to wire the microbe‐electrode interactions through what is known as mediated electron transfer (MET) system .…”

“…Thus, as shown in Figure , the MET can be obtained using exogenous redox compounds (artificial electron shuttles) . MET is the most common BES, and its mechanism is clear, therefore, its use for the detection of microbes has been widely applied .…”

“…Using the double mediator systems was proven more efficient than using thee single‐mediator . In harmony with that, Hassan and Wollenberger 2015 designed a mediated approach using DCIP/ ferricyanide (FCN) for probing the viability and studying the intracellular redox activity of Staphylococcus aureus . In this study, it was demonstrated that the use of a single hydrophilic mediator such as ferricyanide was not able to wire the living bacterial cells with the electrode surface.…”