An electrochemical system for the rapid and accurate quantitation of microbial exoelectrogenic ability

Microbial extracellular electron transfer (EET) plays a vital role in globally important environmental phenomena, including bioremediation, bioenergy generation, and biofuel production. The quantitation of microbial exoelectrogenic ability is fundamental to studying the process of EET. However, there is no accurate and time-saving protocol to directly evaluate EET ability, hindering our understanding and application of EET. In this work, we proposed an accurate and rapid quantitation system for measuring EET ability using a gold-coated membrane filter as a working electrode. The quantitation signals could be recorded within 1 h and accurately normalized by the number of cells with outstanding repeatability and reproducibility. Further, this method could be distinguished microbial direct EET performances of different growth stages, and the results showed the middle logarithmic growth stage of Shewanella onedensis MR-1 had the best electrochemical activity. This method can be widely used for different types of electroactive microorganisms, including gram-negative bacteria, gram-positive bacteria, and fungi. Due to its time savings, accurate quantification and easy operation, this method provides a standard way to assess the role of EET ability.