Plate-Based Kinetic Fluorescence Tests for High-Throughput Screening of Electrochemically Active Bacteria

Electrochemically active bacteria (EAB) have attracted considerable attention in various fields, such as wastewater treatment, energy recovery, and biogeochemistry. However, a rapid, simple, and precise method for the selection of EAB remains a challenge because of the lack of sensitive probes and rapid analytical methods. To solve this problem, riboflavin was adapted as a fluorescent probe and a program was designed to evaluate the extracellular electron transfer (EET) ability using kinetic fluorescence data. With this method, the EET abilities of 1152 strains isolated from environmental sources, including a municipal wastewater treatment plant, freshwater lake sediments, and submarine sediments, were tested, and 49 strains were identified as EAB. Hence, the results provide new insights into the abundance and roles of strains of EAB in different environmental and engineered water samples. Taken together, we developed a simple and practical method for quantitative evaluation of the EET ability of microbes and further rapid screening of EAB from environments.