Cloud-based Smartphone-Assisted Chemiluminescent Assay for Rapid Screening of Electroactive Bacteria

Electroactive bacteria (EAB) can transfer electrons to exocellular solid acceptors and have widespread applications in the fields of pollutant degradation, biosynthesis, and hydrogen generation. Traditional EAB screening methods can precisely measure the bacterial extracellular electron transfer ability, but they suffer from time-consuming and labor-intensive procedures. The chemiluminescence technique is effective for the rapid detection of hemoglobin but has not been applied for EAB screening. Herein, we utilized a chemiluminescent assay to identify EAB through a multiheme c-type cytochrome (c-Cyt) triggered chemiluminescent reaction. The multiheme c-Cyts-triggered chemiluminescence was conveniently determined by taking photographs with commercial smartphones and cloud-based computing. The acquired image signal shows a significant and linear relationship with the bacterial concentration. Measurement results of the chemiluminescence intensity triggered by different bacterial species with the proposed method are strongly associated with those of the microplate reading method (Pearson’s r of 0.9795; P < 0.01) and dissimilatory Fe(III) reduction method (Pearson’s r of 0.9628; P < 0.01). Furthermore, this cloud-based and smartphone-assisted chemiluminescent assay is instrument-free and easy to operate, and results can be obtained within 2 min. The findings demonstrate that the proposed method can effectively detect EAB. Therefore, it will be an alternative approach for EAB screening and can have promising applications in microbiology, environmental science, and bioenergy.