Electricity generation from paddy soil for powering an electronic timer and an analysis of active exoelectrogenic bacteria

In farmlands, most electronic devices have no connection to a power source and have to work on batteries. To explore paddy soil as an in situ power source, herein, we in the present study constructed sediment microbial fuel cells (SMFCs) in paddy soil. An open circuit voltage of 1.596 V and a maximum power density of 29.42 mWm^-2 were obtained by serially connecting three SMFCs. Electrochemical impedance spectroscopy showed that the internal resistance which comprised ohmic resistance and anodic and cathodic charge transfer resistance was approximately 400 Ω for each of the three individual SMFCs. We used the serially connected SMFCs to power an electronic timer through a 1 F capacitor. The SMFCs had powered the timer for 80 h until the potential of the SMFCs dropped below 0.936 V. Then, RNA was extracted from anode samples and 16S rRNA was sequenced following reverse transcription. The results showed that the relative abundance of active exoelectrogenic bacteria-associated genera on the anode was 13.03%, 27.78%, and 16.17% for the three SMFCs with Geobacter and Anaeromyxobacter being the dominant genera. Our findings provide the possibility of powering electronic devices in the field by using soil as a power source.