Mechanical Energy Drives the Growth and Carbon Fixation of Electroactive Microorganisms

Phototrophy and chemotrophy are two dominant types of microbial metabolism. However, to date, the potential of the ubiquitous and versatile mechanical energy as a renewable energy source to drive the growth of microorganisms has remained unknown and not utilized. Here, we present evidence in favor of a previously unidentified metabolic pathway, in which the electronic energy produced from mechanical energy by the piezoelectric materials is used to support the growth of microorganisms. When electroactive microorganism Rhodopseudomonas palustris (R. palustris; with barium titanate nanoparticles) was mechanically stirred, a powerful biohybrid piezoelectric effect (BPE) enabled sustainable carbon fixation coupled with nitrate reduction. Transcriptomic analyses demonstrated that mechanical stirring of the bacteria–barium titanate biohybrid led to upregulation of genes encoding functions involved in electron and energy transfer in R. palustris. Studies with other electroactive microorganisms suggested that the ability of microbes to utilize BPE may be a common phenomenon in the microbial world. Taken together, these findings imply a long-neglected and potentially important microbial metabolic pathway, with potential importance to microbial survival in the energy-limited environments.