Microbial Electrosynthesis Reshapes Energy Metabolism and Physiology in
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
ABSTRACT Microbial electrosynthesis (MES) enables a variety of microorganisms, particularly acetogens, to utilize electrical energy in the form of electrons to produce valuable compounds from CO. In the closely related process of gas fermentation, hydrogen gas (H) is provided as the energy source, whereas in MES, His produced in situ via water electrolysis. Despite the potential of MES for energy and carbon storage, it still faces major limitations, like low efficiency and low‐value products. Here, we identify key limitations of the model MES biocatalystthrough comparative transcriptomics, proteomics, and electron microscopy in both processes. We show that cell integrity is severely impaired in MES, consistent with membrane depolarization hampering ATP synthesis. The struggle for ATP is compensated for by activating arginine catabolism to produce ATP, a reaction that is likely fueled by cyanophycin degradation. Diversion of the Wood‐Ljungdahl pathway toward the glycine synthase‐reductase pathway (GSRP) resulted in a broader spectrum of reduced products, including the two amino compounds ethanolamine and glycine, which appeared exclusively under the electrochemical environment. Additionally, we observed strong induction of bacterial microcompartments, raising questions about their role during MES. This work demonstrates that MES drivesinto a distinct physiological state that challenges cellular fitness and expands our understanding of MES. Microbial electrosynthesis drivesinto
Abstract
ABSTRACT Microbial electrosynthesis (MES) enables a variety of microorganisms, particularly acetogens, to utilize electrical energy in the form of electrons to produce valuable compounds from CO. In the closely related process of gas fermentation, hydrogen gas (H) is provided as the energy source, whereas in MES, His produced in situ via water electrolysis. Despite the potential of MES for energy and carbon storage, it still faces major limitations, like low efficiency and low‐value products. Here, we identify key limitations of the model MES biocatalystthrough comparative transcriptomics, proteomics, and electron microscopy in both processes. We show that cell integrity is severely impaired in MES, consistent with membrane depolarization hampering ATP synthesis. The struggle for ATP is compensated for by activating arginine catabolism to produce ATP, a reaction that is likely fueled by cyanophycin degradation. Diversion of the Wood‐Ljungdahl pathway toward the glycine synthase‐reductase pathway (GSRP) resulted in a broader spectrum of reduced products, including the two amino compounds ethanolamine and glycine, which appeared exclusively under the electrochemical environment. Additionally, we observed strong induction of bacterial microcompartments, raising questions about their role during MES. This work demonstrates that MES drivesinto a distinct physiological state that challenges cellular fitness and expands our understanding of MES. Microbial electrosynthesis drivesinto a distinct stress‐associated physiological state, different from gas fermentation. Comparative multi‐omics and electron microscopy reveal physiological constraints that help explain the poor performance of MES. graphical