Enhanced microbial electrosynthesis by using defined co-cultures.

Area of Science:

• Microbial Physiology
• Electrochemistry
• Synthetic Biology

Background:

• Microbial uptake of cathodic electrons is crucial for electrosynthesis but often requires high overpotentials or yields low rates.
• Current methods for producing sustainable fuels and chemicals via microbial electrosynthesis face limitations in efficiency.

Purpose of the Study:

• To investigate defined co-cultures for efficient microbial electrosynthesis.
• To explore the use of interspecies hydrogen transfer for cathodic electron uptake.
• To overcome limitations of high overpotentials and low reaction rates in electrosynthesis.

Main Methods:

• Utilized a co-culture system with Fe(0)-corroding strain IS4 for cathodic electron uptake.
• Employed Methanococcus maripaludis and Acetobacterium woodii for hydrogenotrophic synthesis of methane and acetate.
• Investigated electron uptake and synthesis rates at varying cathodic potentials (-400 mV and -500 mV vs SHE).

Main Results:

• IS4-M. maripaludis co-cultures achieved electromethanogenesis rates of 0.1-0.9 μmol cm⁻² h⁻¹.
• IS4-A. woodii co-cultures produced acetate at rates of 0.21-0.74 μmol cm⁻² h⁻¹.
• Defined co-cultures demonstrated effective electron transfer via interspecies hydrogen production and consumption.

Conclusions:

• Defined co-cultures coupling cathodic electron uptake with synthesis reactions via interspecies hydrogen transfer offer a viable engineering strategy.
• This approach can significantly improve the efficiency of microbial electrosynthesis for sustainable fuel and chemical production.
• The study lays the foundation for optimizing microbial electrosynthesis processes.