Extracellular electron transfer from cathode to microbes: application for biofuel production

Area of Science:

• Microbiology
• Bioelectrochemistry
• Biotechnology

Background:

• Extracellular electron transfer (EET) in microorganisms is key to bioelectrochemical systems.
• Anodic EET (microbe to anode) generates current; cathodic EET (cathode to microbe) consumes current for biosynthesis.
• Gram-positive bacteria may use membrane-bound complexes for electron uptake, unlike cytochrome c-dependent pathways.

Purpose of the Study:

• To explore the application of cathodic extracellular electron transfer for microbial production of valuable biochemicals.
• To investigate methods for enhancing microbial cathodic electron uptake.
• To demonstrate the potential of electrofermentation for producing reduced compounds.

Main Methods:

• Utilizing exoelectrogenic bacteria (e.g., Shewanella, Geobacter) in bioelectrochemical systems.
• Modifying cathode surfaces with chitosan or porous scaffolds to improve interfacial area and charge.
• Applying cathodic electron transfer to drive microbial metabolic pathways for biosynthesis.

Main Results:

• Cathodic electron transfer can be harnessed for microbial production of biochemicals.
• Cathode modifications (chitosan, 3D scaffolds) enhanced current consumption.
• Electrofermentation shifted metabolic pathways, favoring alcohol production over acids.
• Potential for electrofuel generation via artificial photosynthesis was highlighted.

Conclusions:

• Microbial cathodic extracellular electron transfer is a viable strategy for bioelectrochemical synthesis.
• Optimized electrode interfaces can significantly improve electron uptake efficiency.
• Electrofermentation offers a novel route for producing reduced compounds and potentially electrofuels.