Engineering Microbial Consortia for High-Performance Cellulosic Hydrolyzates-Fed Microbial Fuel Cells.

Area of Science:

• Bio-electrochemical systems
• Microbial fuel cells (MFCs)
• Synthetic biology

Background:

• Microbial fuel cells (MFCs) offer eco-friendly electricity generation from biomass.
• Key sugars like glucose and xylose from cellulose hydrolysates are ideal MFC substrates.
• Well-studied exoelectrogens like *Shewanella oneidensis* cannot directly metabolize glucose or xylose.

Purpose of the Study:

• To engineer a microbial consortium for efficient electricity generation from glucose and xylose in MFCs.
• To enhance substrate utilization and extracellular electron transfer (EET) for increased power density.
• To utilize corn stalk hydrolysates as a sustainable feedstock for MFCs.

Main Methods:

• Designed a *Klebsiella pneumoniae*-*S. oneidensis* microbial consortium.
• Engineered *K. pneumoniae* to convert glucose/xylose to lactate by deleting ethanol/acetate pathways and expressing lactate dehydrogenase and transporter genes.
• Enhanced *S. oneidensis* EET by expressing a biosynthetic flavins pathway from *Bacillus subtilis*.
• Optimized glucose and xylose feeding ratios.

Main Results:

• The engineered consortium achieved a maximum power density of 104.7 ± 10.0 mW/m², a 7.2-fold increase compared to the wild-type consortium (12.7 ± 8.0 mW/m²).
• The modified *S. oneidensis* exhibited improved adhesion and accelerated flavin-mediated EET.
• MFCs using corn straw hydrolysates with the synthetic consortium yielded a power density of 23.5 ± 6.0 mW/m².

Conclusions:

• The engineered microbial consortium effectively harnesses glucose and xylose for electricity production in MFCs.
• Genetic modifications significantly enhanced both substrate conversion and electron transfer efficiency.
• This approach demonstrates a promising strategy for sustainable bioenergy generation from lignocellulosic biomass.