Genetically Boosting Electron Transfer in Electroactive Biofilms for Improved Sensitivity of Microbial Fuel...

Area of Science:

• Microbiology
• Bioelectrochemistry
• Biotechnology

Background:

• Electroactive biofilms (EABs) are crucial for bioenergy, biosensing, and wastewater treatment.
• Inefficient extracellular electron transfer (EET) limits EAB performance, particularly biosensor sensitivity.
• Geobacter sulfurreducens is a key microorganism in natural EABs.

Purpose of the Study:

• To engineer Geobacter sulfurreducens biofilms to enhance extracellular electron transfer (EET).
• To improve the sensitivity and performance of EAB-based biosensors.
• To investigate the molecular mechanisms underlying enhanced EET.

Main Methods:

• Overexpression of cyclic GMP-AMP (cGAMP) synthase in Geobacter sulfurreducens to increase intracellular cGAMP levels.
• Construction and testing of microbial fuel cell biosensors using engineered biofilms.
• Integration of RNA sequencing and quantitative analysis to study gene expression changes.

Main Results:

• Engineered biofilms were thin yet highly conductive, showing a 20-fold improvement in Cd(II) detection limit.
• Increased expression of c-cytochromes and nanowires was observed.
• Reduced exopolysaccharide production was correlated with enhanced EET and biosensor sensitivity.

Conclusions:

• Enhancing intracellular cGAMP levels is a broadly applicable strategy for optimizing EABs.
• This approach significantly improves EET efficiency and biosensor performance.
• The findings advance the development of EAB-based technologies for various applications.