Acetogenic bacteria utilize light-driven electrons as an energy source for autotrophic growth

Area of Science:

• Microbiology
• Biotechnology
• Artificial Photosynthesis

Background:

• Acetogenic bacteria convert CO2 to acetate via the Wood-Ljungdahl (WL) pathway.
• Redox energy for this process can be supplied by H2 or inorganic materials like semiconductors.
• Developing sustainable CO2 conversion methods is crucial for environmental applications.

Purpose of the Study:

• To investigate the mechanism of CO2 conversion by acetogenic bacteria using light-induced electrons from nanoparticles.
• To develop a nanoparticle-microbe hybrid system for enhanced CO2 fixation.
• To explore the potential of artificial photosynthesis using engineered bacteria.

Main Methods:

• Development of a hybrid system with cadmium sulfide nanoparticles (CdS-NPs) on *Clostridium autoethanogenum*.
• Transcriptional analysis to understand gene expression under CdS-driven autotrophic conditions.
• Assessing CO2 fixation rates with and without cofactor addition under light exposure.

Main Results:

• The hybrid system efficiently converted CO2 to acetate using only light-induced electrons from CdS-NPs.
• Genes for metal ion/flavin-binding proteins and the WL pathway were upregulated.
• Addition of cofactors enhanced CO2 fixation rates under light.

Conclusions:

• Acetogenic bacteria can utilize light-induced electrons from nanoparticles for CO2 fixation.
• The study elucidates the molecular mechanisms involved in this artificial photosynthesis process.
• This approach shows promise for improving the efficiency of bio-based CO2 conversion systems.