Tailored enzyme expression modifies Shewanella oneidensis biofilms and increases current density.

Area of Science:

• Microbiology
• Bioelectrochemistry
• Biotechnology

Background:

• Biofilm formation is crucial for electron transfer in bioelectrochemical systems.
• Mechanisms of biofilm formation and factors influencing current generation under anoxic conditions are not fully understood.
• Riboflavin has been identified as a quorum sensing molecule in Shewanella oneidensis, promoting biofilm formation and increasing current densities.

Purpose of the Study:

• To investigate the role of specific proteins, WbpP and WbpA, in riboflavin-mediated quorum sensing and biofilm formation.
• To understand how these proteins influence biofilm architecture and current generation in bioelectrochemical systems.
• To elucidate the relationship between protein co-expression and enhanced electron transfer.

Main Methods:

• Utilized optical coherence tomography to analyze biofilm architecture (biovolume, height, porosity).
• Studied the individual and co-expression of UDP-N-acetylglucosamine C4 epimerase (WbpP) and UDP-N-acetyl-D-glucosamine 6-dehydrogenase (WbpA).
• Measured current density generated by biofilms under varying protein expression conditions.

Main Results:

• Individual expression of WbpP or WbpA altered biofilm architecture but did not significantly increase current density.
• Co-expression of WbpP and WbpA doubled the current density, mimicking the effect of riboflavin-mediated quorum sensing.
• Specific changes in biofilm biovolume, height, and porosity were observed with individual protein expression.

Conclusions:

• WbpP and WbpA play a critical role in biofilm formation and electron transfer in Shewanella oneidensis.
• Co-expression of WbpP and WbpA is essential for significantly enhancing current density, suggesting a synergistic mechanism.
• Riboflavin-based quorum sensing likely leads to WbpA and WbpP overproduction, improving anode attachment and current generation.