Solar-driven PHB synthesis from wastewater by engineered semiconductor-bacteria biohybrids

Area of Science:

• Biotechnology
• Environmental Science
• Materials Science

Background:

• Semiconductor biohybrid systems offer sustainable solar-to-chemical conversion.
• Current methods face challenges in eco-friendly nanoparticle synthesis.

Purpose of the Study:

• To develop a sustainable method for producing semiconductor biohybrids using wastewater pollutants.
• To engineer sulfate-reducing bacteria for self-assembly of nanoparticles and enhanced chemical production.

Main Methods:

• Engineered sulfate-reducing bacteria (rSRB-polyhydroxybutyrate/PHB) to self-assemble extracellular polymeric substance (EPS)-complexed nanoparticles via microbial S2--metal bonding.
• Utilized photogenerated electrons from semiconductor biohybrids to drive sulfate reduction and fuel the Wood-Ljungdahl pathway (WLP) for CO2 fixation.
• Leveraged hole-mediated oxidation for simultaneous pollutant degradation and PHB synthesis.

Main Results:

• Achieved a PHB yield of 15.38 g/l through coupled photoredox reactions and carbon flux channeling.
• Demonstrated self-reinforcing cycles enhancing PHB synthesis and pollutant degradation.
• Observed photoelectrons upregulating sulfate metabolism genes, stabilizing metal sulfide production.

Conclusions:

• Developed a novel semiconductor biohybrid system for solar-driven CO2 reduction and organic conversion in wastewater bioreactors.
• Established a sustainable route for pollutant removal, carbon mitigation, and valuable chemical production.
• Advanced low-carbon wastewater treatment and circular bioeconomy through integrated microbial and semiconductor functions.