Acetate Shock Loads Enhance CO Uptake Rates of Anaerobic Microbiomes

Area of Science:

• Biotechnology and Bioengineering
• Environmental Microbiology
• Renewable Energy

Background:

• Pyrolysis of lignocellulosic biomass yields syngas (CO, CO2, H2) and acetate-rich wastewater.
• Integrating these streams via co-fermentation offers resource circularity and reduced fossil fuel dependence.
• Understanding microbial resilience and product formation under varying conditions is crucial for process optimization.

Purpose of the Study:

• To evaluate the impact of increasing acetate shock loads on syngas co-fermentation.
• To assess the influence of different pH levels (6.7 and 5.5) and temperatures (37°C and 55°C) on microbial community composition and metabolite production.
• To identify microbial candidates responsible for substrate conversion and product formation.

Main Methods:

• Co-fermentation of syngas with anaerobic microbiomes under controlled pH and temperature.
• Exposure to increasing acetate shock loads up to 64 g/L.
• Analysis of substrate consumption, metabolite production, and microbial community composition using molecular techniques.

Main Results:

• Anaerobic microbiomes demonstrated remarkable resilience, converting syngas even at high acetate concentrations (up to 64 g/L) and pH 5.5.
• Process parameter modifications (pH, temperature, acetate load) induced shifts in microbial communities and product profiles.
• Acetate supplementation consistently increased carboxydotrophic conversion rates by up to 20-fold, particularly at pH 5.5 and 55°C.

Conclusions:

• Anaerobic microbiomes are robust and adaptable to integrated syngas and wastewater streams.
• Optimizing pH, temperature, and acetate loads can steer microbial activity towards desired products and enhance conversion efficiency.
• This study supports the integration of process streams for enhanced resource circularity and reduced environmental impact.