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Microbial Methane Conversion to Short-Chain Fatty Acids Using Various Electron Acceptors in Membrane Biofilm Reactors
Hui Chen1, Jinghuan Luo1, Shuai Liu1
1Advanced Water Management Centre , The University of Queensland , St Lucia , Queensland 4072 , Australia.
Environmental Science & Technology
|October 9, 2019
Summary
This study explored electron acceptors for methane bioconversion into valuable short-chain fatty acids (SCFAs). Low oxygen rates proved most effective, yielding diverse microbial communities for future chemical production.
Area of Science:
- Biotechnology
- Environmental Science
- Microbiology
Background:
- Vast methane reserves necessitate conversion to value-added chemicals due to projected crude oil shortages.
- Methane bioconversion offers a sustainable alternative to petroleum-based chemical markets and transportation fuels.
- Limited understanding exists regarding the microbial processes and optimal conditions for methane bioconversion.
Purpose of the Study:
- To identify potential electron acceptors supporting methane bioconversion to short-chain fatty acids (SCFAs).
- To investigate the microbiological features associated with methane bioconversion under different electron acceptor conditions.
- To determine the most favorable conditions for efficient SCFA production from methane.
Main Methods:
- Four membrane biofilm reactors (MBfRs) were operated using nitrate, nitrite, low-rate oxygen, and high-rate oxygen as electron acceptors.
- Methane bioconversion to SCFAs was quantified under each condition.
- Microbial communities were characterized to understand the diversity of bioconversion pathways.
Main Results:
- All tested electron acceptors facilitated methane bioconversion to SCFAs, with rates ranging from 1.1 to 36.7 mg acetate L-1 d-1.
- Carbon efficiency varied from 7.9% to 148.5%, with efficiencies over 100% indicating CO2 assimilation.
- A low oxygen supply rate (46.4 ± 2.3 mg O2 d-1 m-2) was optimal for SCFA production and carbon utilization efficiency.
- Distinct microbial communities developed in each reactor, suggesting diverse bioconversion pathways.
Conclusions:
- Methane bioconversion to SCFAs is feasible with various electron acceptors, including nitrate, nitrite, and oxygen.
- Optimizing electron acceptor supply, particularly low-rate oxygen, enhances SCFA production and carbon efficiency.
- The evolution of diverse microbial communities highlights the potential for developing novel biotechnological routes for methane valorization.
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