Adaptation of a microbial community to demand-oriented biological methanation

• Published in: Biotechnology for biofuels and bioproducts Vol. 15; no. 1; p. 125
• Main Authors: Khesali Aghtaei, Hoda, Püttker, Sebastian, Maus, Irena, Heyer, Robert, Huang, Liren, Sczyrba, Alexander, Reichl, Udo, Benndorf, Dirk
• Format: Journal Article
• Language: English
• Published: London BioMed Central 16.11.2022; BioMed Central Ltd; Nature Publishing Group; BMC
• Subjects: Abundance; acetates; Acetic acid; Acetoclastic methanogens; Adaptation; Alternative energy sources; Archaea; Bacteria; Biogas; Biogas upgrade; Biological methanation; biomass; Biomass energy; Biotechnology; Carbon dioxide; Chemistry; Chemistry and Materials Science; Conversion; Efficiency; Electricity distribution; Energy industry; Energy storage; Environmental Engineering/Biotechnology; Feeding; Feeding regimes; Firmicutes; Flexibility; Food chains; Food webs; Gas composition; Gases; hydrogen; Hydrogenotrophic methanogens; Maintenance; Metabolism; Methanation; Methane; methane production; Methanogenic archaea; Methanogenic bacteria; methanogens; Microbial activity; microbial communities; Microbiology; microbiome; Microbiomes; Microorganisms; Oscillations; pH effects; Plant Breeding/Biotechnology; Power to methane; Process controls; Process parameters; Production management; Reactors; Renewable and Green Energy; renewable electricity; Renewable energy; Robustness; Substrates; taxonomy; Germany; Europe; Acetoclastic methanogens; Power to methane; Hydrogenotrophic methanogens; Renewable energy; Metaproteomics; Biological methanation; Biogas upgrade; Hydrogen starvation; Microbial food web
• ISSN: 2731-3654; 2731-3654
• DOI: 10.1186/s13068-022-02207-w

Background Biological conversion of the surplus of renewable electricity and carbon dioxide (CO 2 ) from biogas plants to biomethane (CH 4 ) could support energy storage and strengthen the power grid. Biological methanation (BM) is linked closely to the activity of biogas-producing Bacteria and methanogenic Archaea . During reactor operations, the microbiome is often subject to various changes, e.g., substrate limitation or pH-shifts, whereby the microorganisms are challenged to adapt to the new conditions. In this study, various process parameters including pH value, CH 4 production rate, conversion yields and final gas composition were monitored for a hydrogenotrophic-adapted microbial community cultivated in a laboratory-scale BM reactor. To investigate the robustness of the BM process regarding power oscillations, the biogas microbiome was exposed to five hydrogen (H 2 )-feeding regimes lasting several days. Results Applying various “on–off” H 2 -feeding regimes, the CH 4 production rate recovered quickly, demonstrating a significant resilience of the microbial community. Analyses of the taxonomic composition of the microbiome revealed a high abundance of the bacterial phyla Firmicutes , Bacteroidota and Thermotogota followed by hydrogenotrophic Archaea of the phylum Methanobacteriota . Homo-acetogenic and heterotrophic fermenting Bacteria formed a complex food web with methanogens. The abundance of the methanogenic Archaea roughly doubled during discontinuous H 2 -feeding, which was related mainly to an increase in acetoclastic Methanothrix species. Results also suggested that Bacteria feeding on methanogens could reduce overall CH 4 production. On the other hand, using inactive biomass as a substrate could support the growth of methanogenic Archaea . During the BM process, the additional production of H 2 by fermenting Bacteria seemed to support the maintenance of hydrogenotrophic methanogens at non-H 2 -feeding phases. Besides the elusive role of Methanothrix during the H 2 -feeding phases, acetate consumption and pH maintenance at the non-feeding phase can be assigned to this species. Conclusions Taken together, the high adaptive potential of microbial communities contributes to the robustness of BM processes during discontinuous H 2 -feeding and supports the commercial use of BM processes for energy storage. Discontinuous feeding strategies could be used to enrich methanogenic Archaea during the establishment of a microbial community for BM. Both findings could contribute to design and improve BM processes from lab to pilot scale.