The Selenoproteome as a Dynamic Response Mechanism to Oxidative Stress in Hydrogenotrophic Methanogenic Communities

Methanogenesis is a critical process in the carbon cycle that is applied industrially in anaerobic digestion and biogas production. While naturally occurring in diverse environments, methanogenesis requires anaerobic and reduced conditions, although varying degrees of oxygen tolerance have been desc...

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Bibliographic Details
Published in:Environmental science & technology 2024-04, Vol.58 (15), p.6637-6646
Main Authors: Kleikamp, Hugo B. C., Palacios, Paola A., Kofoed, Michael V. W., Papacharalampos, Georgios, Bentien, Anders, Nielsen, Jeppe L.
Format: Article
Language:English
Subjects:
Anaerobic conditions
Anaerobic digestion
Anaerobic processes
Anthraquinone
Anthraquinones
Biogas
Bioremediation and Biotechnology
Carbon cycle
Carbon dioxide
Dynamic response
Methane
Methanogenesis
Oxidative stress
Oxygen
Oxygen enrichment
Proteomics
Reactive oxygen species
Reagents
Redox potential
Reducing agents
Selenium
Selenocysteine
Sulfur
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Summary:Methanogenesis is a critical process in the carbon cycle that is applied industrially in anaerobic digestion and biogas production. While naturally occurring in diverse environments, methanogenesis requires anaerobic and reduced conditions, although varying degrees of oxygen tolerance have been described. Microaeration is suggested as the next step to increase methane production and improve hydrolysis in digestion processes; therefore, a deeper understanding of the methanogenic response to oxygen stress is needed. To explore the drivers of oxygen tolerance in methanogenesis, two parallel enrichments were performed under the addition of H2/CO2 in an environment without reducing agents and in a redox-buffered environment by adding redox mediator 9,10-anthraquinone-2,7-disulfonate disodium. The cellular response to oxidative conditions is mapped using proteomic analysis. The resulting community showed remarkable tolerance to high-redox environments and was unperturbed in its methane production. Next to the expression of pathways to mitigate reactive oxygen species, the higher redox potential environment showed an increased presence of selenocysteine and selenium-associated pathways. By including sulfur-to-selenium mass shifts in a proteomic database search, we provide the first evidence of the dynamic and large-scale incorporation of selenocysteine as a response to oxidative stress in hydrogenotrophic methanogenesis and the presence of a dynamic selenoproteome.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.3c07725