Evidence map›Paper›PMID 42527912›Full record

ArticleBMC microbiology2026

Metagenomic and cultivation-based description of a syntrophic butyrate-oxidizing bacterium from a thermophilic and high-ammonia biogas process.

Malin Tiefensee, Nils Weng, Jonas A Ohlsson, Maria Westerholm

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Article in BMC microbiology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

4 authors.

Malin TiefenseeDepartment of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Nils WengDepartment of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Jonas A OhlssonDepartment of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Maria WesterholmDepartment of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden. Maria.Westerholm@slu.se.ORCID 0000-0003-2150-8762

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundAmmonia inhibition in anaerobic digestion can lead to butyrate accumulation and reduced methane yield. Despite the importance of syntrophic butyrate oxidation in mitigating this effect, the microorganisms and interactions involved under high-ammonia conditions remain poorly understood. Here, we combine metagenomics and cultivation studies to describe a novel ammonia-tolerant syntrophic butyrate-oxidizing bacterium and its interactions with acetate-oxidizing bacteria and hydrogenotrophic methanogens enriched from a high-ammonia, thermophilic biogas process.

resultsThe enrichment culture degraded butyrate at rates of 0.12-0.47 mmol/day. Amplicon sequencing and phylogenetic analyses of a retrieved metagenome-assembled genome (MAG) assigned the putative syntrophic butyrate-oxidizing bacterium (SBOB) to the genus Syntrophothermus, for which we propose the provisional species name 'Candidatus Syntrophothermus ammoniitolerans'. Metagenomic analyses revealed the genomic potential for β-oxidation and essential electron transfer pathways associated with syntrophic energy conservation. Furthermore, one additional MAG (MAG9) possessed a complete β-oxidation pathway but lacked key genes associated with reverse electron transfer, making its role as a SBOB uncertain. Acetate produced during butyrate oxidation was further oxidized by syntrophic acetate-oxidizing bacteria and ultimately converted to methane by hydrogenotrophic methanogens, illustrating a tightly coupled metabolic network that supports butyrate degradation under high-ammonia conditions. Three methanogenic MAGs, affiliated with the genera Methanoculleus and Methanothermobacter, were identified as potential hydrogen- or formate-consuming partners.

conclusionsTogether, these results identify a novel syntrophic butyrate-oxidizing candidate that enables butyrate degradation under high-ammonia conditions via tightly coupled interactions with acetate-oxidizing bacteria and hydrogenotrophic methanogens, sustaining methane production under ammonia stress.

Indexed as

AmmoniaBacteriaBiofuelsButyratesMetagenomicsAcetatesAnaerobiosisMetagenomeMethaneOxidation-ReductionPhylogenyRNA, Ribosomal, 16SAcetatesAmmoniaBiofuelsButyratesMethaneRNA, Ribosomal, 16SAnaerobic digestionFunctional gene analysisMetagenome assembled genomeSyntrophic oxidationSyntrophothermusSyntrophy

Identifiers

PMID42527912
PMCPMC13422317

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.