CONDUCTIVE MINERALS AS ELECTRICAL CONDUITS IN METHANE CYCLING

Project Information

MIMET

Grant agreement ID: 101045149

DOI

10.3030/101045149

EC signature date 26 April 2022

Start date 1 September 2022

End date 30 September 2028

Funded under

• European Research Council (ERC)

Total cost

€ 1 999 760,50

EU contribution

€ 1 999 760,50

Coordinated by

SYDDANSK UNIVERSITET
Denmark

Periodic Reporting for period 1 - MIMET (CONDUCTIVE MINERALS AS ELECTRICAL CONDUITS IN METHANE CYCLING)

Reporting period: 2022-09-01 to 2025-02-28

Summary of the context and overall objectives of the project

This proposal aims to gain a fundamental understanding of the impact of anthropogenic conductive particles on methane emissions.
We recently showed that conductive particles are vital for the interspecies cross-feeding of a methane-producing consortium from the
Baltic Sea. Previous to that, we showed that conductive particles accelerate methane production in synthetic dual-species consortia that
typically function via direct electron transfer. Others showed that conductive particles may also stimulate anaerobic methane oxidation.
For the latter, the reports are scarce and contradictory. It is mysterious how microorganisms interact with the conductive particles and
how conductive particles affect the methane cycle in the environment. These knowledge gaps we will study here. We will use synthetic
consortia, enriched environmental consortia, and whole sediment cores. We will identify marker genes for microbe-particle contacts by
combining expression studies with targeted gene-deletion and physicochemical cell surface studies. The marker genes we can then use
to track similar microbe-conductive particle associations in the environment. We will examine the link between increased anthropogenic
particle input and methane emissions in environments from the Mediterranean to the Arctic where higher particle input is likely. I
expect to deliver fundamental knowledge about the microorganisms involved in methane transformations by anthropogenically derived
conductive particles.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Activities Performed and Main Achievements

1. In WP1, we investigated how methane-cycling microorganisms respond to conductive materials (CMs) facilitating CM-mediated interspecies electron transfer (CIET) in lab consortia and enriched environmental consortia:

a) Methanogenic Lab Consortia:

Successfully established Geobacter metallireducens - Methanosarcina barkeri consortia with and without CMs. Gene-expression patterns are being analyzed under varied conditions (with and without conductive particles).
We initiated gene deletion studies in bacteria and archaeal partners to confirm the role of EET gene clusters in CIET.
Surface biology of the archaea led to novel findings regarding its surface biology, including cell surface enzymes and redox-active cell surface molecules.

b) Environmental Methanogenic Consortia:

Hundreds of metagenome-assembled genomes (MAGs) were obtained from different enriched environmental communities, where we identified the novel microbes with EET potential.
For this purpose, we initiated DNA-SIP and RNA-SIP experiments which are ongoing to confirm acetate oxidizers and methanotrophs. We initiated the isolation of novel EET-species.
Enrichments revealed distinct CM-dependent communities with novel species with specific EET signatures.

c) Methane-Oxidizing Consortia:
In environmental enrichments from different sites we observed that anaerobic methane oxidation (AOM) activity was independent of CMs. Ongoing RNA-SIP experiments will be assessing CM effects.


2. In WP2, environmental methane-cycling communities' responses to CMs were examined in glacier-melt sites in Greenland and an agricultural lagoon in Denmark. Incubations and geochemical analyses are complete, and RNA-SIP experiments will soon commence.

General Outcomes of the Action

Identification of novel microorganisms and interspecies partnerships involved in CIET and DIET.
Development of gene deletion methods to disect the mechanisms of interactions between cells and materials.
Novel EET machinery and mechanisms in response to CMs: entirely new genera with unique EET gene signatures, advancing our understanding of electroactive microbes involved in methane cycling in aquatic environments.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

We discovered unique EET machineries in electroactive microbes transforming our understanding of these microorganisms' roles in biogeochemical cycles.
The enrichment and study of sediment-bound microbes using CMs pushed cultivation techniques and microbial ecology beyond current methods.
The widespread association between certain EET-bacteria and certain EET-methanogenic archaea highlights specialized CM-promoted methane emissions in diverse ecosystems.

Further research:
Advanced genomic, transcriptomic, and proteomic analyses of enriched consortia and novel species to elucidate their metabolic networks and interspecies interactions.
Expanded studies on methane emissions and microbial activity across different environmental settings to validate findings and assess broader relevance.

The project provides groundbreaking insights into methane-cycling microbial communities and their interaction with conductive materials, uncovering novel microbial diversity, unique EET mechanisms, and methane-producing partnerships across diverse ecosystems. These discoveries have far-reaching implications for environmental science, industrial applications, and microbial ecology, offering a strong foundation for future research and practical innovation.