NOX2N - Transformation of biogas digestates to a fertilizer which reduce N2O emissions


N2O emissions account for 1/3 of the total climate forcing of food production. This N2O is generated through successive nitrification then denitrification by soil microbiota, fuelled by elevated nitrogen levels from fertilisers. If global warming is to be limited to 2°C as set in the Paris Agreement, mitigation options for these N2O emissions will need to be developed!

NOX2N Technology

The technology pioneers a novel approach to transform inexpensive biogas digestates into a high-density enrichment of non-denitrifying- or denitrifying N2O-reducing bacteria (NRB or NNRB), which creates opportunity for scalable and feasible inoculation of agricultural soils with desired bacteria. The use of NOX2N technology to modify the soil microbiome, be it for for reduced climate emissions or increased crop yields, fits well with current claims that microbiome-based innovations will play crucial roles in circular economy approaches to meet the United Nations sustainable development goals.

NOX2N project

The NOX2N project (project partners: Veas WWTP, NMBU and Ard Innovation) is supported by the Norwegian Research Counsil under the programme "Innovation in the public sector" and aims to increase the Technology Readyness Level (TRL) of the technology to 5-6. This by implementing a pilot plant in the existing sludge treatment line at Veas WWTP and by validating the concept in different organic waste substrates. The projects advisory board consist of stakeholders representing government legislators, environmental agencies, producers and end-users.

NOX2N media coverage

Abels Tårn - Science Podcast/Radio Show -

Bacteria curb emissions in farmland - Nature Microbiology Review - Research Highlight

Nitrogen-hungry bacteria added to farm soil curb greenhouse gas-emissions - Nature News and Views -

Researchers find a tiny organism has the power to reduce a persistent greenhouse gas in farm fields -

Ny norsk metode kan redusere klimagassutslipp fra landbruket -

Vil bruke jordbakterier til å redusere utslippet av lystgass -

Le Blob -

Så kan bakterier minska jordbrukets utsläpp av växthusgas -

Bacteria Offers Promise to Curb N2O Emissions from Farms -

Soil’s carbon power relies on topsoil retention (and maybe a little bacterial boost) -

Wie die Landwirtschaft ihre Lachgas-Emissionen reduzieren könnte -

Iloisia uutisia ilmastolle: Norjalaiset kehittivät aineen, joka vähentää merkittävästi maatalouden päästöjä -

Bakterier rummer måske løsningen til at sænke landbrugets udledning af lattergass -

Bacterias que consomem gas hilariante podem ajudar a reduzir emissoes na agricultura -

Lachgas-Fresser sollen landwirtschaftliche Treibhausgase reduzieren -

Une bactérie pour réduire les émissions de gaz àeffet de serre dans l’agriculture -

Øyner løsning på den vanskelige lystgassen -

Forklart – Aftenposten Podkast - To gode klimanyheter -

NMBU-forskere fant en bakterie som spiser lystgass - "Det ble en del high-fives" -

Nytt våpen mot global oppvarming: - Et særdeles stort gjennombrudd -

Ny metode kan redusere lystgassutslipp fra landbruket med 95 prosent -

Alf Bjørseths inspirasjonspris 2022 -

Winner of Alf Bjørseths Inspirational Award - Scatech Innovation

Bakterier som spiser lystgass, skal hjelpe landbruket med klimakutt -

En glad miljøhistorie om kloakk og lystgass -

Bakterier som spiser lystgass, kan kutte klimagassutslipp fra landbruket -

Veas innvolvert i NMBU-forskningsprosjekt om lystgasspisende bakterier -

Lystige bakterier kan gjøre landbruket mer klimavennlig -


5: Unlocking bacterial potential to reduce farmland N2O emissions (Nature, Open access)


Moving from the laboratory and out in the real world: fertilization with waste from biogas-production, in which the strain Cloacibacterium sp. CB-01 had grown aerobically reduced N2O-emissions by 50-95 %. The strong and long-lasting effect of CB-01 is ascribed to its tenacity in soil, rather than its biokinetic parameters, which were inferior to other NRB-strains. Scaling up to EU level, we find that national anthropogenic N2O-emissions can be reduced by 5-20 %, and more if including other organic wastes.

Hiis, E. G., Vick, S. H., Molstad, L., Røsdal, K., Jonassen, K. R., Winiwarter, W., & Bakken, L. R. (2024). Unlocking bacterial potential to reduce farmland N2O emissions. Nature, 1-doi: 
4: Meta-omics analyses of dual substrate enrichment culturing of nitrous oxide respiring bacteria suggest that attachment and complex polysaccharide utilisation contributed to the ability of Cloacibacterium strains to reach dominance (Preprint)

The dual substrate enrichment strategy effectively selected operational taxonomic units (OTU’s) which were able to grow (or as a minimum survive) both in soil and digestate. The genetic elements and molecular mechanisms responsible for the success of these phenotypes and which were enriched for during dual enrichment, however, are still to be determined. In this work, we used combined metagenomics and metaproteomics to 1) examine the organisms and genes which were enriched during the dual substrate enrichment with a focus on nitrogen transformation genes 2) investigate what traits benefitted the enrichment winners and 3) examine the proteins/metabolisms used by the enrichment winner during growth in the dual-substrate enrichment.

Vick SHWJonassen KRArntzen MØLycus PBakken LR (2023) Meta-omics analyses of dual substrate enrichment culturing of nitrous oxide respiring bacteria suggest that attachment and complex polysaccharide utilisation contributed to the ability of Cloacibacterium strains to reach dominance, 

2: Nitrous oxide respiring bacteria in biogas digestates for reduced agricultural emissions (The ISME Journal, Open access)


Here we show that manipulating soil metabolism by heavy inoculation with NRBs is realistic if one can tap in to the organic waste value chain and use the residue from anaerobic digestion (digestate) as substrate and vector for the growth and transferral of NRBs to soil. However, in these first attempts to enrich and isolate suitable digestate competent NRBs in live digestate it became clear that the enriched organisms’ competitive strengths in soil was modest, with only transient effects on soil N2O emissions, likely because the isolated NRBs were metabolically streamlined to utilization of fermentation intermediates produced by the active methanogenic community.

Jonassen KR, Hagen LH, Vick SHW, Arntzen MØ, Eijsink VGA, Frostegård Å, Lycus P, Molstad L, Pope PB, Bakken LR (2021) Nitrous oxide respiring bacteria in biogas digestates for reduced agricultural emissions. The ISME Journal, 1-11.

1: Biogas digestate as substrate and vector for the intorduction of N2O-respiring bacteria to soil (phd-thesis)

Jonassen KR (2021) Biogas digestate as substrate and vector for the introduction of N2O-respiring bacteria to soil (doctoral thesis), Available from: Brage NMBU Thesis 2021:53 ISBN: 978-82-575-1824-0, Norwegian University of Life Sciences.

Recent and coming conference presentations and events

19th International Symposium on Microbial Ecology (ISME) 2024, Cape Town, South Africa
Vannbransjens Innovasjonskonferanse 2023, Oslo, Norway
Bioseminaret 2023, Stord, Norway
Nordiwa 2023, Gothenburg, Sweden
European N-Cycle Meeting 2023, Oslo
IWA World Water Congress 2022, Copenhagen, Denmark
European N-Cycle Conference 2022, Rome, Italy
European Biosolids-and Biorescources Conference, 2022, Birmingham, UK