Team:Wageningen UR/Description

iGEM Wageningen 2021


Group Photo


Reducing ammonia and methane emissions from cattle farms

Feeding our ever-growing world population comes with a heavy burden to the environment. The agricultural sector is one of the biggest contributors to ammonia and methane emissions in the Netherlands, mainly originating from livestock farming [1]–[4]. Ammonia emissions cause acid deposition, which changes the soil chemistry and water quality. This results in a loss of biodiversity, weakening ecosystems such as the heather fields in the Netherlands [1], [5]. Methane is a greenhouse gas much more potent than CO2, and methane emissions greatly accelerate global warming [6], [7]. Cattle are the biggest producers of both compounds of all livestock in the Netherlands. Whereas ammonia originates primarily from their manure, methane is both released from manure and produced by cattle during digestion, releasing it directly through their breath [3], [4].

Schematic illustration displaying acid deposition and dlimate warming by ammonia and methane, respectively
Figure 1: Schematic illustration displaying the different ways in which cattle stall emissions ammonia and methane affect the environment: (1) ammonia changes soil chemistry by acid deposition, while (2) methane enhances the global greenhouse effect.

Approximately 40% of protected areas worldwide are at risk of biodiversity loss due to excessive reactive nitrogen [8]. In the Netherlands, this is even higher: 73% of nature reserves are under threat [9]. Within Europe, the Netherlands has the highest nitrogen-emission density. Ammonia makes up 60% of total Dutch nitrogen emissions of which more than 90% originates from the livestock sector [10]. Since 2019, a series of court verdicts and rulings by the Dutch Council of State forced the government to act promptly against the country’s excess ammonia emissions [2], [11]. Many governmental parties proposed measures like halving the Dutch livestock population and decreasing the amount of protein fed to livestock [8]. These measures have caused friction between the government and farmers, as their implementation would cause many farmers to go out of business. As a result, thousands of farmers rallied in the streets, in one instance even flooding the center of the Dutch administrative capital The Hague in protest [12].

Although methane emissions did not receive quite the same amount of media attention as the nitrogen crisis in The Netherlands, they are a significant contributor to global warming. Despite the economic and industrial downturn caused by the global pandemic, the largest annual increase of methane measured since 1983 was in 2020 [13]. The European Commission has proposed a European Climate Law to reduce greenhouse gas (GHG) emissions by at least 55% by 2030 compared to 1990 levels [14]. To achieve this goal, The Netherlands would need to cut its GHG emissions by 40% [15].

It is clear we need a solution. One that reduces both methane and ammonia emissions of the livestock sector.

Read more about our Project Background


Cattlelyst is an innovative solution that deals with both of the harmful emissions of the cattle industry, which have contributed to complex environmental and political problems. This solution consists of a biofilter containing genetically modified microorganisms, which convert ammonia to innocuous dinitrogen (N2) and methane to carbon-neutral CO2. As such, the Cattlelyst biofilter applies Synthetic Biology. Figure 2 schematically shows what the system surrounding the biofilter would look like. Methane-rich air from the cattle stalls will be captured by the “hood system”, inspired by the cow-friendly hood sampler described by Wu [12]. This airflow is combined with the ammonia-rich air from the manure pits and pushed through the biofilter. This way, the Cattlelyst biofilter provides an elegant solution for both types of harmful gasses emitted by the livestock sector, allowing farmers to continue feeding the world while nature and the climate remain unharmed.

Schematic farm and application of cattlelyst
Figure 2. Scheme displaying a farm in which the Cattlelyst biofilter is applied: exhaust air coming from the stall cubicles and manure pit pass though the biofilter, where genetically modified bacteria convert ammonia and methane into CO2 and N2.

Our biofilter has an environment with unique conditions, so it is unlikely that naturally occurring organisms will realize the optimal conversion of ammonia and methane. To make sure our biofilter is as efficient as possible, we chose to create our own synthetic organisms to fit the unique environment of the biofilter. These microorganisms should possess several key characteristics to fulfill their function. The Cattlelyst microbes should be able to grow on ammonia and methane and convert them to N2 and CO2 under aerobic conditions. As our microorganisms will be genetically modified (GMOs), they should also be unable to escape the confines of the biofilter. Therefore, they should ideally contain intrinsic safety mechanisms that prevent them from surviving in the outside environment. We divided these fundamental traits into three separate pillars that we worked on extensively both computationally and in the lab. We attempted to implement these pillars into a co-culture of two organisms.

Schematic view inside of the Cattlelyst biofilter
Figure 3. Schematic overview of the inside of the Cattlelyst biofilter. Polluted air coming from the cattle stall passes though the biofilter, where genetically modified bacteria convert ammonia and methane into CO2 and N2.
The three pillars of Cattlelyst
Ammonia icon

Read more on ammonia removal

Methane icon

Read more on methane oxidation

Safety icon

Read more on safety by design

Ammonia icon

Read more on ammonia removal


Read more on methane oxidation

Methane icon
Safety icon

Read more on safety by design

  • References
    1. PBL, Zure regen, een analyse van dertig jaar verzuringsproblematiek in Nederland. Bilthoven: PBL publicatie, 2010.
    2. A. Sikkema, “The nitrogen problem in five questions,” Resource, WUR, 2019.
    3. RVO, “De Nederlandse landbouw en het klimaat,” 2016.
    4. CLO, “Ammoniakemissie door de land- en tuinbouw, 1990-2017,” 2019. [Online]. Available: [Accessed: 16-Sep-2020].
    5. RIVM, “Over de uitspraak op 29 mei 2019: Programma Aanpak Stikstof (PAS) & beweiden en bemesten,” 2019. [Online]. Available: [Accessed: 10-Oct-2020].
    6. A. van Amstel, “Methane. A review,” Journal of Integrative Environmental Sciences. 2012.
    7. Z. Tan, Air Pollution and Greenhouse Gases. Springer, 2014.
    8. J. W. Erisman, M. A. Sutton, J. Galloway, Z. Klimont, and W. Winiwarter, “How a century of ammonia synthesis changed the world,” Nat. Geosci., 2008.
    9. E. Stokstad, “Nitrogen crisis threatens Dutch environment—and economy,” Science (80-. )., 2019.
    10. TNO, “Factsheet Emissies en depositie van stikstof in Nederland,” pp. 1–16, 2019.
    11. RIVM, “Nitrogen and PFAS suddenly big societal issues in the Netherlands,” 2020. [Online]. Available: [Accessed: 07-Sep-2020].
    12. A. J. A. Aarnink, W. J. M. Landman, R. W. Melse, Y. Zhao, J. P. M. Ploegaert, and T. T. T. Huynh, “Scrubber capabilities to remove airborne microorganisms and other aerial pollutants from the exhaust air of animal houses,” Trans. ASABE, vol. 54, no. 5, pp. 1921–1930, 2011.
    13. NOAA Research, “Despite pandemic shutdowns, carbon dioxide and methane surged in 2020 ,” 07-Apr-2021. [Online]. Available: [Accessed: 23-Apr-2021].
    14. European Commission, “Impact Assessment, accompanying Communication ’Stepping up Europe’s 2030 climate ambition - Investing in a climate-neutral future for the benefit of our people - part 1/2,” 2020.
    15. European Parliament and Council of the European Union, “Regulation (EU) 2018/842 of the European Parliamanet and the Council of 30 May 2018,” Off. J. Eur. Union, pp. 26–42, 2018.
    16. M. Martin-Pascual et al., “A navigation guide of synthetic biology tools for Pseudomonas putida,” 2021.
    17. UNFCCC, “Global Warming Potentials (IPCC Second Assessment Report).” [Online]. Available: [Accessed: 08-Sep-2020].
    18. F. Y. H. Chen, H. W. Jung, C. Y. Tsuei, and J. C. Liao, “Converting Escherichia coli to a Synthetic Methylotroph Growing Solely on Methanol,” Cell, vol. 182, no. 4, pp. 933-946.e14, 2020.
About Cattlelyst

Cattlelyst is the name of the iGEM 2021 WUR team. Our name is a mix of 1) our loyal furry friends, cattle, and 2) catalyst, which is something that increases the rate of a reaction. We are developing “the something” that converts the detrimental gaseous emissions of cattle, hence our name Cattlelyst.

Are you curious about our journey? We have written about our adventures in our blog, which you can find here: