Project Description

The human population has grown from approximately 2.6 Billion in 1950 to around 7.8 Billion nowadays (United Nations, 2021). A secondary effect of this growing population is also an increase in the demand for food , for instance red meat originating from cows, sheep and goats.

Graph of meat production since 1961 per continent — Global meat production from 1961 to 2018 in Million tons (Ritchie & Roser, 2021).

Graph of population growth since 1700 — World population from 1700 to 2024 in Billions (Roser, Ritchie & Ortiz-Ospina, 2021)

Cows, sheep and goats belong to the suborder Ruminantia, meaning that they have a four chambered stomach, the first one of which is the rumen (Britannica, 2019). Within the rumen, microorganisms can digest cellulose taken up as grass, hay, straw etc., into compounds that can be taken up by the animal as an energy source. During these processes, side products such as CO2 and H2 are produced (Matthews et al. 2018). These compounds are used by archaea in the rumen to produce methane (CH4) (Kinley et al. 2020). These archaea are also referred to as methanogens.

Schematic of the methanogenesis process in the cow — Ruminant stomach compartments and methanogenesis (Zhao et al. 2020)

CH4 is a greenhouse gas that has a higher potency than CO2. This means that, although there is less of it in the atmosphere, its global warming potential is 86 times stronger than CO2 per unit of mass over a timespan of 20 years and 28 times stronger on a timespan of 100 years (Jackson et al. 2020).

Chart showing difference in the warming potency of CO2 and methane by showing circles with size corresponding to relative potency

The upper graph shows global methane parts per billion (ppb) from 2000 to 2017, with the red line showing seasonal variations and the blue line showing a non-seasonal trend. The lower graph shows the amount of delta C-13 isotope ratios in methane over the same timeframe, showing a negative trend. This trend can potentially be linked to microbial produced methane (Fletcher & Schaefer, 2019).

Graph showing methane parts per billion in the atmosphere, as well as delta C-13 isotope ratios in methane

Photograph of Asparagopsis Taxiformis in the ocean — Asparagopsis Taxiformis (Jean-Pascal Quod, 2013)

Since global warming is an ever-increasing problem worldwide, CH4 emissions from ruminants, especially cows, are getting more and more attention. Therefore the emission of methane from ruminants has been experimentally reduced in various ways. One method of reducing the methane output by ruminants is the usage of the red seaweed Asparagopsis taxiformis, which, depending on the feed amount, could reduce methane output by up to 98% (Kinley et al. 2020). Of the many ways of reducing methane emission, A.taxiformis shows the strongest dose-dependent methane mitigating effects, while having the least impact on rumen fermentation (Chagas et al. 2019).

This methane reducing ability of A. taxiformis is due to it being capable of generating  halogenated compounds, amongst them bromoform (Machando et al. 2017), which is the major halogenated product of these red algae (Machando et al. 2016).

Bromoform has the ability to inhibit a cobamine-dependent methyltransferase, which is required for the synthesis of methyl-coenzyme-M, the key enzyme in the final part of methanogenesis (Machando et al. 2016), ultimately reducing methane production if present in the cow rumen (Kinley et al. 2020). These methyl-coenzyme-M enzymes are present exclusively in methanogens (Zhu et al. 2021), whereof the archaeal genus Methanobreviacter is the most abundant and most studied (Danielsson et al. 2017).

Microscope image of methanogen microbes — Image source: Miller, 2015

The life cycle of A. taxiformis consists of three life stages, which unfortunately means that aquafarms have yet to grow these algae through all life stages, meaning that the cycle could not be closed. This hinders the farming of the species on a global scale dramatically (Zhu et al. 2021).

Image depicting the discrepancy between required Asparagopsis Taxiformis feed and supplied Asparagopsis feed by showing differently sized circles depicting the two

In 2020, Thapa et al. identified the genes from different groups of A. taxiformis which are involved in the production of bromoform, as well as the genes involved in bromoform production in the algae Chondrus crispus, amongst others. The A. taxiformis genes were named Mbb1, Mbb2 and Mbb4, the C. crispus genes CcVHPO1 and CcVHPO3.

Thapa et al. (2020) successfully expressed bromoform in E.coli bacteria. Our team tries to recreate this transformation and expression. Our aim is to produce a microbial feed for ruminants. This feed contains encapsulated E.coli which have the genetic ability to produce bromoform, thereby inhibiting methanogenesis within the cow. Due to E.coli already being naturally present in the rumen, colonization may mean that this feed additive only needs to be administered once in a cow’s lifetime (Khafipour et al. 2009).

If successful, this feed additive is a great demonstration of the power and opportunity that synthetic biology has to offer. If applied for causes like reducing greenhouse gas emissions, synthetic biology will be put into the worldwide spotlight, and can be more approachable and appreciated by the general public.

After adding said feed additive, these cows will not only have reduced methane emissions, but potentially also have increased weight gain. This is due to energy not being lost in the form of methane, but being preserved within the animal (Kinley et al. 2020).

References

Britannica, T. Editors of Encyclopaedia (2019). Ruminant. Retrieved 16th June, 2021 from: https://www.britannica.com/animal/ruminant
Chagas, J.C., Ramin, M., & Krizsan, S.J. (2019). In Vitro Evaluation of Different Dietary Methane Mitigation Strategies. Animals, 9(12), 1120. doi:10.3390/ani9121120
Danielsson, R., Dicksved, J., Sun, L., Gonda, H., Müller, B., Schnürer, A., & Bertilsson, J. (2017). Methane production in dairy cows correlates with rumen methanogenic and bacterial community structure. Frontiers in microbiology, 8, 226.
Fletcher, S. E. M., & Schaefer, H. (2019). Rising methane: A new climate challenge. Science, 364(6444), 932-933.
Jackson, R. B., Saunois, M., Bousquet, P., Canadell, J. G., Poulter, B., Stavert, A. R., ... & Tsuruta, A. (2020). Increasing Anthropogenic Methane Emissions arise Equally from Agricultural and Fossil Fuel Sources. Environmental Research Letters, 15(7), 071002.
Khafipour, E., Li, S., Plaizier, J. C., & Krause, D. O. (2009). Rumen microbiome composition determined using two nutritional models of subacute ruminal acidosis. Applied and environmental microbiology, 75(22), 7115-7124.
Kinley, R. D., Martinez-Fernandez, G., Matthews, M. K., de Nys, R., Magnusson, M., & Tomkins, N. W. (2020). Mitigating the Carbon Footprint and Improving Productivity of Ruminant Livestock Agriculture using a Red Seaweed. Journal of Cleaner Production, 120836. doi:10.1016/j.jclepro.2020.120836
Machado, L., Magnusson, M., Paul, N. A., Kinley, R., de Nys, R., & Tomkins, N. (2016). Identification of Bioactives from the Red Seaweed Asparagopsis taxiformis that Promote Anti-methanogenic Activity in vitro. Journal of Applied Phycology, 28(5), 3117–3126. doi:10.1007/s10811-016-0830-7
Machado, L., Tomkins, N., Magnusson, M., Midgley, D. J., de Nys, R., & Rosewarne, C. P. (2017). In vitro Response of Rumen Microbiota to the Anti-methanogenic Red Macroalga Asparagopsis taxiformis. Microbial ecology, 75(3), 811-818.
Matthews, C., Crispie, F., Lewis, E., Reid, M., O’Toole, P. W., & Cotter, P. D. (2018). The Rumen Microbiome: a Crucial Consideration when Optimising Milk and Meat Production and Nitrogen utilisation efficiency. Gut Microbes, 1–18. doi:10.1080/19490976.2018.1505176
Miller, T. (2015). Methanobrevibacter. Bergey's Manual Of Systematics Of Archaea And Bacteria, 1-14. https://doi.org/10.1002/9781118960608.gbm00496
Quod, J. (2013). Asparagopsis taxiformis - Wikipedia. En.wikipedia.org. Retrieved 20 October 2021, from https://en.wikipedia.org/wiki/Asparagopsis_taxiformis.
Ritchie, H., & Roser, M. (2021). Meat and Dairy Production. Retrieved 7 July 2021, from https://ourworldindata.org/meat-production
Roser, M., Ritchie, H., & Ortiz-Ospina, E. (2021). World Population Growth. Retrieved 7 July 2021, from https://ourworldindata.org/world-population-growth
Thapa, H. R., Lin, Z., Yi, D., Smith, J. E., Schmidt, E. W., & Agarwal, V. (2020). Genetic and Biochemical Reconstitution of Bromoform Biosynthesis in Asparagopsis Lends insights into Seaweed Reactive Oxygen Species Enzymology. ACS Chemical Biology, 15(6), 1662-1670.
United Nations. (2021). Global Issues: Population. Retrieved 16th June, 2021 from: https://www.un.org/en/global-issues/population
Zhao, Y., Nan, X., Yang, L., Zheng, S., Jiang, L., & Xiong, B. (2020). A Review of Enteric Methane Emission Measurement Techniques in Ruminants. Animals, 10(6), 1004.
Zhu, P., Li, D., Yang, Q., Su, P., Wang, H., Heimann, K., & Zhang, W. (2021). Commercial Cultivation, Industrial Application, and Potential Halocarbon Biosynthesis Pathway of Asparagopsis sp. Algal Research, 56, 102319. https://doi.org/10.1016/j.algal.2021.102319

Team:MSP-Maastricht/Description

Project Description

Green Cows for a Green World!

References

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