Project Description

This year, our team is working to mitigate the environmental effects of methane produced in cattle rumen. Enteric methane emissions are one of the largest anthropogenic sources of this potent greenhouse gas (GHG) (Reisinger et al., 2021). Some research has prompted development of some solutions to address this issue, however existing feed additive solutions have limited efficacy and lack incentives for farmers to implement due to added feed cost (Hodge et al., 2024). Our solution involves Chlorella vulgaris microalgae engineered to express phage-based lytic enzymes specifically targeting methanogen populations. Not only is microalgae a nutrient-rich potential feed additive, but due to similar genetic engineering processes, this will act as a proof of concept for genetically modified plants expressing these enzymes (Saadaoui et al., 2021). Existing cellulose fermentation in the rumen degrades microalgae and plant cell walls, providing a release mechanism for the enzymes (Weimer et al., 2022). We envision an engineered crop-based solution to be simple to implement, and cost-effective. Existing research shows that some phage-based enzymes are capable of lysing cells in free form (Altermann et al., 2018). Further, a reduction in certain methanogens can result in a sustained microbiome shift to favour other hydrogen sinks, including reductive acetogenesis.

Why are we tackling this problem?

Methane is a potent GHG. Since 1950, atmospheric methane concentrations have surged by 70%, marking it one of the fastest-growing GHGs (Bačėninaitė et al., 2022). It is a critical concern due to its profound warming effect, which is 84 times more potent than CO2 over a twenty-year period (European Commission, 2023).
The global warming induced by methane has contributed to a range of critical issues, including rising temperatures, more frequent extreme weather events that worsen air quality, increased drought occurrences, and a rise in vector-borne diseases (European Commission, 2023). These factors collectively contribute to higher mortality rates among humans and other organisms.
According to the Global Methane Assessment by the Climate and Clean Air Coalition and the United Nations Environment Programme (UNEP), reducing methane-associated GHGs could prevent more than 200,000 premature deaths, hundreds of thousands of emergency room visits due to asthma, and more than 20 million tonnes of crop losses annually by 2030 (2023).
This is made easier by methane’s relatively shorter life-span of 7-12 years (Reisinger et al., 2021). Unlike persistent GHGs that remain in the atmosphere for centuries, methane's shorter duration means that reducing its emissions can lead to more immediate reductions in its warming effect. By decreasing methane emissions, we can mitigate its rapid contribution to global warming and potentially achieve quicker reductions in atmospheric GHG levels compared to longer-lived gases.

Why cows specifically?

Enteric methane generated by anaerobic activity of methanogenic archaea in the rumen of cattle is the largest source of anthropogenic CH4 emissions (Reisinger et al., 2024). A fully developed cow can emit up to 500 litres of methane each day, accounting for approximately 3.7% of all GHG emissions.
Dairy/beef products are popular, particularly with a growing human population, and consumer behaviour alone is unlikely to change sufficiently to reduce climate change. As of 2023, in North America...

Over

3.5

Million Beef Cattle (Stat. Canada, 2024)

Approximatly

968,500

Dairy Cows (Stat. Canada, 2024)

Over

90

Million Farmed Cattle...

90 million in the United States — raised for a variety of food and consumer products including beef, veal, dairy and leather (United States Department of Agriculture, 2024)
Targeting cattle provides for significant opportunity to reduce methane emissions and mitigate climate change.
The rumen of cattle offers a unique environment for addressing this issue. Unlike greenhouse gases from industrial or domestic sources, mitigation measures can be implemented within a naturally occurring system in a way that is more realistic and less invasive than other means of reducing anthropogenic methane emissions in the sector. Instead of investing in alternate manure management approaches, such as anaerobic digesters, or expensive precision equipment (i.e., sensors), we can address the issue internally by altering microbial activity, at little inconvenience to agricultural stakeholders.
Our solution developed through synthetic biology can be easily scaled up and distributed widely, ensuring that the benefits of reduced methane emissions can be realized across large populations of livestock efficiently without requiring significant changes in farming infrastructure.
Not only that, our approach also easily complements other emission reduction measures, such as improved feeding strategies or breeding programs for low-methane-emitting cattle.

References