The scale and consequences of global climate change can be debated, but its existence and its negative impact on various aspects of human life can no longer be denied. Scientists from various fields are seeking ways to, if not solve, then at least mitigate the climate crisis. How can microscopic bacterial viruses—bacteriophages—help address this vital issue for humanity?

To begin with, it's worth remembering that one of the factors contributing to global warming is the greenhouse effect, which in turn is associated with greenhouse gas emissions from human economic activity. Specifically, this refers to methane, which is emitted in enormous quantities by ruminants such as cows, goats, and sheep.

To control methane emissions, scientists are studying the gut microbiome of livestock, specifically the microscopic inhabitants of the first and largest section of the ruminant's stomach – the rumen.

The rumen is essentially a large sac in which numerous symbiotic microorganisms (bacteria, archaea, and fungi) ferment and, consequently, digest the cellulose and other plant fibers consumed by the animal. This is a complex process that can occur in various ways, but ultimately results in the formation of simple organic compounds that can be absorbed in the intestine, as well as significant amounts of carbon dioxide and hydrogen.

At this stage, archaea—non-nuclear microorganisms that are similar to bacteria in many ways but have important structural and biochemical characteristics—join the process. Some archaea species are capable of producing methane from carbon dioxide and hydrogen, making them methanogens. In the rumen, archaea skillfully synthesize methane, which the animal then regurgitates, releasing the gas into the atmosphere, where it contributes to the greenhouse effect.

Methanogens aren't the only reason for studying the ruminant microbiome, but they are one of the key ones. Various ways to limit methane emissions in cattle have been proposed, including antibiotics, certain food additives, oils, and the like. However, the most promising method for inhibiting methanogen activity today is the use of bacteriophages.

UK scientist Jessica C. Friedersdorff, author of the article on the website Capsid & Tail, studies the microbiome of ruminants and is confident that phages could be useful both for treating intestinal infections in livestock and for reducing methane production by archaea*.

Read also: Use of bacteriophages in the food industry

She believes that research on bacteriophages in the context of ruminants can be divided into three areas:

- bacteriophages as a component of the microbiome of ruminants (review of this topic here ),

- the use of phages for the prevention and treatment of bacterial infections in ruminants (data are available mainly for the treatment of E. coli infections),

- the use of phages in the dairy and meat industries (review of this topic here ).

Jessica Friedersdorf plans to study the use of phages specific to archaeal methanogens, as well as bacteria that consume substances beneficial to the animals themselves, in ruminants. To do this, the scientist believes, it is necessary to clearly identify the target bacteria, effective phage doses, and their impact on methane production.

Read also: Phage cocktail against salmonella tested on poultry farm

* Friedersdorff, J. (2020). Using the little things to tackle the big things: Can we use phages to impact climate change? Capsid & Tail, (82). Retrieved from https://phage.directory/capsid/rumen-phage