Identifying novel microbial drivers to mitigate atmospheric methane emission

Climate change is one of the greatest challenges facing our world. Methane is a powerful greenhouse gas with a global warming potential 25 times that of CO2. In the recent Climate Change Summit COP26 in 2021, an international pledge was made to urgently cut methane emissions by 30% by 2030. This project will study new microbes capable of consuming methane and generate fundamental scientific knowledge required to take the first steps towards contributing to this goal.

Approximately 500-600 million tonnes of methane are emitted into the Earth's atmosphere every year. Methane can be removed by microbes known as methanotrophs. However, we have preliminary data indicating that other, previously unsuspected microbes known as ammonia oxidising archaea may also be able to consume methane in the environment. Ammonia oxidising archaea are among the most numerous living organisms on the planet and play a vital role in the nitrogen cycle. They are responsible for nitrogen loss from agricultural soils, environmental pollution and emission of nitrogen-containing climate-active gases. Ammonia oxidising archaea and methanotrophs both contain a similar enzyme, known as ammonia monooxygenase in archaea and particulate methane monooxygenase in methanotrophs. This is the key enzyme that methanotrophs use to break down methane. Our hypothesis is that archaea can use their ammonia monooxygenase enzyme to break down methane in the environment. Furthermore, we predict that methane will inhibit ammonia oxidation and thus influence nitrogen cycling in the environment. This is important because depending on the environmental conditions, different microbes will be more active than others and this has consequences for the extent of greenhouse gas emission and consumption, and cycling of nutrients.

Our research will identify how different environmental conditions affect the contributions of different groups of microorganisms involved in methane removal from the biosphere. Using cutting-edge techniques, this project will link the activity and identity of the microbes responsible for methane consumption in soil. Our study will determine the mechanisms by which ammonia oxidising archaea and other microbes break down methane in soil. Overall, this will help towards predicting how soils respond to environmental changes and has considerable potential to contribute to sustainable management of soil ecosystems.