Dr Graeme Attwood is leading a team of scientists in New Zealand’s Pastoral Greenhouse Gas Research Consortium are looking at ways of reducing the amount of methane farm animals produce – which in New Zealand accounts for 32 per cent of total greenhouse gas emissions.

The scientists are looking at Methanobrevibacter Ruminantium, a member of a major group of rumen methanogens, which use hydrogen and carbon dioxide to form methane. The existence of these methanogens, bacteria which synthesize methane from carbon dioxide, CO₂, and hydrogen, H₂, means that these bacteria “eat” carbon dioxide, and hydrogen, turning them into methane, CH₄ , and oxygen, O₂.

CO₂ + 2 H_2, -> CH₄ + O₂

The chemistry is very simple: One molecule of carbon dioxide combines with two molecules of hydrogen to form one molecule of methane and one molecule of oxygen. The same things happen in sewage treatment plants.

A layman would say these bacteria “eat” methane and hydrogen. A biochemist would observe that “there exists a metabolic pathway by which carbon dioxide and hydrogen are combined to form methane and oxygen.” An ecologist would observe that this is like photosynthesis, in which carbon dioxide, CO₂, and water, H₂O, are combined into glucose, C₆H₄ O_6, and oxygen, O₂.

6 CO₂ + 6 H₂O -> C₆H₄ O₆ + 6 O₂

A genetic engineer might ask “How can we develop a metabolic pathway by which plastics can be broken down into things like carbon dioxide and hydrogen?”

C₈H₁₈ + 8 O₂ -> 8 C0₂ + 9 H₂

And an environmentalist might listen to the genetic engineer and say “cool!”