New Zealand's ruminant cows and sheep contribute much of our greenhouse gas emissions by belching methane into the air.

But what if we flipped the paradigm and fed them methane instead?

We know methane and carbon dioxide are potent greenhouse gases that drive climate change, and are common by-products from industrial processes.

Although about a third of our emissions come from transport and electricity generation, the greatest proportion - around half of the inventory - comes from agriculture, and much of that from methane belched from ruminant livestock like sheep and cows.


New Zealand has the world's largest methane emission rate - six times the global average - and this primarily comes from enteric fermentation in ruminant livestock, with sheep the greatest single source.

When methane, carbon dioxide and other gases are produced industrially, they're generally at concentrations too dilute to be economically useful, and are commonly disposed of either by flaring or venting into the atmosphere.

A new research project will develop a biotechnology platform taking industrial waste gases and converting them into protein-rich biomass to feed dairy, stock and other farmed animals.

The study draws on the unique characteristics of naturally-occurring, methane-munching, extremophilic micro-organisms, which can comfortably live in some of our most inhospitable environments - including hydrothermal vents where temperatures reach a blistering 121C.

"We already have a good understanding of the metabolism of methane-consuming bacteria, or methanotrophs, and how they make their living in extreme environments," said GNS Science microbiologist Dr Carlo Carere, who is leading the project.

"These bugs eat methane and other gases under very specific conditions and by changing what is fed to them it is possible to manipulate how they grow and what they produce.

"Our approach is to use methanotrophs in combination with other microbes that are found naturally together to produce a nutritional feedstock that is high in protein content."

His team's hypothesis is that these natural "biofilters" can be used together or in tandem to convert industrial gases into something of value.

"We assume that because these species naturally coexist, they will work together in an applied setting."

The team, from GNS, Scion and the University of Canterbury, will cultivate the bacteria with a variety of other micro-organisms using gases, as a food source, that are typical of geothermal and oil and gas industries.

They'll then evaluate the effectiveness with which cultures consume these gases, along with the quality of the biofeedstock that they produce as they grow.

By changing the growth conditions that these microbes face, they expect to change their nutritional properties to meet the demands of different groups or companies that might use them.

"To do this, our team will use a combination of benchtop microbiology cultivations and custom-built bioreactors," he said.

"In combination with various nutritional analysis and genomic techniques, we will not only produce a better biofeedstock, but also better understand how these microbes interact with each other."

To some extent, the approach has been used already.

Protein fishfeeds from methane gas are already well advanced using traditional bacterial species.

But while the benefits of using extremophiles in biotechnology are massive, nobody has yet investigated the suitability of these micro-organisms to produce a biofeedstock using the industrial gases Carere and his colleagues will target.

"We hope that this work will provide the foundation of knowledge needed to develop a process that is capable of converting industrial gases into a high-protein feedstock appropriate for livestock consumption.

"In this way, our project offers to both reduce greenhouse gas emissions and to provide greater food security to New Zealand.

"It's early days but we're enthusiastic about the research that lies ahead."

The study, which has received a million-dollar grant through the Government's Endeavour Fund, follows a recently-published study, co-authored by Carere, that found how methanotrophs could help us fight climate change.