生物工学：魚粉の代用品としてのメタン由来タンパク質の費用対効果の評価

Using bacteria to produce protein from industrial methane emissions in the United States could represent a cost-effective alternative to fishmeal, according to an economic analysis published in Nature Sustainability.

Methane emitted and flared from industrial sources — such as landfills, wastewater treatment plants and the oil and gas industry — across the US is a major contributor to global climate change. Certain types of bacteria — known as methanotrophs — can capture and transform industrial methane emissions into protein. This protein has a favourable nutritional value and can be used as animal feed.

Sahar El Abbadi and colleagues developed a techno-economic model to estimate the annualized cost of using methanotrophic bacteria to produce single cell protein — an ingredient approved for fish feed at limited percentages. The authors disaggregate the costs into several categories, revealing that the main input is electricity for cooling and other uses. Producing a fishmeal substitute from captured waste methane is predicted to be cost-competitive. In other words, at current technology costs, the US alone could produce enough methane-derived protein to be equivalent to 14% of the global fishmeal market at equal or lower prices than fishmeal (approximately US$1,600 per metric ton). Reducing costs in the process, such as cooling or labour requirements, by 20% could increase this volume to satisfy total global demand for fishmeal.

In an associated News & Views article, Richard Cottrell underlines outstanding challenges, such as the need to consider potential, sizeable upfront investments or the overall environmental and social impacts of this system beyond methane reductions. However, he concludes that the authors “make a compelling case that producing bacteria using industrial methane could help to support sustainable animal feed (and thus human food) production while taking action on climate change.”