Discovery of Microbes which Reduce Levels of Harmful Greenhouse Gas

Rising carbon dioxide emissions may be commonly held up as being responsible for the fate of our planet, but nitrous oxide actually poses a much greater threat to the Earth’s atmosphere. Compared to carbon dioxide, nitrous oxide has 310 times the ability per molecule to trap heat in the atmosphere, and is considered to be the single most important ozone depleting substance we emit. Although it is produced naturally in the soil, humans are responsible for huge emissions of nitrous oxides through agriculture, sewage treatment and fossil fuel combustion.

However, the situation may not be as desperate as we thought: scientists have recently discovered that the ability to transform nitrous oxide into harmless nitrogen gas is present in a much larger number of microorganisms than was previously known. Certain enzymes, know to be important in the degradation of nitrous oxide in organisms called denitrifiers, were discovered in many different groups of microbes. Within these groups the enzymes were found to be similar, though evolutionarily distinct, from those found in the denitrifiers.

These new findings could help explain the inconsistencies in data predicting nitrous oxide emissions based on the known processes of nitrous oxide consumption. With microbes possessing the ‘denitrifying’ enzymes likely to be present in nearly all soils and sediments, the extent of their impact on N₂O levels could account for this unexplained “nitrous oxide sink”.

According to Frank Loeffler who conducted the study, this discovery could help advance our understanding of the ecological controls on global nitrous oxide emissions and to refine greenhouse gas cycle models. Given that we need to understand global warming in order to tackle it, knowledge of these nitrogen-producing microbes could help us take steps towards protecting our planet.

Nitrous Oxide (N2O): The Dominant Ozone-Depleting Substance Emitted in the 21st Century”. Science 326 (5949): 123–5.