Methanotrophy
Methanotrophy is the process of consuming methane (CH4). This process of biological oxidation is performed by methanotrophic bacteria and archaea who use the CH4 as an energy and carbon source and transform it into CO2 and water in a few steps. This process takes place under aerobic conditions, in the presence of oxygen, although it can also be performed under anaerobic conditions by specialised microbes.
Methanotrophy is considered a transformation because it does not involve the breakdown of large molecules into smaller parts. As such it contributes to the Carbon and Climate Regulation function by controlling the amount of CH4 a soil releases to the atmosphere. It is estimated that about 80% of the CH4 that is produced in the soil by methanogenic archaea is consumed by methanotrophs before it reaches the atmosphere. When conditions are right, soils can sometimes even take-up atmospheric CH4 and act as CH4 sinks rather than being a source.
Methanotrophy can be measured by incubating soil samples in bottles with CH4 rich air and determine how much CH4 the soil removes from the air during the incubation time1. Measuring the genes that methanotrophs use to perform methanotrophy is a molecular, DNA-based alternative[1],[2],[3].
[1] Gagliano, A. L. et al. 2014. Methanotrophic activity and diversity of methanotrophs in volcanic geothermal soils at Pantelleria (Italy). Biogeosciences, 11, 5865–5875.
[2] Holmes, A. J. et al. 1995. Evidence that particulate methane monooxygenase and ammonia monooxygenase may be evolutionarily related. FEMS Microbiology Letters 132, 203–208.
[3] Qin, H. et al. 2018. Abundance of transcripts of functional gene reflects the inverse relationship between CH4 and N2O emissions during mid-season drainage in acidic paddy soil. Biology and Fertility of Soils, 885–895.