An integrated ecophysiology and omics study of phosphorus limitation in methane-oxidising bacteria (EcoMethane)

Methane is a potent atmospheric greenhouse gas with concentrations continuing to increase in the past decade, leading to a recent global effort at COP26 in Glasgow to reduce methane emissions by 30% by 2030. Methane- oxidising bacteria (methanotrophs) use methane as a carbon and energy source, helping to mitigate as much as 90%

of methane emissions. As such, methanotrophs play a vital role in the global methane cycle and any disturbance, biotic or abiotic, of methanotroph activity in the natural environment would exert significant impacts on our ability

to limit global warming by 1.5 degrees celsius by 2030. However, very little is known about how methanotroph activity is regulated in the real world, particularly by key nutrients like phosphorus (P), a limiting nutrient constraining plant and microbial growth in many ecosystems. Using Methylosinus trichosporium OB3b as the model, I have

demonstrated that methanotrophs can reduce their cellular P quota in response to P limitation by substituting membrane phospholipids with alternative non-P surrogate glycolipids. The genes involved in this so-called lipid remodelling pathway are strictly conserved in all proteobacterial methanotrophs, suggesting that lipid remodelling

is a conserved trait in methanotrophs. However, the ecological and physiological consequences of such an adaptation to P limitation are unknown. This is important because it may have important consequences for methanotroph activity and mortality (biotic interactions of methanotrophs with protist grazers and bacteriophages),

thus affecting the global methane budget. Here, I aim to use an integrated omics approach to uncover the ecophysiology of methanotrophs and their response to P limitation in both model methanotrophs and in their natural habitat. The outcomes of this project will fill a major knowledge gap in our understanding of methanotroph activity

in the natural environment