Ammonium and Lanthanum Impact Methane Oxidation and Methanotrophic Communities in Agricultural Soils

Abstract

An ever-increasing amount of research is being performed on the stability and recovery of soil methane-oxidizing bacteria since this is one of the fundamental processes controlling the amount of methane in the atmosphere. Mineral fertilizers may alter the methane oxidation processes in agricultural soils when they are introduced. Although ammonium (NH4+) is believed to have a significant impact on aerobic methane oxidation activity in soils, there is still little data on how it reacts with lanthanum (La). The recent identification of a novel class of lanthanum-containing enzymes in methanotrophic bacteria may be the foundation for controlling the function of the soil “methane filter” and related microbiota. In the current study, microcosms with agricultural sod-podzolic soils were created and incubated in air or 20% CH4 in the gas phase with the addition of NH4+ (100 µg/g) and La (5 µg/g) to the soil. Using GC analysis and high-performance 16S rRNA sequencing, the methane oxidation potential and composition of soil bacterial communities were studied over the month of incubation. A negative impact of NH4+ on the oxidation of methane was observed, whereas La had a somewhat beneficial effect. Ammonium had an impact on the composition of methanotrophs, and a significant shift was observed upon La addition. Proteobacteria made up a larger share of the soil microbial community, and Gammaproteobacteria dominated the methanotrophic populations. Methylobacter, a methanotroph, and Methylotenera, an obligatory methylotroph, were the two absolute dominants in the La-amended variants. These findings could help evaluate how lanthanum regulates methanotrophic communities in agricultural soils and lead to the creation of new strategies for controlling the “methane filter” in soil.

Keywords

• fertilization
• lanthanum
• methane oxidation
• high-performance 16S rRNA sequencing