Active microbial nitrous oxide consumption captures nitrogen for plant tissues

Nitrous oxide (N₂O) is a strong greenhouse gas with the capacity of depleting ozone layer. Nitrous oxide is naturally produced in nitrogen cycle by microbial processes, but anthropogenic activities have increased the emissions to the atmosphere. Agricultural soil management and excessive use of nitrogen fertilizers are the main reason for increased emissions. Nitrous oxide reductase (nosZ) is a key gene required for the reduction of N₂O and the consumption of it through microbial processes.

The aim of this work was to observe the effects of increased concentration of N₂O to the activation on nosZ genes in microbes from leaf samples. The samples from labelling experiment enabled detecting, whether ¹⁵N-N₂O labelling affected the nitrogen isotope ratio of the plant tissues. The quantitative analysis of nosZ and 16S rRNA genes was used to evaluate the transcription and activity of the genes. The composition of the microbial population of nosZ genes was determined from data obtained from amplicon sequencing with Illumina Miseq using bioinformatic analysing.

The results showed that amplification of clade I was successful in most of the samples, and there was moderate positive correlation between transcription of clade I and nitrogen fixation to the biomass. Clade II amplified only in one sample. Sequencing analyses revealed a wide range of microbial species with nosZ clade I gene, including species associated with nitrogen fixation.