Impact of Viruses on Prokaryotic Communities and Greenhouse Gas Emissions in Agricultural Soils.

Viruses are abundant and ubiquitous in soil, but their importance in modulating greenhouse gas (GHG) emissions in terrestrial ecosystems remains largely unknown. Here, various loads of viral communities are introduced into paddy soils with different fertilization histories via a reciprocal transplant approach to study the role of viruses in regulating greenhouse gas emissions and prokaryotic communities. The results showed that the addition of viruses has a strong impact on methane (CH) and nitrous oxide (NO) emissions and, to a minor extent, carbon dioxide (CO) emissions, along with dissolved carbon and nitrogen pools, depending on soil fertilization history.

Organic fertilizer significantly mitigates NO emissions while increase contributed of comammox Nitrospira in paddy soils.

Nitrification is the dominant process for nitrous oxide (NO) production under aerobic conditions, but the relative contribution of the autotrophic nitrifiers (the ammonia-oxidising archaea (AOA), the ammonia-oxidising bacteria (AOB) and the comammox) to this process is still unclear in some soil types. This is particularly the case in paddy soils under different fertilization regimes. We investigated active nitrifiers and their contribution to nitrification and NO production in a range of unfertilized and fertilized paddy soils, using CO-DNA based stable isotope probing (SIP) technique combined with a series of specific nitrification inhibitors, including acetylene (CH), 3, 4-dimethylpyrazole phosphate (DMPP) and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO).

Diversity and assembly of active bacteria and their potential function along soil aggregates in a paddy field.

Numerous studies have found that soil microbiomes differ at the aggregate level indicating they provide spatially heterogeneous habitats for microbial communities to develop. However, an understanding of the assembly processes and the functional profile of microbes at the aggregate level remain largely rudimentary, particularly for those active members in soil aggregates. In this study, we investigated the diversity, co-occurrence network, assembly process and predictive functional profile of active bacteria in aggregates of different sizes using HO-based DNA stable isotope probing (SIP) and 16S rRNA gene sequencing.