Variations of Bacterial and Archaeal Community Structure and Diversity Along Soil Profiles in a Peatland in Southwest China

As bacteria and archaea are key components in the ecosystem, their alterations along soil profiles are important in understanding the biogeochemical cycles in peatland. However, little is known about the vertical distribution patterns of bacteria and archaea along the Bitahai peatland, as well as their relationship to soil chemical properties. Here, sequencing of 16S rRNA genes (Illumina, MiSeq) was used to analyze bacterial and archaeal abundance, diversity, and composition across 0-100 cm of the soil. Soil pH, total C, N, and P concentrations and stoichiometric ratios also were estimated. Results revealed that total C and total N contents, as well as C:P and N:P ratios, significantly increased with increasing peatland depths, while total P decreased. The top three dominant phyla were Proteobacteria (39.64%), Acidobacteria (12.93%), and Chloroflexi (12.81%) in bacterial communities, and were Crenarchaeota (58.67%), Thaumarchaeota (14.34%), and Euryarchaeota (10.82%) in archaeal communities in the Bitahai peatland, respectively. The total relative abundance of the methanogenic groups and ammonia-oxidizing microorganisms all significantly decreased with soil depths. Both bacterial and archaeal diversity were greatly affected by the soil depths. Soil C, N, and P concentrations and stoichiometric ratios markedly impacted the community structure and diversity just in archaea, not in bacteria. Therefore, these results highlighted that the microbial community structure and diversity depended on soil depths, and the affecting factors for bacteria and archaea were different in the peatlands.