Bacterial communities in the upper soil layers in the permafrost regions on the Qinghai-Tibetan plateau

- The pH, soil carbon, and precipitation affects soil bacteria in the Tibetan plateau.
- Depth significantly affects the relative abundance of bacterial phyla.
- Active layer is not a controlling factor for bacterial community on the plateau.
- Response of bacteria to permafrost degradation will be affected by other factors.

The Qinghai-Tibetan plateau (QTP) is the largest middle-low latitude permafrost region on earth, while little is known about the microbial community in this area. Here, we investigated the bacterial community in the upper 30 cm soils in the permafrost regions on the central QTP using Illumina sequencing technology. In these soils, the most abundant phyla were Acidobacteria, Proteobacteria, and Bacteroidetes. The depth was significantly correlated with Acidobacteria, Proteobacteria, Nitrospirae, and Gemmatimonadetes. The soil pH and the gravel content were significantly positively correlated with Bacteroidetes. The active layer thickness was significantly correlated with Bacteroidetes and Arabinonates. Although these factors were closely correlated with the relative abundances of specific bacterial phyla, the overall bacterial community structure was mainly affected by pH, soil organic carbon content, and the mean annual precipitation, while the community structure had no significant relationship with the active layer thickness. Our results suggested that the permafrost region on the QTP had greatly heterogeneous environmental conditions, and the responses of microbial communities to permafrost degradation would also be affected by other factors such as precipitation, soil texture and vegetation.