Differences and influencing factors of bacterial composition and diversity in seven typical extreme habitats on the Qinghai-Tibetan Plateau

Abstract:

Soil microorganisms play a key role in the sustainability of ecosystems. There are diverse extreme habitats on the Qinghai-Tibetan Plateau (QTP), where the differences of soil bacterial composition and the driving factors remain to be studied. [Objective] To explore the differences and influencing factors of soil bacterial diversity in different extreme habitats on the QTP. [Methods] High-throughput sequencing of 16S rRNA genes was performed for the soil samples from seven typical extreme habitats on the QTP. The bioinformatics tools were employed to analyze the differences in bacterial composition and functions among different habitats. The potential soil factors influencing bacterial composition were further analyzed. [Results] A total of 16 323 712 high-quality reads and 26 504 operational taxonomic units (OTUs) were obtained for the 36 soil samples collected from seven different habitats. At the phylum level, the relative abundance of Actinomycetota and Proteobacteria were the highest in all the habitats. Bacillus, Ambiguous_taxa, Solirubacter, and Pseudoarthrobacter were the dominant genera. In addition, there was no significant difference in bacterial alpha diversity among different habitats, while the bacterial beta diversity showed significant differences, which was further confirmed by Linear discriminant analysis Effect Size (LEfSe). Redundancy analysis (RDA) identified Mg²⁺, Na⁺, and K⁺ as the main factors affecting the bacterial community structure, and the effects of other soil physicochemical factors on the distribution of dominant flora varied in different habitats. Finally, FAPROTAX tool was used to predict the bacterial function, which suggested that the roles of bacteria in the biogeochemical cycling processes of nitrogen and sulfur varied in different habitats. [Conclusion] The bacterial community structure varies greatly in different extreme habitats of the QTP, which is driven by different soil physicochemical factors. The presence of rich unannotated genera in each habitat indicates that the QTP has rich potential new bacterial resources.