Soil bacterial community composition and functional potentials along the vertical vegetation transect on Mount Segrila, Tibet, China

Abstract

Information on the spatial distribution of soil microbial communities on the Tibetan Pla-teau is critical for in-depth understanding the important roles of microbes in typical alpine ecosystems. In this study, 16S rDNA Illumina Miseq sequencing was used to analyze the variations in bacterial community composition and functional potentials in soils sampled from four elevations on Mount Segrila, Tibet, and the driving environmental factors. Results showed that richness and Shannon diversity index of soil bacteria significantly decreased with increasing altitude. The relative abundances of Acidobacteria, Chloroflexi, Gemmatimonadetes, and Nitrospirae significantly increased, whereas that of Proteobacteria, Actinobacteria and Bacteroidetes significantly decreased with increasing altitude. In KEGG pathway (level Ⅱ), the relative abundance of genes related to membrane transport and the metabolism of amino acids, lipids, terpenoids and polyketones was significantly lower at high elevations. In contrast, genes related to carbohydrates metabolism, signal transduction, replication and repair and enzyme family were more abundant at high altitudes. Soil bacterial community composition and predicted functions were significantly affected by vegetation types and soil properties, with soil pH being the key driver. There were significant correlations between the abundances of predicted functions and bacterial taxa, such as Acitnobacteria, Bacteroidetes, and Fibrobacteres. The dissimilarity in the composition of KEGG pathway genes along the elevational gradient (β-diversity) showed a significantly positive correlation with the dissimilarity in bacterial community structure, indicating that there was a strong relationship between microbial community composition and potential functionality.