Contrasting Responses of the Microbial Community Structure and Functional Traits to Soil pH in Purple Soils

Abstract

To clarify the effect of pH on the structure and functional traits of soil microbial communities in purple soils, three purple upland soils developed from the same parent material that differed in pH were selected as the research objects, and metagenomic shotgun sequencing was used to investigate the structure and functional traits of the microbial communities among different pH soils. The shotgun sequencing identified a total of 89 phyla, 222 classes, 527 orders, 1009 families, 2769 genera, and 14354 species in these soils. Regardless of the phylogenetic classification level, the microbial community structures of these three purple soils with different pHs were significantly different. RDA results corroborated the highly significant difference in the microbial community structures among the three purple soils with different pHs, and the soil properties tested here all had significant correlations with soil microbial community structure, in which the soil pH had the greatest effect (R2=0.9985, P=0.001). However, the results of investigating the microbial community functions revealed that the main metabolic processes of the three purple soils were all involved in unknown functions, global and overview maps, amino acid metabolism, carbohydrate metabolism, ammonia assimilation, etc. There was almost no significant difference in the relative abundance of microbes in the three purple soils annotated with the same function regardless of the COG/KEGG functional database and nitrogen cycling functional database, indicating that the overall function trait of soil microbial community was relatively conservative and not easily affected by environmental factors.