紫色土中微生物群落结构及功能特征对土壤pH的差异响应

为明确紫色土中pH对土壤微生物群落结构和功能的影响，选取3种发育于相同母质但pH不同的紫色旱地土为研究对象，通过宏基因组测序技术来研究不同pH紫色土中微生物群落的结构和功能特征的差异.结果表明，宏基因组测序总共发现89门、 222纲、 527目、 1 009科、 2 769属和14 354种.不管是从门还是属分类水平，3种不同pH紫色土的微生物群落结构都有显著差异.RDA结果佐证了3种不同pH紫色土中微生物群落结构差异显著，且测定的土壤性质对微生物群落结构都具有显著的影响，其中土壤pH对微生物群落结构的影响最大（R²=0.998 5,P=0.001）.然而，对微生物群落功能的研究发现，3种不同pH紫色土中微生物群落的功能代谢过程都主要涉及功能未知、全局和总览、氨基酸代谢、碳水化合物代谢和氨同化过程等.不管是COG/KEGG功能分类数据库还是氮循环功能数据库，3种不同pH紫色土中注释到同一功能途径的微生物相对丰度基本都没有显著差异，说明土壤微生物群落水平的总体功能是相对保守的，不容易受环境因子的影响.

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

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.