水热增加下黑土细菌群落共生网络特征

Co-occurrence network of bacterial communities in mollisol soils under increasing hydrothermal conditions

摘要:

黑土是有机质含量高且肥沃的土壤类型之一，气候变化会显著改变黑土中微生物群落的结构，同时影响群落间的潜在相互作用关系。[目的] 揭示水热增加对黑土中的细菌群落结构及潜在互作关系的影响。[方法] 基于土壤移置试验，采用16S rRNA高通量测序解析农田黑土（原位黑土、水热增加1和水热增加2）中的细菌群落结构对水热增加的响应；使用CoNet构建微生物群落共生网络，识别共生网络中的枢纽微生物；利用结构方程模型、相关性分析探究水热条件变化下土壤性质、微生物交互作用、多样性之间的直接、间接关系。[结果] 黑土中的微生物以疣微菌、变形杆菌、酸性杆菌和放线菌为主。水热增加下土壤微生物共生网络的拓扑性质发生显著变化，网络中表征微生物潜在竞争关系的负连线随着水热增加而显著增加。气候因素通过改变微生物潜在相互作用影响了群落水平分类多样性。物种竞争增强可能直接导致了土壤有机碳含量的降低。[结论] 水热增加会显著改变黑土中微生物之间的潜在交互作用，枢纽微生物的响应更加敏感。

关键词:水热增加;土壤移置;微生物共生网络;枢纽微生物

Abstract:

Mollisol soil is one of the soil types with high content of organic matter and fertility, climate change will significantly change the structure and potential interactions of mollisol soils microbial communities. [Objective] This study is aimed to explore the microbial community structure and succession characteristics of mollisol soils under increasing hydrothermal conditions. [Methods] Based on a soil transplantation expriment, 16S rRNA high-throughput sequencing was used to analyze the bacterial community structure of mollisol soils (in-situ, warming1 and warming2); CoNet was used to construct the microbial co-occurrence networks and identify the hub microbes, structural equation models and correlation analysis were used to explore the direct and indirect relationships between soil properties, microbial co-occurrence networks, and diversity under the increasing precipitation and temperature conditions. [Results] We found that mollisol soils were dominated by Verrucomicrobia, Proteobacteria, Acidobacteria, and Actinobacteria. Soil transplantation simulating climate change altered the patterns of microbial co-occurrence network with increased negative edge percentage and different network sizes. Climatic factors affected the taxonomic diversity directly and indirectly from altering the microbial interactions. The strengthen of negative interactions in communities directly induced the loss of soil organic carbon. [Conclusion] The increasing hydrothermal conditions will significantly change the microbial community co-occurrence network of mollisol soils, and the response of network hub microbes will be more sensitive.

Key words:increasing hydrothermal conditions;soil transplantation experiment;microbial co-occurrence network;hub microbes