植物根际促生菌调控土壤氧化亚氮排放的多稳态生态学机制研究

Nitrous oxide (N2O) is an important greenhouse gas, and the nitrogen cycle in farmland soil driven by microorganisms is an important source and sink of atmospheric N2O. Therefore, using functional microbes to regulate the nitrogen cycle of soil is an crucial way to mitigate N2O emissions. However, the in situ micro-ecological system varies in alternative stable states, and the external microorganisms must break through the original stable state and colonize first for further functions. In the previous study, we reduced the N2O emission from acidic soil by using a plant-growth-promoting bacteria, Bacillus amyloliquefaciens (BA), and the BA colonized successfully in the soil, but the change of the stable states and the regime shifting in this process remain poorly understood. Herein, we will combine the microcosms and multi-omics to clarify the mechanisms of BA colonizing and regulating the microbial community in situ. This project aims to investigate the effect of soil property (pH) and indigenous microbial communities on the colonization of BA, the niche occupied by BA after colonization, the different stable states and threshold, establish a prediction model for the change of alternative stable states, and reveal the regulation of BA on the nitrogen cycle around the threshold. The project will provide a theoretical basis for the widespread application of microorganisms in soil biostimulation and bioremediation.

氧化亚氮（N2O）是一种重要的温室气体，由微生物驱动的农田土壤氮循环是大气N2O的重要源和汇。因此，利用微生物技术调控土壤氮循环是减少N2O排放的重要途径。然而，土壤原位的微生态系统处于动态变化的多稳态（alternative stable state）中，外来微生物发挥作用首先要突破原有稳态，达到新稳态。在前期研究中，申请人利用植物根际促生菌解淀粉芽孢杆菌（Bacillus amyloliquefaciens, BA）成功减少了酸性农田土壤N2O的排放，且BA在原位成功定植，但此过程中的多稳态机制尚未进行系统研究。本项目拟采用微宇宙培养结合多组学的方法，对BA原位定植的微生态过程和分子调控机理进行系统深入的研究，旨在阐明土壤性质（pH）和原位微生态对外来微生物定植的影响，明确BA定植前后的不同稳态及临界转换节点，建立BA定植的多稳态预测模型，为微生物技术在土壤中的应用提供理论基础。

外来的有益微生物在土壤或植物根际成功定植后，可以有效的促进植物生长。然而，微生物生态学水平上的定植过程目前尚不清晰。在本研究中，我们构建了两个模型来研究植物促生菌解淀粉芽孢杆菌（Bacillus amyloliquefaciens，BA）在根际和非根际土壤的定植过程和热区。结果显示，BA可以成功地在酸性土壤中定植，而在碱性土壤中则不能定植。我们利用定量PCR和高通量测序技术解析了这两种条件下，土壤细菌群落的多样性、群落结构和互作网络关系，阐明了原位微生物群落对外来微生物定植的关键作用。此外，我们发现BA定植的热区主要是在非根际土壤。本项目为外来微生物的定植提供了理论参考，有助于微生物技术更好地应用于环境修复和改良。