Structure and function of microbial communities at the soil atmosphere interface

最上面几毫米的土壤形成了一个微生物层，被称为生物土壤结皮（BSC），由独特的苔藓植物、藻类、蓝藻、微真菌和细菌群落组成。在土壤表面，BSC暴露在独特的条件下，与散装土壤相比，这使其具有独特的土壤化学和群落结构。这些特性使其在固氮固碳、入渗、产沙、防止土壤侵蚀和农药分解等方面发挥着不可替代的作用，具有重要的农业和环境意义。然而，以往的研究往往集中在干旱土壤上，表明平衡平衡卡发挥这些作用的能力往往取决于群落结构，这已被证明在时间和空间上都有很大差异。因此，土壤表层微生物的多样性、组成和动态仍然知之甚少，不同微生物群落对关键功能的贡献性质尚未得到解决，特别是在温带土壤的农业背景下。在本项目中，下一代测序方法将用于了解温带土壤农田中决定BSC组成和功能的环境因素。利用景观采样方法，解决地理距离、当地环境和季节变量对土壤表层群落组成的影响。分子方法将用于表征微生物群落组织及其生态功能。这些方法将包括DNA和RNA的提取和纯化、PCR、使用下一代平台的核酸测序和生物信息学分析。最后，研究群落组成对农药降解的影响方式，确定土壤表层群落组成与生态系统功能之间的关系。

The top few millimetres of soil forms a microbiotic layer, known as the Biological Soil Crust (BSC), that consists of unique communities of bryophytes, algae, cyanobacteria, microfungi and bacteria. At the soil surface the BSC is exposed to exclusive conditions, which gives it a distinct soil chemistry and community structure in comparison to bulk soil. These properties allow it to play irreplaceable roles in nitrogen and carbon fixation, water infiltration, sediment production, protection from soil erosion and breakdown of pesticides, which are all of great agricultural and environmental importance. However, previous studies, which often focus on arid soils, have suggested that the ability for the BSC to perform these roles often depends on the community structure, which has been proven to differ greatly both temporally and spatially. Consequently, the diversity, composition and dynamics of the microbiology at the soil surface layer remains poorly understood, and the nature of different microbial communities contribution to key functions is unresolved, especially in an agricultural context in temperate soils.In this project, next generation sequencing methods will be used to understand the environmental factors that determine composition and functioning of the BSC in agricultural fields in temperate soils. Using landscape sampling approaches, the roles of geographical distance, local environment and seasonable variables that determine composition of the soil surface community will be resolved. Molecular approaches will be used to characterize the microbial community organisation and its ecological function. These approaches will include DNA and RNA extraction and purification, PCR, nucleic acid sequencing using next generation platforms and bioinformatics analysis. Lastly, the way in which community composition affects the degradation of pesticides will be investigated to identify relationships between soil surface community composition and ecosystem function.