Structure and function of microbial communities at the soil atmosphere interface

最上面几毫米的土壤形成一个微生物层，被称为生物土壤结皮(BSC)，由苔藓、藻类、蓝藻、微真菌和细菌组成的独特群落。在土壤表面，BSC暴露在独特的条件下，这使它与散装土壤相比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、水分渗透、泥沙产生、防止土壤侵蚀和农药分解方面发挥了不可替代的作用，这些都对农业和环境具有重要意义。然而，以前的研究往往集中在干旱土壤上，表明BSC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的差异。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的性质还没有得到解决，特别是在温带土壤的农业背景下。在这个项目中，下一代测序方法将被用来了解决定温带土壤农业领域中BSC的组成和功能的环境因素。利用景观采样方法，将解决地理距离、当地环境和决定土壤表面群落组成的季节性变量的作用。将使用分子方法来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、聚合酶链式反应、使用下一代平台的核酸测序和生物信息学分析。最后，将调查群落组成影响农药降解的方式，以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.