Structure and function of microbial communities at the soil atmosphere interface

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.