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Title: Emergent complexity of microbial communities in the planetary crust
Author: Landenmark, Hanna Klara Emilia
ISNI:       0000 0004 8497 6464
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2019
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Microbial communities are highly complex systems, yet are assembled from basic building blocks of some of the simplest organisms on Earth. We currently have ample information on many individual microbial taxa, but we lack fundamental understanding of how complexity emerges as microbial communities are assembled. As microorganisms almost always exist in complex communities, a series of experiments were implemented in order to study the factors involved in community assembly. Here, focus was placed on investigating two assembly processes described by the metacommunity concept: neutral assembly, dominated by stochastic processes, and species sorting, where the environment selects for the emerging complex community. The process of assembling a complex microbial community on different rock substrates was studied in a series of interlinked experiments. In an experiment examining colonisation of two end-member igneous rock types over the course of 1.5 years, it was hypothesised that neutral processes would dominate at the outset, with environmental selection and thus species sorting becoming more important with time. The results indicate that the opposite is true: the communities are selected for at the outset and converge through neutral processes to a more complex community as the environments become more similar over time. Other experiments were set up in order to probe different factors controlling the assembly of complex microbial communities. Microbial environmental engineering was studied by investigating microbially-mediated rock weathering and its effect on the emerging community. The role of priority effects in building a complex community from simple building blocks was investigated using strains isolated from the colonisation experiment, by mixing together single isolates with some time lag into a co-culture. Lastly, the impact of environmental perturbation on viability of communities at different stages in the assembly process was studied using stresses such as freeze-thaw and desiccation. Together, these experiments have given greater insight into the various factors that influence the assembly of a complex microbial community.
Supervisor: Cockell, Charles ; Allen, Rosalind Sponsor: Engineering and Physical Sciences Research Council (EPSRC)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: sterilised habitats ; microorganisms ; pioneer organisms ; microbial communities ; rock types