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Metagenomic investigations on the effects of uranium and copper on sediment microbial communities

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posted on 29.03.2022, 00:47 authored by Brodie Sutcliffe
Freshwater systems are a reservoir of biodiversity and a hot spot for the biogeochemical processes underpinning global nutrient cycles. Microbial communities are a key component of these systems, forming the base of food webs and providing ecological services on which all higher trophic levels depend. Freshwater sediment microbial communities are particularly vulnerable to exposure to anthropogenic pollutants. This is due, in part, to the binding of pollutants to sediment particulates, and the intimate associations microorganisms form with sediments. To date relatively few studies have investigated the effect of metal contamination on freshwater sediment microbial communities and their function. This work explores the effect of uranium (U) and copper (Cu) on freshwater sediment microbial communities. Concentration gradients of each metal were created by spiking the sediments in the laboratory before deploying them in situ. This novel approach allowed sediments with known metal concentration gradients to be exposed to natural environmental fluctuations and biotic colonisation. Metagenomic sequencing techniques were then employed to investigate compositional shifts in microbial communities along these gradients. This work represents the first metagenomic data of sediment microbial communities along U and Cu concentration gradients in natural settings. The study demonstrates that these communities are responsive to elevated concentrations of U and Cu, and that taxonomic shifts cause functional changes. The study identifies taxa which are sensitive to elevated metal concentrations, as well as those which appear to be specialists in these environments. The ecophysiological profiles of six novel genomes, obtained from the metagenome of sediments spiked with 4 g kg-1 of uranium, were used to explore the life-strategies of taxa thriving under these challenging conditions. Additionally, the profiling of sediment fungal communities represents the first metagenomic survey of these taxa in freshwater sediments, and demonstrated considerable taxonomic novelty. The findings of this study provide insights into sediment microbial communities, their complexity and the structure-function relationships underpinning this complexity. Along with their contribution to our understanding of microbial ecology, findings from this study have broad ecotoxicological implications for the monitoring of contaminated freshwater environments, and are of relevance to ecotoxicologists, regulatory bodies and policy makers.

History

Table of Contents

1 Introduction -- 2 Effects of uranium concentration on microbial community structure and functional potential -- 3 Insights from the genomes of microbes thriving in uranium-enriched sediments -- 4 Diverse fungal lineages in subtropical ponds are altered by sediment-bound copper -- 4 Microbial communities are sensitive indicators for freshwater sediment copper contamination -- 6 Discussion.

Notes

Bibliography: pages 179-184 Thesis by publication.

Awarding Institution

Macquarie University

Degree Type

Thesis PhD

Degree

PhD, Macquarie University, Faculty of Science, Department of Molecular Sciences

Department, Centre or School

Department of Molecular Sciences

Year of Award

2018

Principal Supervisor

Ian Paulsen

Additional Supervisor 1

Andrew Harford

Additional Supervisor 2

Anthony Charlton

Rights

Copyright Brodie Sutcliffe 2018 Copyright disclaimer: http://mq.edu.au/library/copyright

Language

English

Extent

1 online resource (xxiii, 185 pages)

Former Identifiers

mq:72170 http://hdl.handle.net/1959.14/1282093