The structure and function of subglacial microbial communities in Southwest Greenland

Abstract

Life has established survival strategies across all parts of planet Earth. In the extreme environment called the cryosphere, microbial life makes a significant contribution to the available nutrients. Understanding microbial nutrient cycling in this ecosystem is necessary to achieve an accurate understanding of global nutrient cycles. This thesis sets out to explore the metabolic mechanisms present in available subglacial metagenomic samples by bringing together DNA sequence data from geographically similar water and ice locations covering a range of fieldwork years in Southwest Greenland. Four metagenomes are co-assembled into 51 medium and high-quality metagenome assembled genomes. The community is found to be dependent on a variety of sulphur species with the most frequently detected pathway being sulphide oxidation. However, in addition to sulphur cycling, genes involved in dissimilatory nitrogen reduction, nitrogen fixation, and methane cycling were detected in all locations. The recovered genomes are assigned phylogenetic classes spanning 8 different phyla in all locations. All locations are found to be phylogenetically diverse with metagenome assembled genomes carrying metabolic genes across several biogeochemical niches. This thesis provides a detailed insight into the metabolic genes present in subglacial water and ice samples and suggests the environment is dependent on sulphur cycling.

Date of Award	18 Jun 2024
Original language	English
Awarding Institution	University of Bristol
Supervisor	Rachel M Flecker (Supervisor) & Gary L A Barker (Supervisor)