Metagenomic Analysis of Previously Understudied Lakes in the Vestfold Hills, East Antarctica

• Main Author: Haque, Sabrina
• Format: Master Thesis
• Language: English
• Published: UNSW, Sydney 2021
• Subjects: Sterivex; Metagenomics; Biogeography; Endemic; Antarctica; Haloarchaea; Antarctic; Southern Ocean; East Antarctica; Vestfold Hills; Vestfold; Rauer Islands; Antarc*
• Online Access: http://hdl.handle.net/1959.4/70587; https://unsworks.unsw.edu.au/bitstreams/b4c0e682-e961-44e7-b44e-36258df5ad59/download; https://doi.org/10.26190/unsworks/22310

Antarctica, like most natural environments on Earth, contains microbes that dominate the gene pool and biomass of aquatic habitats such as – lakes, stratified marine basins, fjords, and the surrounding Southern Ocean. Within these habitats, the microbes form the basis of the food webs and take part in biogeochemical cycling, thereby influencing global ecosystem function. Various ‘omic’ approaches have been developed to explore diversity of environmental microbial communities without the necessity for growing pure cultures in laboratories. One such approach, called metagenomics, applies shotgun DNA sequencing to millions of random genomic fragments, obtained from environmental samples, and utilizes the resulting sequence data for taxonomic and/or functional profiling purposes. Haloarchaea tend to dominate hypersaline lakes in the Vestfold Hills and the Rauer Islands of East Antarctica. This research aimed to study metagenomes from several hypersaline lakes located within the Vestfold Hills and the Rauer Islands to analyse the effects of two environmental parameters, salinity and distance, on the abundance of haloarchaea within the lakes, and to investigate haloarchaeal species endemicity. DNA was extracted from the biomass of 78 Antarctic lakes that was captured on sterivex filters, and the DNA was quantified using Qubit fluorometry. Metagenome data was obtained for 28 of the samples, together with metagenome data for 17 previously sequenced samples. The data were then analysed using computational tools including Kaiju v1.6.3 and Plymouth Routines In Multivariate Ecological Research v7. The analyses revealed that haloarchaea were the most abundant taxa within the hypersaline lakes with haloarchaeal diversity being highly influenced by lake salinity, rather than the proximity of the lakes to each other. The study further went on to provide stronger evidence that specific haloarchaeal species, Halohashta litchfieldiae, Halorubrum lacusprofundi and Halophilic archaeon DL31, were endemic to Antarctica.