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Wednesday, August 2 • 14:50 - 15:10
Metagenomic exploration of horizontal gene transfer events and phage infections in a South African deep subsurface bacterial population

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In deep subsurface environments viruses in general have been shown to play a role in altering the biogeochemical cycles, microbial diversity profiles and their genetic contents. The role of phages in deep marine and terrestrial environments has been rarely considered and has therefore caused an interest in recent research. In this study, the main objectives were to identify phage genes and the presence of horizontally acquired genes, in the South African subsurface, using bioinformatics approaches to infer their effect on the deep subsurface bacterial communities in terms of evolution and survival. Sampling of fracture water from the South African deep subsurface resulted in identification of phages belonging to the Myoviridae and Podoviridae using TEM analysis. Whole metagenome sequencing of the fracture water microbial population detected phages belonging to the order Caudovirales with the Siphoviridae family being the most abundant. The presence of the Myoviridae and Podovirdae families further confirmed the phage characterization using TEM. The majority of the identified phage sequences were from phages that infect hosts from the phylum Proteobacteria which is the most abundant phyla in the fracture water according to the metagenomics diversity. Partially complete prophages were detected and annotated. The presence of prophages indicated that phages in this environment can be both lytic and lysogenic. Horizontal gene transfer (HGT) was studied by focusing on genomes from binned Proteobacteria. CRISPRs, mobile/transposable elements, transposase and retrons were detected within the binned metagenome data suggesting possible phage mediated HGT events. Specific gene products of HGT events were identified as part of the nitrogen fixation pathway, cobalamin synthesis, sulfide reduction pathways as well as motility and sporulation. This indicates that HGT and viral infections are prevalent evolution events in the studied population as these events would confer novel capabilities to the host for survivability and evolution in the extreme deep subsurface environment.

Wednesday August 2, 2017 14:50 - 15:10
Graduate School of Management Building, room 309 Volkhovskiy Pereulok, 3, St. Petersburg, Russia