Horizontal gene transfer and its directionality in some thermophilic case studies
Microorganisms have evolved through millions of years by adapting their physiological capabilities and their genomes so that they can better thrive under specific conditions. Thermophiles frequently inhabit rapidly changing environments and so the ability to incorporate DNA fragments and gain novel features to adapt to new environmental conditions might be a general characteristic within this group of microorganisms. The transference of genetic material among distantly related phyla has been reported to play a major role in microbial evolution leading to complex web-like appearance of current phylogenetic trees of live. The relationship between specific pairs of thermophiles and their potential transference of gene information is to be analyzed. In this study, we will present a couple of examples of thermophilic microorganisms with metabolic features apparently gained through horizontal gene transfer. These two cases are Caldanaerobacter subterraneus subspecies and Fervidobacterium species. Three genomes are available from Caldanaerobacter subterraneus strains. For example, these strains present carbon monoxide dehydrogenase and energy converting hydrogenase encoding gene clusters, which are key enzymes in the metabolism of CO utilization. These clusters form distinct clades as seen by phylogenetic reconstruction indicating different origins. Four genomes of Fervidobacterium species are publicly available. Each of the Fervidobacterium species contain around 40 transposase genes in their genomes. A large fraction of these transposase genes presents as closest relatives sequences from other phyla suggesting the potential occurrence of horizontal gene transfer (HGT) events involving these genes. These case studies allowed to identify pairs of microorganisms that have potentially been related into HGT events and commonly share environmental conditions. The question on whether the transference of DNA between phylogenetically distant microorganisms (i.e., from different phyla) represents an uni- or bi-directional process remains to be answered. Using the examples of thermophiles mentioned above, this study presents evidence on HGT events and on the direction of horizontal gene transfer events between those thermophiles. Thus, this analysis responds to the question on whether HGT is a general mechanism for the exchange of DNA between microorganisms, and specifically thermophiles, or it is a feature that only specific microbial groups exploit to colonize selected environments.
| Main Authors: | , , |
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| Format: | póster de congreso biblioteca |
| Published: |
Kyoto University
2016-09-12
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| Online Access: | http://hdl.handle.net/10261/159036 |
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