Sunday, November 19, 2006
DNA Sequencing Reveals Bacterial Evolution In Lab
California (USA), 16 November: Whole-genome sequencing allows bacterial evolution to be observed on a laboratory timescale, scientists report in a paper to be published in the December issue of Nature Genetics. Experimental studies of bacterial evolution have been carried out for many years, but the identification of the genetic mutations that underlie the observed changes in bacterial growth properties has been a difficult and laborious process.
Bernhard Palsson and colleagues applied an approach recently developed by Nimblegen Systems, Inc. for rapid, cost-effective genome sequencing. They grew a strain of Escherichia coli in a medium in which glycerol was the main carbon and energy source, and then isolated individual bacteria from each of 5 populations after approximately 660 generations– 44 days. Whole-genome sequencing allowed the authors to identify 9 sequence differences between bacteria isolated at the end of experiment, and the strain that was used at the start.
Some of the mutations could be easily understood in terms of E. coli biology- mutations in the gene encoding glycerol kinase, for example, which catalyzes the first step in glycerol breakdown. Others were found in genes that previously had no known role in glycerol metabolism, hinting at the complexity of a bacterium’s response to changing environmental conditions. This approach promises to improve our understanding of evolution at the genetic level, both in bacteria, and in other organisms with modestly sized genomes.
(ResearchSEA)
Bernhard Palsson and colleagues applied an approach recently developed by Nimblegen Systems, Inc. for rapid, cost-effective genome sequencing. They grew a strain of Escherichia coli in a medium in which glycerol was the main carbon and energy source, and then isolated individual bacteria from each of 5 populations after approximately 660 generations– 44 days. Whole-genome sequencing allowed the authors to identify 9 sequence differences between bacteria isolated at the end of experiment, and the strain that was used at the start.
Some of the mutations could be easily understood in terms of E. coli biology- mutations in the gene encoding glycerol kinase, for example, which catalyzes the first step in glycerol breakdown. Others were found in genes that previously had no known role in glycerol metabolism, hinting at the complexity of a bacterium’s response to changing environmental conditions. This approach promises to improve our understanding of evolution at the genetic level, both in bacteria, and in other organisms with modestly sized genomes.
(ResearchSEA)
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