Still changing after all these years
In a paper published in the current issue of Nature, the Michigan State University (MSU) John Hannah Distinguished Professor of Microbiology and Molecular Genetics and an international team of researchers used cutting-edge technology to study tens of thousands of generations of E. coli bacteria. They sequenced the entire genomes, or genetic code, of the bacteria to pinpoint the genes with beneficial mutations that gave the bacteria a competitive edge over their ancestors.
The bacteria from different generations of the LTEE have been stored in freezers for nearly 30 years, but they were brought back to life to look for the changes in their DNA. Being able to go back into the freezer to study samples from years ago is one of the reasons Lenski calls the LTEE “the experiment that keeps on giving.”
“One of the nice things about such a long-term experiment is that new technologies come along that didn’t exist when I started the LTEE in 1988,” said Lenski, who’s part of MSU‘s BEACON Center for the Study of Evolution in Action. “The first bacterial genome was not sequenced until 1995, and now, in this single paper, we’ve sequenced 264 complete genomes from this one experiment.”
The team sequenced hundreds of E. coli genomes to examine how the bacteria had changed in their DNA over 50,000 generations. The researchers found more than 14,000 changes across the LTEE’s 12 populations. Each population changed in different ways, but there were some important commonalities as well.
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