Sequencing Evolution in Real-Time

Staphylococcus aureus
Staphylococcus aureus. Credit: Erbe, Pooley: USDA, ARS, EMU. Public Domain license.

I mentioned in a recent post that the cost of sequencing DNA was falling exponentially. A good real-world example of the state of the art is this story from the Proceedings of the National Academy of Sciences of the USA (PNAS) that I found over at In the Pipeline:

A team of researchers looked at a single patient undergoing treatment with vancomycin for a serious infection. […] They periodically isolated Staphylococcus aureus bacteria from the patient’s blood during the course of the treatment to look at how resistance to the antibiotic developed. […] the way they watched the process was to sequence the whole genome of each bacterial isolate. What they found were a total of 35 mutations, which developed sequentially as the treatment continued (and the levels of resistance rose). Here’s natural selection, operating in real time

(bold and link are mine)

We’re now at the stage where we can sequence a bacteria’s whole genome multiple times to follow mutations in real-time. That’s amazing! It’s still an expensive experiment, but a few years ago it would have been an impossibly huge undertaking, and we can bet that a few years from now it will be routine and completely unremarkable.

Allow me to repost the log graph of the cost of sequencing base pairs of DNA:

Kurzweil, DNA sequencing
Credit: Ray Kurzweil, The Singularity is Near, p.73.

A straight line on a log graph means exponential change. In this case, it’s an exponential fall in costs. If we extrapolate just a little, we see that sequencing DNA will almost be free very soon.

This almost assuredly means that soon enough we’ll have sequenced pretty much everything on Earth that 1) has DNA and that 2) we know about (we’re still frequently discovering species of insects, deep sea animals, bacteria, etc). Exciting times!



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