Turns out, bacteria grown in an environment with tons of arsenic and very little phosphorus can learn to not only tolerate the arsenic, but to replace some or all of their phosphorus with it.
This is really a pretty cool demonstration of the flexibility of bacteria if it holds up. It is not terribly surprising though. Bacteria are the dominant life form on the planet for a reason: They are incredibly adaptable. Scientists have really only scratched the surface of the bacterial species on earth, most of which have never been successfully cultured in the lab. For that matter, ~90% of the cells in our bodies are non-human cells, mostly bacteria, and we still know very little about those.
I'll probably post a follow up when the results of this study are published. What's been released so far has just been media hype and teasers without any data.