ResearchBlogging.orgOne of the things that inspired me to write a blog about science is that I believe science does not have to be “dumbed down” for everyone to think that it is interesting. Researchers shouldn’t be afraid to use clear and understandable language to explain what is interesting about their results. Sometimes scientists (and science journalists) simplify the results so much that they stretch the actual truth of the report.


For example, I’m sure most of you have heard at least in passing of the results from a NASA funded study that found bacteria that can use Arsenic (As). A sampling of titles in the media include:

These titles are somewhat mis-leading. Combined with the hype surrounding this discovery, some might be led to believe that bacteria based entirely on Arsenic had been discovered, in the same way that humans are Carbon based life forms.  This type of discovery would imply a completely different biological evolution for these microbes with entirely different biological pathways and mechanisms that may have evolved separately from ours over millions of years. This however is not the case.

Arsenic Science

What actually was discovered were bacteria in a lake in California that already had elevated levels of Arsenic. This is interesting in it’s own right because Arsenic is highly toxic. The reason being that Arsenic and Phosphorous have very similar chemistries. For instance take a look at where they appear in the periodic table:


Phosphorous and Arsenic on the Periodic Table. Their location in the same column indicates similar reactivity.

Because they are located in the same column, they will have similar reactivity and can be substituted in certain reactions. Phosphorus is used in the body to make up the backbone of DNA, RNA, and in protiens. Arsenic is similar enough to phosphorous to be incorporated into these molecules, but is not quite similar enough such that it is extremely toxic when ingested.

“Arsenic Life-Forms”

So is this actually an “Arsenic Based Life Form”? Not exactly. Above we’ve determined that arsenic is chemically similar to phosphorous and is typically extremely toxic. How are these new bacteria special? Well, in the wild their only special ability is that they have somehow adapted to survive in an environment with high amounts of Arsenic, where other microbes would typically die. However, when in the wild, they do not have new forms of DNA or proteins or different types of biochemistry. They use phosphorous just like the rest of the life on this planet.

What the scientists were able to do in the laboratory however was slowly remove phosphorous from the environment and replace it with arsenic. These bacteria, under coercion by the environment, started to incorporate arsenic into their biological structures (like DNA and proteins), but this did not result in the death of the cells.  Researchers do not yet know exactly where the arsenic atoms are going and how they get there and how they affect biological processes, but these will certainly be very interesting topics to explore in the future. While this study is quite fascinating, it doesn’t quite match the hype in some of the news reported.

Doing it Right

One of the best explanations I found was in the New York Times with the title “Microbe Finds Arsenic Tasty; Redefines Life.” Without trying to hype up the research by making it sound like extreme radical new forms of life were discovered, it makes the title intriguing and retains scientific accuracy. It also has a great graphic explaining in more detail the results from the Science paper:


Source: New York Times

This is what science journalism should be – interesting without the hype, and yet still scientifically accurate.

In a Nutshell

Scientists found bacteria that could be coerced into using the typically toxic arsenic instead of phosphorous in their molecular makeup. While not actually a “new life form” as hyped in the media, the results are interesting and can be explained without stretching the truth to make it more interesting.


Wolfe-Simon, F., Blum, J., Kulp, T., Gordon, G., Hoeft, S., Pett-Ridge, J., Stolz, J., Webb, S., Weber, P., Davies, P., Anbar, A., & Oremland, R. (2010). A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus Science DOI: 10.1126/science.1197258


2 responses »

  1. I, too, heard all the hype and was confused as to what was really going on. Thank you for clearing things up for me! Again, Paul, you rock 🙂

  2. iampotassium says:

    Nice discussion, Paul! 🙂

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