Skip to main content

Journal Club:”A Bacterium That Can Grow by Using Arsenic Instead of Phosphorous”

By

Since the previous journal club where we covered an article that looked at the microbial synthesis of alkanes, another a curious observation made the rounds in the science world. In the latest Science Journal, Felisa Wolfe-Simon et. al. report their successful isolation of a bacteria that can use arsenic instead of phosphorous.

The group isolated the bacterial strain called, GFAJ-1, by inoculating synthetic media containing glucose, vitamins and trace metals and varying concentrations of AsO43- with sediments from Mono Lake which naturally contains high concentrations of dissolved arsenic (200 M) and performing many serial dilutions. GFAJ-1 was identified to belong to Halomonadaceae family of Gammaproteobacteria.


Various tests were performed to verify that these organisms could not only live but procreate in this environment. Among the remarkable features of this organism is the observation that arsenic can get incorporated into macromolecules most notably DNA where it replaces the need for phosphorous in the backbone. Despite similar chemical properties of AsO43-and PO43- down-stream processes can be affected by the presence of AsO43-explaining the toxic effects of arsenate. It is even more remarkable that this bacterium can switch between the use of AsO43- and PO43-although it has to be noted that the organisms grow much faster in media containing phosphate instead of arsenate. Details on how arsenic was incorporated into macromolecules and how the organism can deal with varying concentrations of arsenic and phosphorus are currently unknown but will surely be part of future publications.


Why is this so important?


There has been the long-standing view that life on earth is mostly based on carbon, hydrogen, nitrogen, oxygen sulfur and phosphorus. The observation that phosphorus which builds the backbone of DNA can be replaced by arsenic expands the view of possible biochemistry that can take place in other parts of the universe.


From an environmental point of view, dissolved arsenic is toxic to most life due to the similar but but not quite identical properties of arsenic which allows some reactions to take place while inhibiting others. Could bio accumulation of arsenic by used to clean up arsenic contamination sites? 


P.S (2011-02-18).: The journal club would not be complete if I did not mention that some people remain skeptical of the claim that arsenate can replace phosphate in these organisms. The criticicsm centers around some of the assumptions underlying some of their indirect methodologies. An alternative hypothesis was suggested: Rather than arsenate incorporation, some scientists hypothesize that arsenate is rather sequestered. Great claims require great proofs which in the minds of these scientists had not been brought forward. In response to the criticism the author decided to submit the strain to two publically available culture collection centers (the American ATCC and the German DSMZ) to allow for their more widespread studies.
 
Literature Cited:


Felisa Wolfe-Simon et. al. "A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus."
Science Express, December 2, 2010, pp 1-9
Link: http://www.sciencemag.org/content/early/2010/12/01/science.1197258.full.pdf
Labels:

Comments

Post a Comment

Popular posts from this blog

In Other Words: A Life on Our Planet

By
I just watched this documentary together with my son and my wife. Different from David's typical approach of sparse objective commentary, this documentary movie is a personal witness statement that David Attenborough is making describing how our planet has changed in his life time. It's compelling, and urgent but still hopeful.   Please, watch this documentary and share with your friends so they get the message!
3 comments
Read more

Sustainable Living - One Step at a time: Toilet Paper

By
Introduction It's been a while since last, I posted here. Today, I want to introduce another blogging series which I call "Sustainable Living - One Step at a time" In the past, I have often written and talked about interesting new technologies and ideas in the biological field, some of which could be used to reduce the impact human kind makes on the environment. Although many dedicated brains are tackling these interesting challenges, there are even more who are not working in these kinds of fields. What can other people do to reduce one's impact on the environment? Generally, by adapting a more sustainable approach of living.  Because so many habits and other aspects of life would need to be changed, many people may not feel that it is worth pursuing these efforts because the perceived sacrifices would be too big. Alternatively, one may not know where to start. I do not exclude myself it the latter group. So, instead of trying to do everything at the same tim...
1 comment
Read more

Freely-Speaking: Quick note on bio-based antennaes

By
With my thesis defense coming up this Monday, I really did not have as much time to share all the interesting things I came across lately. But I did not want to miss the chance to make a quick note to myself and the readers of this site of an interesting paper, titled "DNA-based programming of quantum dot valency, self-assembly and luminescence" just published in Nature Nanotechnology . Grigory Tikhomirov et al. report "the self-assembly of quantum dot complexes using cadmium telluride nanocrystals capped with specific sequences of DNA. Quantum dots with between one and five DNA-based binding sites are synthesized and then used as building blocks to create a variety of rationally designed assemblies, including cross-shaped complexes containing three different types of dots...Through changes in pH, the conformation of the complexes can also be reversibly switched, turning on and off the transfer of energy between the constituent quantum dots." In other w...
3 comments
Read more