Arsenic and old...photosynthesis?

A previously unknown form of photosynthesis discovered in purple bacteria scooped from a Californian hot spring may be an ancient process that arose before the evolution of oxygenic photosynthesis, according to a paper published on Friday (August 15) in linkurl:Science.;http://www.sciencemag.org/ The bacteria use arsenic instead of water for photosynthesis. "It's a fundamental, exciting observation," said linkurl:Tim McDermott,;http://tbi.montana.edu/facultystaff/mcdermott.html a professor of microbial ecophysiology at Montana State University, who was not involved in the research. The discovery "gives me a further appreciation of how talented, metabolically speaking, the microbial world really is," McDermott added. "Nothing surprises me anymore." linkurl:Arsenic;http://www.the-scientist.com/article/display/20753/ is well-known for its toxicity; it was used so often as tool for homicide in the 1800s that it earned the nickname "king of poisons." A molecular analog of phosphate, arsenic disrupts production of ATP and impairs the function of proteins, among other mechanisms. Research has revealed that different oxidative states...