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"Thinking of arsenic as not just a bad guy, but also as beneficial, has reshaped the way that I view the element," said first author Jaclyn Saunders, who did the research for her doctoral thesis at the UW and is now a postdoctoral fellow at the Woods Hole Oceanographic Institution and the Massachusetts Institute of Technology.
The study was published this week in the Proceedings of the National Academy of Sciences.
Time - Levels - Arsenic - Ocean - Co-author
"We've known for a long time that there are very low levels of arsenic in the ocean," said co-author Gabrielle Rocap, a UW professor of oceanography. "But the idea that organisms could be using arsenic to make a living -- it's a whole new metabolism for the open ocean."
The researchers analyzed seawater samples from a region below the surface where oxygen is almost absent, forcing life to seek other strategies. These regions may expand under climate change.
Parts - Ocean - Sandwich - Water - Oxygen
"In some parts of the ocean there's a sandwich of water where there's no measureable oxygen," Rocap said. "The microbes in these regions have to use other elements that act as an electron acceptor to extract energy from food."
The most common alternatives to oxygen are nitrogen or sulfur. But Saunders' early investigations suggested arsenic could also work, spurring her to look for the evidence.
Team - Samples - Research - Cruise - Pacific
The team analyzed samples collected during a 2012 research cruise to the tropical Pacific, off the coast of Mexico. Genetic analyses on DNA extracted from the seawater found two genetic pathways known to convert arsenic-based molecules as a way to gain energy. The genetic material was targeting two different forms of arsenic, and authors believe that the pathways occur in two organisms that cycle arsenic back and forth between different forms.
Results suggest that arsenic-breathing microbes make up less than 1% of the microbe population in these waters. The microbes discovered in the...
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