Researchers stumble on algae that detoxifies arsenic

March 10th, 2009 - 5:00 pm ICT by IANS  

Washington, March 10 (IANS) Researchers have stumbled on an algae that detoxifies arsenic, potentially opening the way for cleaning up underground water reservoirs in West Bengal and Bangladesh contaminated with the poison.
The simple, single-celled algae called Cyanidioschyzon thrives in extremely toxic conditions and chemically modifies arsenic that occurs naturally, said Tim McDermott, professor of environmental sciences at Montana State University (MSU) who led the study.

Cyanidioschyzon could some day help reclaim arsenic-laden mine waste and aid in everything from space exploration to creating safer foods and herbicides, scientists said.

The scientists cloned genes from the algae, then studied the enzymes to figure out how they transformed arsenic. They learned that the algae oxidises, reduces and converts arsenic to several forms that are less toxic than the original.

Arsenic is the most common toxic substance in the environment, ranking first on the list of hazardous substances, the researchers wrote in their paper.

McDermott said arsenic presents real challenges for micro-organisms living in these conditions. The acid in the soil and water is so strong that it sometimes eats holes through his jeans when he kneels to collect samples.

McDermott has worked in Yellowstone for more than a decade and travels year-round to the Norris Geyser Basin to study the microbial mats that grow in acidic springs.

Over the years, he noticed thick algae mats that were so lush and green in December that they looked like Astro-Turf, McDermott said. By June, they were practically gone. While investigating the change, McDermott and his collaborators learned about Cyanidiales algae and its ability to reduce arsenic to a less dangerous form.

“These algae are such a dominant member of the microbiology community that they can’t escape notice, but for some reason they have not attracted much attention,” McDermott said.

The Cyanidioschyzon algae grow all over Yellowstone, but the researchers concentrated on the Norris Geyser Basin. The algae thrives in water up to 55 degrees Celsius (too hot to shower) with a very acidic pH factor ranging from 0.5 to 3.5, said an MSU release. Water is considered acidic if the pH factor is lower than seven.

These findings were described in the online edition of Proceedings of the National Academy of Sciences.

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