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Bacterium protects sponge host from arsenic poisoning: Study

"These sedentary animals evolved to contain an in-house arsenal of chemicals and associated microbiota to deal with predators and pathologies," said zoologist Micha Ilan.

By Brooks Hays

Feb. 27 (UPI) -- Scientists have discovered a bacterium that plays the role of arsenic detoxifier in the sponge it calls home. The bacterium is Entotheonella and its common host is Theonella swinhoei.

Researchers discovered the bacterium while analyzing the microbial communities living in the sponge species, which studies have shown can safely accumulate large concentrations of arsenic and other toxic metals.

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"This particular sponge species, which is among the most ancient animals inhabiting the earth today, is home to a very diverse, very crowded number of microorganisms," Micha Ilan, a professor of zoology at Tel Aviv University, said in a news release. "These sedentary animals evolved to contain an in-house arsenal of chemicals and associated microbiota to deal with predators and pathologies."

Scientists analyzed Entotheonella bacterium cells under an electron scanning microscope. The results -- detailed in the journal Nature Communications -- showed the microbe not only collects and encapsulates arsenic, it also renders it a non-toxic mineral. Thus, turtles and fish who eat the sponge are not at risk of poisoning.

Researchers now hope to harness the microbe's ability to turn arsenic and barium into calcium arsenate and barite. Arsenic is the planet's most common freshwater contaminant, affecting the drinking water of millions of people.

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Scientists are now working to isolate the enzymes used by Entotheonella to mineralize the toxins.

"Once we identify the enzymes involved in the process, we can either look for them in bacteria in polluted water or find a way to grow Entotheonella in polluted areas," said zoologist Ray Keren.

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