Old Extremophiles: using arsenic for energy (Introduction)

by David Turell , Sunday, May 05, 2019, 01:44 (2030 days ago) @ David Turell

Arsenic was used b y early bacteria in evolution:

https://www.sciencedaily.com/releases/2019/05/190502113603.htm

"Arsenic is a deadly poison for most living things, but new research shows that microorganisms are breathing arsenic in a large area of the Pacific Ocean. A University of Washington team has discovered that an ancient survival strategy is still being used in low-oxygen parts of the marine environment.

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"'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.

"'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.

"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 water are probably distantly related to the arsenic-breathing microbes found in hot springs or contaminated sites on land.

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"Biologists believe the strategy is a holdover from Earth's early history. During the period when life arose on Earth, oxygen was scarce in both the air and in the ocean. Oxygen became abundant in Earth's atmosphere only after photosynthesis became widespread and converted carbon dioxide gas into oxygen.

"Early lifeforms had to gain energy using other elements, such as arsenic, which was likely more common in the oceans at that time.

"'We found the genetic signatures of pathways that are still there, remnants of the past ocean that have been maintained until today," Saunders said.

Comment: I assume God provided this form of metabolism in advance of the appearance of oxygen, which He obviously would know it was arriving later on.