Washington: Scientists have discovered microorganisms breathing arsenic – a deadly poison for most living things – in the low-oxygen parts of the Pacific Ocean. The researchers from the University of Washington (UW) in the US analysed 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, according to the study.
“Thinking of arsenic as not just a bad guy, but also as beneficial, has reshaped the way that I view the element,” said Jaclyn Saunders, who conducted the research for her doctoral thesis at the UW. “We’ve known for a long time that there are very low levels of arsenic in the ocean,” said Gabrielle Rocap, a UW professor.
In some parts of the ocean there’s a sandwich of water where there’s no measurable oxygen. The microbes in these regions have to use other elements that act as an electron acceptor to extract energy from food. The team analysed 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. Results suggest that arsenic-breathing microbes make up less than one per cent 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. Biologists believe the strategy is a holdover from Earth’s early history. —PTI
