A Salty Tale: New Bacterial Genome Sequenced From Ancient Salterns

A Salty Tale: New Bacterial Genome Sequenced From Ancient Salterns: "The bacterium is Salinibacter ruber, a bright red, rod-shaped organism. Several years ago, scientists first isolated S. ruber from saltern crystallizer ponds in Alicante and Mallorca, Spain. Although extreme-loving microbes called archaea were known to eke out life in the ponds, scientists were surprised to discover ordinary bacteria also thriving in such a physically demanding environment, at salt concentrations up to 30 percent. How could these microbes--which normally prefer milder environments--thrive in such high salt?
To find out, TIGR researchers Emmanuel Mongodin and Karen Nelson, working with Canadian and Spanish colleagues, set out to sequence S. ruber's genome. In doing so, the scientists discovered evidence that the resourceful bacterium independently evolved some salt-surviving biochemistry. More surprising, S. ruber apparently also borrowed some genes from neighboring archaeal species, in an unusual example of cross-domain lateral gene transfer.

Analyzing the bacterium's genome, researchers found that S. ruber's proteins are typically rich in acidic amino acids and relatively poor in hydrophobic (water-repellent) amino acids, making them soluble and highly stable at such salt concentrations. Researchers recognized this biochemical adaptation: it's the same one used by archaea also living in the salterns.

That wasn't the only similarity. Scientists also found two types of rhodopsin genes: one variety typical for bacteria, and another previously recognized in archaea. A photosynthetic protein, rhodopsin works as a proton pump, capturing light energy and using it to move protons across the membrane and out of the cell. In doing so, the protein maintains a balance of ions inside and outside the cell."

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