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.
"Scientists are increasingly learning how microbes adapt to harsh environments," remarks Mongodin, first author on the PNAS study, funded by a grant from the National Science Foundation and United States Department of Agriculture. "S. ruber illustrates that even in a really extreme environment, bacteria can do what it takes to survive, including exchanging genes with other microbial species that we might not expect."
Normally, high-salt environments denature bacterial proteins. To
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The Institute for Genomic Research
5-Dec-2005