Genome Sequence of Salt-Loving Bacterium Points to Lateral Gene Transfer from Archaea

NEW YORK, Dec. 5 (GenomeWeb News) - Researchers at the Institute of Genomic Research sequenced the genome of Salinibacter ruber, a bacterium that lives in Spain's saltwater lagoons, the institute said today.

TIGR researchers published an analysis of the S. ruber genome in last week's online edition of the Proceedings of the National Academy of Sciences.

While archaea were known to live in Spain's salterns, which can have salt concentrations as high as 30 percent, bacteria generally don't survive in such physically demanding environments.

The TIGR scientists report in their paper that they discovered evidence that S. ruber independently evolved some salt-surviving biochemistry. More importantly, they note, the bacterium appears to have borrowed genes from neighboring archaeal species, in "an unusual example of cross-domain lateral gene transfer."

Researchers found that S. ruber's proteins are typically rich in acidic amino acids and relatively poor in hydrophobic amino acids, making them soluble and highly stable in high salt concentrations.

Scientists also found two types of rhodopsin genes: one variety typical for bacteria, and another previously recognized in archaea.

The scientists analyzed S. ruber specimens from saltern crystallizer ponds in Alicante and Mallorca, Spain.