Sequence of Thermoacidophile Picrophilus torridus Points the Way to Extreme Genes

NEW YORK, June 8 (GenomeWeb News) - Scientists have sequenced the genome of Picrophilus torridus, a euryarchaeote that thrives in strongly acidic environments at very high temperatures.

A team of researchers from the Institute of Microbiology and Genetics at Germany's University of Göttingen led the sequencing project, and published the results of its analysis in today's online version of the Proceedings of the NationalAcademy of Sciences.

P. torridus - which prefers temperatures of around 60°C and a pH of 0.7 - is one of the most thermoacidophilic organisms known, making it an ideal model for studying the requirements for life in hostile environments. Analysis of the organism's 1.55-megabase genome revealed a number of genes that may play a role in this ability, including 170 ORFs -- 12 percent of the organism's total genes - that play a role in transport and are assumed to be required for detoxification of the cell.

In addition, 92 percent of the P. torridus genome sequence is coding, "which represents the highest coding density in the genomes of the thermoacidophile group," the authors wrote. "Although the consequences for cell physiology and DNA integrity are not yet understood, we believe that the combination of two extremophilic conditions, low pH and high temperature, may have led to the small size and one of the highest coding densities for the genome of P. torridus," they concluded.

In addition, it appears from the researchers' analysis that certain genes considered particularly supportive for the organism's extreme lifestyle are the result of horizontal gene transfer from crenarchaea and bacteria.