London: Bacteria inhabiting the sides of a canyon have adapted to extremes of temperatures by modifying their 'skin' or cell membrane make-up.

These bacteria were found to change these complex and important structures to adapt to temperatures when researchers looked at their appearance as well as their genes.

'Evolution Canyons' I and II are in Israel, each with a hot south-facing slope and a cooler north-facing slope. The sun-exposed 'African' south-facing slopes get eight times more solar radiation than the shady, green, lush 'European' north-facing slopes.

Scientists studied 131 strains of Bacillus simplex and found that bacteria on different slopes have evolved differently, forming different 'ecotypes' of the same species.

"We expected that 'ecotype' formation was linked to temperature but we had no initial clue of which specific cell attributes could have led to the adaptation," said Johannes Sikorski from DSMZ in Germany. "To find out, we definitely had to study the appearance of the bacteria, not only their genes."

The cell membrane is one of the most important and complex parts of a cell. Membranes contain different fatty acid molecules; the branching type can change depending on temperature to keep the cell alive. The researchers found significant differences in the fatty acids of several ecotypes that live on different slopes in Evolution Canyon.

"Bacteria respond to temperature by altering their fatty acid composition in a constitutive, long-term fashion," said Sikorski.

"We found that 'African' ecotypes from the hot slopes had more heat-tolerant fatty acids and 'European' ecotypes from the cool slopes had more cold-tolerant fatty acids in their membranes."

In most modern evolutionary studies, scientists rely on genetic data alone. Sikorski and his colleagues focussed on the result of the genetic changes instead: what the bacteria look like.

"It is not a 'sexy' technique like genomics or proteomics but it gives a more comprehensive insight into the result of adaptation of the cell membrane," said Sikorski.

The research will be published in the August issue of Microbiology. (IANS)