Genetic Exchange Between Mutant Strains of Sulfolobus acidocaldarius: Analysis, Applications, and Significance for Hyperthermophiles.

A prokaryotic micro-organism originally isolated from terrestrial hot springs, Sulfolobus acidocaldarius, was studied for its ability to exchange and recombine segments of its chromosome. Mutant strains were isolated and used to quantitatively assay this process. The genetic exchange was found to be a form of conjugation that differs from bacterial conjugation with respect to the symmetry of DNA transfer and other properties. Other fundamental genetic phenomena of prokaryotes from geothermal habitats were studied for the first time using S. acidocaldarius these included photoreactivation, UV-induced mutagenesis, and stimulation of genetic exchange by UV.. The rate of spontaneous mutation was measured at 75 degrees C in S. acidocaldarius and was found to be nearly the same as that of the bacterium Escherichia coli at 37 degrees C. This provided the first evidence that the archaea which populate geothermal habitats can maintain genetic fidelity even at extremely high temperatures The basic information gained in these studies portrays the microbial inhabitants of thermal environments in a new light, suggesting that they may mutate infrequently in nature but may exchange genes at a significant rate.