CINCINNATI, Ohio -- Microbes that survive in extreme environments might have a much higher rate of DNA recombination than other prokaryotes according to research which will be presented Wednesday, May 20 during the annual meeting of the American Society for Microbiology.

Scientists know that Sulfolobus acidocaldarius grows optimally around 80 degrees Celsius and in hot, sulfur springs with a pH of about 3. They know very little else about the microbe or any other member of the archaea, the so-called third domain of life.

"We have amassed a lot of knowledge about the cellular functions of eukaryotic cells and bacteria...then we get to the archaea which do not share many properties with the other groups, and we know almost nothing about them," said Dennis Grogan, assistant professor of biological sciences at the University of Cincinnati. "The ratio of knowledge is something like 10,000 to one."

Grogan is working to understand the genetics of Sulfolobus acidocaldarius. In previous work, Grogan demonstrated that the microbe can use visible light to repair DNA damaged by ultraviolet light. Now, he is searching for tools to study genetic recombination in Sulfolobus.

"Because they are so different, you can't necessarily take experimental methods, especially genetic methods, and transfer things that were done in E. coli (a common intestinal bacterium) and apply them to these organisms."

Grogan began his most recent work by using Sulfolobus mutants in genetic recombination experiments. A common type of microbial mutant is called an auxotroph or nutritional mutant. The mutant requires a supplement in its growth medium to replace a particular nutrient a normal cell could produce on its own. For example, one mutant might need the amino acid histidine while another requires tryptophan in its diet. Finding these mutants was a chore, to say the least.

"The amino acid mutations are hard to get. We checked roughly
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Contact: Chris Curran
chris.curran@uc.edu
513-556-1806
University of Cincinnati
20-May-1998