The goal of this project is to elucidate how a recently isolated novel bacterium, 'Natronanaerobium alkalithermophilum' strain JW/NM-L6 is able to grow under combined triple extreme conditions: temperature above 50 degrees centigrade, pH above 8.5, and salt concentrations in excess of 1.5 M (or 10%, wt/vol, NaCl). These extreme growth conditions are found in natural environments such as sunheated or geothermally heated alkaline salt lakes as well as in man-made environments (e.g., salterns, industrial waste streams). Previously it was assumed that microorganisms could not grow under such conditions. Physiological adaptations to the combined extreme growth conditions are difficult to explain with the common bioenergetic models. In addition, known adaptive mechanisms for individual extremes, i.e. high pH, salt or temperature alone, contradict and do not explain the existence of this halophilic alkalithermophile. Since this bacterium grows under a wide range of temperatures, pH values and salt concentration, various physiological processes, including the pH gradient across the cell membrane and intracellular solute composition will be measured when grown under various combinations of extremes to identify the unique properties which enable this bacterium to live under such extreme conditions.
The results of this project will extend the present understanding of the boundaries under which life can thrive and thus will have a broader impact on several disciplines. The results will provide a novel model for the study of adaptive mechanisms to extreme environmental conditions and thus is of interest to scientists in the fields of biochemistry, microbiology, biogeochemistry, ecology, genetics, and various areas of biotechnology. This project will also involve collaboration between U.S., New Zealand and Egyptian researchers, and will include training for a female graduate student.
