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Project Progress

Our research on psychrophilic (cold-loving) microorganisms and their enzymes examines isolates from cold environments such as the subseafloor, glacial ice, Antarctica, lakes, and cold soils. We have characterized numerous isolates and cloned genes encoding their cold-active enzymes. We are now focusing on expressing large amounts of a protease with high specific activity at low temperatures and with chelators. Another PSARC project investigates microorganisms deposited over 100,000 years ago in a Greenland glacier (GISP2) ice core. This ice core serves as a model for severe conditions, such as cold temperatures, nutrient and oxygen limitations, desiccation, pressure, etc. that could exist extra-terrestrially. We demonstrated that a viable (10⁷ cells/ml) and diverse microbial population exists trapped in this ice and that metabolic activity of model organisms can occur as low as minus 32C. We also isolated ultra-small celled organisms that pass through 0.1 micron filters and retain their small size throughout their growth cycles. These ultra-small cells compose a large fraction of the uncultivated microorganisms in many environments, and alter conclusions in studies where only the cells trapped on filters were examined. Our projects with the ice cores and subseafloor samples both share the need to improve methods for detecting cells and DNA when populations are small. Thus, we are improving and developing detection methods for the bacterial and archaeal populations. One method we are optimizing is the use of whole genome amplification kits for prokaryotic cells. We have amplified genomic DNA from subseafloor sediment containing low cell numbers. The DNA was sequenced by pyrosequencing and the metagenomic data analyzed. These results are consistent with this being a unique environment where archaeal cells are the majority of the population. The detection methods we are developing will augment our ability to search for the presence of life elsewhere.