2008 Annual Science Report
Pennsylvania State University Reporting | JUL 2007 – JUN 2008
Examination of the Microbial Diversity Found in Ice Cores (Brenchley)
Our goal is to discover microorganisms surviving in cold or frozen environments and to use this information to understand how different microorganisms survive extreme habitats. Our recent results demonstrated that abundant populations, including many bacteria representing novel taxa, exist frozen in a Greenland glacier ice core for at least 120,000 years. Current isolates are being characterized as new species of ultra-small celled bacteria. This research provides insight into microbial survival in extreme environments that might exist elsewhere in the solar system.
Our primary 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. Previous research demonstrated the existence of a large population of ultra-small cells about 1/10 the size of an E. coli cell. Currently we are characterizing two isolates representing new species, one designated Herminiimonas glaciei sp. nov. and the other Chryseobacterium greenlandensis sp. nov. Additional ongoing analyses of the ice core include comparing the microbial diversity at different depths to determine whether any specific organisms could be a biomarker for the deposition climate or geographic origin. In addition, we designed long-term, sensitive experiments to test whether microbial metabolism could occur at subfreezing temperatures and demonstrated that model organisms could release gas at the lowest temperature tested, minus 32 degrees C.
Additional findings from our research include discovering and characterizing a plasmid from one of our unique ultrasmall isolates and recombining this to construct a vector that could be useful for genetic studies of Gram-positive organisms. We also concluded a metagenomic study of genomic DNA extracted and amplified from subseafloor sediment showing that archaeal cells, rather than bacteria, comprise the majority of this population. One unifying theme in all of our research is the development of sensitive detection methods that will help examine samples with low biomass and augment the ability to search for the presence of life elsewhere. In addition to these future ramifications, our research is adding considerable knowledge about microbial diversity, new cultivation approaches, and insight into microbial metabolism at sub-freezing temperatures. Our research abstract was selected by the American Society for Microbiology for a press release and was publicized through general articles.
PROJECT INVESTIGATORS:Jean Brenchley
PROJECT MEMBERS:Jennifer Loveland-Curtze
RELATED OBJECTIVES:Objective 2.1
Environment-dependent, molecular evolution in microorganisms
Co-evolution of microbial communities
Biochemical adaptation to extreme environments
Environmental changes and the cycling of elements by the biota, communities, and ecosystems
Adaptation and evolution of life beyond Earth
Biosignatures to be sought in Solar System materials