LEXEN: Longevity and Diversity of Microorganisms Entrapped in Tropical and Polar Ice Cores

点击翻译按钮获取中文摘要

This project is to determine the phylotypes, abundance and antiquity of microorganisms that can be resuscitated from within ice cores taken from such diverse environments as the Tibetan Plateau, the South American Andes, and both polar regions. PCR-amplified small subunit (16S and 18S) rDNAs will be cloned and sequenced to determine the range of phylotypes that are, or were, present in these ice cores that are refractory to laboratory culture. The experiments are conceptually very simple, and technically require only routine microbiological and molecular biology procedures; however, preventing contamination with microorganisms and nucleic acids from exogenous sources will be critical. An automated ice-sampling device will therefore be constructed specifically to eliminate this problem. The ice cores are archived under carefully controlled conditions at the BPRC, and several cores area available from most locations, so that multiple samplings to evaluate different procedures and to confirm positive results are possible without field trips. The experiments proposed will determine the longevity of microorganisms entrapped in ice under different environmental conditions, the diversity of microorganisms deposited at the same geographical sites, but separated by thousands, or possibly by hundreds of thousands of years, and the diversity of microorganisms deposited at the same archeological times but at geographically very different and remote locations. This might be the first concerted effort to apply PCR technology to amplify material from within very ancient ice cores, and it seems very likely that "extinct" genes, or at least fragments of extinct genes will be amplified, facilitating intriguing comparisons with the sequences of their contemporary homologs. Although many of the core isolates are likely to be Actinomycetes, evaluating novel antibiotic synthesis by core isolates is beyond the exploratory goals of this proposal. Determining the antibiotic resistance patterns of microorgan isms that were entrapped in ice before the widespread use of antibiotics will, however, be routinely undertaken.