Single-celled Microbes in Polar Ice: A Proxy for Evolution over 100 Million Generations

Although glacial ice is the purest naturally occurring solid on Earth, it does contain dust particles and micron-size bacterial cells transported by winds from desert soils and oceans. Glacial ice contains a network of liquid veins within which microbes live, metabolize, and die, but do not grow. Using scanning fluorescence spectrometry, fluorescence microscopy, and flow cytometry, we have mapped the distribution and concentration of picocyanobacteria – cells less than 1 micron in size that contain chlorophyll and other naturally fluorescing pigments. They account for half of the photosynthetic biomass in the oceans, half of the primary production, and half of the oxygen in our atmosphere. Theire presence in ice at all depths in both Greenland and Antarctica provides an opportunity to study microbial evolution over about 100 million generations, using recent improvements in sensitivity to analyze the DNA of the cyanobacteria that are trapped in the ice.

Buford Price received his Ph.D. from the University of Virginia in 1958, was a Fulbright Fellow at Bristol University (England), an NSF Post-doctoral Fellow at Cambridge University, did research at General Electric Research Laboratory from 1960 to 1969, was Professor of Physics at Berkeley 1969 to 2001, Chair of Physics 1987-92, Dean of Physical Sciences 1992-2001, and Professor of the Graduate School at Berkeley since 2001. He was a co-founder of what grew into the 1-cubic-kilometer IceCube High-Energy Neutrino Observatory located in clear ice at depths 1.45 to 2.45 kilometers below the South Pole. He leads research on the optical properties of deep glacial ice, the understanding of which make it possible to track neutrinos from distant parts of the universe through the Earth into IceCube with an angular resolution better than 1 degree. In 1999 he realized that micron-size bacterial cells could live in glacial ice and might limit the angular resolution of neutrinos passing through IceCube. Since then his research has focused on how bacterial cells survive while frozen into deep glacial ice in the polar regions and what they can tell us about microbial evolution.

You can watch the video of his talk by clicking on the image below.

Aurora over IceCube - Keith Vanderlinde, NSF
IceCube photo - www.icecube.wisc.edu