Spectroscopy Used to Find Life in Hidden Environments

Fluorescence spectroscopy is being used to detect life in the most unlikely places.

Fluorescence spectroscopy’s ability to fingerprint a substance is a useful tool for researchers, whether they are in the deserts of the Middle East or the remote continent of Antarctica.

One researcher is trying to establish life under thousands of feet of ice in a subglacial lake in the southernmost continent. The researcher is John Priscu, Ph.D. and Regents Professor in the Montana State University College of Agriculture’s Department of Land Resources and Environmental Sciences. His goal is understanding the biogeochemistry and microbiology of icy environments.

Priscu looks at organic matter in the ice on the microbial and cellular levels and describes the organisms in the ice using fluorescence spectroscopy. He and his group use genetic fingerprints to identify these organisms.

In the winter of 2018-2019, Priscu plans to drill under the glacial surface of Antarctica into a lake that’s been hidden from light for hundreds of thousands of years. The exploration of subglacial lakes through boring technology has uncovered a diverse microbial ecosystem.

On a previous expedition, Priscu’s team found microorganisms that mine minerals in rocks at subzero temperatures to obtain the energy that fuels its growth.

After about three to four days of drilling, the research team will have about a week to collect water and sediment samples and conduct experiments in the field labs. One of the team’s key instruments is a HORIBA Scientific Aqualog spectrofluorometer.

The Aqualog will be used to measure dissolved organics in the glacial ice. Aqualog simultaneously measures both absorbance spectra and fluorescence Excitation-Emission Matrices, helping the researcher identify the samples they are studying in fast succession. The Aqualog will be used to search for the fingerprints of microorganisms. It will analyze the quality of dissolved organic matter to see if it’s recalcitrant (resistant), and determine its age.

Robotic tools will capture 4k video and explore the physical characteristics of the lake cavity, while other instruments will collect physical and chemical measurements directly in the drilled water column. His team will be looking at the density of bacteria cells, the genetic content, how fast they grow and what they eat. He will also determine whether the evidence of life is ancient or contemporary.

Priscu has conducted research in Antarctica for the past 35 years. It’s a harsh environment. Temperatures can drop below minus 100 degrees Fahrenheit in the Antarctic winter.

Through fluorescence spectroscopy, his group will try to confirm the theory that sub-ice hydrology and relict deposits of marine organic matter regulate ecosystem processes in these active subglacial lakes.

A subglacial lake is a body of liquid water sandwiched between an ice sheet and the continental land mass. Scientists believe more than 400 lakes exist beneath the Antarctic ice sheet, many interconnected via streams and wetlands. Subglacial lakes could add to our understanding of the evolution of life in these extreme environments on earth and other celestial bodies.