NAU Biologist Confirms There Are Microorganisms Native to Antarctica

Antarctica
Are microorganisms in Antarctica native or visitors from other continents? Dr. Schwartz uses his own testing model to find the answer.

Imagine being able to hold an entire ecosystem in the palm of your hand. There are only a small number of places on Earth where this is possible—Antarctica is one of them. 

On this remote continent there are a series of dry valleys that lack any form of life visible to the naked human eye. There are no plants, no insects, no animals—only communities of microorganisms that reside in plots of exposed soil unique to these regions. Scientists’ understanding of this ecosystem has changed over the past five decades. In the 1970s, it was believed that these soils were sterile. However, when groups of microorganisms commonly found on other continents were later discovered in Antarctica, a debate arose within the scientific community: Had these organisms been blown in from other continents via dust and debris, or were they growing in their native Antarctic soils?

Expedition Goes to Antarctica

Dr. Egbert Schwartz, Professor of Biology at NAU, traveled to the McMurdo Dry Valleys, the largest relatively ice-free area in Antarctica, to apply his own model of testing to this ecological question. The National Science Foundation funded the research expedition.

Joining Schwartz were veteran Antarctic polar scientist, Dr. Dave Van Horn, who is working on a larger ecological project at the University of New Mexico, and Justin Kendhammer, a Flagstaff, Arizona, middle school teacher. Kendhammer was funded by a grant from PolarTREC, whose mission is to bring K-12 educators and polar researchers together to increase polar science education in grade schools. 

The trio flew into New Zealand where they were issued proper cold weather clothing and gear at the International Antarctica Centre. From there, they departed on a C-17 for McMurdo Research Base, where they learned how to adapt to and survive the unfamiliar environment. This included learning new skills such as building snow shelters and relearning basic functions such as sleeping in the freezing weather.

Antarctica 235
The McMurdo Dry Valleys are the largest relatively ice-free area in Antarctica.

“These results are compelling evidence that microorganisms grow in the soils of Antarctica.  Now we get to meet them and figure out what kind of environmental parameters make them grow.”

A New Approach to Studying Microbial Communities

In the past, soil microbiologists have conducted tests by adding different elements, such as carbon, nitrogen, and glucose, to soil. They observed that the microbial communities were affected and certain organisms replicated, but the results were flawed because they came from an unnatural environment.

In 2007, Dr. Schwartz developed a new approach to characterizing microorganisms, based on a technique he created for labeling microbial DNA with a chemical compound that is naturally occurring in many parts of Earth—water.  Schwartz explained, “What I discovered is that if you add 18O water to a soil sample, the 18O will become incorporated in the DNA of the microorganisms in the soil.”

Out in the Field

There were two types of days in the field. The first included multihour hikes over loose rock and ice to travel to and from testing sites. On these fatiguing days, it was difficult to maintain hand dexterity in the freezing cold temperatures. The small test tubes could only be handled for 10 minutes at a time, and the scientists kept their bodies warm by running and doing jumping jacks in between. A much easier workday involved transportation via helicopter, and 30 minute-windows to collect samples.

Once collected, soil samples were placed in an ultra-centrifuge tube containing cesium chloride that rotates at more than 60,000 rpms. What occurs is a separation of DNA from cells that grew (whose DNA was consequently labeled with 18O), and DNA from cells that did not. The bottom of the tube is then pierced, and the density of the recovered fractions is measured as well as the amount of DNA present. Once the DNA has been sequenced, scientists are able to identify which microorganisms are present in the samples.

Schwartz and his team found that numerous microorganisms were replicating in their native environment. Oxalobacteraceae, an organism that also thrives under alpine conditions, accounted for almost 20 percent of the microbial DNA sequence results.

According to Dr. Schwartz, “These results are compelling evidence that microorganisms grow in the soils of Antarctica.  Now we get to meet them and figure out what kind of environmental parameters make them grow.”

--Ryan Zepp