Researchers are reanimating 40,000-year-old microbes
In the research of the body of American army engineers in the center of Alaska, a single tunnel descends underground. Measuring more than 350 feet deep, mammoth bones stand out from its surrounding walls. However, a team of researchers did not go to the distant site for the old fossils. They were looking for something much smaller and more fragrant.
“The first thing you notice when you come there is that it smells really bad. It smells a moldy basement that has been left for too long,” said geological scientist Tristan Caro in a press release. “For a microbiologist, it is very exciting because the interesting odors are often microbial.”
After adapting to the rough scent, Caro and his colleagues focused on the extraction of permafrost samples, each of which contained thousands of microscopic organisms. The microbes had spent up to 40,000 years frozen inside the icy ground, but after millennial hibernation, it was time to wake up. What they did then would help researchers better understand – and perhaps to prepare – for what seems almost inevitable in the midst of warming temperatures of the earth.
“This is one of the biggest unknowns of climatic responses,” said Sebastian Kopf, a geological scientist at the University of Colorado. “How does the thaw of all this frozen soil, where we know that there are tons of stored carbon, will affect the ecology of these regions and the rate of climate change?”
The microbes feast on organic matter and then release methane and carbon dioxide in the atmosphere. Unfortunately, these are two of the most powerful and harmful greenhouse gases that humanity is trying to reduce. The dominant concern is that the Décongee Pérgélisol will release a greater number of microbes, which will contribute to a vicious and closed loop of gas emissions.
“These are in no case dead samples. They are always very capable of accommodating a robust lifespan that can decompose organic matter and release it in the form of carbon dioxide,” said Caro.
To see what could happen as arctic temperatures continue to increase, Caro and Kopf have added water to the samples. In addition to decomposing organic matter, microbes also consume water to be used for oily membranes that frame all living cells. They then incubated their Alaska samples in a temperature range from 39 to 54 degrees Fahrenheit. It may not seem particularly hot, but it is still above the gel – and extremely hot for the Arctic.
“We wanted to simulate what is happening during a summer in Alaska, in future climatic conditions where these temperatures reach deeper areas of permafrost,” said Caro.
Their recent results published in the journal Biogeoscience JGR documented an unexpected trajectory. The bacteria generally replace the cells with all its colony in a few hours, but the permafrost samples began this extremely slow process, sometimes replacing approximately one cell per 100,000 per day. About six months later, however, their populations exploded. Some colonies have become so large that they have created a viscous substance called Biofilm which could be seen without a microscope.
At the same time, the temperature seemed to play a smaller role in cell growth than expected researchers. Exposure to sudden and warmer temperatures has not much accelerated microbial reproduction. The discovery has major implications for the Arctic because its summers become both warmer and longer.
“You may have a single hot day in summer in Alaska, but what matters much more is the extension of the summer season where these hot temperatures extend in the fall and spring,” said Caro.
We still do not know why the old microbes worked as they did when leaving hibernation. In addition, it remains to be seen whether slow starting also occurs in other microbial colonies found in the world.
“There are so many permafrosts in the world – in Alaska, Siberia and other cold northern regions. We have only sampled a small slice,” said Caro.
There is also at least another major problem to consider. While the study authors doubted that their samples of Alaska microbes can infect humans, they played safely by keeping them in a regulated closed environment. Other species of bacteria that wake up their long naps in permafrost could be a little more grumpy.
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