There’s life under ice. Scientists found an entire community of bacteria living 800 metres under the surface of glaciers in Antarctica. These bacteria rely on each other to survive in the dark, isolated, subzero lake.
At the south-eastern edge of the Ross Ice Shelf, under the ice of glaciers, lies the liquid water of Lake Whillans. The thick layer of ice keeps the freshwater lake isolated from the world above, stopping nutrients from flowing down into it. How could anything survive there?
Recently, almost 4000 species of bacteria were found in Lake Whillans. The bacteria seem to survive by getting nutrients from the bedrock. The weight of the ice crushes the rocks, and the minerals in the rocks react with oxygen in the water. This reaction makes the rocks a source of energy for the bacteria.
The bacteria living in Lake Whillans also carefully recycle all the nutrients they can. The ecosystem of bacteria relies on rescuing nitrogen, another important nutrient, from dead bacterial cells.
When studying Lake Whillans, scientists had to be careful not to contaminate the lake with bacteria from above ground. If samples from the lake were contaminated, the researchers wouldn’t know if bacteria actually came from the lake, or if they were just carried on the equipment.
Introducing new bacteria into Lake Whillans could also be dangerous for the bacteria living beneath the ice. After being isolated for so long, the ecosystem could be disrupted by visitors. To break into the lake, researchers melted a hole in the ice using hot water. The hot water was kept super clean by filtering it, blasting it with ultraviolet radiation, heating it, and disinfecting it with hydrogen peroxide.
The ecosystem of bacteria in Lake Whillans shows how life can survive in harsh conditions. Perhaps single-celled life could also live beneath sheets of ice on Mars, feasting on the rocks.
Do magnifying glasses use convex lenses or concave lenses?
Which is the largest moon of Neptune?
What is a diatom?
Which two metals are most common in Earth’s core? Are they a) zinc and aluminium, b) cobalt and copper or c) nickel and iron?
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Put half a cup of cold water, warm water and hot water into marked containers. These are heat-resistant glasses, which do not break from boiling water.
Add a quarter of a teaspoon of sugar to each container, and stir.
Add a quarter of a teaspoon of dried yeast to each container, and start the timer.
After 5 minutes, check the yeast. Which containers have a foam on top?
Safety: This activity uses boiling water. Children should ask an adult for help. For more information, go to the Double Helix safety page.
You will need
Three mugs, heat-resistant glasses or containers
Pen and paper for labels
Measuring cups
Measuring spoons
Spoons for stirring
Water
Kettle
Fridge
Sugar
Dried yeast, available in the baking aisle of supermarkets
Timer
What to do
Mark the three containers as cold, warm and hot.
Put half a cup of water into the container marked cold, and put it in the fridge for 15 minutes.
Take the cold water out of the fridge, and place aside.
Put half a cup of warm water in the container marked warm. The water should feel slightly warm, not too hot.
Boil the kettle. Put half a cup of boiling water in the container marked hot.
Add half a teaspoon of sugar to each of the three containers. Stir each container so most of the sugar dissolves.
Add half a teaspoon of yeast to each of the three containers.
Watch what happens to the yeast in the containers. Start the timer.
After 5 minutes, check the yeast again. Has anything changed?
After another 5 minutes, check the yeast again. The yeast is active and growing when a foam forms on top of the container. Which containers have active yeast?
What’s happening?
If your boiling water is really hot, and your cold water is quite cold, the yeast probably will just sit in the bottom of those containers. The yeast in the warm water will foam up and become active. As the cold water slowly warms up, the yeast might start foaming in that container too. Like Goldilocks’ favourite porridge, yeast needs to be not too cold, not too hot, but just right.
Yeast is a single-celled organism. It’s not a bacterium, but a fungus. The species of yeast used in baking is called Saccharomyces cerevisiae, and it is useful because it eats sugar and produces carbon dioxide gas, which makes bread light and fluffy. Look at a slice of bread and you can see it is full of small holes. These are bubbles from the gas.
Yeast needs to be at the right temperature to grow, and grows best when it is about 27–32 degrees Celsius. It can survive cold temperatures, so you can keep it in the fridge, but it doesn’t grow very well. Really hot water will kill yeast.
Applications
Keeping yeast at the right temperature is very important in baking. Bakers use warm water to make sure the yeast is active and producing lots of carbon dioxide gas, so when they add the yeast to dough, the bread will rise.
Different organisms need different temperatures to survive. Humans are healthy when their internal temperature is around 37 degrees Celsius. In extreme conditions, a single-celled organism called Pyrococcus furiosus lives at 100 degrees Celsius, the temperature of boiling water. This single-celled microorganism is not a bacterium, or a fungus – it’s an archaeon. It was first discovered in Italy near a volcano.
Recently, 4000 species of bacteria were found in Lake Whillans in Antarctica. These bacteria live in liquid water that is below 0 degrees Celsius, the temperature that water turns into ice in a freezer.
Discover the world’s last great wilderness. The Discovering Antarctica website is full of cool clips and interactive material. Take a journey south and explore the incredible icy environment.
Do it!
How much do you know about Antarctica? Take this quiz from the Kiwi Conservation Club to find out where Antarctic animals get their food and the size of the biggest iceberg ever seen in Antarctica.
Collagen is the most abundant protein in your body.
Magnifying glasses use convex lenses.
Triton is the largest moon of Neptune.
A diatom is a type of algae that photosynthesises, meaning it gets its energy from the Sun.
c) Nickel and iron are the most common metals in Earth’s core.
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