03/12/2023
COLD LOVING BACTERIA IN ICE:
1. INTRODUCTION:
- Did you know that our Earth is quite a frozen planet? In fact, about half of Earth’s land environments are seasonally or permanently covered in snow or ice! Brrr! From the North Pole to the South Pole, from the ice caps on mountaintops to icebergs floating on the sea, cold habitats are everywhere, and they make up the frozen part of the Earth called the CRYOSPHERE Places on the Earth where water is frozen as ice or snow.
- Extremely cold temperatures in the cryosphere make it especially challenging for microbesLiving things that are very small and can only be seen through a microscope. Examples of microbes are bacteria, algae, protozoa and viruses. to survive. In a cold environment, it is very difficult to find water, which is essential for life, because most of the water turns into solid ice.
- It is also difficult for organisms to find food and generate energy in the cryosphere, because the chemical reactions that keep living things alive happen more slowly in the cold.
2. BACTERIAL LIFE IN ICE:
- Frozen environments were once thought to be lifeless. Scientists initially thought that microbes in frozen environments were brought there by the wind and were “asleep” due to the cold.
- However, they later found that permanently frozen environments contain a lot of living microbes. Some of these microbes were found to have adapted in special ways (over a long period of time) to survive in the snow and ice. These microbes are called psychrophiles. Microbes, especially bacteria, that have adapted to life in cold environments.
- The term comes from the Greek “psychros” meaning “cold and frozen” and “philia” meaning “loving.”, which means “cold-loving” in Greek.
- Microbes cannot survive in solid ice. So far, all the communities of psychrophiles found within ice, from ice sheets to glaciers, survive inside very tiny veins of liquid water trapped in the ice when it forms.
3. HOW DO PSYCROPHILES PROTECT THEMSELVES FROM COLD?
-A. Psychrophilic bacteria have ways to survive in cold conditions. One of the most basic challenges to living in the cold is that everything takes more time, including nutrient movement and important chemical reactions. Therefore, to get enough food from the water around them, many psychrophiles increase the number of transporters on the cell surface, which actively grab nutrients from the surroundings.
B. Another problem associated with this frozen environment is ice formation. Just as 70% of the human body is made up of water, most bacteria cells are also full of water, which can easily turn into ice crystals at freezing temperatures. Ice crystals inside living cells are dangerous because they grow outward like little thorns, eventually piercing the bacteria from the inside out and killing them. Psychrophiles have therefore evolved multiple strategies to avoid this gruesome fate. For instance, they take in dissolved salts and sugars to lower the freezing temperature of water inside themselves. Some species also have special antifreeze proteins that attach to any forming ice crystals and lower their freezing point, preventing their growth. These strategies reduce the danger of living in the cold.
C. Psychrophiles also have enzymesThe workers of the cell; proteins that help chemical reaction to happen. that are different from those of non-psychrophile bacteria. Enzymes are like the factory workers inside cells. Each type of enzyme carries out an essential chemical reaction, keeping the bacteria alive and happy. Enzymes only work best within a small range of temperatures called the optimum temperature. To keep the psychrophiles alive at freezing temperatures, enzymes called cold-active enzymesEnzymes that work the fastest at temperatures of 20°C (68°F) or below. have evolved, which have an optimum temperature of 20°C or less.
4. IMPORTANCE OF PSYCHROPHILIC BACTERIA.
Many scientists are also putting our growing knowledge of psychrophiles to use in new technologies. Cold-active enzymes, for example, have already been used to increase the effectiveness of industrial processes, such as fruit processing, that take place at low temperatures (so that the fruit does not spoil). Scientists have also identified many of the active chemicals in psychrophiles that help them respond to the cold. We can use these chemicals in medicines to treat infections and even cancer. Additionally, with psychrophiles so well-adapted to surviving in harsh environments with poor nutrients, they can break down pretty much anything they get access to. This means psychrophiles might be very useful for breaking down plastics and treating waste. Psychrophiles are as useful as they are diverse.
