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How bacteria works?

Bacteria were among the first forms of life on earth, billions of years ago!  Scientists have found fossils of bacteria that are older than three and a half billion years old, that’s a lot older than humans (see the magazine article attached!)!  A bacterium (a single bacteria) is a very simple form of life, just a single cell, compared to humans who have about a trillion cells (that’s 1 x 1013!!).  Bacteria have different shapes and can look like balls, rods or spirals.  Some, like GI Jake, a bifidobacterium, has two lobes that look like he has two ears (Figure1)!  

GI Jake - a bifidobacterium!



No matter what shape they have, all bacteria are basically made the same.  They have a tough cell wall that gives them their shape and protects the bacterium.  Underneath the cell wall, the have a cell membrane that lets nutrients get in and out of the bacterium cell.  A bacteria keeps its genes (these are its instructions on how to be a bacterium, just like our genes are instructions on how to be a human!) just floating around inside it, it the space called the cytoplasm

Some bacteria can move by themselves!  These bacteria have one or many things called flagella that look like little tails that let the bacteria swim from place to place.  If bacteria don’t have flagella, they need water, wind, passing animals or you to spread them around! 

Although they are small, bacteria are very clever and they have learnt to live everywhere!  Bacteria live in the air, in the ground, in water, in and on plant and animals, even on and inside of you!  In the many different places on earth where humans cannot live, you can find bacteria.  They are in the coldest parts of the arctic, the hottest parts of the desserts or the deepest parts of the seas.  Some even manage without oxygen and some can even learn to use oxygen when it is there or live without it when it is not!  Most can hibernate for many years without any ill effects (see ‘Article 1’ below for news of a bacterium that woke up and grew after being asleep for 8 million years!)!  For most bacteria however, the temperature and conditions of the average healthy human body is their idea of paradise!

Bacteria are like all living organisms, they need to eat for energy and growth.  But what do bacteria eat?  Well, many bacteria eat starches and sugars which can be found on more or less all organic matter.  For other bacteria their diet is not very different from yours because they live in your mouth or digestive system and eat the food you eat!  Other bacteria eat or dead and decaying matter (they are, along with fungi the ‘decomposers’ of organic matter) and some even eat waste products or dangerous materials like oil.  Basically, there are lots of different bacteria out there and between them they will eat just about anything!

Bacteria can make copies of themselves (multiply) wherever they find the right conditions.  This could be anywhere, including on or inside you!  To make more copies of themselves, most bacteria need; food, light, moisture and nutrients, the usual ingredients that allow them to survive.  However, there are bacteria that can live anywhere so they can multiple anywhere, even without light, oxygen, heat or any of the other things a lot of bacteria need!


Bacteria make copies of themselves using a process called binary fission.  This simply means they split in two and make two identical copies with the same structure, genetic information and capabilities of the original cell.  Bacteria can multiply amazingly fast – as fast as once every 20 minutes!  That means if you have 1 bacterium at 9am on Monday, by noon you will have 512, by 4pm you will have over 2 million and by the time you go to bed (8pm) you will have nearly 9 thousand million!  There are some checks in place that keep bacteria from taking you over altogether! They can begin to run out of space, food and other things they need to stay alive.  The good bacteria that live on and in your body reach a state of equilibrium – a point where they are happy and you are happy because they are doing you good!

Article 1

New Scientist is one of the worlds leading popular science magazines.

Eight-million-year-old bug is alive and growing 

An 8-million-year-old bacterium that was extracted from the oldest known ice on Earth is now growing in a laboratory, claim researchers.  If confirmed, this means ancient bacteria and viruses will come back to life as ice melts due to global warming. This is nothing to worry about, say experts, because the process has been going on for billions of years and the bugs are unlikely to cause human disease.

Kay Bidle of Rutgers University in New Jersey, US, and his colleagues extracted DNA and bacteria from ice found between 3 and 5 metres beneath the surface of a glacier in the Beacon and Mullins valleys of Antarctica. The ice gets older as it flows down the valleys and the researchers took five samples that were between 100,000 and 8 million years old.  They then attempted to resuscitate the organisms in the oldest and the youngest samples. "We tried to grow them in media, and the young stuff grew really fast. We could plate them and isolate colonies," says Bidle. The cultures grown from organisms found in the 100,000-year-old ice doubled in size every 7 days on average.

Whereas the young ice contained a variety of microorganisms, the researchers found only one type of bacterium in the 8-million-year-old sample. It also grew in the laboratory but much more slowly, doubling only every 70 days.  By examining the average length of DNA fragments found in all the ice samples, the researchers determined that frozen DNA is progressively degraded as time passes. Its half life is 1.1 million years – that is, after 1.1 million years half the original DNA has been degraded.

The researchers believe the DNA is degraded by cosmic rays, which are particularly strong at the poles where the Earth's magnetic field is at its weakest.  Paul Falkowski of Rutgers University, who led the study, describes the ancient bacteria as small round cells that had been in a "suspended state of animation for 8 million years". He says the increasingly rapid flow of glaciers into the ocean as a result of global warming could release new organisms into the sea but he does not believe this is cause for concern because marine bacteria and viruses are typically far less harmful to human health than, for instance, those found on land.

07 August 2007


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