Friday, July 13, 2012
1.What is bacteria?
Bacteria are microorganisms that are ubiquitous in our environment including in our body, on food and in soil. Bacteria have a wide range of shapes, ranging from spheres to rods.
There are typically 40 million bacteria in a gram of soil, a million bacteria in a millilitre of fresh water and 10(15) bacteria that is ten times as many bacteria as human cells in the human body. In all, there are approximately 5×10(30) bacteria on Earth.
Most of the bacteria in our environment are harmless and important for our body. For example, they have roles to produce nutrients, protect from pathogens and help to establishment of our immune system. In addition, bacteria are important for the production of fermented food such as cheese and yogurt, as well as the manufacture of antibiotics and other chemicals. However, some of the bacteria are pathogenic and they attack our body. Therefore, our immune systems try to block these bacteria infecting us.