What is Bacteria and Useful & harmful effects of bacteria

What is Bacteria

Bacteria can be identified as unicellular (single-celled) plants that are found everywhere in water, air, soil, food, and inside and outside living bodies. A single cell is known as a Bacterium. Can you imagine the size of a bacterium? Bacteria are extremely small; their size ranges from 0.2 to 100 microns (one micron is a millionth of a metre). They are generally thought to be the first living organisms that evolved on earth. They are believed to have appeared around three thousand million years ago. They are the simplest living organisms found on earth.

The cell of a bacterium has an outermost covering the cell wall hence, they are considered as plants. There is no well-developed nucleus, but the nuclear material is found scattered in the jelly-like substance known as cytoplasm present inside the cell. Bacteria moves with the help of thread-like structures called flagella, present all over the body. A cyst, which is a hard protective coating, is present on the cell wall. It helps the bacteria to withstand adverse conditions. When unfavourable conditions prevail, bacteria remain inactive but start the process of reproduction when favourable conditions return. 

Bacteria are found in various shapes?

Like other organisms, bacteria need nutrition. Most bacteria cannot make their own food; only a few of them can do so. They do this by a process quite similar to photosynthesis, with the help of sulphur, hydrogen sulphide, etc. Many types of bacteria display saprophytic mode of nutrition, i.e., they mostly derive their food from dead and decaying matter. Some are parasitic in nature and can take shelter inside the body of a suitable host. They then proceed to extract food from the body of the host. All parasitic bacteria are not harmful; some are quite harmless and can live in the intestines of living organisms without causing any harm.

Some species of bacteria require oxygen during respiration to break down food and release energy; they are called aerobic bacteria, whereas the few that can live without oxygen are known as anaerobic bacteria. 

A warm and moist environment is the most favourable environment for the growth and reproduction of bacteria although even otherwise, they reproduce at a fast rate. Some bacteria reproduce at moderate temperatures ranging from 25°C to 37°C. Some can grow and multiply even in extreme conditions of moisture and temperature. Bacterial growth is also dependent on the amount of nutrition available in the near vicinity. 

Reproduction in bacteria commonly takes place by binary fission. Growing under favourable conditions, the nuclear material of the bacterial cell divides first. This is followed by the division of cytoplasm, which finally divides the cell into two daughter cells that can separate or sometimes cling together forming clusters, chains or filaments. The E.coli bacteria, which are usually found in the intestines of animals and human beings, reproduce very fast under favourable conditions. It is said that they take just 20 minutes to multiply, that is, a single bacterium can give rise to millions of bacteria in just one day!

Useful and harmful effects of bacteria

Useful bacteria

1. Used in making antibiotics for the treatment of infectious diseases.

2. Used in making food and beverages. Lactobacillus helps in fermentation of carbohydrate and helps in setting of curd.

3. Used in jute and leather industry for processing and tanning.  

4. Rhizobium bacteria helps in nitrogen fixation.

5. Helps in decomposition of biodegradable wastes, thus helping to clean the environment and produce compost. 

6. Bacteria present in the intestine help to break down the food (in humans) and cellulose (present in the digestive system of the animals, such as goat, cow, etc.)

Harmful bacteria

1. Cause diseases in plants and animals by producing poisonous substances called toxins.

2. Responsible for causing typhoid, cholera, pneumonia, tetanus, leprosy, whooping cough, etc., in humans.

3. Responsible for causing citrus canker and wilt diseases in plants.

4. Responsible for causing tuberculosis, anthrax and brucellosis in animals.

5. Spoils food by producing toxins.

6. Bacteria Clostridium botulinium grows in canned food and causes a serious type of food poisoning.

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