1.4 BACTERIA

1.3 BACTERIA

Bacteria are found in everywhere, in , air, water, living and dead bodies of organisms and even in glaciers and hot springs. On basis of shape and form, bacteria are of four types, round ,rod-shaped, spiral and comma shaped.

  Bacteria are found singly or in groups and even in beaded form. Bacteria are unicellular microscopic organisms. A distinct nucleus is absent in bacteria , however , only a single large , circular molecule of DNA is present. This is not bounded by nuclear membrane. Bacterial cell is surrounded by a cell wall. A few bacteria have an additional slime capsule around their cell wall. Some bacteria have one or more thread like flagella (Singular flagellum), which help them in locomotion.

Some bacteria are autotrophs while majority of them are heterotrophs. Bacteria, which live on other living organisms for their nutrition, are called parasitic bacteria. The parasitic bacteria cause diseases in plants and animals and are known as pathogenic bacteria. Bacteria are transmitted from one living organisms to another through touch, air, contaminated water and food, insects and other animals.

Importance of bacteria  :

  Bacteria play an important role in our lives. They are beneficial as well as harmful to us

Advantages:

 Bacteria act as decomposers. They decompose dead bodies of plants and animals so increase soil fertility. Some bacteria add nitrogenous compounds in soil, thus maintain its fertility.

    Bacteria are used for industrial and commercial purposes such as in manufacturing butter, cheese and yogurt in processing of vinegar, tobacco , coffee and leather.

Antibiotics such as streptomycin, tetracycline and terramycin are obtained from bacteria. These antibiotics destroy harmful bacteria.

Disadvantages:

 Food is decomposed and putrefied by bacteria.

THINK ABOUT!

  Many bacteria are harmful and cause many diseases in plants, animals and human beings. Canker disease in citrus fruits (lemon and orange) ; fire blight in peach, pear, apple and scab in potatoes are caused by bacteria.

What would happen, if there were no bacteria in this  world???

   In animals like cattle, bacteria are responsible for T.B. and Anthrax. Bacteria also caused diseases in man like T.B., whooping cough, diphtheria, typhoid, pneumonia, tetanus, plague, cholera, leprosy and anthrax.