Microbiology and Micro Organisms


The word microbiology is derived from the two Greek words 

(a) Micron means small

(b) Biologia Means studying life.

By combining this two-word microbiology formed and it is defined as the study of micro-organisms and their activities.

It is concerned with form, structure, reproduction, physiology, metabolism and microbial identification. It includes the study of their distribution in nature, their relationship with each other and with other living things, the beneficial and harmful effects for man and the physical and chemical changes, they make in their environment. It may also be defined as.


“The branch of biology that deals with microorganism and their effects on other living organisms.”

MICROBE is a term for tiny creature that individually is too small to be seen with naked eye. E.g. Bacteria,Virus,Archaea ,Fungi,Protozoa,Mycoplasma,Rickettsia, etc.


The cellular world is divided into two major groups, on the basis of cells have a nucleus or not. Cells that have a well-defined nucleus are called eukaryotic, whereas cells that lack a nucleus are called prokaryotic. All prokaryotic organisms are classified as bacteria, whereas eukaryotic organisms include fungi, protozoa, and helminth’s, as well as humans.

Groups of cellular organisms:

  1. Prokaryotes
  2. Eukaryotes



Prokaryotes are those organisms which cells lack a membrane-bounded nucleus



Eukaryotes are those organisms which contain a nucleus and other structures enclosed within membranes.


In 1665 Robert Hooks English scientist gave description of microscope and its uses, but he did not invent it. He described a slice of cork and suggested that cork was composed of compartment, which he called cells.

The discoveries of Hook and other scientist showed that microscope is an important tool for discover the secrets of life.

 Leven Hook revealed his descriptions of microorganism in 1670 by inventing his simple and single lens microscope.

In 1674 he called tiny microorganism as aninmicuies which was a term used for microorganisms by him, He outlined the structural details of the familiar protozoa and paramecium and amoeba. He ‘died in 1723.


  • The science of microbiology includes the study of micro-organism algae bacteria, Rickettsia, protozoa, fungi, yeasts and viruses.

  • The fermentation of fruit juice and the souring of milk are natural processes.Yet why these changes occurred were unknown, study of micro biology tells that yeasts and bacteria converted sugars to alcohols and acids

  • Injections are also subjected to a test for pyrogens. These are substances that cause a rise in body temperature when introduced into the body.

  • It is obvious that medications contaminated with pathogenic microorganisms are a safety hazard, so medications administered by fragile routes (e.g., injections) or to vulnerable areas of the body (such as the eyes) are manufactured as sterile products.

  • Spoilage of medicines as a result of microbial contamination is undesirable, it results in financial loss and ill health of the patient.

  • The microbiologist has discovered vaccines for the prevention of disease such as smallpox and polio, and drugs such as penicillin, for the treatment of disease.

  • The discovery of the vitamins and other basic food materials has resulted from the study of microorganisms.

  • Knowledge of the chemistry of the cell and the importance of certain cell parts in heredity is a contribution of the microbiologist.

  • The biologist may use microorganisms as possible sources of food and oxygen for the space travelers.

  • The physician needs knowledge of microbiology to fight disease.

  • Industrial scientists often utilize microbiology in the manufacturing of useful chemical products.

  • The geologist frequently uses information about microorganism in his search for oil. Thus, microbiology is important from the core of the earth to the far reaches of outer space.