Introduction to Microbiology


Studying all living organisms that are too small to view with the naked eye is known as microbiology. The term microbes refers to this group of organisms, which includes bacteria, viruses, archaea, fungus, prions, algae, and protozoa.

A microbiologist investigates the features of pathogens, their means of transmission, methods of infection and their growth in developing a treatment. Robert Koch, a German doctor and microbiologist, who founded modern bacteriology, was recognised with the Nobel Prize in Medicine for being the first to identify the bacterial species that caused cholera, anthrax, and tuberculosis. Robert Koch led the introduction to microbiology and further branches of microbiology.

Defining Microorganisms

A microbe, also known as a microorganism, is a microscopic organism made up of a single cell (also referred to as a unicellular organism), clusters of cells, or multicellular, relatively complex organisms. In 1675, using the microscope of his invention, Anton van Leeuwenhoek made the first discovery of microbes.

Microorganisms can be found in soil, ocean floor, hot springs, high in the atmosphere and buried deep beneath rocks that make up the Earth’s crust. They also play other vital functions in the entire ecosystem, such as recycling the waste products and dead remains of other organisms through decomposition.


Microbiological culture is the primary technique used to isolate infectious pathogens in laboratories. The presence of a particular pathogen is checked in tissue or fluid samples using in vitro growth in a selected or differential medium. The medium can be a cell culture (primarily for virus growth), a liquid culture (for some parasites) or a solid culture (for most bacteria and fungi).

A light microscope can be used to examine the pathogen once it has been isolated.

Types of microscope

There are various types of microscopes, including:

  • Compound microscope:

It is an instrument with two lenses—an objective lens and an ocular lens. It also uses visible light as a source of illumination.

  • Electron microscope:

Instead of using light to create images, this microscope uses an electron flow. This microscope also improves the appearance of proteins, ribosomes, lipids, viruses and even tiny molecules.

  • Darkfield microscope:

These microscopes have a feature that scatters light coming from the illuminator. This also helps the specimen to stand out against the dark background because it appears white.

  • Fluorescence microscope:

These microscopes illuminate fluorescent specimens with ultraviolet light. Moreover, the specimen being examined is usually combined with a fluorescent antibody or dye.

  • Contrast/phase microscope:

Using a unique condenser in this microscope enables the investigation of cellular structures. The final image generated by these microscopes combines bright and dark elements.

Parts of Microscope

1. Arm:

It is located at the back of a microscope and supports the ocular and objectives.

2. Foot or base:

The microscope’s base contains the light source and is the handle for carrying the instrument.

3. Focusing knobs:

The location of the objective lenses is adjusted using a coarse focusing knob. Once the specimen is seen through the coarse focusing knob, the fine-focusing knob is used to bring the sample into perfect focus.

4. Illuminator:

It serves as the light source of the microscope.

5. Objective lens/numerical aperture:

It is found in a compound microscope and is the lens that is nearest to the specimen.

6. Ocular lens:

In a compound light microscope, it is the lens closest to the viewer.

7. Oil immersion lens:

This lens has a 100x (100 times) objective. This lens is very compact for high resolution and magnification. Moreover, the lens must receive the maximum light possible due to its size.

The above-mentioned major microscope parts comprise the compound microscope’s mechanical and optical parts.

Different fields use microscopes for various tasks. They are used for multiple things, including forensic evidence analysis, ecological health evaluation, the function of proteins in cells and atomic structure studies.

Stay tuned to BYJU’S Biology for more information.

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