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Last Updated : 16 Nov, 2023
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Microbiology as the name suggests micro means tiny entities, and biology means the study of living organisms. In simpler terms, microbiology means the study of small living things that we can’t see with the naked eye. This field helps us understand how these microorganisms function, their roles in nature, and their impact on our health. From the bacteria in yogurt to the viruses causing illnesses, microbiology plays a major role in shaping our lives by studying all about the microorganisms. It delves into their structure, function, behavior, and interactions with the environment.

This field plays a major role in fields like medicine, agriculture, and environmental science. Microorganisms have also played a key role in the evolution of Earth and other organisms. The most useful instrument for studying these microorganisms is called a microscopy. Examples of these microscopic organisms are bacteria, viruses, fungi, algae, and protozoa.


What are Microorganisms?

Microorganisms are organisms invisible to the naked eye; they are minute life forms that include bacteria, viruses, fungi, protozoa, and algae. Microorganisms constitute a vast and diverse kingdom, microorganisms thrive in various environmental conditions and are present in the depths of oceans to the human digestive system. Some of the most common microorganisms are:

Bacteria, they are single-celled prokaryotes, are ubiquitous (meaning present everywhere)and play vital roles in nutrient cycling, food production, and even aiding digestion in the human gut. Viruses, although not considered living on their own, are genetic material encapsulated in protein, causing infections in host cells and take control of the host. Fungi, including molds and yeasts, are eukaryotic organisms vital for decomposition and nutrient recycling. Protozoa, single-celled eukaryotes, exhibit diverse behaviors and can be both beneficial and harmful. Algae, ranging from microscopic phytoplankton to larger seaweeds, are photosynthetic organisms contributing significantly to oxygen production and aquatic ecosystems.Many microorganisms cause diseases in crops and human beings.

Examples of some common human diseases are:

  • Bacteria: cholera, dysentery, diphtheria, pneumonia, typhoid.
  • Virus: Chickenpox, measles, mumps.
  • Protozoa: amoebic dysentery, malaria.
  • Fungi: athlete’s foot,ringworm.

Microorganisms exhibit significant adaptability, with some living in extreme environments like hot springs or deep-sea. Their impact on human life is profound; they are involved in processes like fermentation for food production, the synthesis of antibiotics, and the development of vaccines. However, some microorganisms can cause infectious diseases, highlighting the importance of understanding and managing their roles in ecosystems and human health. The study of microorganisms, microbiology, continually unveils the details of these tiny life forms, shaping our comprehension of the microbial world and its implications for the broader biological context. There are both harmful and useful microorganisms

Harmful Microorganisms

Some of the harmful microorganisms are given below:

  • Salmonella: This is a Bacteria, causing food poisoning, with symptoms like diarrhea, and abdominal cramps.
  • Mycobacterium tuberculosis: This bacterium responsible for tuberculosis, a respiratory disease.
  • Plasmodium falciparum: A protozoan parasite causing the deadliest form of malaria in humans.
  • HIV (Human Immunodeficiency Virus): A virus that weakens the immune system, causing AIDS if left untreated.
  • Aspergillus fumigatus: A fungus known to cause invasive Aspergillosis, a severe lung infection in individuals.

Useful Microorganisms

Some of the useful microorganisms are given below:

  • Lactobacillus acidophilus: A beneficial bacterium found in yogurt and probiotics , helps in improving digestive health.
  • Saccharomyces cerevisiae: Commonly known as baker’s yeast, it is essential for baking and brewing processes.
  • Rhizobium: Nitrogen-fixing bacteria that form symbiotic relationships with leguminous plants, enriching soil fertility.
  • Escherichia coli (E Coli): Some strains are used in biotechnology for protein production and research purposes
  • Penicillium chrysogenum: The source of penicillin, the first antibiotic, revolutionizing medicine by fighting bacterial infections.

Different Branches of Microbiology

Microbiology can be broadly categorized into several branches based on the types of microorganisms studied and the focus of research:


This focuses on the study of bacteria, study about their structure, function, genetics, and ecological roles. Bacteriologists investigate various aspects, including bacterial diseases and the beneficial roles of bacteria in processes like fermentation.


Virologists specialize in the study of viruses, examining their structure, replication mechanisms, and interactions with host cells. This class plays a crucial role in understanding and combating viral diseases.


It is the study of fungi. Mycologists concentrate on fungi, exploring their diversity, life cycles, and ecological functions. This plays a significant role in agriculture, medicine, and environmental science.


This focuses specifically on protozoa, single-celled eukaryotic microorganisms. Protozoologists investigate their biology, behavior, and roles in various ecosystems.


Phycologists specialize in the study of algae, ranging from microscopic forms to larger seaweeds. They explore their roles in aquatic ecosystems, photosynthetic processes, and potential applications in biotechnology.

These are the major branches of microbiology,some other branches of microbiology are:

Environmental Microbiology

Environmental microbiologists study the roles of microorganisms in natural environments, including soil, water, and air. They investigate processes like nutrient cycling, decomposition, and bio-remediation.

Medical microbiology

It is a branch that studies about disease causing microorganisms. They basically study about all disease causing microorganisms in detail. They are also involved in finding pathogens and their mode of transmission, mechanism of infection and even about their reproduction and growth.


Parasitologists study parasites, which can be protozoa, helminths, or arthropods, examining their life cycles, host interactions, and the diseases they cause in humans and other organisms.

Microbial Genetics

This branch delves into the genetic makeup and mechanisms of inheritance in microorganisms, providing insights into evolutionary processes, antibiotic resistance, and genetic engineering.

These branches within microbiology collectively contribute to our understanding of the microbial world, impacting fields such as medicine, agriculture, industry, and environmental science.

FAQ’s – Microbiology

1. Who is the Father of Microbiology?

The father of microbiology is Anton van Leeuwenhoek. He made huge contributions to this field and observed and described microorganisms including bacteria and protozoa.

2. What are the 2 main Branches of Microbiology?

Microbiology can be divided into two branches: pure and applied.In pure microbiology organisms themselves are examined in-depth and in applied microbiology, the organisms are not studied but are applied to a certain process like fermentation etc…

3. Which is the Smallest Microorganism?

Among all the microorganisms, viruses are the smallest. Viruses have the size as small as 0.02 microns. Viruses are living only inside the host body and are non-living outside. Viruses are pathogenic in nature and cause diseases in living organisms.

4. What are the Useful Microorganisms?

Being decomposers, bacteria and fungi are an important role in an ecosystem. They break down the dead or waste organic matter and release it as inorganic molecules. These nutrients are then taken by the plants which in turn are consumed by animals and the products of these plants and animals are again broken down by the decomposers. It also plays a major role in process like fermentation

5. Give an Example of a Useful Microorganism.

Yeast, it is a fungus and is single-celled that lives naturally on the surface of the fruits and plays an economically important role in bread making and brewing beer. It is also important in the making of yogurt.

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