The document presents a classification of microorganisms, detailing the taxonomy and characteristics of different groups, including bacteria, viruses, fungi, protozoa, and algae. It discusses the historical development of classification, highlighting the three-domain system proposed by Carl Woese, which classifies life into Bacteria, Archaea, and Eukarya. Each type of microorganism is characterized by their size, structural features, mode of reproduction, and practical significance in environments and industries.

1. Classification of Microorganisms
Presented by
Mr. Sujit Kakade
Assistant Professor
Pune District Education Association’s
Shankarrao Ursal College of Pharmaceutical Sciences
& Research Centre, Kharadi, Pune.

4. Taxonomy: It is the science that deal with logical arrangement of
living thing into categories .
1)Aristotle classified living thing into plant and animals
2)Karls linaus classified living thing into kingdom Plantae and
Animalia.
He also devised binomial (genus and species) scheme of
nomenclature.
3) In 18th century the German zoologist E.H. Haeckel proposed 3rd
kingdom named as the protista.
• Include unicellular m.o. typically they are neither plant nor animal.
• Protista, include bacteria, fungi, algae, protozoa but virus not
classified as protista.
• Bacteria is classified as a lower protista and fungi, algae, protozoa
classified as a higher protista.
Classification of Micro-organisms

5. • In 1940 it was discovered in some cell e.g typical
bacteria, the genetic material was not enclosed by
nuclear membrane.
• In other cells i.e (algae, fungi, protozoa) the nucleus
was enclosed in membrane this resulted into
division of organism Prokaryotes Eukaryotes
• Bacteria are prokaryotic microbes (absence of
nuclear membrane)
• Fungi, algae, protozoa, plant and animal cell are
eukaryotic microbes (presence of nuclear
membrane)

8. The Three Domains of Life
(Carl Woese, 1990)
Starting in the early 1970s, Dr. Carl Woese, began to find evidence for a
previously unknown group of prokaryotic organisms.
These organisms lived in extreme environments - deep sea hydrothermal
vents, "black smokers", hot springs, the Dead Sea, acid lakes, salt
evaporation ponds - environments that scientists had never suspected
would contain a profusion of life!
Because they appeared prokaryotic, they were considered bacteria and
named "archaebacteria" ('ancient' bacteria).
However, became obvious from biochemical characteristics and DNA
sequence analysis (Genetics) that there were numerous differences
between these archaebacteria and other bacteria. Before long, it was
realized that these archaebacteria were more closely related to the
eukaryotes than to bacteria. Today, these bacteria have been
renamed Archaea.

9. The three-domain system is a biological classification
introduced by Carl Woese

11. Major Groups of Microorganisms
1.Bacteria
2.Viruses
3.Fungi
4.Protozoa
5.Algae

12. Bacteria
Size:
• Most bacteria range from 0.2–5.0 µm (micrometers) in diameter.
Important Characteristics:
• Prokaryotic
• Unicellular
• Simple Internal structure
• Grow on artificial laboratory media
• Reproduction asexual (mostly simple cell division, binary fission)
Practical significance:
• Some cause diseases
• Some perform role in natural cycling of elements and increase soil
fertility
• Manufacture of valuable compounds in Industry.
Examples: E. Coli, Salmonella typhi, Vibrio cholera,
Staphylococcus aureus, Bacillus anthracis, Clostridium tetani, etc

14. Viruses
Size:
0.015-0.2 μm
Important Characteristics:
• Do not grow on artificial media
• Obligate intracellular parasites
• Electron microscopy required to observe
Practical significance:
• Cause diseases in humans animals & plants
• Also infect microorganisms like bacteria
Examples:
Rabies virus, Polio virus, Influenza virus, HIV, Corona virus,
T-even bacteriophage, etc.

16. Fungi (Yeasts)
Size:
5.0-10.0 μm
Important Characteristics:
• Eukaryotic & Non-motile
• Unicellular
• Grow on artificial laboratory media
• Reproduction asexual (cell division/ budding) or
sexual
• Have Rigid Cell wall Made up of Chitin, Cellulose
Practical significance:
• Some cause diseases like Athlet’s foot, thrush
• some are used as food supplements
• Manufacture of alcoholic beverages
Examples: Saccharomyces Cerevisae ,etc

18. Fungi (Molds)
Size:
2.0-10.0 μm by several mm some are visible with naked eyes
Important Characteristics:
• Eukaryotic & Non-motile
• Multicellular
• • Many distinctive structural features (Filamentous structure )
showing Vegetative mycellium & Aerial mycellium
• Cultivated on artificial laboratory media
• Have Rigid Cell wall Made up of Chitin, Cellulose
• Reproduction asexual or sexual
Practical significance:
• Decomposition of many materials
• Industrial production of many chemicals like antibiotics
• Can cause diseases, penicilliosis, otomycosis.
Examples:Penicillium notatum, Aspergillus niger, etc.

20. Protozoa
Size:
2.0-200 μm
Important Characteristics:
• Eukaryotic
• Unicellular
• Some cultivated on laboratory media while some are
intracellular parasites
• Reproduction asexual or sexual
Practical significance:
• Some cause diseases like Maleria, Sleeping sickness, etc
• Food for aquatic animals
Examples:
Entamoeba histolytica, Plasmodium falciparum, Trypanosoma
cruzi, etc.

22. Algae
Size:
1.0 μm to several centimeters
Important Characteristics:
• Eukaryotic
• Unicellular or Multicellular
• Photosynthetic
• Most occur in aquatic environments
• Reproduction asexual or Sexual
Practical significance:
• Production of food in aquatic environments
• Source of food and in Pharmaceuticals (Like Agar)
• Some produce toxic substances
Examples:
Red algae, Green algae, etc