Classification of Microorganisms

1. Classification of Microorganisms
Course: B.Sc. Microbiology
Sem II
Sub: Bacteriology
Unit I

2. Types of Classification Systems cont.
• Carlolus Linnaeus proposed the Two Kingdom
Classification in 1758.
• The two kingdoms consisted of:
– Plantae
– Animalia

3. THREE KINGDOM SYSTEM
• ERNEST HAECKEL‐1866
• KINGDOM PROTISTA:
– It includes unicellular & colonial eukaryotes such as
bacteria, algae, fungi & protozoans.
• KINGDOM PLANTAE:
– It includes multicellular photosynthetic plants.
• KINGDOM ANIMALIA:
– It includes multicellular animals.

4. Types of Classification Systems cont.
• The next classification system that came about
consisted of 5 kingdoms.
• It was proposed by Robert Whittaker in 1969.
• The 5 kingdoms consisted of:
– Plantae
– Animalia
– Fungi
– Protista
– Monera

5. Robert Whittaker’s Five Kingdom System
• Plantae
– Plants are immobile, multicellular eukaryotes that produce
their food by photosynthesis and have cells encased in
cellulose cell walls.
– Examples: Ferns, pine trees, roses
• Animailia
– Animals are multicellular, heterotrophic eukaryotes that
are capable of mobility at some stage during their lives,
and that have cells lacking cell walls.
– Examples: Humans, worms, spiders

6. Robert Whittaker’s Five Kingdom System
• Fungi
– Fungi are a eukaryotic, heterotrophic, usually multicellular group
having multinucleated cells enclosed in cells with cell walls.
– They obtain their energy by decomposing dead and dying
organisms and absorbing their nutrients from those organisms.
– Examples: Mushrooms, moulds, yeast
1

7. • Protista
• The most ancient eukaryotic kingdom, protista include a variety of
eukaryotic forms.
• Perhaps they are best defined as eukaryotes that are not fungi, animals,
or plants.
• Cell wall is usually absent, if present it is impregnated with silica
(diatoms).
• Photosynthetic or non photosynthetic.
• Locomotory structure may be cilia, flagella, pseudopodia or absent.
• Examples: Paramecium, amoeba, diatom, euglena, some algae
(unicellular), slime moulds
Robert Whittaker’s Five Kingdom System

8. Protista
Paramecium diatom
amoeba euglena
2 3
4
5

9. Robert Whittaker’s Five Kingdom System
• Monera
– Monera are the only kingdom composed of prokaryotic
organisms, they have a cell wall, and lack both membrane-
bound organelles and multicellular forms.
– Examples: Bacteria, blue-green bacteria (cyanobacteria)

10. Characteristics of Monera:
• Unicellular or filamentous prokaryotes
• Omni present (air, soil, hot springs, deserts, deep sea, snow & as
parasites)
• Cell wall is composed of polysaccharides & amino acids(peptido
glycons ormurein)
• Autotrophic (photo & chemosynthetic) & heterotrophic
(saprophytic & parasitic)
• Reproduce by vegetative, asexual & sexual methods

11. • MAJOR GROUPS OF MONERA:
1. Archaebacteria: Methanogens,
Halophyles, thermoacidophyles
2. Eubacteria: Vibrio, mycobacteria
3. Cyanobacteria: Nostoc, Anabena
1
1
HalobacteriumVibrioAnabenaNostoc
6 7 8 9

12. Types of Classification Systems cont..
• In the 1970’s, microbiologist Carl Woese, among other
researchers conducted studies and concluded that a group of
prokaryotic microorganisms called archaebacteria are
separate from other monerans.
• Therefore, they decided to split kingdom monera into two
separate kingdoms:
– Eubacteria
– Archaebacteria

13. • Archaebacteria
– Unicellular
– Prokaryotic
– Exist in extreme environments – they do not need oxygen or
light to live
– Examples: methanogens, extreme thermophiles, extreme
halophiles
• Eubacteria
– Unicellular
– Prokaryotic
– Heterotrophic, autotrophic, and chemotrophic
– Examples: Bacteria, cyanobacteria (blue-green bacteria)

14. Three Domain System
• The Three Domain System, developed by Carl Woese,
is a system for classifying biological organisms.
• Over the years, scientists have developed several
systems for the classification of organisms.
• From the late 1960's, organisms had been classified
according to a Five Kingdom system.
• This classification system model was based on
principles developed by Swedish scientist Carolus
Linnaeus, whose hierarchical system groups organisms
based on common physical characteristics.

15. The Three Domain System
• As scientists learn more about organisms, classification systems change.
• Genetic sequencing has given researchers a whole new way of analyzing
relationships between organisms.
• The current system, the Three Domain System, groups organisms
primarily based on differences in ribosomal RNA structure.
• Ribosomal RNA is a molecular building block for ribosomes.
• Under this system, organisms are classified into three domains and six
kingdoms.
• The domains are Archaea, Bacteria, and Eukarya. The kingdoms are
Archaebacteria (ancient bacteria), Eubacteria (true bacteria), Protista,
Fungi, Plantae, and Animalia.
• The Archaea and Bacteria domains contain prokaryotic organisms.
These are organisms that do not have a membrane bound nucleus.
• Eubacteria are classified under the Bacteria domain and archaebacteria
are classified as Archaeans.
• The Eukarya domain includes eukaryotes, or organisms that have a
membrane bound nucleus. This domain is further subdivided into the
kingdoms Protista, Fungi, Plantae, and Animalia.

16. Comparison of Classification Systems
• Five Kingdom System
Kingdoms: Monera, Protista, Fungi, Plantae, and Animalia.
Three Domain System
• Archaea Domain
– Archaebacteria Kingdom
• Bacteria Domain
– Eubacteria Kingdom
• Eukarya Domain
– Protista Kingdom
– Fungi Kingdom
– Plantae Kingdom
– Animalia Kingdom

17. References
Books:
1. Biology of microorganisms By M. T. Madigan, J. M. Martinko, D. A.
Stahl and D. P. Clark
Images:
1. https://lh4.ggpht.com/BL8zyuw37iAzWft6GzMuHTWQ7LmX1pGCKxaXjY_wF8R
uMzVbHGnNAsu-XFO-r6w_ozc8hHM=s125
2. http://cfb.unh.edu/phycokey/Choices/Amoebae_Flagellates_Ciliates/Ciliates/P
ARAMECIUM/Paramecium_05_600x395_caudatum.jpg
3. http://www.bodc.ac.uk/projects/uk/mfmb/introduction/images/diatoms.jpg
4. http://www.microscopy-uk.org.uk/mag/imgsep01/amoebaproteus450.jpg
5. https://lh6.ggpht.com/mkGhpDrT154r8rgB0tTM4wfgOG0-
ULTlnUzmbRT7pvKbgVUoTrBC9XuJEqxTdQkEniP1jQ=s170
6. http://www.ohio.edu/plantbio/vislab/algaeimage/jpegs/nost1nitr.JPG
7. http://protist.i.hosei.ac.jp/PDB/images/Prokaryotes/Nostocaceae/Anabaena/A
nabaena9c.jpg
8. https://s3.amazonaws.com/healthtap-public/ht-
staging/user_answer/reference_image/8742/large/Cholera.jpeg?1344948822
9. http://plantphys.info/organismal/lechtml/images/halobacterium.jpg