Classification of Microorganisms

1. Dr. Pulipati Sowjanya
Associate Professor
Vignan Pharmacy College
Guntur
PRESENTED BY

2. CLASSIFICATION OF MICROORGANISMS
• Classification is the arrangement of organisms in groups or taxa
based on mutual similarity or evolutionary relatedness.
• Taxonomy:
• The science of classifying organisms
• Provides universal names for organisms
• Provides a reference for identifying organisms.
Phylogeny
• The study of the evolutionary history of organisms

3. CLASSIFICATION OF MICROORGANISMS
• Traditionally the living organisms were placed in two kingdoms by Carlous
Linnaeus
• Plants
• Animals
•Leewenhoeck discovered microorganisms and proposed 3rd kingdom
• Haeckel realized that fungi, algae, protozoa & bacteria were unlike plants & animals and
proposed kingdom Protista.
• Invention of electron microscope
Membrane bound nucleus – Eukaryotes
Membrane unbound nucleus - Prokaryotes

4. CLASSIFICATION OF MICROORGANISMS
PROBLEMS WITH TWO KINGDOM CLASSIFICATION
 Didn’t distinguish between the eukaryotes and prokaryotes
 Unicellular and multicellular organisms
 Photosynthetic (green algae) and non-photosynthetic (fungi)
organisms.
 A large number of organisms did not fall into either category.

5. R.H. WHITTAEKAR 5 KINGDOM CLASSIFICATION
R.H. WHITTAEKAR
CLASSIFICATION OF MICROORGANISMS

6. CLASSIFICATION OF MICROORGANISMS
FIVE KINGDOM CLASSIFICATION
 Proposed by R.H. Whittaker
 Monera, Protista, Fungi, Plantae, Animalia
 CRITERIA:
 Cell structure
 Mode of nutrition
 Reproduction
 Phylogenetic relationships

7. CLASSIFICATION OF MICROORGANISMS
 All prokaryotic organisms bacteria & cyanobacteria (blue-green algae).
 The organisms could be unicellular or multicellular,
 Possess rigid cell wall
 Absorptive mode of nutrition
 Nutrition might be heterotropic, photoautotropic or chemotropic.
 Bacteria are grouped under 4 categories based on their shape:
the spherical – Coccus
the rod shaped – Bacillus
the comma shaped – Vibrium
the spiral - Spirillum
MONERA

8. CLASSIFICATION OF MICROORGANISMS
 Eukaryotic organisms like protozoa, algae, lower fungi, amoeba
etc.,
 Unicellular have a heterotropic or phototropic mode of nutrition
by ingestive or absorptive type of food uptake.
 Some have flagella or cilia.
 Reproduce asexually or sexually by cell fusion and zygote
formation.
PROTISTA

9. CLASSIFICATION OF MICROORGANISMS
Multicellular higher fungi having eukaryotic cells.
They grow in warm and humid places.
They possess multinucleate mycelium & heterotropic
Mode of nutrition is absorption
Mostly filamentous (except yeast)
Their bodies consists of long, slender thread-like
structures called hyphae. The network of hyphae is
known as mycelium
FUNGI

10. CLASSIFICATION OF MICROORGANISMS
…..FUNGI
 Cell walls of fungi are composed of chitin and polysaccharides
 They are saprophytes/parasites
 Reproduction:
Vegetative – fragmentation, budding, fission
Asexual – Conidia, Sporangiospore, Zoospore
Sexual – Oospores, Ascospore, Basidiospore

11. CLASSIFICATION OF MICROORGANISMS
 Eukaryotic chlorophyll containing organisms commonly called
plants.
 Partially heterotropic
 They possess chloroplast
 The cell wall is made up of cellulose
 Plantae include algae, bryophytes, pteridophytes, gymnosperms
and angiosperms
PLANTAE

12. CLASSIFICATION OF MICROORGANISMS
ANIMALIA
Heterotropic eukaryotic organisms that are multicellular
Lack cell wall
Mode of nutrition is ingestion
Follow a definite growth pattern and grow into adults that
have a definite shape and size.
Usually capable of locomotion.

13. CLASSIFICATION OF MICROORGANISMS
VIRUS
 Viruses did not find a place in classification since they are not
truly living.
 The viruses are non-cellular organisms
 Have an inert crystalline structure outside the living cell.
 Once they infect a cell, it becomes living

14. 6 Kingdom Classification
Problems with 5 Kingdom
Classification
The kingdoms Protista, Plantae and Fungi
are ill defined in 5 kingdom classification.
Lack of distinction between archae and
bacteria.
6 Kingdom Classification
It divides kingdom monera into Eubacteria
and Archaebacteria
CLASSIFICATION OF MICROORGANISMS

15. Cavalier – Smith Classification
Cavalier – Smith Classification
Cellular structure and genetic organization are important in
determining phylogeny.
He used ultrastructural characteristics as well as rRNA sequence.
2 Empires & 8 Kingdoms
Bacteria: Eubacteria & Archaebacteria
Eucaryota:
Archaezoa – primitive eukaryotic unicellular organisms such as
Giardia that have 70s ribosomes and lack golgi apparatus,
mitochondria, chloroplasts
Chromista – brown algae
Plantae, Fungi, Animalia and Protozoa
CLASSIFICATION OF MICROORGANISMS

16. Universal Phylogenetic Tree
Universal Phylogenetic Tree
• Proposed by Carl Woese
• Based on rRNA Sequence
comparisons
• Here the archaebacteria &
eubacteria have been recognized as
two major groups of prokaryotic
organisms
CLASSIFICATION OF MICROORGANISMS