1. Topic 1 - BAcTERiAL cLASSiFicATioN
ScHEMES
20/09/12 1

2. Topic content
Characterisation of species
Binomial system
Problems of classification
Phylogenetic classification
20/09/12 2

3. 20/09/12 3

4. Characterisation
Why?..Great number and diversity of organisms.
Classification:
Grouping of related organism together.
Many m/o look alike to be classified according to the
structure
Literally hundreds of bacterial species are small rods
or small cocci.
20/09/12 4

5. 5

6. Basic Shapes
Bacillus (rod-shaped)
Coccus (spherical)
Spiral
Spirillum
Vibrio
Spirochete
Figures 4.1a, 4.2a, 4.2d, 4.4a, 4.4b, 4.4c

7. Arrangements
20/09/12 7

8. Prokaryotic Cells: Shapes
Average size: 0.2 –1.0 µm × 2 – 8 µm
Most bacteria are monomorphic
A few are pleomorphic
Figure 4.7a

9. The Cell Wall
Prevents osmotic lysis
Made of peptidoglycan (in bacteria)
Figure 4.6

10. Gram-Positive Bacterial Cell
Wall
Figure 4.13b

11. Gram-Negative Bacterial Cell
Wall
Figure 4.13c

12. Gram-positive Gram-positive
Cell Wall
Cell Wall
Thick peptidoglycan  Thin peptidoglycan
Teichoic acids  Outer membrane
 Periplasmic space
Figure 4.13b–c

13. Motile Cells
Rotate flagella to run or tumble
Move toward or away from stimuli (taxis)
Flagella proteins are H antigens
(e.g., E. coli O157:H7)

14. Arrangements of Bacterial
Flagella
Figure 4.7

15. 20/09/12 15

16. History of Binomial Nomenclature
Father of taxonomy?
Two name system,Latin scientific name.
Formal system of naming organisms
Organizing,classifying and naming organisms into
groups-according to the specific criteria.
How to write these names??
Vibrio cholerae
Staphylococcus sp
E.coli
20/09/12 16

17. Genus and species
Genus - capitalized
species – specific epithet.
Example:
Escherichia coli,E.coli
• Information gained: shape,who discovered,where it is
found,what disease they cause.
20/09/12 17

18. 20/09/12 18

19. General problems
Establishing a standard names for organisms so that
we can communicate about them
Usually classified according to their phylogenetic or
evolutionary, but not always easy
Leads to introduction of a dichotomous key
20/09/12 19

20. Dichotomous key
Has paired statements describing characteristic of
organisms
Paired statement can only have one statement true
Each paired statement relate to each other
20/09/12 20

21. 20/09/12 21

22. Dichotomous
Key
Figure 10.8

23. Reasons causing problems
1. Deciding what constitutes a species – because of
some bacteria have the similar characteristics so
taxonomist try to tolerate the organism within
species
2. Deciding what constitutes a kingdom – because
most of organism having sexually reproduction so
have very factors affecting the variable of the
characteristics
20/09/12 23

24. Focusing on bacterial classification
Other organism categorized from domain to species,
but for prokaryotic cell, start from strain to genus
However facing problems reaching the classes and
orders level
Wide range of studies needed on identification and
building up taxonomy of bacteria
20/09/12 24

25. 20/09/12 25

26. Phylogenetic hierarchy
Grouping organism according to
common properties that implies that a
group of organisms evolved from
common ancestors.
Each species retains some
characteristics of the ancestor.
20/09/12 MIC250 by Miss Rashidah Iberahim 26

27. Hierarchy
domain – Bacteria
kingdom – none assign for bacteria
phylum – Proteobacteria
class – Gamma-proteobacteria
order – Enterobacteriales
family – Enterobacteriacea
genus – Eschericia
Species – E.coli
start
20/09/12 27

28. Three domain system classification
20/09/12 28

29. Terminologies (answer)
Taxa – subdivisions used to classify organism:
domain, kingdom, phylum
Phylogeny / sytematic – the evolutionary history of a
group of organism; phylogenetic relationships are
evolutionary relationship
Taxonomy – the science of the classification of
organism
20/09/12 m 29

30. The enD
Short lecture ,but!!!
MAKE MORE
revision on it….
TQ
20/09/12 30