bacterial shape , bacterial size and structure, cell wall of bacterial, gram positive and gram negative cell wall, bacterial spores, formation and structure of spores, movement of bacteria using various kind of fagylla, list of motile and non motile bacteria

1. Dr. Rahul
Acharya

2. 1. CELL ENVELOPE- CELL WALL
CYTOPLASMIC
MEMBRANE
2. CYTOPLASM- NUCLEAR BODY
CYT. ORGANELLAE-
RIBOSOMES ,
MESOSOMES , GOLGI APP., CYT. GRANULES,
VACUOLES
3. CAPSULE OR SLIME OR GLYCOCALYX
4. APPENDAGES- FLAGELLA , FIMBRIA, AXIAL
FILAMENTS
5. SPECIAL STRUCTURE- SPORE

4. Capsule (firm) or slime layer
(loose)
◦polysaccharide and/or
polypeptide
◦Inhibits phagocytosis
◦Attaches to host surfaces
◦Protects against desiccation

5.  Outside cell wall
 Usually sticky
 A capsule is neatly organized
 A slime layer is unorganized &
loose
 Extracellular polysaccharide
allows cell to attach
 Capsules prevent phagocytosis
Figure 4.6a, b
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6. Strengthens the cell
surface
Helps attach cells
together
Cell to cell recognition
Sticky carbohydrates

7.  negative staining
 clear microorganisms against a
dark background
 better view of microbial shape due to lack
of distortion
stain is not taken up by the
microorganism
 very useful with microorganisms with
capsules
negatively stained mixed bacteria culture

8. Streptococcus pneumoniae
capsule

9.  These are structures surrounding the outside of the cell envelope. They
usually consist of polysaccharide; however, in certain bacilli they are
composed of a polypeptide (polyglutamic acid). They are not essential to
cell viability and some strains within a species will produce a capsule,
whilst others do not. Capsules are often lost during in vitro culture.
 Attachment
 Protection from phagocytic
engulfment.
 Resistance to drying.
 Depot for waste products.
 Reservoir for certain
nutrients.
 protection

10.  Outside cell wall
 Made of chains of
flagellin
 Attached to a
protein hook
 Anchored to the
wall and
membrane by the
basal body
 They propel
bacteria around

11. Flagella

13. 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. Peritrichous
Monotrichous
Lophotrichous

15. Types of Flagella

16. Types of Flagella
Main function: to propel bacteria to and from area’s
of nutrients/toxic environments

17. Monotrichate/Amphitrichate/Lophotrichate/Peritrichate
 Identification
of Bacteria
 Pathogenesis
 Motility of
bacteria
Some bacterial species are mobile and possess
locomotory organelles - flagella. Flagella consist of a
number of proteins including flagellin
The diameter of a flagellum is thin, 20 nm, and
long with some having a length 10 times the
diameter of cell. Due to their small diameter,
flagella cannot be seen in the light microscope
unless a special stain is applied. Bacteria can have
one or more flagella arranged in clumps or
spread all over the cell.

18.  Present in spiral cells
 Similar to flagella, but they wrap
around the cell
 Corkscrew motion enables a
bacterium such as T.pallidum
(causative agent of Syphilis) to move
effectively through body fluids
(vaginal secretions)

20. Short thin appendages
◦Fimbriae and pili
Help cells to adhere to
surfaces
◦Sex pili
Bridge between bacterial
cells for DNA transfer

21.  Pili are hair-like projections of the cell , They are known
to be receptors for certain bacterial viruses. Chemical
nature is pilin
 Classification and Function
a. Common pili or fimbriae: fine , rigid
numerous, related to bacterial adhesion
b. Sex pili: longer and coarser, only 1-4, related
to bacterial conjugation
c. COL-1 PILI

22. DNA transfer
through a sex pili

23.  Fimbriae allow
attachment to
teeth, stones in
creeks, plastic
catheter's in
hospitals
 Pili are used to
transfer DNA
from one cell to
another
Fimbriae

24. TYPE 1-THICK,H.A.,M.S eg.Esch.coli,Klebs.,
TYPE 2-NON-H.A., eg.
S.gallinarum,S.pullorum
TYPE 3-THIN,M.R., eg.klebs.,serratia
Type4- thinner,M.R.,H.A . Eg.proteus
TYPE 5-monopolar eg.one sps.
pseudomonas
TYPE 6-very long eg. One sps. Of klebs.

25. • Dormant cell
• Resistant to
adverse conditions
- high
temperatures
• Produced when starved
• Contain calcium
dipicolinate
DPA, Dipicolinic acid
• Bacillus and Clostridium
 Identification of
Bacteria
 Pathogenesis
 Resistance

26. ◦Only Gram-positives
Bacillus spp.
Clostridium spp.
◦Highly resistant
◦Spore coat has a form of
dipicolinic acid and Ca+ ions
in it

27. IV. Special Structure
* Endospores
Spore former: sporobactobacilli and sporosarcinae - no
medical importance. bacillus and clostridium have
medical importance.
* Position: median, sub-terminal and terminal have
small water, high calcium content and dipicolinic acid
(calcium dipicolinate)
extremely resistant to heat, UV, chemicals etc. may be
due to many S containing A.A for disulfide groups.

28. • After the active growth period approaching the
stationary growth phase, a structure called forespore
develops within the cells.
• It consists of coat, cortex and nuclear structure.
The process of endospore
formation

30. Negatively Stained Bacillus: (A) Vegetative
Cell (B) Endospore