1. Pharmaceutical Microbiology- I
Dr. Rasheeda Hamid Abdalla
Assistant professor of Microbiology

2. Bacterial Morphology and Structure

3. Bacterial cells Morphology Structure of Bacteria
OBJECTIVES
Bacterial cells Morphology
Structure of Bacteria
Functions of the bacterial organelles

4. Bacterial cells Morphology
Cocci: sphere, 1μm
Bacilli: rods , 0.5-1 μm in width -3 μm in length
Spiral bacteria: 1~3 μm in length and   μm in
 width.
Unit for measurement Micron or micrometer, μm:
1μm=10-3mm
Size: Varies with kinds of bacteria, and also related to their age and external environment

5. Bacterial Shapes and Arrangements

6. Structure of Bacteria 1-Essential structure Cell wall Cell membrane
Cytoplasm
Nuclear material
2-Particular structures
Capsule
flagella
pili
Spore

7. Gram Stain
1884: Christian Gram: First publication for the Gram stain method.
Gram staining is a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents. The Gram stain procedure distinguishes between Gram positive and Gram negative groups by coloring these cells red or violet.

8. Cell Wall of Bacteria

9. Cell Wall: common peptidoglycan layer
A back bone of N-acetyl glucosamine and N-acetyl muramic acid: Both discovered in Gram positive and Gram negative bacteria.
A set of identical tetrapeptide side chain attached to N-acetyl-muramic acid: different components and binding modes in Gram positive and Gram negative bacteria.
A set of identical peptide cross bridges: only in Gram positive bacteria

10. Special Components of Gram Positive Cell Wall
Teichoicacid

11. Special Components of Gram Negative Cell Wall
lipopolysaccharide

13. Functions of Cell Wall Maintaining the cell's characteristic shape
The rigid wall compensates for the flexibility of the phospholipid membrane
keeps the cell from assuming a spherical shape
Countering the effects of osmotic pressure
Providing attachment sites for bacteriophages
Providing a rigid platform for surface appendages- flagella, fimbriae, and pili all emanate from the wall and extend beyond it
Play an essential role in cell division
Be the sites of major antigenic determinants of the cell surface
Resistance of Antibiotics

14. Wall-less forms of Bacteria
 When bacteria are treated with
1) enzymes that are lytic for the cell wall e.g. lysozyme or
2) antibiotics that interfere with biosynthesis of peptidoglycan, wall-lles bacteria are often produced
Usually these treatments generate non-viable organisms.
L-form bacteria, also known as L-phase bacteria, L-phase variants, and cell wall-deficient (CWD) bacteria, are strains of bacteria that lack cell walls

15. Cell membrane
Site of biosynthesis of DNA, cell wall polymers and membrane lipids.
Selective permeability and transport of solutes into cells
Electron transport and oxidative phosphorylation
Excretion of hydrolytic exoenzymes

17. Mesosomes
Mesosomes are folded invaginations in the plasma membrane of bacteria  that are produced by the chemical fixation techniques used to prepare samples for electron microscopy.
Although several functions were proposed for these structures in the 1960s, and are no longer considered to be part of the normal structure of bacterial cells.

19. Cytoplasm Composed largely of water, together with proteins,
nucleic acid, lipids and small amount of sugars and
salts 
 Ribosomes:
numerous, 15-20nm in diameter with 70S; Distributed throughout the cytoplasm; sensitive to streptomycin and erythromycin site of protein
 synthesis  
 Plasmids: 
Extra-chromosomal genetic elements 
 Inclusions: 
Sources of stored energy, e,g volutin

20. Ribosomes

21. Plasmid Plasmids are small，circular/line，
Extrachromosomal，double-stranded DNA molecules。
They are capable of self replication and contain genes 
that confer some properties，such as: 
-antibiotic resistance，
-virulence factors。
Plasmids are not essential for cellular survival. 

22. Cell Inclusions and Storage Granules
Bacteria have different methods of
nutrient storage that are employed
in times of plenty, for use in times
of want.
Inclusions are aggregates of various
compounds that are normally involved
 in storing energy reserves or building
blocks for the cell
Inclusions accumulate when a cell is 
grown in the presence excess nutrients 
and they are often observed under
laboratory conditions.

23. Nucleus Lacking nuclear membrane absence of nucleoli, hence
known as nucleic material 
or nucleoid
one to several per bacterium.

24. Capsules and slime layers
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, while others do not.
 Capsules are often lost during in vitro culture.

25. Capsules and slime layers
Functions:
Attachment
Protection from phagocytic engulfment.
Resistance to drying.
Depot for waste products.
Reservoir for certain nutrients.
Protection
A bacterial capsule is similar, but is a well ordered structure that is resistant to washing off

27. Flagella
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.
Functions
-Pathogenesis
-Motility of bacteria
-And also used in Identification of Bacteria

29. Flagellum Structure

30. Pili 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

31. Bacterial Pili& Flagella

32. Endospores(spores)
A bacterial spore is a spore or spore- like structure produced by bacteria
Spore formation in bacteria is not a method of reproduction but simply a method of surviving in an unfavorable conditions
Produced when starved
Contain calcium dipicolinate
DPA, Dipicolinic acid
E.g.Bacillus and Clostridium
Dormant cell
Resistant to adverse conditions
- high temperatures
- organic solvents

33. Thanks