This document is my

1. Microbiology
Dr. Bakhtyiar Sh. Azeez
D.V.M&S, MSc
Veterinary Department
27.2.2022

2. Semester Outlines
• Introduction
• Bacteriology (Gram + & Gram -ve)
• Antibiotic & Antimicrobials.
• Virology (DNA, RNA viruses)
• Parasitology (Int,Ext, and Protozoa)
• Mycology (Main Fungal group)

3. Introduction
Microbiology is the study of all living organisms that are
too small to be visible with the naked eye. This includes
bacteria, viruses, fungi, prions, protozoa and algae.
• Bacteriology: Science deal with Bacteria.
• Parasitology: Science deal with Parasite.
• Virology: Science which deal with Virus.
• Mycology: Science which deal with Fungus.

4. Branches of Microbiology:
• Medical microbiology
• Industrial microbiology
• Food microbiology
• Soil microbiology

5. Bacteria
Bacteria: are single celled free lining organisms without
chlorophyll having both DNA and RNA. They are capable of
performing all essential processes of life, example: growth
metabolism and reproduction.
Bacteria are found in every habitat on Earth: soil, rock, oceans and
even arctic snow. Some live in or on other organisms including
plants and animals including humans. There are approximately 10
times as many bacterial cells as human cells in the human body.

6. Shape of Bacteria
On the basis of shape, bacteria are classified as under:
1. Cocci (from kokkos, meaning berry): They are spherical. On the basis of
arrangement of individual organisms.
Cocci in cluster =staphylococci
Cocci in chain-streptococci
Cocci in pair-diplococcic
Cocci in groups of four- tetrad
Cocci in groups of eight-sarcina

7. Bacilli
2. Bacilli is a rod-shaped bacterium
• Single bacilli
• Diplobacilli
• Streptobacilli
• Coccobacilli

8. Spiral bacteria
3. Spiral bacteria
• Vibrios look like curved rods.
• Spirilla have a helical shape

10. Structure of bacteria
• Slime Layer: Some bacteria secrete viscid substance which may
diffuse out into surrounding media or remain outside cell wall.
This viscid carbohydrate material is called slime layer.
• Capsule: It is gelatinous secretion of bacteria which gets
organized as a thick coat around cell wall and is known as capsule.
It may be composed of complex polysaccharide e.g. pneumococi
and klebsella or polypeptide e.g. bacillus anthrax or hyaluronic
acid e.g. streptococcus pyogenes. Capsules have no affinity for
dyes and so they are not seen in stained preparations

11. Capsule Function:
• Protection against deleterious agents e.g. lytic enzymes.
• Contribute to the virulence of pathogenic bacteria by inhibiting
phagocytosis.
Cell Wall: The cell wall is the outermost supporting layer which
protects the internal structure.
Chemical structure of cell wall:
Cell wall is composed of mucopeptide (muerin), scaffolding
formed by N acetyle glucosamine and N. acetyle muramic acid
molecules alternating in chain cross linked by peptide chain

12. Function of cell wall:
• Protection of internal structure (supporting layer).
• Gives shape to the cell.
• Confers rigidity and ductility (Mucopeptide).
• Role in division of bacteria.
• Offers resistance to harmful effect of environment.
Cytoplasmic Membrane
It is thin semipermeable membrane which lies just beneath the cell wall.
It is 5-10 nm in width. Electron microscope shows the presence of three
layers constituting a unit membrane structure.
Function: it controls inflow and outflow of metabolites to and from
protoplast.

13. Cytoplasm
The bacterial cytoplasm is suspension of organic and inorganic
solutes in viscous watery solution. Bacterial cell is of prokaryotic type
(doesn’t have real nucleus).
Ribosome
These are ribonucleoprotein granules, they are a sites of protein
synthesis.
Mesosome
They are vesicular structure form as invagination of plasma
membrane into the cytoplasm, they are the sites of respiratory
enzyme.

14. Flagella
locomotion. Each flagellum is originated in the spherical body
(basal granule) located just inside cell wall. They are composed of
protein called flagellin.
Function of flagella: is bacterial motility.
Types of flagella: flagella may be arranged on bacterial body in
following manner

15. Fimbriae (pilli):
They are filamentous short thin straight hair like appendage.
Function:
1. Organ of adhesive.
2. Conjugation tube thought which genetic material is transferred from donor
to recipient cell.
Spores
They are highly resistant dormant state of bacteria found in certain genera
(example: Bacillus sp. & Clostridium sp.).
The spores are characterized of 5% to 20% dipecolinic acid which is not found in
vegetative cell and by their high calcium content.
Function: the spore make survival of bacteria possible under unfavorable
condition like dry state. spores are resistant to heat, drying, freezing and toxic
chemicals.

17. Formation of spore:

18. Types of spore: