This document provides information on bacterial morphology and classification. It describes the key structures of bacterial cells including the cell wall, cell membrane, flagella, pili, and endospores. It outlines the differences between gram-positive and gram-negative bacteria cell walls. Classification systems are discussed ranging from the early two kingdom system to the current three domain system. The document contrasts characteristics of prokaryotic and eukaryotic cells.
2. Introduction :
Medical Microbiology – Branch of medicine that deals with the study of
Microorganisms and their role in human health and diseases (Diagnosis, treatment and
Prevention).
Branches – General Microbiology
Immunology
Bacteriology
Virology
Mycology
Prasitology.
3. Important Pioneers
1. Louis Pasteur:
Father of Modern Microbiology
Proposed principles of Fermentation
Introduced sterilization techniques
Described- Pasteurization of milk
Vaccine development – Anthrax, Fowl Cholera, and Rabies.
Postulated – Germ Theory of disease.
Identified silk worm disease
4. 2. Robert Koch:
Introduced Solid Media
Introduced methods for isolation of bacteria.
Discovered Anthrax bacilli, Tubercule bacilli,
and cholera bacilli.
Koch Posulate:
Four criteria to identify the causative agent of a particular disease, these
include:
1. The microorganism or other pathogen must be present in all cases of the
disease
2. The pathogen can be isolated from the diseased host and grown in pure
culture
3. The pathogen from the pure culture must cause the disease when inoculated
into a healthy, susceptible laboratory animal
4. The pathogen must be reisolated from the new host and shown to be the
same as the originally inoculated pathogen.
5. Classification : hierarchy based arrangement of bacteria into
taxonomic groups or taxa.
On the basis of similarities or differences in their biochemical,
physiological, genetic and morphological properties.
Nomenclature: Naming of the taxa according to characters in
International rules.
Kingdom: Phylum- Proteobacteria
Class –Gamma proteobacteria (-ia)
Subclass-(idae)
Order-Enterobacteriales(ales)
Suborder-(ineae)
Family-Enterobacteriaceae(aceae)
Subfamily-(oideae)
Tribe-Escherichieae (eae)
Genus- Escherichia
Species- E.coli
6. Classification :
1. Two Kingdom: Plantae and Animalia.
2. Three Kingdom: Protisa, Plantae and Animalia.
3. Two Empires : Prokaryota , and Eukaryota.
4. Four Kingdom: Monera, Protista, Plantae and Animalia.
5. Five Kingdom : Monera, Protista, Plantae, Animalia and Fungi.
6. 3 domains: Bacteria, Archea& Eucarya
7. 6 kingdom: Bacteria, Protozoa, Chromista, Plantae, Fungi & Animalia
BACTERIA
ARCHAE
PROKARYOTES Eukaryotes.
Eg. Higher plants
and animals.
7. Difference between Prokaryotes and Eukaryotes
Prokaryotes
• Do not have membrane
bound nucleus.
• Pro- Primitive nucleus.
• Ex: Bacteria, Blue green
algae.
Eukaryotes
• Membrane bound
organelles.
• Eu- True nucleus.
• Ex: Plant and Animal Cell,
Protozoa, Fungi, Other
Algae.
8. ARCHEA EUBACTERIA
Live in Extreme
conditions .
Pseudomurein
No muramic acid
Seen in
enivironments.
True bacteria
Human pathogens
Muramic acid
Human pathogens
16. Functions- Cell Wall
Protection to the cell- Osmotic Lysis
Gives rigidity and shape of the cell
Cell division
Protect from toxin, Heavy metals, Antibiotics, etc.
Contain Virulence factors – Pathogenicity
17. Cell Membrane
Also called as Plasma membrane
Essential for survival of bacteria.
Composed of Bilayered Phospholipids and several proteins (Integeral and
peripheral proteins).
Functions:
Semipermeable membrane
Transport systems- Proteins and enzymes involved in uptake of nutrients and
waste excretion.
Oxidative phosphorylation occurs at cell membrane (since there are no
mitochondria).
18. Cell Wall Appendages
1. Capsule and slime layer :
Present outside of the cell wall
Well organised- Capsule
Un organised- Slime Layer
Mostly Polysaccharide.
Function:
Protects from phagocytosis
Prevent from cell drying out
Protects from Lysozyme
Biofilm formation and adhesion
19. 2. Flagella
It is thread like appendages, protruding from the cell wall,
Helps in the Motility of bacteria
Measure – 5-20µm in length and 0.01-0.02µm in thickness.
It contain,
Basal part – 4 rings in gram negative ( L,P,S,M). Gram Positive – 2 basal
ring.
Hook – Short, curved flexible segment.
Filament- contain Flagellin
21. Types of Flagella
Monotrichous - the flagellum is located at the end of the cell.
Lopotrichous- flagella appear to have a tuft ("lopho") of hair
("trichous") at one or both ends. Ex. Bartonella bacilliformis
Peritrichous- Flagella are distributed uniformly over the surface of
each bacterial cell. Ex Proteus vulgaris
Amphitrichous- Bacteria have a single flagellum at each pole. Ex.
Spirillum serpens
24. Pilli
Short, fine, hair-like appendages
Thinner than flagella
not involved in motility
Pilli – made up of protein – Pillin
Acts as anttigenic,
Sex pilli helps in gene transfer
Fimbriae
Fimbriae - small, measuring o.5 µm long and 10 nm thickness
Bacteria – more than 1,000 fimbriae
Helps in Adhesion,
26. Bacterial Spore
Dormant cell , formed within the parent cell – Endospores.
Produced when starved (Unfavorable condition)
Resistant to adverse conditions
- high temperatures
- organic solvents
contain calcium dipicolinate
Example : Bacillus and Clostridium
27. • These are characteristically seen with some of
the rods. Mostly gram positive rods.
Seen in some of the rods. Mostly gram positive rods.
Central, Ex: Cl.bifermentans
Subterminal, Ex: Cl. Perfringens
Terminal Oval, Ex: Cl.tertium
Terminal Round, Ex: Cl.tetani
Ex; Bacillus anthracis
Protude outside the body Inside the bacillary body
Central
Swollen sporangium
Terminal
Sub
terminal
28. Mesosomes
Conuoluated or multilaminated membraneous bodies
Formed- invaginations of plasma membrane into cytoplasm
Shape- vesicle, tubules or lamellae.
Site of the respiratory enzymes, responsible of compartmenting of DNA at cell
division and spourlation.
Types: 1. Septal mesosomes, 2. Lateral mesosomes
Intracytoplasmic Inclusion bodies
Storeage site of nutrients
Formed under nutrient deficiency and disappear when the deficient nutrients are
supplied.
Types : 1. Organic inclusion bodies 2. Inorganic inclusion bodies
EX: Glycogen granules and
polyhydroxy butyrate
granules.
EX: sulfur granules,
metachromatic granules
29. Protoplast :
Gram positive cell wall is almost completely destroyed by lysozyme
Cellular contents surrounded by plasma membrane if lysis does not occur.
Wall less cell – protoplast.
Cell wall lacking but still metabolism is carrying out.
Shape : Spherical
Spheroplast:
Gram negative cell wall is not destroyed to some extent when lysozyme applied.
Cellular contents, plasma membrane and remaining outer wall layer – Spheroplast.
Shape : Spherical.
Capable of reverting into parent bacterial form when cell wall inhibitor is removed
frrom culture medium.
30. Branching Bacteria
These are considered to be the higher bacteria,existing in a branching pattern.
Ex. Actinomycetes
Actinomycetes are a specific group as bacteria. Morphologically they
resemble fungi because of their elongated cells that branch into filaments or
hyphae
