2-MORPHOLOGY AND DESCRIPTION OF BACTERIA I I.ppt

2-MORPHOLOGY AND DESCRIPTION OF BACTERIA I I.ppt

1. 
HISTORY OF MICROBIOLOGY

MORPHOLOGY OF BACTERIA

DR ARVIND NANERA

MD (MICROBIOLOGY & IMMUNOLOGY )

2. History of Microbiology:
Introduction
Macro-organism & Micro-organism – exist on earth
What does Microbiology deal with?
The science that deals with the study of micro-organisms
and their activities is called Microbiology.
The micro-organisms are studied with reference to their
Form & structure, reproduction, Physiology & metabolism
Identification, distribution in nature, Beneficial &
detrimental effects on humans & animals.

3. 
What are beneficial & harmful effect of M’orgs on
human, animal & plant life ?

Beneficial- some produce organic acids like citric, lactic,
acetic etc

Vitamins, amino acids, enzymes

Wines & alcohols

Antibiotics eg penicillin, streptomycin etc used for
treatment of infectious diseases.

Harmful effects-Disease, death, decay etc…

4. 
Microbiology is the science of living organisms that
are only visible under microscope.
Medical,Industrial,milk,water,soil,air etc

Medical microbiology deals with microbes

that infects humans,

diseases they cause,

their diagnosis,

prevention,&treatment.

Also the response of humans to them.

Disease &death have always held the attention of
human mind.

Ancient people thought because of divine
curse&supernatural forces.Later –environment,faulty
diet.

5. 
Disease &death have always held the attention of
human mind.

Ancient people thought --divine curse &
supernatural forces.

Varo & Columella-
st
centuryB.C-diseases due to
invisible beings an.

Fracastorius of Verona(1546) -proposed contagium
vivum(living germs)

6. Louis Pasteur(1822-1895)

.

7. Scientific development of Microbiology

Louis Pasteur-(1822-1895):Father of Microbiology

-trained chemist of France.

Important contributions in microbiology:

1.Developed methods,tech.. Of bacteriology.

2.Proved conclusively all forms of life arose only from their like &not
de novo.

3.Disproved spontaneous generation theory of microbes.

4.Introduction of sterlisation tech..

developed steam sterlilizer,autoclave,hot air oven

5.Studies on Anthrax

6.Live vaccine

8. J .
LISTER

9. 
Joseph Lister(1827-1912)

Father of Antiseptic Surgery

Professor of Surgery in Glasgow Royal Infirmary.

Introduced antiseptic techniques in surgery(1867)

decrease in mortality, morbidity due to surgical sepsis.

Milestone in surgical practice

Use of carbolic acid.

10. Robert Koch

11. 
Robert koch(1843-1910):

Father of Bacteriology:

German general practitioner.

Contributions:

Perfected bacteriological techniques.

Introduced -solid media (Isolation)

Introduced staining techniques.

Discovered Anthrax bacillus(1876)

Tubercle bacillus(1882),

Cholera vibrios(1883)

12. 
Koch’s Postulates:

According to Koch’s Postulates,

a micro…can be accepted as the causative agent of an
infectious disease only if following conditions are fulfilled.

1)The organism -constantly associated with the lesions of the disease.

2) to isolate the organism in pure culture from the lesion of the disease.

3)The isolated organism - inoculated into suitable lab animals should
produce a similar disease

4) to re-isolate the organism in pure culture from the lesion produced in
experimental animals

5)An additional criteria-Specific antibodies to the bacteria

13. 
Pasteur &Koch attracted many gifted disciples who
discovered the causative agents of several
infections.

Important discoveries by other scientists

Lepra bacillus-- Hansen (1874)

Gonococcus-- Neisser (1881)

Diphtheria-- Klebs (1883), Loeffler (1884)

Peumococcus-- Frankel (1886)

Meningococcus-- Weichselbum (1887)

Diphtheria toxin-- Roux and Yersin (1888)

Tetanus bacillus-- Kitasato (1889)

Plague bacillus-- Yersin (1890)

14. 
Paul Ehrlich(1854-1915):Father of
Chemotheraphy:

German scientist

:Contributions:

Discovered Salvarsan,arsenical compound

(magic bullet) destroyed spirochaetes of syphillis.

Reported acid fast nature of TB bacilli.

Applied stains to cells&tissues to study functions.

15. 
Sir Alexander Fleming

:accidently discovered ..

substance produced by mould Penicillium inhibited a
number of disease producing organisms.

This substance was named Penicillin.

This marked the beginning of antibotic era.

16. 
Virology:
infectious diseases e.g Small pox,Chicken
Pox,Measles,Influenza for which no bacterial
cause could be established.
During studies on Rabies,Pasteur suspected the
causative agent could be too small to be seen
under microscope.

17. 
1
st
human disease -of viral origin

yellow fever-Walter Reed proved that it was
caused by filterable virus&transmitted by mosquito
bite.

Detailed study of viruses-- only with the
introduction

of Electron microscope by Ruska(1934

18. 
Good Pasteur(1930) --techniques of viral cultivation in
chick embryos.

Further Tissue culture.

viruses causing malignancies discovered.

Bacteriophages discovered,.

Edward Jenner

accidentally came to know that the milk maids who
suffered from cowpox were immune to smallpox.

In (1796) introduced the first successful immunisation in
smallpox by related but mild live virus of cowpox.

19. 
Immunology:Von-Behring&Kitasato

produced antibody in guineapigs serum

Bordet:demonstrated 2 components of serum

protective –antibody &complement

Metchnikoff (1883) proposed that phagocytic response
was the prime defence mechanism against microbial
invasion

Opsonin in serum was described by Denys and Leclef
(1895) and Wright douglas (1903).

20. 
In 1955, Jerne proposed the ‘natural selection’ theory of
antibody synthesis.

Burnet (1957) modified this into the clonal selection theory.

In 1967, Burnet proposed the concept of ‘immunological
surveillance’,

Malignancy was visualised as a failure of ‘immunological
surveillance’.

Successful transplants could be made possible by

elective immunosuppression and proper selection of
donors on the basis of histocompatibility.

21. Bacterial cell

22. Cell wall

23. Morphology of bacteria
1.Cytoplasmic membrane:

It is 5-10 um thick elastic semipermeable layer

which lies beneath cell wall seperating it from cytoplasm.

Act as an semipermeable membrane controlling inflow & outflow
of metabolites to & from the protoplasm.

Site of numerous enzymes (permease, oxidase, polymerase)
involved in the active transport of selective nutrients

24. 2.Cytoplasm: Bacterial Cytoplasm is a colloidal
system containing a variety of organic & inorganic
solutes in a viscous watery solution.

Lacks mitochondria & endoplasmic reticulum.

Consists of ribosomes, mesosomes, vacuoles &
inclusions.

25. Ribosomes: these are centres of protein synthesis, composed
of ribosomal RNA (r RNA) & proteins.
ii.Intracytoplasmic Inclusions: sources of stored energy & are
iii. present in some species of bacteria.

They may be present as polymetaphosphate (volutin) lipids,
polysaccharide (starch or glycogen) & granules of sulphur.

Special staining techniques like Alberts or Neisser's demonstrate
them more clearly.
iii. Mesosomes (Chondroids): Are vesicular, multilaminated or c
onvulated structures formed as invaginations of the plasma
membrane into cytoplasm

Principle centres of respiratory enzymes.

26. Nucleus:

No neclear memb or nucleolus. Cannot be seen by ordinary
Microscope (only electron M.s)

DNA does not contain any basic protein.

DNA- is double stranded in form of a circle.

Measures 1mm(1000 um)- straightened.

DNA is haploid-replicates-simple fission.

.


27. 
Some-extranuclear genetic material in cytoplasm
consisting of DNA-plasmids or episomes.

Replicates autonomously. Not essential for life of
bacteria.

Besides being transmitted to daughter cells
during binary fission they can be transmitted from
1 bacteria to another-conjugation, thru'
bacteriophages.

Confers-properties like drug(R) & toxigenicity
thus survival advantage to bacteria.


28. Flagella:
Cytoplasmic appendages protruding thru' cell wall.
Thread like long (3-20 um x0.01 um). Made up of Protein i.e
flagellin. Organs of Locomotion- All motile bacteria (except
spirochaetes) possess 1 or more flagella.

29. 
3 parts: 1.Filament, 2.Hook, 3.Basal body.
Filament lies external to cell. Connected to
hook at cell surface. Hook basal body-embeded
in cell envelope.
Basal body has-outer & inner rings- by which it
is attached to cell membrane.
Outer rings absent in gram positive

31. Number and arrangement characteristic of different bacteria

Perithrichous- flagella arranged all round the cell e.g. Salmonella
typhi.Or Polar i.e situated at 1 or both ends of the cell.Polar flagella
may be either

Amphitrichous-Single flagellum at both the ends e.g. Alcaligenes
faecalis.

Monotrichous- Single polar flagellum (at one end) e.g. Vibrio
cholerae.

Lophotrichous- Tufts of flagella at one or both ends e.g. spirilla.

32. Arrangement of flagella

33. 
Fimbriae or Pili

Some gram negative bacteria carry very fine hair like surface
appendages called fimbriae or pili.They are shorter,thinner than
flagella(0.5um long & less than 10nm thick)& project from cell
surface as straight filaments.


34. 
8 morphologigal types of pili are known
classifiable as either common or sex pili on the
basis of their function. They can be seen only
under electron microscope. They are unrelated
to motility and are found on motile as well as
non motile cells.

35. Functions
1.Adhesion- fimbriae are organs of adhesion. This property
enhances the virulence of bacteria.
2.Transfer of genetic material- Sex pili are present in male
bacteria. These pili are longer (18-20 um) and 1-4 in number. They
help the male cells to attach with non-male (female) cells in
forming “conjugation tubes” through which genetic material is
believed to be transferred from the donor (male) to the recipient
(female) cell.

36. Detection of fimbriae
1. Electron microscopy
2. Haemagglutination- Many fimbriated bacteria
(e.g. E.coli) strongly agglutinate RBCs of guinea
pigs, fowl,horses & pig etc.

37. Capsule: When this secretion is organised into a
sharply defined structure it is known-capsule e.g.
in Streptococcus pneumoniae (pneumococci)

Both slime layer & capsule present in
streptococcus-salivarius.

Klebsiella secretes large amount of slime and
produces mucoid growth on agar.

38. Functions:
1.Capsule enhances bacterial virulence by inhibiting phagocytosis.
2.Acts as a protective covering against antibacterial substances
such as bacteriophages, phagocytes, enzymes.
3.Capsular antigen is specific for bacteria and can be used for
identification & typing of bacteria.

40. Methods for demonstration:
1. India Ink staining (Negative staining)- Capsule appears as a
clear halo around bacterium as the ink cannot penetrate the
capsule .
2. Serological methods- Capsule swelling reaction or Quellung or
Neufeld
3. Special Capsule Staining- Copper salts are used as mordants for
staining capsule.

42. Bacterial Spore
Bacterial Spore: Spores are highly resistant resting stage formed
in unfavorable environmental contitions (depletion of nutrients). e.g.
Bacillus & Clostrium

Sporulation is not method of reproduction.

Each bacterium- 1 spore-germination (favorable conditions)form
single vegetative cell. Endospores (form within parent cell.

43. Morphology of spore: cell membrane grows in
wards & forms spore wall around the core (fore
spore). Inner most layer of spore wall forms spore
membrane from which C.W. Of future veg cell
develops. Outside spore membrane is thick layer
cortex and a multi layered tough spore coat.

Some spores additional loose outer covering
Exosporium

44. 
Sporulation is initiated by the appearance of a clear area,
usually near one end of the cell, which gradually becomes more
opaque to form the forespore

. The fully develop spore has at its core the nuclear body
surrounded by the spore wall, a delicate membrane from which
the cell wall of the future vegetative bacterium will develop.
Outside this is the thick spore cortex which in term is enclosed
by multilayer spore coat. Some spores may have outer covering
called exosporium.

45. 
The fully develop spore has at its core the
nuclear body surrounded by the spore wall, a
delicate membrane from which the cell wall of
the future vegetative bacterium will develop.
Outside this is the thick spore cortex which in
term is enclosed by multilayer spore coat.
Some spores may have outer covering called
exosporium

46. spore

47. Young spores are seen attached to the parent cell. Shape &
position of the spore and its size relative to the parent cell are
species characteristics.
Shape & Position: Bulging/Nonbulging

Terminal, subterminal, central-position

Oval or spherical-shape.
E.g. terminal spherical- Clostridium tetani

48. Resistance: R- boiling, disinfectants, drying. But
most pathogenic spores- autoclaving 121*c-15
min (destroyed)
Demonstration:
1. gram stain-spores seen as unstained refractile
body within cell.
2. Modified ZN stain-(0.25-0.5% sulphuric acid as
decolourizer)-appear pink/red (Acid fast)
Uses- Some spores e.g. B.stearo thermophilus-
indicators for proper sterilization

50. Pleomorphism and involution forms

Some species of bacteria exhibit great variation in the shape &
size of individual cells. This is known as pleomorphism. Certain
species (for example, plague bacillus, gonococcus.
Pleomorphism and involution form are often caused by
defective cell wall synthesis).

L forms-

51. 
Kleineberger-Nobel, studying cultures of
streptobacillus moniliformis, observed swollen
cells and other aberrant morphological forms
and named them L forms, after Lister Institute,
London, where the observation was made. L
forms are seen in several species of bacteria,
developing either spontaneously or in the
presence of penicillin or other agents that
interfere with the cell wall synthesis.

52. 
L forms may be unstable in that the morphological abnormality
is maintained only in the presence of penicillin or other inducing
agents, or stable, when the aberrant form becomes the
permanent feature of the strain and is retained in serial
subcultures. L forms resemble mycoplasma in several ways,
including morphology , type of growth on agar and filterability. It
is possible that mycoplasmas represent stable L forms of as yet
unidentified parent bacteria.