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1. 201119946 MOSELANE
T.T

2. THE SCIENCE OF MICROBES

3. What is Microbiology?
Microbes, or microorganisms are minute living
things that are usually unable to be viewed with the
naked eye.
What are some examples of microbes?
Bacteria, fungi, protozoa, algae, viruses are
examples!
Some are pathogenic
Many are beneficial
Dr.T.V.Rao MD 3

4. ………………continues
 Study of different
Microorganisms
 Can be
Bacteria
Viruses
Parasites
Fungus
4

5. HISTORY OF MICROBIOLOGY
5

6. Dutchman anton van leeuwenhoek observed
microorganisms>>”animalcules” suspended in a drop of
pond water in front of a ground hand lens
6

7. History; contd.
 ROBERT HOOKE built simple compound microscope and observed
structure of thin layer of cork>>used the word “CELLS”
 Theory of spontaneous generation: from non-living matter
 Theory of biogenesis: from preexisting living cells
 LOUIS PASTEUR>>Pasteur’ experiment>>boiled nutrient broth in a
flask & curved it in to S-shape>>after cooling>>bacteria trapped in
curve but no organism in flask; dicovered souring in alcohol is due
to fermentation and can be prevented by heating wine at56oC for
30mins…..now called PASTEURISATION>>
7

8. History contd;
 IGNAZ SEMMELWEIS was concerned at high incidence of puerperal
fever and latter instituted hand washing in chlorinated solutions;
ridiculed by colleagues and was dismissed; died of
STREPTOCOCCAL INFECTION
 JOHN SNOW: transmission of cholera due to contamination of the
river Thames….later confirmed by ROBERT KOCH in German
8

9.  Bacteriology is the study of bacteria.
 Mycology is the study of fungi.
 Parasitology is the study of protozoa and
parasitic worms.
 Recent advances in genomics, the study of an
organism’s genes, have provided new tools for
classifying microorganisms.
 Proteomics is looking at the gene products
Definitions
3/10/2014Dr.T.V.Rao MD 9

10. Classification of micro-organisms
 All living organisms are classified into:
Kingdom
Phylum (family)
Genus
Species
 Organisms that can cause disease are many and varied
and include:
Viruses
Bacteria
Fungi
Parasites 3/10/2014Dr.T.V.Rao MD 10

11.  Different:
Diseases
Modes of
transmission
Treatment-e.g.
routinely use
antibiotics don’t
cure vira
lfungalinfections
Relevance of Classification
3/10/2014Dr.T.V.Rao MD 11

12. Microorganisms
Non-cellular organism
Prokaryotes
Eukaryotes
Others Prions Viroid
Fungi
Bacterium
Virus
Dr.T.V.Rao MD 12

13. Prokaryotic cells Eukaryote cells
Small cell (< 5µm) Larger cells (> 10 µm)
Always unicellular Often multicellular
No nucleus or any membrane bound organelles Always have nucleus and membranes bound
organelles.
DNA circular, without proteins DNA is linear and associated with proteins to
form chromatin.
Ribosomes are small 70S Ribosomes are large 80S
No cytoskeleton Always have cytoskeleton
Motility by rigid rotating flagellum made from
flagellin
Motility by flexible waving cilia or flagella
made from tubulins.
Cell division is by binary fission Cell division is by meiosis and mitosis.
Reproduction is always asexual Reproduction is sexual and asexual.
Summary of differences between
prokaryote and eukaryote cells

14. Prokaryotic Cell Structure
• Prokaryotic cells are about 10 times smaller
than eukaryotic cells.
• prokaryotes are very simple cells when
compared with eukaryotic cells,
• Reproduction of prokaryotic cells is by binary
fission, the simple division of one cell into two
cells.

15. Bacteria
 Prokaryotes
 Peptidoglycan cell
walls
 Binary fission
 For energy, use
organic
chemicals, inorganic
chemicals, or
photosynthesisDr.T.V.Rao MD 15

16. Bacterial Cell Wall structure

17. Morphologic arrangements of
bacteria.

18. Capsule stain. The capsule stain is an example of a negative staining technique. The
bacterial cells and the background stain, but the capsules do not. The capsules are
seen as unstained “halos” around the bacterial cells.

19. Binary fission. Note that DNA replication must occur before the actual
splitting (fission) of the parent cell.

20. Pathogenic Prokaryotes
Mycoplasma
Bacteria
Spirochetes
Rickettsia
Chlamydiae
Actinomyces
Dr.T.V.Rao MD 20

21. Viruses
Viruses lack many of the attributes of cells, including the ability
to replicate. Only when it infects a cell does a virus acquire the
key attribute of a living system: reproduction
A viral particle consists of a nucleic acid molecule, either DNA
or RNA, enclosed in a protein coat, or capsid
Viruses are known to infect all cells, including microbial cells.
Host-virus interactions tend to be highly specific
Dr.T.V.Rao MD 21

22. Discovery of Virus
 Iwanovski
 a Russian chemist, 1892
 Tobacco Mosaic Disease
 Beijerinck confirmed
 Walter Reed, USA
 Yellow fever virus
 Ist human virus
Tobacco mosaic disease,
caused by the tobacco
mosaic virus
Dr.T.V.Rao MD 22

23. Viruses
 A virus is not a cell!
 Viruses are replicated only when
they are in a living host cell
 Consist of DNA or RNA core
 Core is surrounded by a protein
coat
 Coat may be enclosed in a lipid
envelope
Dr.T.V.Rao MD 23

24. What are Viruses
 Viruses Dependent on Host cells
for necessary functions and
Multiplication
Intracellular parasites
Contain either DNA or
RNA never both.
Dr.T.V.Rao MD 24

25. Fungi
 Complex, large organisms
 Eukaryotes (as are
humans!)
 Divided into yeasts &
moulds
 Cause a range of diseases
e.g.:
 Thrush
 Athletes foot
 Invasive & allergic
aspergillosis
 Many diseases are
opportunistic.
3/10/2014Dr.T.V.Rao MD 25

26. Protozoa
Eukaryotes
Absorb or ingest
organic chemicals
May be motile via
pseudopods, cilia,
or flagella
Figure 1.1c
3/10/2014Dr.T.V.Rao MD 26

27. Multicellular Animal Parasites
 Eukaryote
 Multicellular animals
 Parasitic flatworms and round worms are called Helminths.
 Microscopic stages in life cycles.
Figure 12.28a
3/10/2014Dr.T.V.Rao MD 27

28. Disease-causing microorganisms
are called pathogens.
 Pathogenic microorganisms have
special properties that allow
them to invade the human body or
produce toxins.
 When a microorganism overcomes
the body’s defenses, a state of
disease results.
Diseases and Infections
3/10/2014Dr.T.V.Rao MD 28

29. Pathology, Infection, and Disease
 Pathology is the scientific study of disease.
 Pathology is concerned with the
 etiology (cause),
 pathogenesis (development),
 effects of disease – structural and functional changes
brought about by disease.
 Infection is the invasion and growth of pathogens in the body.
 A host is an organism that shelters and supports the growth of
pathogens.
 Disease is an abnormal state in which part or all of the body is
not properly adjusted or is incapable of performing normal
functions.
 Infection disease – presence of particular microorganism in part
of the body where is not usually found. 3/10/2014Dr.T.V.Rao MD 29

30. Classifying Infectious Diseases
 Communicable diseases are transmitted directly
or indirectly from one host to another.
Chicken pox, genital herpes,
A contagious disease is one that is easily
spread from one person to another.
 Noncommunicable diseases are caused by
microorganisms that normally grow outside the
human body and are not transmitted from one host
to another
Tetanus, Clostridium tetani
3/10/2014Dr.T.V.Rao MD 30

31.  Recombinant DNA Technology
 Genes in
microbes, plants, and animals
manipulated for practical
applications
 Production of human blood-
clotting factor by E. coli to
aid hemophiliacs
 Gene Therapy
 Inserting a missing gene or
repairing a defective one in
humans by inserting desired
gene into host cells
The Modern Age of Microbiology
3/10/2014Dr.T.V.Rao MD 31

32. Discovery of Antimicrobial Agents
_________
 Alexander Fleming (1881 – 1955), a
Scottish biologist and
pharmacologist, observed
bacterial staphylococci colonies
disappearing on plates
contaminated with mold.
 Fleming extracted the compound
from the mold responsible for
destruction of the bacterial
colonies.
 The product of the mold was
named penicillin, after the
Penicillium mold from which it
was derived.
 Nobel Prize in Physiology of
Medicine in 1945.
Images: Penicillium mold, PHIL #8396; Staphylococcus aureus on
antibiotic test plate, PHIL #2641; Poster attached to a mailbox
offering advice to World War II servicemen, 1944, NIHFrom the Virtual Microbiology Classroom on ScienceProfOnline.com
3/10/2014 Dr.T.V.Rao MD 32

33. The Modern Age of Microbiology
 How Do We Defend Against Disease?
 Serology
The study of blood serum
Von Behring and Kitasato – existence in the blood
of chemicals and cells that fight infection
 Immunology
The study of the body’s defense against specific
pathogens
 Chemotherapy
Fleming discovered penicillin
Domagk discovered sulfa drugs
3/10/2014Dr.T.V.Rao MD 33

34. REFERENCES
 Picture on slide no: 1 taken from
http://www.123rf.com/photo_10012159_background-concept-wordcloud-
illustration-of-microbiology-science--microorganisms.html
 Picture on slide no: 15 taken from;
http://upload.wikimedia.org/wikipedia/commons/thumb/5/5a/Average_prok
aryote_cell-_en.svg/494px-Average_prokaryote_cell-_en.svg.png
 HISTORY OF MICRO ORGANISMS AND PICTURES, DR PRABESH K CHOUDHARY
http://www.authorstream.com/Presentation/prabeshc-1456031-medical-
microbiology-introduction/ 2001

35.  Definition of terms; Dr.T.V.Rao
MD, http://www.authorstream.com/Presentation/doctorrao-1594767-
microbiology-medical-graduates/ , 2014
 Notes on classification and pictures, DR PRABESH K CHOUDHARY
http://www.authorstream.com/Presentation/prabeshc-1456031-medical-
microbiology-introduction/
 Microbes diseases and pictures, R
Saravanan, http://www.authorstream.com/Presentation/rssrmcp-923598-
introduction-of-microbiology-saravanan/ , 2010
 NOTES BACTRIA AND VIRUS and pictures, vidhyakalai
http://www.authorstream.com/Presentation/vidhyakalai-1897393-history-
microbiology-vidyakalaivani/ 2000