Introduction to microbiology

1. Microbial World
Dr Mazhar Qayyum
Department of Zoology

2. What is Microbiology?
• Micro - too small to be seen with the naked eye
• Bio - life
• ology - study of
• Clinical Bacteriology: Bacteria that can cause infection in
human beings

3. Organisms included in the
study of Microbiology
• 1. Bacteria
• 2. Protozoans
• 3. Algae
• 4. Parasites
• 5. Yeasts and Molds
• Fungi
• 6. Viruses
• Bacteriology
• Protozoology
• Phycology
• Parasitology
• Mycology
• Virology
Microorganisms - Microbes - Germs

4. 5 Kingdoms of Living
Organisms
• 1. Animalia
• 2. Plantae
• 3. Fungi
• 4. Protista
• 5. Monera - Bacteria and Cyanobacteria
• Eukaryotic vs. Prokaryotic

5. 5 Characteristics of Life
• 1. Cells
• 2. Maintain structure by taking up chemicals and energy from
the environment
• 3. Respond to stimuli in the external environment
• 4. Reproduce and pass on their organization to their offspring
• 5. Evolve and adapt to the environment

6. Taxonomic Classification
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• species
• Man
• Animalia
• Chordata
• Mammalia
• Primate
• Hominidae
• Homo
• Homo sapien

7. Binomial System of Taxonomic
Classification
• Use only the Genus and species
• Homo sapien
• Felis domestica
• Escherichia coli
• Genus and species are either underlined or italicized
• Genus is always capitilized
• species is never capitilized

8. Classification System
• 3 Domains 1978 Carl Woese
• 1. Bacteria
• Unicellular prokaryotes with cell wall containing peptidoglycan
• 2. Archaea
• Unicellular prokaryotes with no peptodoglycan in cell wall
• 3. Eukarya
• Protista
• Fungi
• Plantae
• Animalia

9. Bacteria - what comes to mind?
• Diseases
• Infections
• Epidemics
• Food Spoilage
• Only 1% of all known bacteria cause human diseases
• About 4% of all known bacteria cause plant diseases
• 95% of known bacteria are non-pathogens

10. Microbes Benefit Humans
• 1.Bacteria are primary decomposers - recycle nutrients back
into the environment (sewage treatment plants)
• 2. Microbes produce various food products
• cheese, pickles, sauerkraut, green olives
• yogurt, soy sauce, vinegar, bread
• Beer, Wine, Alcohol

11. 3. Microbesare usedto produceAntibiotics
• Penicillin
• Mold
• Penicillium notatum
• 1928 Alexander Fleming

12. 4. Bacteria synthesize chemicals that our
body needs, but cannot synthesize
• Example: E. coli
• B vitamins - for metabolism
• Vitamin K - blood clotting
• Escherichia coli
• Dr. Escherich
• Colon (intestine)

13. 5. Biochemistry and
Metabolism
• Very simple structure
• rapid rate of reproduction
• provides “instant” data

14. 6. Microbial Antagonism
• Our normal microbial flora prevents potential pathogens from
gaining access to our body

15. 7. Insect Pest Control
• Using bacteria to
control the growth of
insects
• Bacillus thuringiensis
• Cotton Bollworms
• bollworms
• corn bollworms

16. 8. Bioremediation
• Using microbes to clean up pollutants and toxic wastes
• Exxon Valdez - 1989
• 2 Genera
• Pseudomonas sp.
• Bacillus sp.

17. 9. Recombinant DNA Technology
Gene Therapy
Genetic Engineering
• Bacteria can be manipulated to produce enzymes and proteins
they normally would not produce
• Insulin
• Human Growth Hormone
• Interferon
• Enzymes

18. 10. Microbes form the basis of
the food chain
• Marine and fresh water microorganisms

19. Microbesdobenefitus,buttheyarealsocapableofcausingmany
diseases
Causative or Etiologic agents Diseases
Streptococcus pneumoniae Pneumonia
Vibrio cholerae Cholera
Helicobacter pylori Gastric Ulcer
Clostridium tetani Tetanus
Clostridium perfrigens Gas Gangrene
Clostridium botulism Botulism
Mycobacterium tuberculosis Tuberculosis
Mycobacterium leprae Leprosy
Brucella abortus Brucellosis
Bordetella pertussis Whooping Cough
Corynebacterium diptheriae Diphtheria
Shigella dysenteriae Dysentery
E. coli (Enteropathogenic) Diarrhea
Salmonella typhi Typhoid fever (enteric fever)
Neisseria gonorrhea Gonorrhea
Bacillus anthracis Anthrax
Treponema pallidium Syphilis
Neisseria meningitides Meningitis
Yersinia pestis Plague

20. Spontaneous Generation
• Theory that life just “spontaneously” developed from non-
living matter
• Example:
• toads, snakes and mice - moist soil
• flies and maggots - manure and decaying flesh

21. Experiments to disprove
Spontaneous Generation
• Francesco Redi 1668
• Rudolph Virchow 1858
• Theory of Biogenesis
• Cells can only arise from preexisting cells
• Louis Pasteur 1861

22. Pasteur designed special “swan-necked flasks”
with a boiled meat infusion
Shape of flask allowed air in (vital force) but trapped
dust particles which may contain microbes

23. Spontaneous Generation
livingorganismscandevelopfromnonlivingor
decomposingmatter

24. Spontaneous Generation
Controversy

25. Spontaneous Generation
Controversy

26. Final blow to theory
of spontaneous generation
• John Tyndall (1820-1893)
demonstrated that dust carries
microorganisms
showed that if dust was absent, nutrient
broths remained sterile, even if directly
exposed to air
also provided evidence for the existence of
 exceptionally heat-resistant forms of
bacteria

27. Germ Theory of Disease
• Hard for people to believe that diseases were caused by tiny
invisible “wee animalcules”
• Diseases, they thought, were caused by:
• demons
• witchcraft
• bad luck
• the wrath of God
• curses
• evil spirits

28. Robert Koch- 1st to prove that
bacteria actually caused diseases
• 1876
• Microbial Etiology of Infectious Disease
• etiology - the cause of a disease
• Established “scientific rules” to show a cause and effect
relationship between a microbe and a disease
• Koch’s Postulates

29. Figure 14.3 - Overview

31. Anton van Leeuwenhoek 1674
- 1st person to actually see living microorganisms
“wee animalcules”

32. Exceptions to Koch’s Postulates
• Microorganisms that are unable to be cultured on artificial
media
• (example: Treponema pallidum)
• 2 or more organism work in synergy to cause a disease.
• Symptoms and diseases can be causes by any one of several
microbes.

33. Exceptions to Koch’s Postulates
• In exclusively human diseases, it is not morally acceptable to
inoculate a deadly pathogen into a “human guinea pig”
• HIV

34. Koch established the Microbial Etiology
of 3 important diseases of his day
• 1. Cholera (fecal-oral disease)
• Vibrio cholerae
• 2. Tuberculosis (pulmonary infection)
• Mycobacterium tuberculosis
• 3. Anthrax (sheep and cattle)
• Bacillus anthracis

35. The Development of Techniques for
Studying Microbial Pathogens
• Koch - 1st to use Agar to solidify culture media
• Koch’s work led to discovery or development of:
– agar
– petri dish
– nutrient broth and nutrient agar
– methods for isolating microorganisms