1. The Microbial World and You
Chapter 1
The Microbial World and You
Lectures prepared by Christine L. Case
© 2013 Pearson Education, Inc. 1

3. Microbes in Our Lives
Microorganisms are organisms that are too small to be seen with the unaided eye
Have to use microscopes to see them
Germ refers to a rapidly growing cell

4. Microbes in Our Lives Decompose organic waste
The food chain for the oceans, lakes and rivers.
Photosynthetic
Produce industrial chemicals such as ethanol and acetone
Aid in digestion of food and vitamin synthesis
Produce fermented foods such as pickles, soy sauce, vinegar, cheese, and bread
Produce products used in manufacturing (e.g., cellulase) and disease treatment (e.g., insulin)

5. Designer Jeans: Made by Microbes?
Stone-washing: Trichoderma
Indigo: E. coli

6. Microbes in Our Lives Knowledge of microorganisms allows humans to
Prevent food spoilage
Prevent disease occurrence
Led to aseptic techniques to prevent contamination in medicine and in microbiology laboratories

7. Naming and Classifying Microorganisms
Carolus Linnaeus established the system of scientific nomenclature
Each organism has two names: the genus and species
Genus is ALWAYS capitalized.
species is ALWAYS lower case.
Both words have to either be in ITALICS or UNDERLINED.
Examples:
Staphylococcus aureus, S. aureus
Streptococcus pyogenes, S. pyogenes

8. Scientific Names Which is a correct scientific name? a. Baker’s yeast
b. Saccharomyces cerevisiae
c. Saccharomyces cerevisiae 8

9. Types of Microorganisms
Bacteria
Archaea
Fungi
Protozoa
Algae
Viruses
Helminths

10. Figure 1.1 Types of microorganisms.
Sporangia
Bacteria
Prey
Pseudopods
HIVs
CD4+ T cell

11. Bacteria Prokaryotes- no nucleus Peptidoglycan cell walls
Binary fission- 1 parent cell  2 daughter cells
For energy, use organic chemicals, inorganic chemicals, or photosynthesis

12. Figure 1.1a Types of microorganisms.
Bacteria
(a) The rod-shaped bacterium Haemophilus influenzae, one of the bacterial causes of pneumonia.

13. Archaea Prokaryotic Lack peptidoglycan in cell walls
Live in extreme environments
Include:
Methanogens
Extreme halophiles
Extreme thermophiles

14. Figure 4.5b Star-shaped and rectangular prokaryotes.
Rectangular bacteria
© 2013 Pearson Education, Inc.

15. Fungi Eukaryotes Chitin cell walls Use organic chemicals for energy
Types:
Molds and mushrooms are multicellular, which are composed of filaments called hyphae
Yeasts are unicellular

16. (b) Mucor, a common bread mold, is a type of fungus.
Figure 1.1b Types of microorganisms.
Sporangia
(b) Mucor, a common bread mold, is a type of fungus.
© 2013 Pearson Education, Inc.

17. Protozoa Eukaryotes- has nucleus Absorb or ingest organic chemicals
May be motile via pseudopods, cilia, or flagella

18. (c) An ameba, a protozoan, approaching a food particle.
Figure 1.1c Types of microorganisms.
Prey
Pseudopods
(c) An ameba, a protozoan, approaching a food particle.
© 2013 Pearson Education, Inc.

19. Algae Eukaryotes Cellulose cell walls Use photosynthesis for energy
Produce molecular oxygen and organic compounds

20. (d) The pond alga Volvox.
Figure 1.1d Types of microorganisms.
(d) The pond alga Volvox.
© 2013 Pearson Education, Inc.

21. Viruses Acellular- tiny particles Consist of DNA or RNA core
Core is surrounded by a protein coat
Coat may be enclosed in a lipid envelope
Are replicated only when they are in a living host cell

22. Figure 1.1e Types of microorganisms.
CD4+ T cell
HIVs
(e) Several human immunodeficiency viruses (HIVs), the causative agent of AIDS, budding from a CD4+ T cell.
© 2013 Pearson Education, Inc.

23. Helminths Eukaryotes Multicellular animals
Parasitic flatworms and roundworms
Microscopic stages in life cycles

24. Rod of Asclepius, symbol of the medical profession.
Figure 1.6 Parasitology: the study of protozoa and parasitic worms.
Rod of Asclepius, symbol of the medical profession.
A parasitic guinea worm (Dracunculus medinensis)
is removed from the subcutaneous tissue of a patient
by winding it onto a stick. This procedure may have
been used for the design of the symbol in part (a).

25. Classification of Microorganisms
Three domains
Bacteria
Archaea
Eukarya
Protists
Fungi
Plants
Animals

26. Figure 10.1 The Three-Domain System.
Eukarya
Origin of mitochondria
Fungi
Animals
Bacteria
Origin of chloroplasts
Amebae
Mitochondria
Slime molds
Archaea
Cyanobacteria
Plants
Ciliates
Extreme
halophiles
Proteobacteria
Green
algae
Chloroplasts
Methanogens
Dinoflagellates
Diatoms
Hyperthermophiles
Gram-positive
bacteria
Euglenozoa
Giardia
Thermotoga
Horizontal gene transfer
occurred within the
community of early cells.
Mitochondrion degenerates
Nucleoplasm grows larger

27. A Brief History of Microbiology
Ancestors of bacteria were the first life on Earth
The first microbes were observed in 1673

28. The First Observations
1665: Robert Hooke reported that living things are composed of little boxes, or cells
1673–1723: Anton van Leeuwenhoek described live microorganisms
1858: Rudolf Virchow said cells arise from preexisting cells
Cell theory: All living things are composed of cells and come from preexisting cells

29. Microscope replica Lens Location of specimen on pin
Figure 1.2b Anton van Leeuwenhoek’s microscopic observations.
Lens
Location of specimen
on pin
Specimen-positioning
screw
Focusing control
Stage-positioning screw
Microscope replica

30. The Debate over Spontaneous Generation
Spontaneous generation: the hypothesis that living organisms arise from nonliving matter; a “vital force” forms life
Biogenesis: the hypothesis that living organisms arise from preexisting life

31. Evidence Pro and Con
1668: Francesco Redi filled 6 jars with decaying meat
Conditions
Results
Three jars covered with fine net
No maggots
Three open jars
Maggots appeared
From where did the maggots come?
What was the purpose of the sealed jars?
Spontaneous generation or biogenesis?

32. Evidence Pro and Con
1745: John Needham put boiled nutrient broth into covered flasks
Conditions
Results
Nutrient broth heated, then placed in sealed flask
Microbial growth
From where did the microbes come?
Spontaneous generation or biogenesis?

33. Evidence Pro and Con
1765: Lazzaro Spallanzani boiled nutrient solutions in flasks
Conditions
Results
Nutrient broth placed in flask, heated, then sealed
No microbial growth
Spontaneous generation or biogenesis?

34. Evidence Pro and Con
1861: Louis Pasteur demonstrated that microorganisms are present in the air
Conditions
Results
Nutrient broth placed in flask, heated, NOT sealed
Microbial growth
Nutrient broth placed in flask, heated, then sealed
No microbial growth
Spontaneous generation or biogenesis?

35. Figure 1.3 Disproving the Theory of Spontaneous Generation.
Pasteur first poured
beef broth into a
long-necked flask.
Next he heated the neck
of the flask and bent it
into an S-shape; then he
boiled the broth for
several minutes.
Microorganisms did not
appear in the cooled solution,
even after long periods.
Bend prevented microbes
from entering the flask.
Microorganisms were
present in the broth.
Microorganisms were not present in the broth after boiling.
Microorganisms were
not present even after
long periods.

36. The Golden Age of Microbiology
1857–1914
Beginning with Pasteur’s work, discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs

37. Fermentation and Pasteurization
Pasteur showed that microbes are responsible for fermentation
Fermentation is the conversion of sugar to alcohol to make beer and wine
Pasteur showed microbial growth is also responsible for spoilage of food
Pasteur demonstrated that spoilage bacteria could be killed by heat
Pasteurization is the application of a high heat for a short time

39. The Germ Theory of Disease
1840s: Ignaz Semmelweis advocated handwashing to prevent transmission of puerperal fever from one obstetrical patient to another
1860s: Applying Pasteur’s work showing microbes are in the air, can spoil food, and cause animal diseases, Joseph Lister used a chemical disinfectant to prevent surgical wound infections
1876: Robert Koch proved that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, to prove that a specific microbe causes a specific disease

41. Koch’s Postulates Take a specimen from a sick person.
Grow it out on media.
Inoculate a healthy person with the specimen from the media.
When person demonstrates disease symptoms, take a specimen from him/her and grow it on media.

43. Vaccination
1796: Edward Jenner inoculated a person with cowpox virus, who was then protected from smallpox
Vaccination is derived from vacca, for cow
Immunity- protection given from a vaccine
First time a living virus was use to produce immunity

44. The Birth of Modern Chemotherapy
Chemotherapy- treatment of a disease with chemicals
Types:
Synthetic Drugs- prepared from chemicals in a lab
Antibiotics- chemicals produced by bacteria and fungi that inhibit or kill other microbes

45. The First Synthetic Drugs
Paul Ehrlich- speculated about a “magic bullet” that could destroy a pathogen without harming the host
1910: Ehrlich developed a synthetic arsenic drug, salvarsan, to treat syphilis
1930s: Sulfonamides(made from dyes) were synthesized

46. A Fortunate Accident—Antibiotics
1928: Alexander Fleming discovered the first antibiotic
Fleming observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus
1940s: Penicillin was tested clinically and mass produced

47. Modern Developments in Microbiology
Bacteriology- study of bacteria
Mycology- study of fungi
Virology- study of viruses
Parasitology- study of protozoa and parasitic worms (helminths)
Immunology- study of immunity

48. Recombinant DNA Technology
Microbial genetics: the study of how microbes inherit traits
Molecular biology: the study of how DNA directs protein synthesis
Genomics: the study of an organism’s genes; has provided new tools for classifying microorganisms
Recombinant DNA: DNA made from two different sources
In the 1960s, Paul Berg inserted animal DNA into bacterial DNA, and the bacteria produced an animal protein

49. Biotechnology
Recombinant DNA technology, a new technique for biotechnology, enables bacteria and fungi to produce a variety of proteins, including vaccines and enzymes
Missing or defective genes in human cells can be replaced in gene therapy
Genetically modified bacteria are used to protect crops from insects and from freezing

50. Microbial Ecology
Studies the relationship between bacteria and plants/animals
Bacteria recycle carbon, nutrients, sulfur, and phosphorus that can be used by plants and animals

51. Bioremediation Bacteria degrade organic matter in sewage
Bacteria degrade or detoxify pollutants such as oil and mercury

52. Solid municipal wastes being turned by a specially designed machine
Figure Composting municipal wastes.
Solid municipal wastes being turned by a specially designed machine

53. Biological Insecticides
Microbes that are pathogenic to insects are alternatives to chemical pesticides in preventing insect damage to agricultural crops and disease transmission
Bacillus thuringiensis- fatal in many insects but harmless to other animals, including humans, and to plants

54. Biotechnology
Biotechnology, the use of microbes to produce foods and chemicals, is centuries old

55. Figure 28.8 Making cheddar cheese.
The milk has been coagulated by the action of rennin (forming curd) and is inoculated with ripening bacteria for flavor and acidity. Here the workers are cutting the curd into slabs.
The curd is chopped into small cubes to facilitate efficient draining of whey.
The curd is milled to allow even more drainage of whey and is compressed into blocks for extended ripening. The longer the ripening, the more acidic (sharper) the cheese.

56. Normal Microbiota
Bacteria were once classified as plants, giving rise to use of the term flora for microbes
This term has been replaced by microbiota
Microbes normally present in and on the human body are called normal microbiota

57. Figure 1.7 Several types of bacteria found as part of the normal microbiota on the surface of the human tongue.
© 2013 Pearson Education, Inc.

58. Normal Microbiota Prevent growth of pathogens
Produce growth factors, such as folic acid and vitamin K
Resistance is the ability of the body to ward off disease
Resistance factors include skin, stomach acid, and antimicrobial chemicals

59. Biofilms Microbes attach to solid surfaces and grow into masses
They will grow on rocks, pipes, teeth, and medical implants

60. Figure 1.8 Biofilm on a catheter.
Staphylococcus

61. Infectious Diseases
When a pathogen overcomes the host’s resistance, disease results
“ It is time to close the book on infectious diseases, the war against pestilence is over.”- Luther Terry, Surgeon General of the US
“ Infectious diseases a rising peril; Death rates in US up 58% since 1980.”- David Satcher, 1999 Surgeon General of the US
Emerging infectious diseases (EIDs): new diseases and diseases increasing in incidence

62. What changed since the 1960s?
Organisms have changed or adapted.
People are living longer.
Population is more mobile.
Emerging diseases and Reemerging diseases.

63. H1N1 influenza
Swine flu
Seen in the US for the first time in April 2009

64. Avian Influenza A Influenza A virus Primarily in waterfowl and poultry
Sustained human-to-human transmission has not occurred yet

65. MRSA Methicillin-resistant Staphylococcus aureus
1950s: Penicillin resistance developed
1980s: Methicillin resistance
1990s: MRSA resistance to vancomycin reported
VRSA: vancomycin-resistant S. aureus

66. West Nile Encephalitis
Caused by West Nile virus
First diagnosed in the West Nile region of Uganda in 1937
Appeared in New York City in 1999
In nonmigratory birds in 47 states
September cases in MS

67. Bovine Spongiform Encephalopathy
Caused by a prion
Also causes Creutzfeldt-Jakob disease (CJD)
New variant CJD in humans is related to cattle that have been fed sheep offal for protein

68. Escherichia coli O157:H7 Toxin-producing strain of E. coli
First seen in 1982
Leading cause of diarrhea worldwide

69. Cryptosporidiosis Cryptosporidium protozoa First reported in 1976
Causes 30% of diarrheal illness in developing countries
In the United States, transmitted via water

70. Acquired immunodeficiency syndrome (AIDS)
Caused by human immunodeficiency virus (HIV)
First identified in 1981
Worldwide epidemic infecting 33 million people; 7500 new infections every day
Sexually transmitted infection affecting males and females
HIV/AIDS in the United States: 26% are female, and 49% are African American