lectures prepared by christine l....

Copyright © 2013 Pearson Education, Inc.Lectures prepared by Christine L. Case

Chapter 1

The Microbial World and You

© 2013 Pearson Education, Inc. Lectures prepared by Christine L. Case

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© 2013 Pearson Education, Inc.

Microbes in Our Lives

� Microorganisms are organisms that are too small to be seen with the unaided eye

� Germ refers to a rapidly growing cell

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� A few are pathogenic (disease-causing) � Decompose organic waste� Are producers in the ecosystem by photosynthesis� Produce industrial chemicals such as ethanol

and acetone� Produce fermented foods such as vinegar, cheese,

and bread� Produce products used in manufacturing

(e.g., cellulase) and disease treatment (e.g., insulin)

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� 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

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Learning Objectives


Naming and Classifying Microorganisms

1-2 Recognize the system of scientific nomenclature that uses two names: a genus and a specific epithet.

1-3 Differentiate the major characteristics of each group of microorganisms.

1-4 List the three domains.

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Naming and Classifying Microorganisms

� Linnaeus established the system of scientific nomenclature

� Each organism has two names: the genus and specific epithet

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Scientific Names

� Are italicized or underlined� The genus is capitalized; the specific epithet is lowercase

� Are “Latinized” and used worldwide� May be descriptive or honor a scientist

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Escherichia coli

� Honors the discoverer, Theodor Escherich� Describes the bacterium’s habitat—the large

intestine, or colon

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Staphylococcus aureus

� Describes the clustered (staphylo-) spherical (cocci) cells

� Describes the gold-colored (aureus) colonies

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Scientific Names

� After the first use, scientific names may be abbreviated with the first letter of the genus and the specific epithet:� Escherichia coli and Staphylococcus aureus are found in

the human body� E. coli is found in the large intestine, and S. aureus is on

skin

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Scientific Names

� Which is a correct scientific name?a. Baker’s yeastb. Saccharomyces cerevisiaec. Saccharomyces cerevisiaed. S. cerevisiae

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Types of Microorganisms

� Bacteria� Archaea� Fungi� Protozoa� Algae� Viruses� Multicellular animal parasites

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Figure 1.1 Types of microorganisms.

BacteriaSporangia

Prey

Pseudopods

CD4+ T cell HIVs

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Bacteria

� Prokaryotes� Peptidoglycan cell walls� Binary fission� For energy, use organic chemicals, inorganic

chemicals, or photosynthesis

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Bacteria

Figure 1.1a Types of microorganisms.

(a) The rod-shaped bacterium Haemophilus influenzae, one of the bacterial causes of pneumonia.

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Archaea

� Prokaryotic� Lack peptidoglycan� Live in extreme environments� Include:

� Methanogens� Extreme halophiles� Extreme thermophiles

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Fungi

� Eukaryotes� Chitin cell walls� Use organic chemicals for energy� Molds and mushrooms are multicellular,

consisting of masses of mycelia, which are composed of filaments called hyphae

� Yeasts are unicellular

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Figure 1.1b Types of microorganisms.

Sporangia


(b) Mucor, a common bread mold, is a type of fungus.

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Protozoa

� Eukaryotes� Absorb or ingest organic chemicals� May be motile via pseudopods, cilia, or flagella

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Prey

Pseudopods


Figure 1.1c Types of microorganisms.

(c) An ameba, a protozoan, approaching a food particle.

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Algae

� Eukaryotes� Cellulose cell walls� Use photosynthesis for energy� Produce molecular oxygen and organic compounds

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Figure 1.1d Types of microorganisms.


(d) The pond alga Volvox.

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Viruses

� Acellular: are not cells, are not living� 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

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Figure 1.1e Types of microorganisms.

CD4+ T cellHIVs


(e) Several human immunodeficiency viruses (HIVs), the causative agent of AIDS, budding from a CD4 + T cell.

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Multicellular Animal Parasites

� Eukaryotes� Multicellular animals� Parasitic flatworms and roundworms are called

helminths� Microscopic stages in life cycles

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Rod of Asclepius, symbol of the medical profession.

A parasitic guinea worm (Dracunculus medinensis) is removed from the subcutaneous tissue of a patien t by winding it onto a stick. This procedure may have been used for the design of the symbol in part (a).

Figure 1.6 Parasitology: the study of protozoa and parasitic worms. 26


Classification of Microorganisms

� Three domains� Bacteria� Archaea� Eukarya

− Protists− Fungi− Plants− Animals

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Figure 10.1 The Three-Domain System.

Bacteria

Mitochondria

Cyanobacteria

Chloroplasts

Thermotoga

Gram-positivebacteria

Proteobacteria

Horizontal gene transferoccurred within thecommunity of early cells.

Nucleoplasm grows larger

Mitochondrion degenerates

Giardia

Euglenozoa

Diatoms

Dinoflagellates

Ciliates

AnimalsFungi

Amebae

Slime molds

Plants

Greenalgae

Eukarya

Extremehalophiles

Methanogens

Hyperthermophiles

Origin of chloroplasts

Origin of mitochondria

Archaea

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A Brief History of Microbiology

� Ancestors of bacteria were the first life on Earth� The first microbes were observed in 1673

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The First Observations

� 1665: Robert Hooke reported that living things are composed of little boxes, or cells

� 1858: Rudolf Virchow said cells arise from preexisting cells

� Cell theory : All living things are composed of cells and come from preexisting cells

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The First Observations

� 1673–1723: Anton van Leeuwenhoek described live microorganisms

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Figure 1.2b Anton van Leeuwenhoek’s microscopic obs ervations.

Microscope replica

LensLocation of specimenon pin

Specimen-positioningscrew

Focusing control

Stage-positioning screw

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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

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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?

Evidence Pro and Con

� 1668: Francesco Redi filled 6 jars with decaying meat

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Conditions Results

Nutrient broth heated, then placed in sealed flask

Microbial growth

From where did the microbes come?Spontaneous generation or biogenesis?


� 1745: John Needham put boiled nutrient broth into covered flasks

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Conditions Results

Nutrient broth placed in flask, heated, then sealed

No microbial growth

Spontaneous generation or biogenesis?


� 1765: Lazzaro Spallanzani boiled nutrient solutions in flasks

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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?


� 1861: Louis Pasteur demonstrated that microorganisms are present in the air

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The Theory of Biogenesis

� Pasteur’s S-shaped flask kept microbes out but let air in� This was a control experiment that allowed the “vital force”

access to the broth

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Figure 1.3 Disproving the Theory of Spontaneous Gen eration.

Pasteur first pouredbeef broth into along-necked flask.

Microorganisms werepresent in the broth.

Next he heated the neckof the flask and bent itinto an S-shape; then heboiled the broth forseveral minutes.

Microorganisms were not present in the broth after boiling.

Microorganisms did notappear in the cooled solution,even after long periods.

Bend prevented microbesfrom entering the flask.

Microorganisms werenot present even afterlong periods.

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The Golden Age of Microbiology

� 1857–1914� Beginning with Pasteur’s work, discoveries included

the relationship between microbes and disease, immunity, and antimicrobial drugs

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Fermentation and Pasteurization

� Pasteur showed that microbes are responsible for fermentation

� Fermentation is the conversion of sugar to alcohol to make beer and wine

� Microbial growth is also responsible for spoilage of food

� Bacteria that use alcohol and produce acetic acid spoil wine by turning it to vinegar (acetic acid)

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Fermentation and Pasteurization

� Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine

� Pasteurization is the application of a high heat for a short time

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The Germ Theory of Disease

� 1835: Agostino Bassi showed that a silkworm disease was caused by a fungus

� 1865: Pasteur believed that another silkworm disease was caused by a protozoan

� 1840s: Ignaz Semmelweis advocated handwashing to prevent transmission of puerperal fever from one obstetrical patient to another

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� 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

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� 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

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Vaccination

� 1796: Edward Jenner inoculated a person with cowpox virus, who was then protected from smallpox

� Vaccination is derived from vacca, for cow� The protection is called immunity

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The Birth of Modern Chemotherapy

� Treatment with chemicals is chemotherapy� Chemotherapeutic agents used to treat infectious

disease can be synthetic drugs or antibiotics� Antibiotics are chemicals produced by bacteria and

fungi that inhibit or kill other microbes

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The First Synthetic Drugs

� Quinine from tree bark was long used to treat malaria

� 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 were synthesized

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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

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Normalbacterialcolony

Area of inhibition of bacterial growth

Penicilliumcolony

Figure 1.5 The discovery of penicillin. 53


Modern Developments in Microbiology

� Bacteriology is the study of bacteria� Mycology is the study of fungi� Virology is the study of viruses� Parasitology is the study of protozoa and parasitic

worms

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Modern Developments in Microbiology

� Immunology is the study of immunity� Vaccines and interferons are being investigated to prevent

and cure viral diseases

� The use of immunology to identify some bacteria according to serotypes was proposed by Rebecca Lancefield in 1933

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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

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Recombinant DNA Technology

� 1941: George Beadle and Edward Tatum showed that genes encode a cell’s enzymes

� 1944: Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that DNA is the hereditary material

� 1961: François Jacob and Jacques Monod discovered the role of mRNA in protein synthesis

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Nobel Prizes for Microbiology Research

� * The first Nobel Prize in Physiology or Medicine1901* von Bering Diphtheria antitoxin1902 Ross Malaria transmission1905 Koch TB bacterium1908 Metchnikoff Phagocytes1945 Fleming, Chain, Florey Penicillin1952 Waksman Streptomycin1969 Delbrück, Hershey, Luria Viral replication1997 Prusiner Prions2005 Marshall & Warren H. pylori & ulcers2008 zur Hausen HPV & cancer2008 Barré-Sinoussi

& Montagnier HIV

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Microbial Ecology

� Bacteria recycle carbon, nutrients, sulfur, and phosphorus that can be used by plants and animals

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Bioremediation

� Bacteria degrade organic matter in sewage� Bacteria degrade or detoxify pollutants such as oil

and mercury

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Figure 27.10 Composting municipal wastes.

Solid municipal wastes being turned by a specially designed machine

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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 infections are fatal in many insects but harmless to other animals, including humans, and to plants

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Insert Fig 11.15a

(a) Bacillus thuringiensis. The diamond-shaped crystals shown next to the endospore are toxic to insects th at ingest them. This electron micrograph was made using the technique of shadow casting described on page 62.

Figure 11.15a Bacillus. 64


Biotechnology

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

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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.

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Applications of Microbiology, unnumbered figure, pa ge 808.

Xanthan

Xanthomonas campestris producing gooey xanthan.


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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

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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

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Figure 1.7 Several types of bacteria found as part of the normal microbiota on the surface of the huma n tongue.


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Normal Microbiota

� Normal microbiota prevent growth of pathogens� Normal microbiota 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

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Biofilms

� Microbes attach to solid surfaces and grow into masses

� They will grow on rocks, pipes, teeth, and medical implants

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Figure 1.8 Biofilm on a catheter.

Staphylococcus

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Infectious Diseases

� When a pathogen overcomes the host’s resistance, disease results

� Emerging infectious diseases (EIDs) : new diseases and diseases increasing in incidence

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Avian Influenza A

� Influenza A virus� Primarily in waterfowl and poultry� Sustained human-to-human transmission has not

occurred yet

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Figure 13.3b Morphology of an enveloped helical vir us. 76


MRSA

� Methicillin-resistant Staphylococcus aureus� 1950s: Penicillin resistance developed� 1980s: Methicillin resistance� 1990s: MRSA resistance to vancomycin reported

� VISA: vancomycin-intermediate-resistant S. aureus� VRSA: vancomycin-resistant S. aureus

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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

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Disease in Focus 22.2 Types of Arboviral Encephalit is, unnumbered figure.

Culex mosquito engorged with human blood.

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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

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Insert Fig 22.18b

Figure 22.18b Spongiform encephalopathies.

Holes

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Escherichia coli O157:H7

� Toxin-producing strain of E. coli� First seen in 1982� Leading cause of diarrhea worldwide

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Ebola Hemorrhagic Fever

� Ebola virus� Causes fever, hemorrhaging, and blood clotting� First identified near Ebola River, Congo� Outbreaks every few years

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Figure 23.22 Ebola hemorrhagic virus. 84


Cryptosporidiosis

� Cryptosporidium protozoa� First reported in 1976� Causes 30% of diarrheal illness in developing

countries� In the United States, transmitted via water

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Figure 25.18 Cryptosporidiosis.

Intestinal mucosa

Oocyst

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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

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