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SOLUTION MANUAL

CHAPTER

The Microbial World and You Global Edition

Learning Objectives

Check Your Understanding

1-1 List several ways in which microbes affect our lives.

Describe some of the destructive and beneficial actions of microbes.

1-2 Define microbiome, normal microbiota, and transient microbiota.

What percentage of all cells in the human body are bacterial cells?

1-3 Recognize the system of scientific nomenclature that uses two names: a genus and a specific epithet.

Distinguish a genus from a specific epithet.

1-4 Differentiate the major characteristics of each group of microorganisms.

Which groups of microbes are prokaryotes? Which are eukaryotes?

1-5 List the three domains.

What are the three domains?

1-6 Explain the importance of observations made by Hooke and van Leeuwenhoek.

What is the cell theory?

1-7 Compare spontaneous generation and biogenesis.

What evidence supported spontaneous generation?

1-8 Identify the contributions to microbiology made by Needham, Spallanzani, Virchow, and Pasteur.

How was spontaneous generation disproved?

1-9 Explain how Pasteur’s work influenced Lister and Koch.

Summarize in your own words the germ theory of disease.

1-10 Identify the importance of Koch’s postulates.

What is the importance of Koch’s postulates?

1-11 Identify the importance of Jenner’s work.

What is the significance of Jenner’s discovery?

1-12 Identify the contributions to microbiology made by Ehrlich and Fleming.

What was Ehrlich’s “magic bullet”?

1-13 Define bacteriology, mycology, parasitology, immunology, and virology.

Define bacteriology, mycology, parasitology, immunology, and virology.

1-14 Explain the importance of microbial genetics, molecular biology, and genomics.

Differentiate microbial genetics, molecular biology, and genomics.

1-15 List at least four beneficial activities of microorganisms.

Name two beneficial uses of bacteria.

1-16 Name two examples of biotechnology that use recombinant DNA technology and two examples that do not.

Differentiate biotechnology from recombinant DNA technology.

1-17 Define resistance.

Differentiate normal microbiota and infectious disease.

1-18 Define biofilm.

Why are biofilms important?

1-19 Define emerging infectious disease.

What factors contribute to the emergence of an infectious disease?

New in This Edition  The resurgence in microbiology is highlighted in sections on the Second and Third Golden Ages of Microbiology.  The Emerging Infectious Diseases section has been updated.  A discussion of normal microbiota and the human microbiome has been added.

Chapter Summary Microbes in Our Lives (p. 28) The Microbiome (pp. 28–29) ASM 5.4: Microorganisms, cellular and viral, can interact with both human and nonhuman hosts in beneficial, neutral, or detrimental ways. ASM 6.2: Microorganisms provide essential models that give us fundamental knowledge about life processes. 1. Living things too small to be seen with the unaided eye are called microorganisms. 2. Microorganisms are important in maintaining Earth’s ecological balance. 3. Everyone has microorganisms in and on the body; these make up the normal microbiota or human microbiome. The normal microbiota are needed to maintain good health. 4. Some microorganisms are used to produce foods and chemicals. 5. Some microorganisms cause disease.

Naming and Classifying Microorganisms (pp. 30–32) ASM 2.4: While microscopic eukaryotes (e.g., fungi, protozoa, and algae) carry out some of the same processes as bacteria, many of the cellular properties are fundamentally different. Nomenclature (p. 30)

INSTRUCTOR'S GUIDE FOR MICROBIOLOGY: AN INTRODUCTION, GE, 13e

1. In a nomenclature system designed by Carolus Linnaeus (1735), each living organism is assigned two names. 2. The two names consist of a genus and a specific epithet, both of which are underlined or italicized.

Types of Microorganisms (pp. 30–32) 3. Bacteria are unicellular organisms. Because they have no nucleus, the cells are described as prokaryotic. 4. Most bacteria have a peptidoglycan cell wall; they divide by binary fission, and they may possess flagella. 5. Bacteria can use a wide range of chemical substances for their nutrition. 6. Archaea consist of prokaryotic cells; they lack peptidoglycan in their cell walls. 7. Archaea include methanogens, extreme halophiles, and extreme thermophiles. 8. Fungi (mushrooms, molds, and yeasts) have eukaryotic cells (cells with a true nucleus). Most fungi are multicellular. 9. Fungi obtain nutrients by absorbing organic material from their environment. 10. Protozoa are unicellular eukaryotes. 11. Protozoa obtain nourishment by absorption or ingestion through specialized structures. 12. Algae are unicellular or multicellular eukaryotes that obtain nourishment by photosynthesis. 13. Algae produce oxygen and carbohydrates that are used by other organisms. 14. Viruses are noncellular entities that are parasites of cells. 15. Viruses consist of a nucleic acid core (DNA or RNA) surrounded by a protein coat. An envelope may surround the coat. 16. The principal groups of multicellular animal parasites are flatworms and roundworms, collectively called helminths. 17. The microscopic stages in the life cycle of helminths are identified by traditional microbiological procedures.

Classification of Microorganisms (p. 32) 18. All organisms are classified into one of three domains: Bacteria, Archaea, and Eukarya. Eukarya include protists, fungi, plants, and animals.

A Brief History of Microbiology (pp. 32–40) ASM 7.4: Ability to understand the relationship between science and society The First Observations (pp. 32–33) 1. Hooke’s observations laid the groundwork for development of the cell theory, the concept that all living things are composed of cells. 2. Anton van Leeuwenhoek, using a simple microscope, was the first to observe microorganisms (1673). Copy right © 2021 Pearson Education Ltd.

CHAP TER 1 The Microbial World and You

The Debate over Spontaneous Generation (pp. 33–35) 3. Until the mid-1880s, many people believed in spontaneous generation, the idea that living organisms could arise from nonliving matter. 4. Francesco Redi demonstrated that maggots appear on decaying meat only when flies are able to lay eggs on the meat (1668). 5. John Needham claimed that microorganisms could arise spontaneously from heated nutrient broth (1745). 6. Lazzaro Spallanzani repeated Needham’s experiments and suggested that Needham’s results were due to microorganisms in the air entering his broth (1765). 7. Rudolf Virchow introduced the concept of biogenesis: living cells can arise only from preexisting cells (1858). 8. Louis Pasteur demonstrated that microorganisms are in the air everywhere and offered proof of biogenesis (1861). 9. Pasteur’s discoveries led to the development of aseptic techniques used in laboratory and medical procedures to prevent contamination by microorganisms.

The First Golden Age of Microbiology (pp. 35–37) 10. The science of microbiology advanced rapidly between 1857 and 1914. 11. Pasteur found that yeast ferment sugars to alcohol and that bacteria can oxidize the alcohol to acetic acid. 12. A heating process called pasteurization is used to kill bacteria in some alcoholic beverages and milk. 13. Agostino Bassi (1835) and Pasteur (1865) showed a causal relationship between microorganisms and disease. 14. Joseph Lister introduced the use of a disinfectant to clean surgical wounds in order to control infections in humans (1860s). 15. Robert Koch proved that microorganisms cause disease. He used a sequence of procedures, now called Koch’s postulates (1876), that are used today to prove that a particular microorganism causes a particular disease. 16. In 1798, Edward Jenner demonstrated that inoculation with cowpox material provides humans with immunity to smallpox. 17. About 1880, Pasteur discovered that avirulent bacteria could be used as a vaccine for fowl cholera; he coined the word vaccine. 18. Modern vaccines are prepared from living avirulent microorganisms or killed pathogens, from isolated components of pathogens, and by recombinant DNA techniques.

The Second Golden Age of Microbiology (pp. 37–40) 19. The Second Golden Age began with the discovery of penicillin’s effectiveness against infections. 20. Two types of chemotherapeutic agents are synthetic drugs (chemically prepared in the laboratory) and antibiotics (substances produced naturally by bacteria and fungi to inhibit the growth of other microorganisms). 4

INSTRUCTOR'S GUIDE FOR MICROBIOLOGY: AN INTRODUCTION, GE, 13e

21. Paul Ehrlich introduced an arsenic-containing chemical called salvarsan to treat syphilis (1910). 22. Alexander Fleming observed that the Penicillium fungus inhibited the growth of a bacterial culture. He named the active ingredient penicillin (1928). 23. Researchers are tackling the problem of drug-resistant microbes. 24. Bacteriology is the study of bacteria, mycology is the study of fungi, and parasitology is the study of parasitic protozoa and worms. 25. The study of AIDS and analysis of the action of interferons are among the current research interests in immunology. 26. New techniques in molecular biology and electron microscopy have provided tools for advancing our knowledge of virology. 27. The development of recombinant DNA technology has helped advance all areas of microbiology.

The Third Golden Age of Microbiology (p. 40) 28. Microbiologists are using genomics, the study of all of an organism’s genes, to study microbiomes in different environments.

Microbes and Human Welfare (pp. 40–42) ASM 4.5: Cell genomes can be manipulated to alter cell function. ASM 6.1: Microbes are essential for life as we know it and the processes that support life (e.g., in biogeochemical cycles and plant and/or animal microflora). ASM 6.2: Microorganisms provide essential models that give us fundamental knowledge about life processes. ASM 6.3: Humans utilize and harness microorganisms and their products. 1. Microorganisms degrade dead plants and animals and recycle chemical elements to be used by living plants and animals. 2. Bacteria are used to decompose organic matter in sewage. 3. Bioremediation processes use bacteria to clean up toxic wastes. 4. Bacteria that cause diseases in insects are being used as biological controls of insect pests. Biological controls are specific for the pest and do not harm the environment. 5. Using microbes to make products such as foods and chemicals is called biotechnology. 6. Using recombinant DNA, bacteria can produce important substances such as proteins, vaccines, and enzymes. 7. In gene therapy, viruses are used to carry replacements for defective or missing genes into human cells. Copy right © 2021 Pearson Education Ltd.

CHAP TER 1 The Microbial World and You

8. Genetically modified bacteria are used in agriculture to protect plants from frost and insects and to improve the shelf life of produce.

Microbes and Human Disease (pp. 42–45) ASM 5.4: Microorganisms, cellular and viral, can interact with both human and nonhuman hosts in beneficial, neutral, or detrimental ways. 1. The disease-producing properties of a species of microbe and the host’s resistance are important factors in determining whether a person will contract a disease. 2. Bacterial communities that form slimy layers on surfaces are called biofilms. 3. An infectious disease is one in which pathogens invade a susceptible host. 4. An emerging infectious disease (EID) is a new or changing disease showing an increase in incidence in the recent past or a potential to increase in the near future. Contributions to the field of microbiology by the following individuals are noted in this chapter: Oswald Avery Agostino Bassi Françoise BarréSinoussi George Beadle Martinus Beijerinck Francis Crick Paul Ehrlich Alexander Fleming Robert Hooke Dmitri Iwanowski François Jacob Edward Jenner

Robert Koch Rebecca Lancefield Antoine Lavoisier Joshua Lederberg Carolus Linnaeus Joseph Lister Colin MacLeod Maclyn McCarty César Milstein Jacques Monod John Needham Louis Pasteur Francesco Redi

Ignaz Semmelweis Lazzaro Spallanzani Wendell Stanley Edward Tatum Youyou Tu Anton van Leeuwenhoek Rudolf Virchow James Watson Chaim Weizmann Sergei Winogradsky Carl Woese

The Loop The chapter defines organisms studied in microbiology. Topics introduced in the overview of microbiology can be covered in more depth by reading the following sections: Bioremediation Classification Emerging infectious diseases Industrial microbiology/biotechnology Koch’s postulates Vaccines Biofilms

p. 41, Chapter 2 (p. 57) Chapter 10 pp. 43–45 Chapters 9 and 28 p. 36, Chapter 14 (Figure 14.3) pp. 36–37, Chapter 18 p. 42, Chapter 6 (pp. 183–184)

Exploring the Microbiome How Does Your Microbiome Grow? 6

INSTRUCTOR'S GUIDE FOR MICROBIOLOGY: AN INTRODUCTION, GE, 13e

This introductory chapter contains an introductory segment on how the microbiome of people may vary depending on their diet. Discussion questions: 

Is the ability to break down red algae a desirable trait (from the perspective of humans) or is it just beneficial to bacteroides?

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If the ability to break down red algae is indeed beneficial, should the FDA consider allowing raw algae? What are the potential risks and benefits?

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A related topic to discuss is how infants acquire their microbiome. A January 2017 article discusses vertical transmission of microbes. Blum, K. (2017) Researchers Use Innovative Methods to Study Vertical Transmission of Microbes. https://www.asm.org/index.php/mbiosphere/item/5474-researchers-use-innovativemethods-to-study-vertical-transmission-of-mi-crobes?utm_source=TrendMD&utm_ medium=cpc&utm_campaign=mBiosphere_TrendMD_0

Answers Figure Questions Figure

Question

Answer

1.1

How do we benefit from the production of vitamin K by microbes?

Vitamin K is necessary for blood clotting.

1.2

How are bacteria, archaea, fungi, protozoa, algae, and viruses distinguished on the basis of cellular structure?

Bacteria are prokaryotic with peptidoglycan cell walls. Archaea are prokaryotes lacking peptidoglycan. Fungi are eukaryotes with chitin cell walls. Protozoa are unicellular eukaryotes without cell walls. Algae are unicellular eukaryotes with chloroplasts and cell walls. Viruses are not composed of cells. They consist of a protein coat enclosing a nucleic acid.

1.3

Why was van Leeuwenhoek’s discovery so important?

It led the way to look for microbial causes of disease and changes in food.

1.5

Why do you think the First Golden Age of Microbiology occurred when it did?

Technology (microscopes) combined with Pasteur’s discovery that microbes cause “diseases” of food.

1.6

Why do you think penicillin is no longer as effective as it once was?

Overuse has selected for penicillin-resistant bacteria.

1.7

What advances occurred during the Second Golden Age of Microbiology?

Discovery and development of antibiotics and other antimicrobial agents, development of techniques for sequencing DNA and for producing monoclonal antibodies.

CHAP TER 1 The Microbial World and You, GE

1.8

How do you think parasitic worms survive and live off a human host?

Worms could actively ingest human tissue or could absorb nutrients from the host’s intestinal contents.

1.9

Why is it important to identify streptococci quickly?

Streptococci include several important pathogens including Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus pneumoniae.

1.10

How does a biofilm’s protective barrier make it resistant to antibiotics?

The barrier makes it difficult for the antibiotics to penetrate the biofilm and access the microorganisms.

Review 1. Rudolf Virchow’s concept of biogenesis, stating that living cells arise only from preexisting ones, challenged the case for spontaneous generation. 2. a. Certain microorganisms cause diseases in insects. Microorganisms that kill insects can be effective biological control agents because they are specific for the pest and do not persist in the environment. b. Carbon, oxygen, nitrogen, sulfur, and phosphorus are required for all living organisms. Microorganisms convert these elements into forms that are useful for other organisms. Many bacteria decompose material and release carbon dioxide into the atmosphere that plants use. Some bacteria can take nitrogen from the atmosphere and convert it into a form that can be used by plants and other microorganisms. c. Normal microbiota are microorganisms that are found in and on the human body. They do not usually cause disease and can be beneficial. d. Organic matter in sewage is decomposed by bacteria into carbon dioxide, nitrates, phosphates, sulfate, and other inorganic compounds in a wastewater treatment plant. e. Recombinant DNA techniques have resulted in insertion of the gene for insulin production into bacteria. These bacteria can produce human insulin inexpensively. f. Microorganisms can be used as vaccines. Some microbes can be genetically engineered to produce components of vaccines. g. Biofilms are aggregated bacteria adhering to each other and to a solid surface.

3. a. 1, 3

d. 2

g. 6

b. 8

e. 5

h. 7

c. 1, 4, 5

f. 3

4. a. 7

d. 2

g. 1

b. 4

e. 6

c. 3

f. 5

5. a. 11

g. 10

m. 7

b. 14

h. 2

n. 5

c. 15

i. 1

o. 6

d. 17

j. 12

p. 8

INSTRUCTOR'S GUIDE FOR MICROBIOLOGY: AN INTRODUCTION, 13e, GE