New From GarlaNd ScieNce

www.garlandscience.com

liviNG iN a

THe aUTHorBruce V. Hofkin received his Ph.D. from the University of New Mexico where he is currently a faculty member in the Department of Biology. His primary research interest is the epidemiology of vector-borne diseases.

GarlandJune 2010496 pages l 413 illustrationsPaperback l 978-0-8153-4175-8£40.00

is a textbook written for students taking a general microbiologyor microbiology-themed course. It teaches the essential concepts of microbiology through practical examples and a conversational writing style intended to make the material accessible to a wide audience.

In order to make the science relevant to students, every chapter of the book contains a series of cases intended to motivate learning the microbiology concepts. The cases present microbiology in the news, in history, in literature, and in scenarios of everyday life. Each case ends with several questions intended to pique student interest, and those questions are answered in the next section of the chapter.

By clearly and succinctly explaining the fundamentalsof microbiology through practical examples, the book provides a scientific framework through which students can understand critical issues about microorganisms and disease that they will encounter throughout their lives. They will learn the role that microorganisms play not only in our health but also in ecosystem processes, our diet, industrial production, and human history. Topics that we hear about every day,from global warming to energy independence to bioterrorism, all have a microbial angle. This text is designed to provide the reader with the background needed to understand and discuss such topics with a genuine understanding rooted in science.

microbial world

STUdeNT aNd iNSTrUcTor reSoUrceS: The following supplements are available for students and instructors. They can be accessed at http://www.garlandscience.com/lmw.

THe arT oF liviNG iN a microbial world The images and tables from the book come in two convenient formats: PowerPoint® and JPEG. The PowerPoint slides can be customized for lectures.

microbioloGy movieS Short movies have been developed to complement material in a select numberof chapters, with a special emphasis on molecular genetics, virology, and immunology. Each movie has a voiceover narration, and the text of the narration is available for download.

STUdeNT QUizzeS Short online quizzes for each chapter test basic reading comprehension.

FlaSHcardS Online flashcards test mastery of the key terms listed at the end of each chapter.

GloSSary The glossary at the end of the book can be searched and browsed online.

Chapter 1: Living in a Microbial World

10

The Scientific MethodA proper scientific experiment involves a series of well-

defined stepsCASE: FLEMING rEVISITED The British scientist Alexander Fleming discovered the first antibiotic

in 1929. He noticed that when certain molds contaminated his bacterial

culture plates, the bacteria were unable to grow close to the mold. Fleming

reasoned that the mold was secreting a substance that killed the bacteria.

This proved to be the case, and the mold was identified as Penicillium

notatum. Fleming named the secreted antibiotic penicillin (Figure 1.10a).

Two microbiology students, Rich and Shawn, learn of Fleming’s work

in their class, and later, when they must perform a small, independent

research project as part of their laboratory grade, they decide to repeat

Fleming’s work with a different yet closely related mold, Penicillium

roqueforti. This mold is commonly used in the production of blue cheese.

The mold digests milk sugars, and the waste products that are released

contribute to the taste of the cheese. The mold also gives blue cheese its

characteristic blue streaks (Figure 1.10b). Does it also, like P. notatum,

have antibacterial properties? To find out, Rich and Shawn buy a block of blue cheese and transfer

mold cells onto nutrient agar plates, which will support the growth of a

wide range of bacteria as well as the P. roqueforti mold. They inoculate 12

plates with “lawns” of the bacterium Staphylococcus epidermidis. Lawns

are prepared by swabbing a plate with a uniform coating of bacteria. The

bacteria then grow over the entire surface of the plate (Figure 1.11a).

Rich and Shawn, using an inoculating loop, next streak P. roqueforti in a

zigzag pattern over six of their plates (Figure 1.11b). The other six plates

are “streaked” with an uninoculated loop without the mold. All 12 plates

are then incubated at 35°C for 24 hours. Rich and Shawn then examine

their plates, comparing those with and without P. roqueforti for evidence

of antimicrobial activity.1. What hypothesis are Rich and Shawn testing?

2. Which of their nutrient agar plates are serving as controls? Which are

the experimental plates? Why are the control plates critical?

3. What is the experimental variable in this experiment? What are the

important control variables?4. Why is it important to use six plates with and without the mold, rather

than just one of each?The scientific method and the process of scientific inquiry begin with an

observation. A curator in a museum, for example, may have observed that

the yellows in a famous van Gogh painting were beginning to turn brown.

Fleming noticed that Staphylococcus was unable to grow close to a mold

contaminant. Observations such as these lead to questions. Why was the

color in the painting changing? How did the mold inhibit bacterial growth?

To answer such questions, the scientist formulates an appropriate hypoth-

esis. A hypothesis is a tentative explanation for a specific question. To be

valid, a hypothesis must be testable. In other words, it must be possible to

collect evidence that either supports or refutes the hypothesis. To gather

such evidence, one must be able to make predictions based on the hypoth-

esis. Experiments or observations of future events are then used to deter-

mine whether the prediction was realized. If so, the hypothesis is supported.

If the prediction proves to be inaccurate, the hypothesis is rejected as false.

In the case of the damaged artwork, the initial hypothesis may have been

that some air pollutant was affecting the yellow color. The prediction that

results from this hypothesis is that if the air quality is carefully maintained,

the degradation of the color will stop. Rich and Shawn are testing the

Microbiology for Non-Majors | chapter 01 | figure 10

Hofkin | 978-0-8153-4175-X © www.garlandscience.com design by www.blink.biz

(b)

(a)

Figure 1.10 Penicillium molds. (a) Penicillin secreted by the mold Penicillium notatum prevents the bacteria

from growing near the mold colony. (b) Penicillium roqueforti, seen as blue

streaks, is used to make blue cheese.11

hypothesis that P. roqueforti produces compounds that can inhibit bacterial

growth. They therefore predict that Staphylococcus will be unable to grow

close to the mold.

The next step is to test the hypothesis with a valid experiment. Such an

experiment will compare an experimental group with a control group

(Figure 1.12). The experimental group is the group in which a crucial factor

will be manipulated. In the control group, that same factor will be left

unchanged, as a means of comparison. If the manipulation of this factor

results in a specific change as predicted by the hypothesis, and if that change

does not occur in the unmanipulated control group, the hypothesis is

supported.

Forexample,inRichandShawn’sexperiment,theexperimentalgroupcon-

sists of those bacterial lawns onto which the mold was streaked. No mold

was placed on the control plates. Consequently, if their hypothesis that P.

roqueforti is able to produce antibiotic compounds is correct, bacterial

growth on the experimental and control plates should be different. If the

hypothesis is incorrect, bacterial growth on the two types of plates will be

similar, and the hypothesis can be rejected.

The experimental and control groups in any experiment should be identical

forallfactorsexceptone.InRichandShawn’sexperiment,allplatescon-

tained the same nutrients and they were incubated at identical tempera-

tures. These represent controlled variables. The only difference was the

experimental variable, in this case, the presence or absence of mold. After

24 hours, the two students compared bacterial growth on their experimen-

tal plates streaked with mold with their control plates lacking it. Because

they carefully controlled all variables except one, any differences in

Microbiology for Non-Majors | chapter 01 | figure 11

Hofkin | 978-0-8153-4175-X

© www.garlandscience.com design by www.blink.biz

(a)

(b)

Dip a cotton swab in a liquid

sample of a bacterial culture and

draw it across the surface of an

agar plate.

Dip the same swab in the liquid

culture a second time and

reswab the plate at a 90� angle

to the first swabbing.

Repeat a third time, swabbing at a

45� angle to the second swabbing.

The plate should now be covered

with an almost solid layer of

bacteria, which will grow into

a lawn.

Transfer mold to a plate with a bacterial

lawn. Protect agar surface from

contamination. Streak over surface in a

zigzag motion.

Sterilize an inoculating

loop in flame and allow

it to cool.

Load the loop by pressing it

firmly onto colonies of mold

growing on an agar plate.

1.

2.

3.

1.

2.

3.

Figure 1.11 Testing a mold for

antimicrobial activity. (a) Prepare

bacterial lawns on several agar plates.

(b) Inoculate some of the plates with mold.

After an incubation period, compare the

inoculated and the uninoculated plates for

evidence of inhibited bacterial growth.

The Scientific Method

STUdeNT aNd iNSTrUcTor reSoUrceS: The following supplements are available for students and instructors. They can be accessed at http://www.garlandscience.com/lmw.

THe arT oF liviNG iN a microbial world The images and tables from the book come in two convenient formats: PowerPoint® and JPEG. The PowerPoint slides can be customized for lectures.

microbioloGy movieS Short movies have been developed to complement material in a select numberof chapters, with a special emphasis on molecular genetics, virology, and immunology. Each movie has a voiceover narration, and the text of the narration is available for download.

STUdeNT QUizzeS Short online quizzes for each chapter test basic reading comprehension.

FlaSHcardS Online flashcards test mastery of the key terms listed at the end of each chapter.

GloSSary The glossary at the end of the book can be searched and browsed online.

TexTbookS oF relaTed iNTereST

978-0-8153-6514-3 978-0-8153-4142-0

Table oF coNTeNTSVisit www.garlandscience.com/Hofkin to view sample chapters.

1. Living in a Microbial World

2. The Chemistry of Life

3. The Cell: Where Life Begins

4. A Field Guide to the Microorganisms

5. The Microbiology of History and the History of Microbiology

6. Microbial Genetics

7. Metabolism and Growth

8. Microbial Evolution: The Origin and Diversity of Life

9. An Ecologist’s Guide to Microbiology

10. The Nature of Disease: A Pathogen’s Perspective

11. Host Defense

12. Control of Microbial Growth

13. Epidemiology: Who, What, When, Where, and Why?

14. The Future Is Here: Microorganisms and Biotechnology

15. Guess Who’s Coming to Dinner: Microorganisms and Food

16. Better Living With Microorganisms: Industrial and Applied Microbiology

“ The key strengths of this text are the overall ‘readability’ and interesting stories/facts sprinkled throughout. I think it’s also a strength that the text doesn’t cater to a particular concentration of students but truly presents a broad overview of microbiology as a whole.” linda bruslind, oregon State University, USa

key FeaTUreSl The conversational writing style of Living in a Microbial World makes the text accessible and enjoyable.

l The art work is conceptual and appealing.

l Cases are integrated throughout the text to connect the science to the social world.

l Concept Questions are provided at the end of each chapter to help students think carefully about what they have learned and apply that knowledge to new situations.

l The text is streamlined to 16 chapters, and is ideal for a one-semester course.

l Fundamental topics, such as the Central Dogma and metabolism, have special introductory sections and figures to provide context to the molecular details of these processes.

l An entire chapter is devoted to microbial evolution, and evolutionary concepts are reinforced throughout the text.

l The immunology chapter is unique to this book, and offers a conceptual overview of the immune response, explained through a series of cases that explore what happens to different passengers exposed to the same pathogen on an airplane.

Chapter 1: Living in a Microbial World

10

The Scientific MethodA proper scientific experiment involves a series of well-

defined stepsCASE: FLEMING rEVISITED The British scientist Alexander Fleming discovered the first antibiotic

in 1929. He noticed that when certain molds contaminated his bacterial

culture plates, the bacteria were unable to grow close to the mold. Fleming

reasoned that the mold was secreting a substance that killed the bacteria.

This proved to be the case, and the mold was identified as Penicillium

notatum. Fleming named the secreted antibiotic penicillin (Figure 1.10a).

Two microbiology students, Rich and Shawn, learn of Fleming’s work

in their class, and later, when they must perform a small, independent

research project as part of their laboratory grade, they decide to repeat

Fleming’s work with a different yet closely related mold, Penicillium

roqueforti. This mold is commonly used in the production of blue cheese.

The mold digests milk sugars, and the waste products that are released

contribute to the taste of the cheese. The mold also gives blue cheese its

characteristic blue streaks (Figure 1.10b). Does it also, like P. notatum,

have antibacterial properties? To find out, Rich and Shawn buy a block of blue cheese and transfer

mold cells onto nutrient agar plates, which will support the growth of a

wide range of bacteria as well as the P. roqueforti mold. They inoculate 12

plates with “lawns” of the bacterium Staphylococcus epidermidis. Lawns

are prepared by swabbing a plate with a uniform coating of bacteria. The

bacteria then grow over the entire surface of the plate (Figure 1.11a).

Rich and Shawn, using an inoculating loop, next streak P. roqueforti in a

zigzag pattern over six of their plates (Figure 1.11b). The other six plates

are “streaked” with an uninoculated loop without the mold. All 12 plates

are then incubated at 35°C for 24 hours. Rich and Shawn then examine

their plates, comparing those with and without P. roqueforti for evidence

of antimicrobial activity.1. What hypothesis are Rich and Shawn testing?

2. Which of their nutrient agar plates are serving as controls? Which are

the experimental plates? Why are the control plates critical?

3. What is the experimental variable in this experiment? What are the

important control variables?4. Why is it important to use six plates with and without the mold, rather

than just one of each?The scientific method and the process of scientific inquiry begin with an

observation. A curator in a museum, for example, may have observed that

the yellows in a famous van Gogh painting were beginning to turn brown.

Fleming noticed that Staphylococcus was unable to grow close to a mold

contaminant. Observations such as these lead to questions. Why was the

color in the painting changing? How did the mold inhibit bacterial growth?

To answer such questions, the scientist formulates an appropriate hypoth-

esis. A hypothesis is a tentative explanation for a specific question. To be

valid, a hypothesis must be testable. In other words, it must be possible to

collect evidence that either supports or refutes the hypothesis. To gather

such evidence, one must be able to make predictions based on the hypoth-

esis. Experiments or observations of future events are then used to deter-

mine whether the prediction was realized. If so, the hypothesis is supported.

If the prediction proves to be inaccurate, the hypothesis is rejected as false.

In the case of the damaged artwork, the initial hypothesis may have been

that some air pollutant was affecting the yellow color. The prediction that

results from this hypothesis is that if the air quality is carefully maintained,

the degradation of the color will stop. Rich and Shawn are testing the

Microbiology for Non-Majors | chapter 01 | figure 10

Hofkin | 978-0-8153-4175-X © www.garlandscience.com design by www.blink.biz

(b)

(a)

Figure 1.10 Penicillium molds. (a) Penicillin secreted by the mold Penicillium notatum prevents the bacteria

from growing near the mold colony. (b) Penicillium roqueforti, seen as blue

streaks, is used to make blue cheese.