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Chapter 1. A Brief History of Microbiology. The Early Years of Microbiology. What Does Life Really Look Like? Antoni van Leeuwenhoek (Dutch) Began making and using simple microscopes Often made a new microscope for each specimen

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A brief history of microbiology 1330387

Chapter 1

A Brief History of Microbiology


The early years of microbiology

The Early Years of Microbiology

What Does Life Really Look Like?

Antoni van Leeuwenhoek (Dutch)

Began making and using simple microscopes

Often made a new microscope for each specimen

Examined water and visualized tiny animals, fungi, algae, and single-celled protozoa: “animalcules”

By end of 19th century, these organisms were called microorganisms

© 2012 Pearson Education Inc.


Figure 1 1 antoni van leeuwenhoek

Figure 1.1 Antoni van Leeuwenhoek


Figure 1 2 reproduction of leeuwenhoek s microscope

Specimen holder

Lens

Figure 1.2 Reproduction of Leeuwenhoek’s microscope


Figure 1 3 the microbial world

Figure 1.3 The microbial world


The early years of microbiology1

The Early Years of Microbiology

How Can Microbes Be Classified?

Carolus Linnaeus developed taxonomic system for grouping similar organisms together

Leeuwenhoek’s microorganisms grouped into six categories:

Bacteria

Archaea

Fungi

Protozoa

Algae

Small multicellular animals

© 2012 Pearson Education Inc.


The early years of microbiology2

The Early Years of Microbiology

Bacteria and Archaea

Unicellular and lack nuclei

Much smaller than eukaryotes

Found everywhere there is sufficient moisture

Reproduce asexually

Two kinds

Bacteria – cell walls contain peptidoglycan

Archaea – cell walls composed of polymers other than peptidoglycan

© 2012 Pearson Education Inc.


Figure 1 4 cells of the bacterium streptococcus

Nucleus ofeukaryotic cheek cell

Prokaryoticbacterial cells

Figure 1.4 Cells of the bacterium Streptococcus


The early years of microbiology3

The Early Years of Microbiology

Fungi

Eukaryotic (have membrane-bound nucleus)

Obtain food from other organisms

Possess cell walls

Include

Molds – multicellular; grow as long filaments; reproduce by sexual and asexual spores

Yeasts – unicellular; reproduce by budding or sexual spores

© 2012 Pearson Education Inc.


Figure 1 5 fungi overview

Figure 1.5 Fungi-overview


The early years of microbiology4

The Early Years of Microbiology

Protozoa

Single-celled eukaryotes

Similar to animals in nutrient needs and cellular structure

Live freely in water; some live in animal hosts

Asexual (most) and sexual reproduction

Most are capable of locomotion by

Pseudopodia

Cilia

Flagella

© 2012 Pearson Education Inc.


Figure 1 6 locomotive structures of protozoa overview

Figure 1.6 Locomotive structures of protozoa-overview


The early years of microbiology5

The Early Years of Microbiology

Algae

Unicellular or multicellular

Photosynthetic

Simple reproductive structures

Categorized on the basis of pigmentation, storage products, and composition of cell wall

© 2012 Pearson Education Inc.


Figure 1 7 algae overview

Figure 1.7 Algae-overview


Figure 1 8 an immature stage of a parasitic worm in blood

Red blood cell

Figure 1.8 An immature stage of a parasitic worm in blood


Figure 1 9 viruses infecting a bacterium

Virus

Figure 1.9 Viruses infecting a bacterium

Bacterium

Virusesassemblinginside cell


The golden age of microbiology

The Golden Age of Microbiology

Scientists searched for answers to four questions

Is spontaneous generation of microbial life possible?

What causes fermentation?

What causes disease?

How can we prevent infection and disease?

© 2012 Pearson Education Inc.


The golden age of microbiology1

The Golden Age of Microbiology

Some thought living things arose from three processes

Asexual reproduction

Sexual reproduction

Nonliving matter

Aristotle proposed spontaneous generation

Living things can arise from nonliving matter

© 2012 Pearson Education Inc.


The golden age of microbiology2

The Golden Age of Microbiology

Redi’s Experiments

When decaying meat was kept isolated from flies, maggots never developed

Meat exposed to flies was soon infested

As a result, scientists began to doubt Aristotle’s theory

© 2012 Pearson Education Inc.


Figure 1 10 redi s experiments

Figure 1.10 Redi’s experiments

Flask coveredwith gauze

Flask sealed

Flask unsealed


The golden age of microbiology3

The Golden Age of Microbiology

Needham’s Experiments

Scientists thought microbes, but not animals, could arise spontaneously

Needham’s experiments reinforced this idea

© 2012 Pearson Education Inc.


The golden age of microbiology4

The Golden Age of Microbiology

Spallanzani’s Experiments

Conclusions

Needham failed to heat vials sufficiently to kill all microbes or had not sealed vials tightly enough

Microorganisms exist in air and can contaminate experiments

Spontaneous generation does not occur

Critics argued against experiments

Sealed vials did not allow enough air for organisms to survive

Prolonged heating destroyed “life force”

© 2012 Pearson Education Inc.


Figure 1 11 louis pasteur

Figure 1.11 Louis Pasteur


The golden age of microbiology5

The Golden Age of Microbiology

Pasteur’s Experiments

When the “swan-necked” flasks remained upright, no microbial growth appeared

When the flask was tilted, dust from the bend in the neck seeped back into the flask and made the infusion cloudy with microbes within a day

© 2012 Pearson Education Inc.


Figure 1 12 pasteur s experiments with swan necked flasks

Figure 1.12 Pasteur’s experiments with “swan-necked” flasks

Steam escapesfrom open endof flask.

Dust fromair settlesin bend.

Air moves inand out of flask.

Months

Infusion remainssterile indefinitely.

Infusion sits;no microbes appear.

Infusionis heated.


The golden age of microbiology6

The Golden Age of Microbiology

The Scientific Method

Spontaneous generation debate led in part to scientific method

Observation leads to question

Question generates hypothesis

Hypothesis is tested through experiment(s)

Results prove or disprove hypothesis

Accepted hypothesis leads to theory/law

Reject or modify hypothesis

© 2012 Pearson Education Inc.


Figure 1 13 the scientific method

Figure 1.13 The scientific method

Observations

Theoryor law

Experimentaldata supporthypothesis

Accepthypothesis

Repeat

Question

Experiment,includingcontrol groups

Rejecthypothesis

Hypothesis

Observations

Experimentaldata do notsupporthypothesis

Modifyhypothesis

Modifiedhypothesis


The golden age of microbiology7

The Golden Age of Microbiology

What Causes Fermentation?

Spoiled wine threatened livelihood of vintners

Some believed air caused fermentation

Others insisted living organisms caused fermentation

Vintners funded research to prevent spoilage during fermentation

This debate also linked to debate over spontaneous generation

© 2012 Pearson Education Inc.


Figure 1 14 pasteur s application of the scientific method

Spontaneousfermentationoccurs.

I.

Air fermentsgrape juice.

II.

Bacteria fermentgrape juiceinto alcohol.

III.

Yeasts fermentgrape juiceinto alcohol.

IV.

Figure 1.14 Pasteur's application of the scientific method

Observation:

Microscopic analysisshows juice containsyeasts and bacteria.

Fermentinggrape juice

Experiment

Conclusion

Hypothesis

Observation

Day 1: Flasks of grapejuice are heated sufficientlyto kill all microbes.

Day 2

Reject hypothesis I.

No fermentation;juice remainsfree of microbes

Flask is sealed.

No fermentation;juice remainsfree of microbes

Reject hypothesis II.

Flask remainsopen to airvia curved neck.

Bacteria reproduce;acids are produced.

Modify hypothesis III; bacteria fermentgrape juice intoacids.

Juice in flask is inoculated withbacteria and sealed.

Yeasts reproduce;alcohol is produced.

Accept hypothesis IV; yeasts fermentgrape juice intoalcohol.

Juice in flask is inoculated withyeast and sealed.


Table 1 1 some industrial uses of microbes

Table 1.1 Some Industrial Uses of Microbes


The golden age of microbiology8

The Golden Age of Microbiology

What Causes Disease?

Pasteur developed germ theory of disease

Robert Koch studied causative agents of disease

Anthrax

Examined colonies of microorganisms

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Figure 1 15 robert koch

Figure 1.15 Robert Koch


The golden age of microbiology9

The Golden Age of Microbiology

Koch’s Contributions

Simple staining techniques

First photomicrograph of bacteria

First photomicrograph of bacteria in diseased tissue

Techniques for estimating CFU/ml

Use of steam to sterilize media

Use of Petri dishes

Techniques to transfer bacteria

Bacteria as distinct species

© 2012 Pearson Education Inc.


Figure 1 16 bacterial colonies on agar

Figure 1.16 Bacterial colonies on agar

Bacterium 6

Bacterium 7

Bacterium 8

Bacterium 5

Bacterium 9

Bacterium 4

Bacterium 3

Bacterium 10

Bacterium 2

Bacterium 11

Bacterium 1

Bacterium 12


The golden age of microbiology10

The Golden Age of Microbiology

Koch’s Postulates

Suspected causative agent must be found in every case of the disease and be absent from healthy hosts

Agent must be isolated and grown outside the host

When agent is introduced into a healthy, susceptible host, the host must get the disease

Same agent must be found in the diseased experimental host

© 2012 Pearson Education Inc.


A brief history of microbiology 1330387

Table 1.2 Other Notable Scientists of the “Golden Age of Microbiology” and the Agents of Disease They Discovered


The golden age of microbiology11

The Golden Age of Microbiology

Gram’s Stain

Danish scientist Hans Christian Gram developed more important staining technique than Koch’s in 1884

Involves the applications of a series of dyes

Some microbes are left purple, now labeled Gram-positive

Other microbes are left pink, now labeled Gram-negative

Gram procedure used to separate into two groups

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Figure 1 17 results of gram staining

Gram-negative

Gram-positive

Figure 1.17 Results of Gram staining


The golden age of microbiology12

The Golden Age of Microbiology

How Can We Prevent Infection and Disease?

Semmelweis and handwashing

Lister’s antiseptic technique

Nightingale and nursing

Snow – infection control and epidemiology

Jenner’s vaccine – field of immunology

Ehrlich’s “magic bullets” – field of chemotherapy

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Figure 1 18 florence nightingale

Figure 1.18 Florence Nightingale


Figure 1 19 some scientific disciplines and applications

BIOLOGISTS

MODERN DISCIPLINES

Bacteriology (bacteria)Protozoology (protozoa)Mycology (fungi)Parasitology (protozoa andanimals)Phycology (algae)

Pre-1857

Leeuwenhoek

Figure 1.19 Some scientific disciplines and applications

Taxonomy

Linnaeus

SemmelweissSnow

Infection controlEpidemiology

The Golden Age ofMicrobiology (1857–1907)

Industrial microbiology

Pasteur

Food and beverage technology

Pasteurization

Microbial metabolism

GeneticsGenetic engineering

Buchner

Koch’s postulates

Etiology

Koch

Virology

Ivanowski

BeijerinckWinogradsky

Environmental microbiologyEcological microbiology

Microbial morphology

Gram

ListerNightingale

Antiseptic medical techniquesHospital microbiology

Jennervon BehringKitasato

SerologyImmunology

Ehrlich

Chemotherapy

Fleming

Pharmaceutical microbiology


Table 1 3 fields of microbiology

Table 1.3 Fields of Microbiology


The modern age of microbiology

The Modern Age of Microbiology

What Are the Basic Chemical Reactions of Life?

Biochemistry

Began with Pasteur’s and Buchner’s works

Microbes used as model systems for biochemical reactions

Practical applications

Design of herbicides and pesticides

Diagnosis of illness and monitoring responses to treatment

Treatment of metabolic diseases

Drug design

© 2012 Pearson Education Inc.


The modern age of microbiology1

The Modern Age of Microbiology

How Do Genes Work?

Microbial genetics

Molecular biology

Recombinant DNA technology

Gene therapy

© 2012 Pearson Education Inc.


The modern age of microbiology2

The Modern Age of Microbiology

Microbial Genetics

Avery, MacLeod, and McCarty: genes are contained in molecules of DNA

Beadle and Tatum: a gene’s activity is related to protein function

Translation of genetic information into protein explained

Rates and mechanisms of genetic mutation investigated

Control of genetic expression by cells described

© 2012 Pearson Education Inc.


The modern age of microbiology3

The Modern Age of Microbiology

Molecular Biology

Explanation of cell function at the molecular level

Pauling proposed that gene sequences could

Provide understanding of evolutionary relationships/processes

Establish taxonomic categories

Identify microbes that have never been cultured

Woese determined cells belong to bacteria, archaea, or eukaryotes

Cat scratch disease caused by unculturable organism

© 2012 Pearson Education Inc.


The modern age of microbiology4

The Modern Age of Microbiology

Recombinant DNA Technology

Genes in microbes, plants, and animals manipulated for practical applications

Production of human blood-clotting factor by E. coli to aid hemophiliacs

Gene Therapy

Inserting a missing gene or repairing a defective one in humans by inserting desired gene into host cells

© 2012 Pearson Education Inc.


The modern age of microbiology5

The Modern Age of Microbiology

What Roles Do Microorganisms Play in the Environment?

Bioremediation uses living bacteria, fungi, and algae to detoxify polluted environments

Recycling of chemicals such as carbon, nitrogen, and sulfur

© 2012 Pearson Education Inc.


The modern age of microbiology6

The Modern Age of Microbiology

How Do We Defend Against Disease?

Serology

The study of blood serum

Blood contains chemicals and cells that fight infection

Immunology

The study of the body’s defense against specific pathogens

Chemotherapy

Fleming discovered penicillin

Domagk discovered sulfa drugs

© 2012 Pearson Education Inc.


Figure 1 20 effects of penicillin on a bacterial lawn in a petri dish

Figure 1.20 Effects of penicillin on a bacterial “lawn” in a petri dish

Fungus colony(Penicillium)

Zone of inhibition

Bacterial colonies(Staphylococcus)


The modern age of microbiology7

The Modern Age of Microbiology

What Will the Future Hold?

Microbiology is built on asking and answering questions

The more questions we answer, the more questions we have

© 2012 Pearson Education Inc.


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