Microbiology Chapter 1

Who first wondered whether there was a link between environment and disease?

Hippocrates (Greek physician)

Who questioned why they and other survivors of the plague could have close contact with victims and not fall ill again?

Thucydides (Greek historian)

What does the science of microbiology study?

Life forms too small to see with the unaided eye.

Are most microorganisms harmful or harmless to people?

Most microorganisms are harmless to people.

Who first discovered the bacterial world?

Antoni Van Leeuwenhoek (a Dutch clothier, merchant, & lens grinder)

When did Antoni Van Leeuwenhoek report the existence of protozoa? Bacteria?

Protozoa in 1674 & Bacteria in 1676.

• protozoa are bigger than bacteria

Microorganism

An organism (or virus) too small to be seen without a microscope.

• Also called a microbe

Antoni van Leeuwenhoek Background

• curious about how everything looked close up

• began making & using simple microscopes

• new microscope for each specimen

• examined drops of water & visualized tiny animals, fungi, algae, and single-celled protozoa

True or false: antoni van leeuwenhoek described what he saw as “animalcules” of “wee little beasties” to the Royal Society of London in 1674.

TRUE

When did organisms begin being call microorganisms?

End of the 19th century.

Taxonomic system

A system for naming plants and animals and grouping similar organisms together.

Who developed the taxonomic system?

Carolus Linnaeus

What are the six categories Leeuwenhoek’s microorganisms can be grouped into?

1. Bacteria

2. Archaea

3. Fungi

4. Protozoa

5. Algae

6. Small multicellular animals

What is the only type of microbe not described by van leeuwenhoek?

Viruses (need an electron microscope to see)

Bacteria and Archaea Overview

• unicellular prokaryotes (lack nucleus)

• reproduce asexually

• much smaller than eukaryotic cells

• live in sufficient moisture

• archaea found in extreme environments

True or false: archaea cell wall is made of peptidoglycan

FALSE - bacterial cell walls are made of peptidoglycan, archaea cell walls are composed of other polymers

True or false: bacteria help degrade dead plants and animals

TRUE

True or false: no archaea are known to cause diseases in humans

TRUE

Fungi Overview

• eukaryotic (has nucleus)

• obtain their food from other organisms

• have cell walls

What are different types of fungi?

molds and yeasts

Molds

• multicellular organisms

• long filaments

• reproduce by sexual & asexual spores

• grow on cheese, bread, jams

• penicillium chrysogenum → produces penicillin

Yeasts

• unicellular organism

• oval to round in shape

• reproduce asexually by budding (some sexual)

• saccharomyces cerevisiae → causes bread to rise + alcohol from sugar

• candida albicans → yeast infections

Protozoa Overview

• single-celled eukaryotes

• similar to animals in nutritional needs & cellular structure

• capable of locomotion

• live freely in water (but some live in animals)

• most reproduce asexually but some are sexual

Protozoa psuedopods

extensions of a cell that flow in the direction of travel

Protozoa cilia

numerous short protrusions of a cell that beat rhythmically to propel a protozoan through its environment

Protozoa flagella

extensions of a cell but are fewer, longer, and more whiplike than cilia

Algae Overview

• unicellular or multicellular photosynthetic eukaryotes

• simple reproductive structures

• categorized on basis of pigmentation & composition of cell wall

• large algae used as emulsifier; unicellular algae in ponds, streams, lakes

Spirogyra

microscopic algae grows as chains of cells containing helical photosynthetic structures

Diatoms

algae that have glasslike cell walls

Parasites Overview

• parasitic worms

• cause diseases

• diagnosed by finding microscopic eggs in blood, feces, urine

Virus Overview

• much smaller than smallest bacteria

• not seen until electron microscope (1932)

• all are acellular (not composed of cells)

Why is Antoni Van Leeuwenhoek the “father of microbiology”?

• suspicious + secretive man

• built over 400 microscopes

• never sold or gave any away

• never trained an apprentice

• didn’t let anyone look through his microscopes

What scientific device did van Leeuwenhoek create?

the first good microscope

What is the modern name for organisms that are too small to be seen without a microscope?

microorganisms

Van Leeuwenhoek described bacteria, archaea, fungi, algae, small multicellular animals, and one other type of microorganism. What was it?

Protozoa

All eukaryotic cells contain most of their genetic material inside what structure?

nucleus

What four questions were asked during the “Golden Age of Microbiology?”

• Is spontaneous generation of microbial life possible?

• What causes fermentation?

• What causes disease?

• How can we prevent infection and disease?

Spontaneous Generation

The theory that living organisms can arise from nonliving matter.

• created by Aristotle

What three processes did past philosophers and scientists believe living things arose from?

• asexual reproduction

• sexual reproduction

• nonliving matter → spontaneous generation

Francesco Redi experiment

• when decaying meat was kept isolated from flies, maggots never developed

• meat exposed to flies was soon infested

• lead to doubt about spontaneous generation

John T. Needham experiment

• beef gravy and infusion of plant material

• scientists agreed that large animals could not arise spontaneously, but microbes could

Lazzaro Spallanzani experiment

• contradicted Needham’s findings

• conclusions = needham failed to heat vials sufficiently to kill all microbes, microbes exist in the air and contaminate experiment, spontaneous generation of microorganisms does not occur → all living things must arise from other living things

• critics said he did not allow enough air for organisms to thrive & he heated too much, killing life force

Louis Pasteur

• experiments with swan-necked flasks

• upright flasks = no microbial growth appeared

• tilted flasks = dust from bend in neck went into flask and created microbes within a day

• spontaneous generation does NOT exist

Scientific Method

Process by which scientists attempt to prove or disprove hypotheses through observations of the outcomes of carefully controlled experiments

• created following spontaneous generation debate

Scientific method rules

1. group of observations leads a scientists to ask a question about a phenomenon

2. the scientist generates a hypothesis - a potential answer to the question

3. scientist designs & conducts experiment to test hypothesis

4. based on observed results, the scientist either accepts, rejects, or modifies the hypothesis

Control groups

Groups that are treated exactly the same as the other groups in the experiment except for the one variable that the experiment is designed to test.

What terms describes the idea that living organisms can come from nonliving substances?

spontaneous generation

The investigating of which researcher finally disproved that living organisms can come from nonliving substances?

Pasteur

Who answered the question what causes fermentation?

Pasteur

Pasteur’s Fermentation Experiments

• some scientists believed air caused fermentation but others believed living organisms caused fermentation

• first = yeast growing & budding in sugar solutions + showed yeast cells arise from other yeast cells

• second = sealed sterile flasks containing sugar and yeast but left some open to air → yeast grew in both environments

• third = bacteria & yeast in different flasks of sterile sugar juice → bacteria ferment sugar to produce acids & yeast ferment sugar to produce alcohol

• determined yeast are facultative anaerobes (no oxygen)

Pastuerization

• developed by Pasteur

• process of heating liquids just enough to kill most contaminating bacteria without changing the juice’s basic qualities

  • created the field of industrial microbiology

Industrial microbiology

• Pasteur

• microbes are intentionally used to manufacture products

Who are the rivals as the “Father of Microbiology”?

Antoni van Leeuwenhoek & Pasteur

Industrial uses of microbes → Pasteur

• cheese = flavor & ripening

• alcohol = produced by bacteria/yeast fermentation

• soy sauce = fungal fermentation of soybeans

• vinegar = bacterial fermentation of sugar

• yogurt = bacteria in milk

• sour cream = bacteria in cream

• artificial sweetener = amino acids from bacteria in sugar

• bread = rising by yeast

• antibiotics = bacteria & fungi

• human growth hormone = engineered bacteria

• laundry enzymes = bacteria

• vitamins = bacteria

• diatomaceous earth = microscopic algae

• pest control = insect-destroying bacteria

• drain opener = protein-digesting & fat-digesting bacteria enzymes

Eduard Buchner’s Experiments

• demonstrated fermentation does not require living cells

• enzymes promote chemical reactions

• began field of biochemistry & study of metabolism

Biochemistry

Branch of chemistry that studies the chemical reaction of living things

Metabolism

The sum of all chemical reactions, both anabolic and catabolic, within an organism

Today we understand that yeasts and bacteria can cause fermentation. That understanding comes to us from the work of which scientist?

Pasteur

What industry has the work of Pasteur most influenced?

Food and beverage

Who first conjectured that “germs of contagion” causes disease?

Girolamo Fracastoro

When Pasteur discovered that bacteria were responsible for spoiling wine, this led to the development of what theory?

Germ theory of disease

Germ theory of disease

hypothesis formulated by Pasteur in 1857 that microorganisms are responsible for disease

What did early scientists suspect that diseases such as cholera, tuberculosis, and anthrax were caused by?

a specific germ (pathogen)

Pathogen

A microorganism capable of causing disease

Koch’s Experiments

• studied the causation of disease

• demonstrated a specific bacterium causes anthrax

• examined colonies of microorganisms

Fanny Hesse

Introduced Koch to agar, gel derived from red agar.

Koch Advancements

• simple staining techniques for bacterial cells & flagella

• first photomicrograph of bacteria

• first photograph of bacteria in diseased tissue

• technique for estimating number of bacteria in a solution

• used steam to sterilize growth media

• use of petri dish to hold solid growth media

• lab techniques to transfer bacteria

• bacteria is a distinct species

Koch’s Postulates

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

2. the agent must be isolated and grown outside the host

3. when agent is introduced to a healthy, susceptible host, the host must get the disease

4. the same agent must be found in the diseased experimental host

Edwin Klebs

• diphtheria

• bacterium

Theodor Escherich

• traveler’s diarrhea; bladder infection

• E. Coli → bacteria

Albert Fraenkel

• pneumonia

  • bacteria

David Bruce

• undulant fever

• brucella melitensis → bacteria

Anton Weichselbaum

• meningococcal meningitis

• bacteria

A.A Gartner

• salmonellosis

• bacteria

Shibasaburo Kitasato

• tetanus

• bacteria

Dimitri Ivanovsky & Martinus Beijerinck

• tobacco mosaic disease

• virus

William Welch & George Nuttall

• gas gangrene

• clostridium peregrines → bacteria

Alexandre Yersin & Shibasaburo Kitasato

• bubonic plague

• yersinia pestis → bacteria

Kiyoshi Shiga

• shigellosis

• shigella dysenteriae → bacteria

Walter Reed

• yellow fever

• flavivirus yellow fever → virus

Robert forde & Joseph dutton

• african sleeping sickness

• trypanosoma brucei gambiense → protozoan

Gram’s Stain

• developed by Hans Christian Gram

• most widely used technique

• one of first steps to identify bacteria

• application of dyes → some microbes pink or purple

Which researcher ultimately gave us a method for providing that a particular microbe caused a particular disease?

Robert Koch

Which researcher developed the staining technique most widely used in microbiology to visualize and to begin identifying microbes under the microscope?

Hans Christian Gram

Ignaz Semmelweis

• recognized importance of handwashing to prevent transfer of disease between patients and physicians

• tried to introduce sanitary practices in hospitals but was ridiculed for his ideas

Joseph Lister

• considered as the father of antiseptic surgery

• used dilute carbolic acid on bandages and surgical instruments to reduce infection in surgical wounds

Florence Nightingale

• antiseptic technique in nursing

• political activist for health reform

• used statistics

• founded modern nursing

John Snow

infection control & epidemiology

• studied cholera and found it went to 1 water source

Infection control

Branch of microbiology studying the prevention and control of infectious disease

Epidemiology

The study of occurrence, distribution, and spread of disease in humans

Lady Mary Wortley Montagu

Introduced inoculation against smallpox to Europe

Edward Jenner

• began the field of immunology → vaccine

• developed a smallpox vaccine using cowpox fluid

Immunology

the study of the body’s defenses against pathogens

Paul Ehrlich

• “magic bullets” → field of chemotherapy

• discovered compounds to combat sleeping sickness & syphilis

Chemotherapy

A branch of medical microbiology in which chemicals are studied for their potential to destroy pathogenic microorganisms.

Which health care practitioner improved our understanding of the importance of hand washing?

Ignaz semmelweis

The use of antiseptic chemicals during surgical techniques was the direct result of which surgeon’s innovations?

Joseph Lister

The work of Paul Ehrlich brought us chemicals that destroy pathogens while remaining nontoxic to humans. What is the modern term for this concept?

Chemotherapy

Bacteriology

bacteria & archaea

Phycology

algae