introduction to microbiology

Welcome to Microbiology 1

For Today…

Introduction to the course

Explore the history and foundation of microbiology

Dimensional Analysis

Chapter 1The Microbial World and You

Chapter 1 The Microbial World and You

What is Microbiology?

Microbes, or microorganisms are minute living things that are usually unable to be viewed with the naked eye.

What are some examples of microbes?Bacteria, fungi, protozoa, algae, viruses are examples!

Some are pathogenic“Germ” refers to a rapidly growing cell.



Microbes (benefits):Decompose organic wasteAre producers in the ecosystem by photosynthesisProduce industrial chemicals such as

ethyl alcohol and acetoneProduce fermented foods such as vinegar,

cheese, and bread



Knowledge of Microbes allows humans toPrevent food spoilagePrevent disease occurrence

Led to aseptic techniques to prevent contamination in medicine and in microbiology laboratories.


History of MicrobiologyAncestors of bacteria were the first life on Earth.


History of Microbiology

The first microbes were observed in 1673.

In 1665, Robert Hooke (Englishman) reported that living things were composed of little boxes or cells.



1673-1723, Antoni van Leeuwenhoek (Dutch) described live microorganisms that he observed in teeth scrapings, rain water, and peppercorn infusions.



Many believed spontaneous generation: life can arise from non-living matter

In 1668, the Italian physician Francesco Redi performed an experiment to disprove spontaneous generation.

Can you think of an experiment that could disprove spontaneous generation?



Conditions Results3 jars covered with fine net

No maggots

3 open jars Maggots appeared

From where did the maggots come?What was the purpose of the sealed jars?Spontaneous generation or biogenesis?

Redi filled six jars with decaying meat.

Redi placed meat in three containers. One was uncovered, a second was covered with paper, and the third was covered with fine gauze that would exclude flies.

Flies laid their eggs on the uncovered meat and maggots developed.

The other two pieces of meat did not produce maggots spontaneously.


However, flies we attracted to the gauze-covered container and laid their eggs on the gauze; these eggs produced maggots.

Thus the generation of maggots by decaying meat resulted from the presence of fly eggs, and meat did not spontaneously generate maggots.




So now there are two hypotheses:The hypothesis that living organisms arise from nonliving matter is called spontaneous generation. According to spontaneous generation, a “vital force’ Forms life.

The Alternative hypothesis, that the living organisms arise from preexisting life, is called biogenesis.



Rudolf Virchow (German) presented biogenesis: living cells can arise only from preexisting cells.

Read up on the historical contribution(s) of microbiology made by:

John Needem (1713-1781)

Lazzaro Spallanzani (1729-1799)

Theodore Schwann (1810-1882)

Theodorvon Dusch (1824-1890)




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

Conditions ResultsNutrient broth placed in flask, heated, not sealed

Microbial growth

Nutrient broth placed in flask, heated, then sealed

No microbial growth

Spontaneous generation or biogenesis?

Pasteur experiment –Pasteur first filtered air through cotton and found that objects resembling plant spores had been trapped.If a piece of the cotton was placed in sterile medium after air had been filtered through it, microbial growth occurred.Next he placed nutrients solutions in flasks, heated their necks in a flame, and drew them out into a variety of curves.


Cont’dThe swan neck flasks that he produced in this way had necks open to the atmosphere.Pasteur then boiled the solutions for a few minutes and allowed them to cool. No growth took place even though the contents of the flasks were exposed to the air.Pasteur pointed out that no growth occurred because dust and germs had been trapped on the walls of the curved necks.

Cont’dIf the neck were broken, growth commenced immediately.


History of Microbiology Pasteur’s S-shaped flask kept microbes out but let air in. These experiments form the basis of aseptic technique



The Golden Age of Microbiology 1857-1914

Beginning with Pasteur’s work, discoveries included the relationship between microbes and disease, microbes and fermentation, immunity, and antimicrobial drugs



Pasteur showed that microbes are responsible for fermentation (Germ theory of fermentation).Fermentation is the conversation 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).



Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine. This application of a high heat for a short time is called pasteurization.



The Germ Theory of Disease1835: Agostino Bassi showed a silkworm

disease was caused by a fungus.1865: Pasteur believed that another silkworm

disease was caused by a protozoan.1840s: Ignaz Semmelwise advocated

handwashing to prevent transmission of puerperal fever from one OB patient to another.



The Germ Theory of Disease• 1860s: Joseph Lister used a chemical

disinfectant to prevent surgical wound infections after looking at Pasteur’s work showing microbes are in the air, can spoil food, and cause animal diseases.



The Germ Theory of Disease1876: Robert Koch provided proof that a

bacterium causes anthrax and provided the experimental steps, Koch’s postulates, used to prove that a specific microbe causes a specific disease.

Koch was a physician and Pasteur’s young rival



Koch's Postulates are used to prove the cause of an infectious disease.



Koch's Postulates are a sequence of experimental steps to relate a specific microbe to a specific disease.



A young milkmaid informed the physician Edward Jenner that she could not get smallpox because she had already been sick from cowpox.

1796: Edward Jenner inoculated a person with cowpox virus. The person was then protected from smallpox.

Called vaccination from vacca for cowThe protection is called immunity



What can you say about the cowpox and smallpox viruses?



Vaccinationsproduced from avirulent microbial strainsproduced from live virusesproduced from viral particles



Chemotherapy – treatment with chemicals• 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.

• Quinine from tree bark was long used to treat malaria.



Chemotherapy – treatment with chemicals• 1910: Paul Ehrlich developed a synthetic

arsenic drug, salvarsan, to treat syphilis.• 1930s: Sulfonamides were synthesized.


History of Microbiology1928: Alexander

Fleming discovered the first antibiotic.

He observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus (bacteria).

1940s: Penicillin was tested clinically and mass produced.


Modern Developments

• Bacteriology is the study of bacteria.• Mycology is the study of fungi.• Parasitology is the study of protozoa and

parasitic worms.• Recent advances in genomics, the study of

an organism’s genes, have provided new tools for classifying microorganisms.

Read up on these branches of microbiology and their uses of microorganism, for example:

Environmental Microbiology

Industrial Microbiology

Agricultural microbiology


Scope of MicrobiologyMicroorganisms are usually divided into six subgroups:Bacteria, archaea, alage, fungi, protozoa, and viruses. These subgroups are not close related.Bacteria are less like archaea or algae or fungi or protozoa or virus than a shark is like a giraffe or an orchid is like an eagle.

Scope of MicrobiologyThese are grouped based on the techniques for identifying, cultivating and studying which are similar. Read up on primary distinction among sub groups.Example: prokaryotes and eukaryotes.


Classification of MicrobesTaxonomy

• The science of classifying organisms• Provides universal names for organisms• Provides a reference for identifying

organisms


Classification of MicrobesTaxonomy

• Systematics or phylogeny• The study of the evolutionary history

of organisms• All Species Inventory (2001-2025)• To identify all species of life on Earth


Classification of MicrobesTaxonomic Hierarchy

DomainKingdom

Phylum Class Order

Family Genus Species

DumbKingsPlayChessOn FunnyGreen Squares


Classification of MicrobesTaxonomic Hierarchy

DomainKingdom

Phylum Class Order

Family Genus Species

Binomal Nomenclature uses the Genus and Species name to identify each creature.


Classification of Microbes

Taxonomic HierarchyEach name is LatinizedThere is a specific way to write each name.

Homo sapiens

The first word is capitalized

Name is in italics

Homo sapiensH. sapiens


Bacteria (or Eubacteria)

Most abundant on earth

They are nitrogen fixers and recycle carbon

No membrane bound organelles


Archaea

Methanogens

Halophiles

Hyperthermophiles


•Eukaryotic species:•A group of closely related organisms that breed among themselves

•Prokaryotic species:•A population of cells with similar characteristics•Clone: Population of cells derived from a single cell•Strain: Genetically different cells within a clone

•Viral species:•Population of viruses with similar characteristics that occupies a particular ecological niche



Let’s examine some microbes

Paramecium caudatum

Euglena acus

Peridiniumis - a dinoflagellate



Microbes and Human Disease

• Bacteria were once classified as plants which gave 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.



• 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.



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

• Emerging Infectious Diseases (EID): New diseases and diseases increasing in incidence

Chapter 1 The Microbial World and You Major Taxonomic Groups of Bacteria per Bergey’s manual

Gracilicutes – gram-negative cell walls, thin-skinnedFirmicutes – gram-positive cell walls, thick skinnedTenericutes – lack a cell wall & are softMendosicutes – archaea, primitive procaryotes with unusual cell walls & nutritional habits

species –a collection of bacterial cells which share an overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly

strain or variety – a culture derived from a single parent that differs in structure or metabolism from other cultures of that species (biovars, morphovars)

type – a subspecies that can show differences in antigenic makeup (serotype or serovar), susceptibility to bacterial viruses (phage type) and in pathogenicity (pathotype).

introduction to microbiology

Documents