Introduction to General Microbiology Instructor: Laura Hunt, PhD Time: TTHR 8-9:20am.

Introduction to General Microbiology

Instructor: Laura Hunt, PhD

Time: TTHR 8-9:20am

Why is microbiology interesting?

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Microbes can be harmful but are a necessary part of our lives

CNN: “Superbug succeeds by blowing up defender cells, scientists learn” Nov 2007





What you will get out of this class:

A general introduction to basic concepts and principles of microbiology

There is a lot of material to cover but thankfully it is interesting and applicable

The Importance of Microorganisms

The emergence of higher life forms

Biogeochemical cycling

Huge diversity and physiological capacities

Relationships with higher organisms

What does microbiology refer to?

Microbiology is the study of microorganisms, which can be unicellular or cell-cluster microscopic organisms– This includes eukaryotes: fungi and protists AND

prokaryotes: bacteria and certain algae– Viruses, though not strictly classed as living

organisms, are also studied. – Microbiology is a broad term which includes many

branches including virology, mycology, parasitology and others.

Microorganisms as cells

Cell is fundamental unit of life

Compartmentalized Dynamic systems Cells constantly

communicate and exchange materials with their environment

Cell Chemistryand Key Structures Four main components (macromolecules):

– Proteins– Nucleic acids– Lipids– Polysaccharides

Key structures:– Cytoplasmic membrane– Cytoplasm– Nucleus

Characteristics of Living Systems

Cells as Machines andas Coding Devices

The First Cells: when/where did the first cell come from a non cell?? Your just a bag of carbon,

oxygen, and hydrogen The RNA world

– Naked RNA are agents of catalysis and coding

First self replicating entity had at least two properties: – 1. Means of obtaining

energy – 2. Form of heredity

More in Ch 11



Microorganisms and Their Natural Environments

Cells live in assemblages called populations

Habitat: location in the environment where microbial population lives

Microbial communities:– Where populations live and

interact with other populations

Study of microorganisms in their natural habitat is called microbial ecology

The Effect of Organisms on Each Other and on Their Habitats

Populations interact in various ways that can be both harmful and beneficial

Interaction between populations and with physical/chemical environment

The Extent of Microbial Life

Reservoirs of essential nutrients for life Total carbon equals that of all plants on

earth Prokaryotes comprise the major portion

of the Earth’s total biomass: 5 X 1030 cells

Most prokaryotes lie underground in oceanic and terrestrial subsurfaces

1.4 The Impact of Microorganisms on Humans

Microorganisms as disease agents Agriculture Food Energy and the Environment The Future: biotech

Important in C,N,S cycle

Convert elements to a form that is readily accessible to plants

Negatives: Food spoilage and food borne diseases– E.coli in spinach

Energy of the Future??

Microbial fuel cells– Geobacter sp. are of interest

because of their novel electron transfer capabilities

Obtain energy from iron oxides Can transfer electrons to the

surface of electrodes Use “nanowires” to shunt

electrons produced during metabolic reactions onto the surface of mineral grains in the soil, to be taken up by metal ions




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“The role of the infinitely small in nature is infinitely large” --Louis Pasteur

The birth of microbiology: Pathways of discovery

Slow to develop Two events:

– Invention of the microscope– Spontaneous generation controversy

The Historical Roots of Microbiology: Hooke, van Leeuwenhoek, and Cohn

Early Microscopy

Microscopes were crude, and lacked resolution even though they were compounding.

Some descriptions of bacteria, but very poorly seen

Yet, considering the tools many discoveries were made





Robert Hooke

Described fruiting structures of molds in 1665

First person to describe microorganisms



Antoni van Leeuwenhoek

Dutch draper and amateur microscope builder

Contemporary of Robert Hooke

First person to observe bacteria in 1676

“wee animalcules”



Slow growth

After initial discovery of tiny organisms, the field was slow to develop for the next 150 yrs.

Two things became focus as the field moved from the mid to late 19th century– Spontaneous generation– Nature of infectious diseases

Ferdinand Cohn (1828-1898): Science of Bacteriology

Contemporary of Koch and Pastuer

A botanist by trade Discovered endospores Laid groundwork for

bacterial classification Sterilization techniques Founded a major

scientific journal



Cohn cont.

Identified sulfur bacterium Beggiatoa mirabilis

Became interested in heat resistant bacterium– Led him to discover

Bacillus genus– Described entire life cycle– (vegetative cell-

endospore-vegetative cell)

– Heat did not kill the endospore

Louis Pasteur (1822-1895)

French microbiologist and chemist

Multi-faceted career



Pasteur and the Downfall of Spontaneous Generation

Ancient belief that organisms arise from nonliving materials

Louis Pasteur was a major opponent to spontaneous generation

Pasteur showed that microorganisms present in air resembled those on putrefying materials

Showed that if you sterilized you would not have purification



Pasteur’s Experiment

In 1864, he crushed spontaneous generation Pasteur used a swan necked flask for his

experiment, now called a Pasteur flask Simple experiment ended the controversy

Pasteur and Vaccination

Discovered that attenuated strains would provide protection against disease– Made discovery with

chickens and cholera Helped solidify the

concept of germ theory of disease



Pasteur and Rabies Vaccine

Known as the man who invented the rabies vaccine

“Benefactor of Humanity”

First exp were on dogs Then, July 6, 1885 tried

vaccine on Joesph Miester, a boy bitten by a rabid dog



Pasteur Institute: 120yrs of discoveries

Diptheria Plague Immunology Tuberculosis Sulfamides Molecular biology AIDS





Pasteur’s main contributions Instituting changes in hospital/medical

practices to minimize the spread of disease by microbes or germs

Coined the term “vaccine” --from the Latin vacca, meaning “cow”

Weak forms of disease could be used as an immunization against stronger forms

Rabies was transmitted by viruses too small to be seen under the microscopes of the time, introducing the medical world to the concept of viruses.

Robert Koch and the Germ Theory of Disease:

The Development of Koch’s Postulates Major contributions:

– Discovered anthrax– Discovered the bacterium

that causes tuberculosis and chlorea

Koch’s postulates– Developed based on

experiments with anthrax in mice

– He took experiment one step further and showed that even after many transfers in culture, the bacteria could still cause disease



1.2 Koch’s Postulates

Koch’s Postulate and Coral Disease

Corals are declining at an alarming rate

30% worldwide decline in corals

Satisfying Koch’s Postulate to determine the causative agent in coral disease is challenging and very controversial

Coral Disease Hard to duplicate the reef Many diseases have been

described solely on the basis of field characteristics, and in some instances there is disagreement as to whether an observed coral condition is actually a disease.

A disease pathogen has been identified for only handful coral diseases

The etiology of white pox, a lethal disease of the Caribbean elkhorn coral, Acropora palmata Kathryn L. Patterson* , James W. Porter�, Kim B. Ritchie ､ｦ , Shawn W. PolsonDeborah L. Santavy 珥 , and Garriet W. Smith ､ PNAS 2002



A Test of Koch’s Postulates: Tuberculosis

Discovered that the causative agent of tuberculosis was Mycobacterium tuberculosis

Considered his greatest accomplishment

Used microscopy, staining, pure culture isolation, and animal systems

Won Nobel prize in 1905 his work on tuberculosis

Koch and Pure Cultures Developed methods to isolate a specific

microorganism into pure culture He observed individual colonies on

potato slices represented pure cultures He later developed other media that

was more uniform and reproducible with gelatin and later with agar

Microbial Diversity and the Rise of General Microbiology From 19th to 20th century, microbiology

grew and improved significantly Several subdisciplines arose leading to

an era of “molecular microbiology” Two giants helped with this transition:

– Martinus Beijerinck– Sergei Winogradsky

Martinus Beijerinck (1851-1931)

Biggest achievement: developed the enrichment culture technique

Microorganisms isolated in a selective fashion

Aerobic nitrogen-fixing, sulfate-reducing,sulfur-oxidizing, nitrogen-fixing root nodule, Lactobacillus, and green algae

Using selective filter techniques, discovered that the infectious agent in tobacco mosaic disease, was not bacteria--described the first virus



Sergei Winogradsky (1856-1953): the Concept of Chemolithotrophy

Interested in bacteria involved in the cycling of nitrogen and sulfur

Introduced the concept that bacteria could be important biogeochemical agents



Sergei cont.

From studies on sulfur-oxidizing bacteria:– Chemolithotrophy: the oxidation of

inorganic compounds linked to energy conservation

From studies on nitrogen fixing bacteria, concluded that they obtained their carbon from CO2

From studies, proposed these organisms were autotrophs, specifically chemoautotrophs

Also isolated the first nitrogen-fixing bacteria

The Modern Era of Microbiology

Development of the Major Subdisciplines ofApplied Microbiology– Medical microbiology– Immunology– Agricultural microbiology– Industrial microbiology– Aquatic microbiology– Marine microbiology– Microbial ecology

Basic Science Sub disciplinesin Microbiology

Microbial systematics Microbial physiology Cytology Microbial biochemistry Bacterial genetics Molecular biology Virology

The Era of Molecular Microbiology

By 1970’s, experimental manipulation of genetic material– Restriction enzymes– Biotechnology

Genomics:comparative analysis of genes of different organisms– Nucleic acid sequencing– Phylogenetic relationships

Proteomics: the study of protein expression in cells

New Frontiers

350yrs of research!



Introduction to General Microbiology Instructor: Laura Hunt, PhD Time: TTHR 8-9:20am.

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