introduction to general microbiology instructor: laura hunt, phd time: tthr 8-9:20am
TRANSCRIPT
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
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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
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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
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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
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Robert Hooke
Described fruiting structures of molds in 1665
First person to describe microorganisms
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Antoni van Leeuwenhoek
Dutch draper and amateur microscope builder
Contemporary of Robert Hooke
First person to observe bacteria in 1676
“wee animalcules”
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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
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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
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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
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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
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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
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Pasteur Institute: 120yrs of discoveries
Diptheria Plague Immunology Tuberculosis Sulfamides Molecular biology AIDS
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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
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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
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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
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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
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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
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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!
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