Scope of Microbiology
Impact of Microbes on Earth
General Characteristics of Microorganisms
Historical Foundations
Taxonomy; Organizing, Classifying, and Naming Microorganisms
Scope
Microbiology: the study of small organisms, most of which are too small to be seen with the naked eye
Fields of Study
Ex. Rabies vaccine
Ex. AIDS and influenza, food poisoning
Ex. Clostridium botulinum causes botulism (a deadly form of food poisoning)
Ex. Cheese, beer and wine
Ex. Enzymes added to laundry detergent to remove stains
Ex. Bacteria that enhance soil fertility
Ex. Breakdown of organic matter and recycling of nutrients
Ex. Strains of bacteria that produce human insulin
Ex. Sewage and drinking water
Microorganisms and Their Impacts
-Soil, oceans, deep underground, extreme environments, on and in higher organisms ~100 trillion (1014) microorganisms per person 10 X number of cells of the human body ! Most are in the intestinal tract ~1 trillion bacteria on the skin
-Soil, oceans, deep underground, extreme environments, on and in higher organisms
~100 trillion (1014) microorganisms per person 10 X number of cells of the human body ! Most are in the intestinal tract ~1 trillion bacteria on the skin
~100 trillion (1014) microorganisms per person
10 X number of cells of the human body ! Most are in the intestinal tract ~1 trillion bacteria on the skin
10 X number of cells of the human body !
Most are in the intestinal tract
~1 trillion bacteria on the skin
-Formation of oxygen by photosynthesis (required for survival by many organisms) -Formation of carbon dioxide and methane during decomposition (Greenhouse gasses) -Transformations of nitrogen (major plant nutrient)
-Formation of oxygen by photosynthesis (required for survival by many organisms)
-Formation of carbon dioxide and methane during decomposition (Greenhouse gasses)
-Transformations of nitrogen (major plant nutrient)
-Dead plants, human and animal waste, pesticides
-Carbon, nitrogen, phosphorus, sulfur
Table 1.1 and Fig. 1.4 -Animal and plant diseases affect agriculture, lowering production and increasing cost of food production
Table 1.1 and Fig. 1.4
-Animal and plant diseases affect agriculture, lowering production and increasing cost of food production
-Cells are composed of a membrane that separates the interior from the exterior
-The interior is filled with the cytoplasm and other constituents needed for growth and reproduction
-A cell wall is often present on the outside of the membrane
-There are two main types of microbial cells
1. Prokaryotic
Small Lack a nucleus or organelles Often exist as single cells (unicellular) All bacteria are prokaryotes
Small
Lack a nucleus or organelles
Often exist as single cells (unicellular)
All bacteria are prokaryotes
2. Eukaryotic
Larger than prokaryotes Have a nucleus and organelles May be unicellular or multicellular Yeast, fungi, protozoa, algae, helminths
Larger than prokaryotes
Have a nucleus and organelles
May be unicellular or multicellular
Yeast, fungi, protozoa, algae, helminths
-Viruses are small particles composed of protein and nucleic acid (DNA or RNA)
Do not have the characteristics that define cellullar organisms (see below) Only able to reproduce when inside a cell
Do not have the characteristics that define cellullar organisms (see below)
Only able to reproduce when inside a cell
Sizes of Microorganisms
Fig. 1.7
The micrometer, mm, is the unit of measure often used to describe the size of microorganisms
1 mm = 1/1,000,000 meter = 0.000001 m = 1 x 10-6 m
Typical sizes
Viruses 0.01 to 0.2 mm Bacteria 0.2 to 5 mm Yeast 5 to 10 mm Algae 10 to 100 mm Protozoa 50 to 1000 mm
Viruses 0.01 to 0.2 mm
Bacteria 0.2 to 5 mm
Yeast 5 to 10 mm
Algae 10 to 100 mm
Protozoa 50 to 1000 mm
Historical Foundations of Microbiology
Biblical times. Protection from disease by isolation of lepers and burial of wastes
400 B.C. Hippocrates. Diseases could be transmitted from 1 person to another by objects such as clothing
1 B.C. Romans. Disease could be caused by invisible animals that entered body
1500's Fracastoro. Contagious disease caused by passage of unseen germs from 1 person to another
1600's Microorganisms discovered. -Leeuwenhoek made 1st microscope capable of seeing bacteria
1700's Smallpox vaccination introduced by Edward Jenner
1800's
-Cell theory proposed -Spontaneous generation disproved -Germ theory of disease proven -Introduction of sterilization and antiseptic procedures in medicine
1900's Microbiology became a scientific discipline
-Development of laboratory methods -Major disease-causing pathogens discovered -Development of chemotherapy and immunology
Spontaneous generation
-Non-living objects can give rise to living organisms
Ex. rotting meat -->maggots mud --> frogs rags --> mice plant & meat broth --> microorganisms
-Widely believed but disproved by Redi, Pasteur and others
Cell Theory
-The cell is the fundamental unit of life
-All living things are composed of cells
-All cells arise from preexisting cells
-Proposed by Schleiden and Schwann and proved by Virchow
Characteristics of a living cell
1. highly organized structure
2. obtains energy from its surroundings
3. performs chemical reactions
4. responds to environmental stimuli
5. reproduces
Germ Theory
-Infectious diseases are caused by living microorganisms called germs (Henle)
-A specific disease is caused by a specific type of microorganism
-Proved by Pasteur and Koch
Louis Pasteur 1822-1895
-Used swan-necked flasks to disprove spontaneous generation
-Discovered that fermentation of wine and beer was caused by microorganisms that lived in the absence of oxygen
-Developed vaccines for immunization against anthrax, chicken pox, cholera and rabies
-Developed pasteurization to destroy harmful microorganisms and slow spoilage in food
Robert Koch 1843-1910
-Developed methods to isolate and grow microorganisms as pure cultures
-Isolated pathogens responsible for several diseases
Anthrax, tuberculosis, cholera
-Established the criteria (called Koch's Postulates) needed to prove that an organism caused a specific disease
-Ex. Bacillus anthracis: cause of a disease known as anthrax
Koch's Postulates
1. Same microorganism is present in all cases of a disease and absent from healthy animals
2. The microorganism must be isolated from a diseased animal and grown as a pure culture 3. Inoculation of healthy animal with a pure culture must cause the disease
4. Same microorganism must be reisolated from the inoculated animal
Other Milestones During Development of (Medical) Microbiology
-Introduction of sanitary medical practices
~1850 Ignaz Semmelweis: Hand washing by physicians 1867 Joseph Lister: Use of antiseptics during surgery
~1850 Ignaz Semmelweis: Hand washing by physicians
1867 Joseph Lister: Use of antiseptics during surgery
-Chemotherapy for treatment of diseases caused by microorganisms
1908 Paul Erlich: Discovered chemical agents to cure syphilis
-Antibiotics
1929 Alexander Fleming: Discovered penicillin
Effects of the Application of Microbiology on Human Life Expectancy
Mortality
Increase mainly due to:
-Development of vaccines, antibiotics and antiseptics -Sanitary food handling -Drinking water treatment -Sewage treatment and disposal
-Development of vaccines, antibiotics and antiseptics
-Sanitary food handling
-Drinking water treatment
-Sewage treatment and disposal
Microbial Taxonomy
Naming, classifying and identifying microorganisms
1. Naming
-Linnaeus introduced binomial nomenclature -Every organism is given a unique two-part name Genus + specific epithet = species name Ex. Escherichia coli, Yersinia pestis, Bacillus anthracis
-Linnaeus introduced binomial nomenclature
-Every organism is given a unique two-part name
Genus + specific epithet = species name Ex. Escherichia coli, Yersinia pestis, Bacillus anthracis
Genus + specific epithet = species name
Ex. Escherichia coli, Yersinia pestis, Bacillus anthracis
2. Classification
-Organisms with similar characteristics are grouped together Ex. Genus Bacillus Bacillus anthracis, Bacillus subtilus, Bacillus cerus -Higher levels of organization are used to group species having similar characteristics Ex. Bacillaceae is the name of a Family that contains several different species of rod-shaped, spore-forming, Gram positive, aerobic bacteria such as Bacillus anthracis, Bacillus subtilus and Bacillus cereus
-Organisms with similar characteristics are grouped together
Ex. Genus Bacillus
Bacillus anthracis, Bacillus subtilus, Bacillus cerus
-Higher levels of organization are used to group species having similar characteristics
Ex. Bacillaceae is the name of a Family that contains several different species of rod-shaped, spore-forming, Gram positive, aerobic bacteria such as Bacillus anthracis, Bacillus subtilus and Bacillus cereus
3. Identification
-Determination of the name of an organism that has been isolated by observing its characteristics
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SIUC / College of Science / Microbiology / Microbiology 201 http://www.micro.siu.edu/micr201/chapter1N.html Last updated: Jan 20, 2007 /jdh