Biology 732Health Science Microbiology

Spring ‘08

Kurt Smartkasmart1@dmacc.edu

-Iowa State University – PhD in Microbiology (In progress)

-The University of Mississippi – MS in Biology (’08)

-California State University, Chico – BS in Microbiology (’05)

Random microbe of the week!!!

Every week an interesting microbe or an interesting story about a particular microbe will be discussed for your personal enjoyment(Super terrific happy random microbe of the week is for your listening pleasure only and will not be included on exams. Please feel free to sit back, relax, and hear an interesting tale)

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Microbiology

• The study of organisms too small to be seen without magnification

• Microorganisms include:– Bacteria– Viruses– Fungi– Protozoa – Helminths (worms) – Algae

Some different types of microorganisms

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Microbial Dimensions

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Lifestyles of Microorganisms• Majority are harmless and beneficial to

humans (10x more bacteria than human cells associated w/ human body - approximately 1014 vs 1013 cells)

• Many microorganisms have close associations with other organisms(e.g. Host-parasite, mutualism, commensalism)

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Human Uses of Microorganisms

• Biotechnology– Production of foods (bread, cheese, yogurt,

various beverages, etc.)– Drugs and vaccines

• Genetic engineering– Recombinant DNA

• Bioremediation (removal of contaminants from an environment)

Microbes at Work

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Infectious Diseases(emphasis of this course)

• Pathogens: Microorganisms that do harm (from Greek ‘pathos’, meaning ‘suffering’)

• Nearly 2,000 different microbes cause diseases

• 10 B new infections/year worldwide

• 12 M deaths from infections/year worldwide

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Characteristics of Microbes

• Two cell types – Prokaryotes – unicellular organisms, lack nuclei

and membrane-bound organelles– Eukaryotes – unicellular (microscopic) and

multicellular, contain nucleus and membrane-bound organelles

• And then Viruses – Acellular, parasitic particles composed of nucleic

acid and protein (commonly accepted that they are non-living)

Basic structure of cells and viruses

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Anton van Leeuwenhoek (1632-1723)

• Dutch linen merchant• First to observe living

microbes• Called them “animalcules” • Single-lens magnified up to

300X

Insert figure 1.8

History of Microbiology

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Insert figure 1.9 (a)microscope

Spontaneous Generation

- Early belief that some forms of life could arise from vital forces present in nonliving or decomposing matter (flies from manure, etc.)

- No purpose in considering how diseases were transmitted or how they could be controlled

The Development of Medical Microbiology

• Early experiments led to the realization that microbes are everywhere

• This discovery led to immediate applications in medicine– Germ theory of disease: the theory that microbes

may be responsible for diseases in humans– Resulted in the use of sterile, aseptic, and pure

culture techniques

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Louis Pasteur (1822-1895)

• Showed microbes caused fermentation and spoilage

• Disproved spontaneous generation of microorganisms

• Developed pasteurization• Rabies vaccine

Insert figure 1.11

Rabies Vaccine - attenuated virus by

multiple transmission through different species

- tested on 9 yr old boy bitten by rabid dog

- 13 injections given (one per day)

- vaccine worked

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Development of Aseptic Techniques

• The human body is a source of infection– Dr. Oliver Wendell Holmes – observed that

mothers of home births had fewer infections than those who gave birth in hospitals

– Dr. Ignaz Semmelweis – correlated infections with physicians coming directly from autopsy room to maternity ward

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• Joseph Lister – introduced aseptic techniques reducing microbes in medical settings and preventing wound infections– Involved disinfection of hands using chemicals

prior to surgery– Use of heat for sterilization

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Discovery of Spores and Sterilization

• John Tyndall and Ferdinand Cohn each demonstrated the presence of heat resistant forms of some microbes.– Cohn determined these forms to be heat-

resistant bacterial endospores.

• Sterility requires the elimination of all life forms including endospores and viruses.

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Robert Koch (1843-1910)

• Established Koch’s postulates - a sequence of experimental steps that verified the germ theory

• Identified cause of anthrax, TB, and cholera

• Developed pure culture methods

Insert figure 1.12

Koch’s postulates (1890)

Taxonomy

• Taxonomy: organizing, classifying, and naming living things– Formal system originated by Carl von Linné

• Concerned with: – Classification – orderly arrangement of organisms into

groups

– Nomenclature – assigning names

– Identification – determining and recording traits of organisms for placement into taxonomic schemes

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Levels of Classification• Domain - Archaea, Bacteria, & Eukarya• Kingdom• Phylum or Division• Class • Order• Family• Genus• Species

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Assigning Specific Names

• Binomial (scientific) nomenclature • Gives each microbe 2 names:

– Genus - capitalized– species - lowercase

• Both italicized or underlined– Staphylococcus aureus (S. aureus)

• Inspiration for names is extremely varied and often imaginative

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The Origin and Evolution of Microorganisms

• Phylogeny: natural relatedness between groups of organisms

• Evolution– All new species originate from preexisting species

– Closely related organism have similar features because they evolved from common ancestral forms

• Evolution usually progresses toward greater complexity

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3 Domains

• Bacteria – prokaryotic organisms• Archaea - prokaryotes that are typically

thought of living in extreme environments, (high or low temp or pH, high salt, pressure, etc.)

• Eukarya - have a nucleus and membrane bound organelles

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