Microbiology

Microbiology

* The study of organisms too small to be seen without magnification
* Microorganisms include:

o viruses
o protozoa
o helminths (worms)

Branches of Study Within Microbiology


* Public health microbiology and epidemiology
* Food, dairy and aquatic microbiology
* Genetic engineering and recombinant DNA technology

Microbes are Involved in
* Nutrient production and energy flow
* Biotechnology
o production of foods, drugs and vaccines
* Bioremediation

Infectious Diseases
* Nearly 2,000 different microbes cause diseases.
* 10 Billion new infections/year worldwide
* 13 Million deaths from infections/year worldwide

Characteristics of Microbes

* Procaryotes and eukaryotes
o procaryote – microscopic, unicellular organisms, lack nuclei and membrane-bound organelles
o eucaryote – unicellular (microscopic) and multicellular, nucleus and membrane-bound organelles
* Viruses
o acellular, parasitic particles composed of a nucleic acid and protein

Basic cell and virus structures
Microbial Dimensions

* Procaryotes are measured in micrometers.
* Viruses in nanometers
* Helminths are measured in millimeters.

Historical Foundations of Microbiology
* 300 years of contributions by many
* Prominent discoveries include:
o microscopy
o scientific method
o development of medical microbiology
o microbiology techniques

Antonie van Leeuwenhoek

* Dutch linen merchant
* First to observe living microbes
* Single-lens magnified up to 300X

Spontaneous Generation
Early belief that some forms of life could arise from vital forces present in nonliving or decomposing matter (flies from manure, etc)
Scientific Method
* A general approach to explain a natural phenomenon
* Form a hypothesis - a tentative explanation that can be supported or refuted by observation and experimentation
* A lengthy process of experimentation, analysis and testing either supports or refutes the hypothesis.
* Results must be published and repeated by other investigators.
* If hypothesis is supported by a growing body of evidence and survives rigorous scrutiny, it moves to the next level of confidence - it becomes a theory.
* If evidence of a theory is so compelling that the next level of confidence is reached - it becomes a Law or principle.

Discovery of Spores and Sterilization

* John Tyndall and Ferdinand Cohn each demonstrated the presence of heat resistant forms of some microbes.
o Cohn determined these forms to be
* requires the elimination of all life forms including endospores and

Development of Aseptic Techniques

* Dr. Oliver Wendell – observed that mothers of home births had fewer infections than those who gave birth in hospital
* Dr. Ignaz – correlated infections with physicians coming directly from autopsy room to maternity ward
* Joseph – introduced aseptic techniques reducing microbes in medical settings to prevent infections
o involved disinfection of hands using chemicals prior to surgery
o use of heat for sterilization


Pathogens and Germ Theory of Disease

* Many diseases are caused by the growth of microbes in the body and not by sins, bad character, or poverty, etc.
* Two major contributors:

Louis Pasteur
* Showed microbes caused fermentation and spoilage
* Disproved spontaneous generation of microorganisms
* Developed pasteurization
* Demonstrated what is now known as Germ Theory of Disease
* Developed a rabies vaccine

Robert Koch

* 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

Taxonomy: Organizing, Classifying and Naming Living Things
* Formal system originated by Carl von Linné (1701-1778)

* Concerned with:
o classification – orderly arrangement of organisms into groups
o nomenclature – assigning names
o identification – discovering and recording traits of organisms for placement into taxonomic schemes

Levels of Classification
* Domain - Archaea, Bacteria & Eukarya
* Kingdom - 5
* Phylum or Division
* Class
* Order
* Family
* Genus
* species

Naming Micoorganisms

* Binomial (scientific) nomenclature
* Gives each microbe 2 names:
o Genus - noun, always capitalized
o species - adjective, lowercase
* Both italicized or underlined
o Staphylococcus aureus (S. aureus)
o Bacillus subtilis (B. subtilis)
o Escherichia coli (E. coli)

Evolution - living things change gradually over millions of years

* Changes favoring survival are retained and less beneficial changes are lost.
* 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.

* Bacteria - true bacteria, peptidoglycan
* Archaea - odd bacteria that live in extreme environments, high salt, heat, etc.
* Eukarya- have a nucleus and organelles

Woese-Fox System
Microbiology.ppt