Chapter 1 The Main Themes of Microbiology

2 Microbiology  Microbiology is a specialized area of biology that deals with living organisms ordinarily too small to be seen without magnification  Such microscopic organisms are collectively referred to as microorganisms or microbes  Microorganisms include:  bacteria  viruses  fungi (microscopic, fungal spores)  protozoa (unicellular)  helminths (parasitic worms)  algae

3 Microbiology  Microbiology is one of the largest and most complex of the biological sciences because it integrates subject matter from many diverse disciplines  Microbiologists study every aspect of microbes  their genetics  their physiology  characteristics that may be harmful or beneficial  the ways they interact with the environment and with their hosts  their uses in industry and agriculture

4 Microbiological Endeavors-A sampler  Immunology  Public health microbiology and epidemiology  Food, dairy and aquatic microbiology  Agricultural microbiology  Biotechnology  Genetic engineering and recombinant DNA technology

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9 Specialty Professions of Microbiology  Geomicrobiologists - focus on the roles of microbes in the development of earth’s crust  Marine microbiologists - study the oceans and its smallest inhabitants  Pharmaceutical microbiologists - discover and develop new drugs from microbial sources  Nurse epidemiologists - analyze the occurrence of infectious diseases in hospitals  Astrobiologists - study the possibilities of organisms in space

10 The Impact of Microbes on Earth  For billions of years, microbes have extensively shaped the development of the earth’s habitats and the evolution of other life forms  Procaryotes (no nucleus) appeared first  Eucaryotes (with nucleus) appeared later  Microbes can be found nearly everywhere, from the deep in the earth’s crust, to the polar ice caps and oceans, to the bodies of plants and animals

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12 Microbial Involvement  Nutrient production (photosynthesis)  Energy flow through the earth’s ecosystems  Decomposition and nutrient recycling  Biotechnology  production of foods, drugs and vaccines  Genetic engineering  Bioremediation  Infectious diseases

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15 Infectious Diseases and the Human Condition  Humanity is plagued by nearly 2,000 different microbes that can cause various types of diseases - pathogens  Infectious diseases still devastate human populations worldwide, despite significant strides in understanding and treating them  10 B new infections/year worldwide (WHO)  12 M deaths from infections/year worldwide

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18 The General Characteristics of Microorganisms  Prokaryotes and eukaryotes  prokaryote – microscopic, unicellular organisms, lack nuclei and membrane-bound organelles  eukaryote – unicellular (microscopic) and multicellular, nucleus and membrane-bound organelles  Viruses  acellular, parasitic particles composed of a nucleic acid and protein

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21 Microbial Dimensions  Prokaryotes are measured in micrometers (10 -6 m)  Viruses in nanometers (10 -9 m)  Helminths are measured in millimeters (10 -3 m)

22 Insert figure 1.7 measurements

23 Lifestyles of Microorganisms  The majority of microorganisms live a free existence in habitats such as soil and water, where they are relatively harmless and often beneficial  A free-living organism can derive all required foods and other factors directly from a nonliving environment  Many microorganisms have close associations with other organisms  parasites - harbored and nourished in the bodies of larger organisms called hosts  a parasite’s actions may cause damage to its host through infection and disease

24 Historical Foundations of Microbiology  300 years of contributions by many microbiologists  Prominent discoveries include:  microscopy  The rise of the scientific method  development of medical microbiology  germ theory  modern microbiological techniques

25 Antonie van Leeuwenhoek ( )  Dutch linen merchant  First to observe living microbes  Single-lens magnified up to 300X Insert figure 1.8

26 Insert figure 1.9 (a) microscope

27 Spontaneous Generation  Early belief that some forms of life could arise from vital forces present in nonliving or decomposing matter (flies from rotten meat, mushrooms on rotting tree, rats and mice from piles of litter. etc)

28 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

29 Scientific Method  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

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31 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 endospores  Sterility requires the elimination of all life forms including endospores and viruses

32 Development of Aseptic Techniques  Dr. Oliver Wendell Holmes – observed that mothers of home births had fewer infections than those who gave birth in hospital  Dr. Ignaz Semmelweis – correlated infections with physicians coming directly from autopsy room to maternity ward

33 Development of Aseptic Techniques  Joseph Lister – introduced aseptic techniques reducing microbes in medical settings to prevent infections  involved disinfection of hands using chemicals prior to surgery  use of heat for sterilization

34 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 and Robert Koch

35 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 Insert figure 1.11

36 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 Insert figure 1.12

37 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 – discovering and recording traits of organisms for placement into taxonomic schemes

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

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

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41 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 organisms have similar features because they evolved from common ancestral forms  Evolution usually progresses toward greater complexity

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43 3 Domains  Bacteria - true bacteria, peptidoglycan  Archaea - odd bacteria that live in extreme environments, high salt, heat, etc.  Eukarya- have a nucleus and organelles

44 Insert figure 1.15 Woese-Fox System