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Fundamentals of Microbiology. “Introduction to the biology of bacterial and archaeal organisms” Topics include microbial cell structure and function, methods of cultivation, genetics, phylogeny and taxonomy, and metabolic and genetic diversity. ” . Lecture 1. 1.1 Microbiology

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Fundamentals of Microbiology

“Introduction to the biology of bacterial and archaeal organisms”

Topics include microbial cell structure and function, methods of cultivation, genetics, phylogeny and taxonomy, and metabolic and genetic diversity.”

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Lecture 1

  • 1.1 Microbiology

  • 1.2 Microorganisms as Cells

  • 1.3 Microorganism and Their Natural Environments

  • 1.4 The Impact of Microorganisms on Humans

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What is Microbiology?

  • The science of microorganisms (very small, unicellular organisms)

  • The discipline is just over a century old

  • Has given rise to molecular biology and biotechnology

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Early Microbiology

  • 3 historical discoveries

    • Invention of the microscope

    • Disproving spontaneous generation

    • Demonstrating microorganisms cause disease

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Antoni van Leeuwenhoek

  • Inventor of the first microscope (1684)

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Spontaneous Generation

  • Spontaneous generation:

    • Life can arise from non-living materials.

  • Pasteur demonstrated that microorganisms in the air were responsible for food spoilage

    • Constructed a swan-necked flask

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Germ Theory of Disease

  • Proof that microorganisms caused disease

  • Robert Koch demonstrated that anthrax was caused by Bacillus anthracis

    • Blood from a diseased animal caused disease in a healthy animal

    • Cultivated the disease causing agent outside the animal’s body, then introduced the agent into a healthy animal which subsequently developed the disease

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Methods in Microbiology

  • Three important techniques that allowed the advanced study of microbiology:

    • Microscopy

    • Sterilisation

    • Pure culture

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Electron Microscopy

  • To visualise the internal structure - TEM

  • Electrons instead of light

  • Greater resolving power

  • Disadvantages:

    • Expensive

    • A high vacuum is required

    • Very thin sections (<100 nm thick)

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Root Nodule microscope

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Sterilisation and Pure Culture microscope

  • Culture: population of microorganisms grown under well defined conditions

    • Pure culture – one that contains one type of microorganism

    • Mixed culture – more than one microorganism

  • Need to isolate microorganism from mixed cultures

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Sterilisation Techniques microscope

  • Sterilisation using heat

    • Dry heat: 160 ºC for 2 h

    • Wet heat: Autoclave, 120 ºC

  • Sterilisation using chemicals

    • Volatile, toxic (ethylene oxide)

    • Sterilise plastics

  • Filtration

    • Pore size approx. 0.22 µm

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Pure Culture Technique microscope

  • Isolation pure cultures by plating (streak plate)

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The Microbial World microscope

  • Microorganisms are everywhere: air, soil, water, plants, animals

  • Microbial life is diverse

    • Bacteria have existed for 3x109 years

    • Evolved to flourish in the most inhospitable environments

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What are Microbes? microscope

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Microbes show morphological diversity microscope

  • Size - most are 1-5 microns, but range from 0.1 to 660 microns per cell. Viruses even smaller

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eukarotic cell microscope

prokaryotic cell

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Why study Microbiology? microscope

  • Microorganisms were the first life on earth

  • Microorganisms created the biosphere that allowed multicellular organisms to evolve

  • Multicellular organisms evolved from microorganisms

  • >50% of the biomass on earth is comprised of microorganisms

  • Microorganisms will be on earth forever

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First microorganisms? microscope

Formation of O2 atmosphere

Cyanobacterial microfossils

(oxygenic photosynthesis)


marine invertebrates


Earth formed


4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0

No free O2

Reducing environment


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Why study Microbiology? microscope

  • Our understanding of life has arisen largely from studies of microorganisms (biochemistry and genetics)

  • Studies of microorganisms continue to contribute to fundamental knowledge of life processes

  • We still know very little about the microorganisms that are present on Earth

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Figure 1.4 microscope

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Why study Microbiology? microscope

  • Health

  • Agriculture

  • Food

  • Environment

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Infectious diseases are no longer the leading cause of death in North America, due to the development and use of antimicrobial agents, and improved sanitary practices