Transcript Fundamentals of Microbiology

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
• 1.2 Microorganisms as Cells
• 1.3 Microorganism and Their Natural
Environments
• 1.4 The Impact of Microorganisms on
Humans
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
Early Microbiology
• 3 historical discoveries
– Invention of the microscope
– Disproving spontaneous generation
– Demonstrating microorganisms cause disease
Antoni van Leeuwenhoek
• Inventor of the first microscope (1684)
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
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
Methods in Microbiology
• Three important techniques that allowed the
advanced study of microbiology:
– Microscopy
– Sterilisation
– Pure culture
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)
Figure 1.2a
Bacterial cells viewed with light microscope
Figure 1.2b Bacterial cell viewed with electron microscope
Root Nodule
Bacteroids within Root Nodule
Sterilisation and Pure Culture
• 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
Sterilisation Techniques
• 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
Pure Culture Technique
• Isolation pure cultures by plating (streak plate)
The Microbial World
• 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
What are Microbes?
Microbes show morphological diversity
• Size - most are 1-5 microns, but range from 0.1 to
660 microns per cell. Viruses even smaller
eukarotic cell
prokaryotic cell
Why study Microbiology?
• 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
First microorganisms?
Earth formed
4.5
Formation of
O2 atmosphere
Cyanobacterial microfossils
(oxygenic photosynthesis)
4.0
No free O2
Reducing environment
3.5
3.0
2.5
BYA
2.0
1.5
algae,
marine invertebrates
1.0
0.5
insects
mammals
0
Why study Microbiology?
• 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
Figure 1.4
Why study Microbiology?
•
•
•
•
Health
Agriculture
Food
Environment
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