General Microbiology
Dr Jalees Khalid Khan
Assistant Prof Microbiology
KEMU
As you can see
Sometimes there is a blur between
what we do in lab and what we do in
class.
What is a Microbe
• Smaller than 0.1mm
• Includes bugs, things, germs, viruses,
protozoan, bacteria, animalcules, small
suckers
Nomenclature
• Carolus Linnaeus (1735)
• Genus species
• By custom once mentioned can be
abbreviated with initial of genus followed
by specific epithet. E. coli
• When two organisms share a common
genus are related.
Why study Microbiology
• Microbes are related to all life.
– In all environments
– Many beneficial aspects
– Related to life processes (food web, nutrient
cycling)
– Only a minority are pathogenic.
– Most of our problems are caused by microbes
EID’s
• Emerging infectious diseases
– Weapons of mass destruction
– New evolutionary features
– Response to man encroaching on the
environment
• Can you name an example?
Microbes in research
• 10 trillion human cells
10x this number
microbes
• Easy to grow
• Biochemistry is
essentially the same
• Simple and easy to
study
Biotechnology
• Use of biological systems to produce useful
items
• The use of biological information to make
things or improve the human condition
Diversity of Microbes
• Bacteria-single celled prokaryotes
• Protozoa-eukaryotic, single celled, colonial,
many ways of nutrition
• Fungi- absorb nutrients, single celled
filamentous
• Viruses-acellular entities
• Others- worms, insects
Bacteria
• Prokaryotes
• Peptidoglycan cell
walls
• Binary fission
• For energy, use
organic chemicals,
inorganic chemicals,
or photosynthesis
Figure 1.1a
Archaea:
• Prokaryotic
• Lack peptidoglycan
• Live in extreme
environments
• Include:
– Methanogens
– Extreme halophiles
– Extreme thermophiles
Halobacteria not
from book
• Eukaryotes
• Chitin cell walls
• Use organic
chemicals for energy
• Molds and
mushrooms are
multicellular
consisting of masses
of mycelia, which are
composed of
filaments called
hyphae
• Yeasts are unicellular
Fungi
Figure 1.1b
Protozoa
• Eukaryotes
• Absorb or ingest
organic chemicals
• May be motile via
pseudopods, cilia, or
flagella
• Most free some
parasites
Figure 1.1c
Algae
• Eukaryotes
• Cellulose cell walls
• Use photosynthesis for
energy (primary
producers)
• Produce molecular
oxygen and organic
compounds
• Metabolically diverse
Figure 1.1d
Viruses
• Acellular
• Consist of DNA or
RNA core
• Core is surrounded by
a protein coat
• Coat may be enclosed
in a lipid envelope
• Viruses are replicated
only when they are in
a living host cell
Figure 1.1e
Multicellular Animal Parasites
• Eukaryote
• Multicellular
animals
• Parasitic
flatworms and
round worms are
called helminths.
• Microscopic
stages in life
cycles.
Figure fluke
The Scientific Method
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Make an observation
Make a hypothesis
Test the hypothesis
Draw your conclusions
repeat
Requirements for Scientific
methods
• Single variables
• Experimental controls
• How can this be used to discover things?
• Does HIV cause AIDS??? Discuss
Knowledge of microorganisms:
• Allows humans to
– Prevent food spoilage
– Prevent disease occurrence
– Others?
• Led to aseptic techniques to prevent
contamination in medicine and in
microbiology laboratories.
Universal precautions set up by
CDC
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Use gloves, gowns, masks and goggles
Minimize risk of needle sticks
Disinfections procedure
Preventative treatment after exposure
Reduce risk
Treat all patients the same
HBV greater risk than HIV
The Debate Over Spontaneous
Generation
• The hypothesis that living organisms arise from
nonliving matter is called spontaneous
generation. According to spontaneous
generation, a “vital force’ forms life.
• The Alternative hypothesis, that the living
organisms arise from preexisting life, is called
biogenesis.
Evidence Pro and Con
• 1668: Francisco Redi filled six jars with
decaying meat.
Conditions
Results
3 jars covered with fine
net
3 open jars
No maggots
Maggots appeared
From where did the maggots come?
What was the purpose of the sealed jars?
Spontaneous generation or biogenesis?
Evidence Pro and Con
• 1765: Lazzaro Spallanzani boiled nutrient
solutions in flasks.
Conditions
Results
Nutrient broth placed in
No microbial growth
flask, heated, then sealed
Spontaneous generation or biogenesis?
The Theory of Biogenesis
• Pasteur’s S-shaped flask kept microbes out
but let air in.
Figure 1.3
Where is Microbiology currently
being practiced? I.e. jobs
• Put your Choice here
A timeline of Microbiology
• Fig 1.4
• Some highlights
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1665 Hooke
1673 van Leeuwenhoek’s microscopes
1735 Linnaeus Nomenclature
1798 Jenner vaccine
1857 Pasteur Fermentation
1876 Koch germ theory of disease
The Golden Age of
Microbiology
• 1857-1914
• Beginning with Pasteur’s work,
discoveries included the relationship
between microbes and disease,
immunity, and antimicrobial drugs
Fermentation and Pasteurization
• Pasteur showed that microbes are responsible for
fermentation.
• Fermentation is the conversation of sugar to
alcohol to make beer and wine.
• Microbial growth is also responsible for spoilage
of food.
• Bacteria that use alcohol and produce acetic acid
spoil wine by turning it to vinegar (acetic acid).
Fermentation and Pasteurization
• Pasteur demonstrated that
these spoilage bacteria
could be killed by heat that
was not hot enough to
evaporate the alcohol in
wine. This application of a
high heat for a short time is
called pasteurization.
Figure 1.4
The Germ Theory of Disease
• 1835: Agostino Bassi showed a silkworm disease
was caused by a fungus.
• 1865: Pasteur believed that another silkworm
disease was caused by a protozoan.
• 1840s: Ignaz Semmelwise advocated hand
washing to prevent transmission of puerperal
fever from one OB patient to another.
The Germ Theory of Disease
• 1860s: Joseph Lister used a chemical disinfectant
to prevent surgical wound infections after
looking at Pasteur’s work showing microbes are
in the air, can spoil food, and cause animal
diseases.
• 1876: Robert Koch provided proof that a
bacterium causes anthrax and provided the
experimental steps, Koch’s postulates, used to
prove that a specific microbe causes a specific
disease.
The Birth of Modern
Chemotherapy
• Treatment with chemicals is chemotherapy.
• Chemotherapeutic agents used to treat infectious
disease can be synthetic drugs or antibiotics.
• Antibiotics are chemicals produced by bacteria
and fungi that inhibit or kill other microbes.
• Quinine from tree bark was long used to treat
malaria.
• 1910: Paul Ehrlich developed a synthetic arsenic
drug, salvarsan, to treat syphilis.
• 1930s: Sulfonamides were synthesized.
The Birth of Modern
Chemotherapy
• 1928: Alexander
Fleming discovered
the first antibiotic.
• He observed that
Penicillium fungus
made an antibiotic,
penicillin, that killed S.
aureus.
• 1940s: Penicillin was
tested clinically and
mass produced.
Similar to
Figure 1.5
Modern Developments in
Microbiology
• Bacteriology is the study of bacteria.
• Mycology is the study of fungi.
• Parasitology is the study of protozoa and
parasitic worms.
• Recent advances in genomics, the study of an
organism’s genes, have provided new tools for
classifying microorganisms.
• Proteomics is looking at the gene products
Selected Novel Prizes in
Physiology
or
Medicine
von Behring
Diphtheria antitoxin
1901*
1902
Ross
Malaria transmission
1905
Koch
TB bacterium
1908
Metchnikoff
Phagocytes
1945
Fleming, Chain, Florey
Penicillin
1952
Waksman
Streptomycin
1969
Delbrück, Hershey, Luria
Viral replication
1987
Tonegawa
Antibody genetics
1997Prusiner
Prions
2003Agre, Mackirron
water and ion channels
2005 Marshall, Warren
Helicobacter and ulcers
2008 Hausen
Papilloma and viruses
* The first Nobel Prize in Physiology or Medicine.
Principles of Microscopy
• Metric units (table 3.1)
– Micrometer
– Nanometer
– angstrom
Compound light microscopy
• Basic parts
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Eyepieces (ocular lens)
Base
Condenser
Iris diaphragm
Objective lens
Body tube
Mechanical stage
Adjustment knobs
Magnification
• Calculation:
– Objective power x ocular power = total power
• Parafocial
• Paracentric
• Microscopic measurement
– Micrometer? Why must we calibrate it?
Modern Developments in
Microbiology
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Diagnostics
Prevention
Use as a tool
Surveys and vigilance
What you should know?
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What are microbes?
What types of microbes?
Some history Highlights
The Magic Bullet
Microbes and human Welfare
Microbes and Human Disease
The CDC