Download MICRO-Chapter One Notes

Micro – Chapter One
Scope & History of Microbiology
. . . my work, which I've done for a long time, was not pursued in
order to gain the praise I now enjoy, but chiefly from a craving
after knowledge, which I notice resides in me more than in most
other men. And therewithal, whenever I found out anything
remarkable, I have thought it my duty to put down my discovery
on paper, so that all ingenious people might be informed thereof.
Antony van Leeuwenhoek. Letter of June 12, 1716
Explain why the study of
microbiology is important.
Microorganisms have always been and will
continue to be a major influence in our lives.
Because of their relationship to our health
and welfare, it is essential that we
understand their characteristics.
By studying their features we can also gain
insight into the processes and relationships
of all life forms.
Outline the scope of
microbiology.
The study of microbes, but it is not just the study of bacteria…
It also includes the study of viruses, algae, protists, fungi,
and even the helminths (intestinal parasites).
Also included are a great variety of
diverse fields such as immunology
and genetics that indirectly or
directly relate to these microbes.
There is tremendous diversity in
this field of science.
Detail some of the major events in
the early history of microbiology.
The Greeks, Romans, and Jews all
contributed to early understandings
of the spread of disease.
Diseases such as bubonic plague,
smallpox, and syphilis caused
millions of deaths because of the
lack of understanding of how to
control or treat the infections.
Also, the making of beer, bread,
wine, and cheese are ancient
practices which all rely on the
actions of microorganisms (yeasts).
Plague buboe
Smallpox
Syphilis (secondary)
a.k.a. “Large Pox”
The development of high–
quality lenses (it was his
hobby!) by Leeuwenhoek
(even though his was not the
first microscope) made it
possible to observe
microorganisms and later to
formulate the cell theory.
Cephalodella Video No. 1
About 200 species belong to this genus.
They are found in many habitats including
soft sandy substrates called psammon.
They are fast swimmers with a typical
turning movement. Some are raptorial. The
shape of the toes, their proportion to body
length, and the type of trophi (chitinous
jaws) are important characteristics for
identifying individual species.
These bell-shaped ciliates live in fresh or salt
water attached by a slender stalk to aquatic
plants, surface scum, submerged objects, or
aquatic animals. The stalk contains a
contractile fibril called a myoneme that
causes it to coil like a spring when
stimulated. Vorticella eat bacteria and small
protozoans, using their cilia to sweep their
prey into mouth-like openings.
Vorticella Video No. 1
explain the germ theory of disease and
outline the historical developments that
led to its formulation.
The germ theory of disease states that
microorganisms (germs) can invade other
organisms and cause disease.
Idea of spontaneous generation (that
living things arise out of nonliving
materials, with the help of a “life force” in
the air) had to first be disproved.
Enter in the clever studies of Redi and
Spallanzani…
Redi showed that flies must touch the meat
(Redi had did not see the eggs, but he
presumed they were there) to make
maggots, and Spallanzani boiled gravy and
sealed the flasks while they were boiling to
show that when they cooled no
animalcules would ever appear.
There were still doubters, so now enter in
Pasteur and his swan necked flasks…boil
the liquid to kill everything, and yet air can
still get in, and still no life forms. Ha!
Koch's postulates:
• the causative agent must be present in every case of the disease
and must not be present in healthy animals.
• the pathogen must be isolated from the diseased host animal and
must be grown in pure culture.
• the same disease must be produced when microbes from the pure
culture are inoculated into healthy susceptible animals.
• the same pathogen must be recoverable once again from this
artificially infected animal and it must be able to be grown in pure
culture.
Koch's postulates not only proved the germ theory but also gave a
tremendous boost to the development of microbiology by stressing a
laboratory culture and identification of microorganisms.
E.Coli
Legionaires Disease
staphylococcus
Aseptic Technique-The handling of objects so as to maintain sterility.
Joseph Lister made the link between lack
of cleanliness in hospitals and deaths after
operations, starting in the late 1860’s.
For this reason, he is known as the
‘Father of Antiseptic Surgery’.
Lister believed that it was microbes
carried in the air that caused diseases to
be spread in wards.
highlight the events that marked the emergence of
immunology, virology, chemotherapy, genetics, and
molecular biology as branches of microbiology.
-Immunology: smallpox vaccine by Jenner
-Virology: discovery of pathogenic, filterable agents by Beijerinck &
Iwanowski
-Chemotherapy (using chemical substances to treat or cure diseases):
pioneered by Ehrlich and Fleming with the discovery of sulfa drugs
and antibiotics
-Genetics and Molecular Biology: Griffith’s discovery of
transformation and Avery who demonstrated that this genetic change
was due to DNA
Edward Jenner was a country doctor who had studied nature and his natural surroundings since
childhood. He had always been fascinated by the rural old wives tale that milkmaids could not get
smallpox. He believed that there was a connection between the fact that milkmaids only got a weak
version of smallpox – the non-life threatening cowpox – but did not get smallpox itself. A milkmaid
who caught cowpox got blisters on her hands and Jenner concluded that it must be the pus in the
blisters that somehow protected the milkmaids.
Jenner decided to try out a theory he had developed. A young boy called James Phipps would be
his guinea pig. He took some pus from cowpox blisters found on the hand of a milkmaid called
Sarah. She had milked a cow called Blossom and had developed the tell-tale blisters. Jenner
‘injected’ some of the pus into James. This process he repeated over a number of days gradually
increasing the amount of pus he put into the boy. He then deliberately injected Phipps with
smallpox. James became ill but after a few days made a full recovery with no side effects. It seemed
that Jenner had made a brilliant discovery.
He then encountered the prejudices and conservatism of the medical world that dominated
London. They could not accept that a country doctor had made such an important discovery and
Jenner was publicly humiliated when he brought his findings to London. However, what he had
discovered could not be denied and eventually his discovery had to be accepted – a discovery that
was to change the world.
So successful was Jenner's discovery, that in 1840 the government of the day banned any other
treatment for smallpox other than Jenner's.
Jenner did not patent his discovery as it would have made the vaccination more expensive and out
of the reach of many. It was his gift to the world. CREDIT:http://www.historylearningsite.co.uk/edward_jenner.htm
On 12th February 1892, Dmitri
Iwanowski, a Russian botanist,
presented a paper to the St.
Petersburg Academy of Science
which showed that extracts from
diseased tobacco plants could
transmit disease to other plants after
passage through ceramic filters fine
enough to retain the smallest known
bacteria. This is generally recognized
as the beginning of Virology.
Unfortunately, Iwanowski did not
fully realize the significance of these
results.
(from: http://www.microbiologybytes.com/introduction/introduction.html)
A few years later, in 1898,
Martinus Beijerinick
confirmed & extended
Iwanowski's results on
tobacco mosaic virus & was
the first to develop the modern
idea of the virus, which he
referred to as contagium
vivum fluidum ('soluble living
germ').
(CREDIT: http://www.microbiologybytes.com/introduction/introduction.html)
The "magic bullet" concept comes from the
experience of 19th century German chemists
with selectively staining tissues for
histological examination, and in particular,
selectively staining bacteria.
In the late 1890’s Paul Ehrlich reasoned that
if a compound could be made that selectively
targeted a disease causing organism, then a
toxin for that organism could be delivered
along with the agent of selectivity. Hence, a
"magic bullet" would be created that killed
only the organism targeted.
CREDIT: http://en.wikipedia.org/wiki/Paul_Ehrlich
Alexander Fleming’s observations in 1928 that a neglected colony of
Staphylococcus bacteria had been invaded by a fungus that seemed to kill
the bacteria led to the isolation and purification of what we now know as
Penicillin.
German scientists were making synthetic antibiotics (sulfa drugs) in the
late 1930’s, but they didn’t work on all bacterial infections (nor did
penicillin).
Penicillium culture
Staphylococcus culture