Download spontaneous generation. - University of Colorado Boulder

History of microbiology :
Food preservation
Religion and mythology
Microscopes
Medicine
Function in the biosphere
Wine making dates to about
5000 years ago in Persia (Iran)
Also very ancient evidence in Egypt
(see overheads)
Beer and wine were ways to
preserve food...ethanol in the wine
acts as a preservative
Religion and Mythology:
Roman God of Mildew - holiday
April 25th - sacrifice a red dog
1600's
microscopes
Robert Hooke (1635-1700)
Pay attention to the history but also to
the ideas……
Prehistory?
EARLY HISTORY (food preservation):
Babylonians / yeast (a fungus)
beer over 8000 years ago.
Instructions for making beer in 6000
year-old hieroglyphics in Egypt.
Medicine:
ancient peoples realized that diseases
could be transmitted via contaminated
clothing and that humans could develop
immunity to some diseases.
Varro (Roman) proposed that diseases
were caused by tiny animals.
Dark Ages = big zero for science
Anton von Leeuwenhoek
(1632-1723) Dutch draper
Used magnifying glasses to inspect cloth.
Started grinding lenses as a past-time
30x magnification
cork cells (L. cellulae, meaning small rooms)
(see overhead)
first to observe microscopic fungi.
Fashioned a simple
microscope by
grinding grains of
sand.
Items could be
magnified 300 times
or more.
Looked at water in his microscope and saw:
Where did the “animacules” come from???
Took clean dish, caught some rain - no
critters!
Not until the fourth day did he observe things
swimming in the water.
Tiny “animacules”
Louis Pasteur
Looked in other places
The plaque between his
teeth!
Saw lots and lots of critters
Found a guy who had never cleaned his teeth
in his whole life - he had tons!
(1822-1895) French
- chemist
Asked to help out at a winery - some vats were
“sick” - not making any alcohol.
Pasteur took samples from the sick vats and
from some healthy vats.
In the healthy ones, he
saw globules -->
and realized they were
yeast.
In the liquid from the “sick” wine, he did not see
any yeast, just small rod-shaped things
swimming about.
He also noticed the smell of sour milk from
these vats.
Pasteur reasoned that the yeasts must
ferment the juice into alcohol, but that the
bacteria fermented the juice into lactic
acid instead.
He put on a “show”. He said to the
winemakers,
“Bring me a half dozen bottles of wine that
has gone bad with different sicknesses. Do
not tell me what is wrong with them, and I’ll
tell you what ails them without tasting them.”
The winemakers tried to fool him and slipped
in a bottle of perfectly good wine…
But, Pasteur got them all right.
Where were these microbes coming from?
Now the issue was how to keep these
microbes out of the wine.
At this point in time, people still believed in
the theory of
They found that it simply took heating the wine
gently - below the point of boiling - to keep the
microbes out.
SPONTANEOUS GENERATION.
This process is of course now known as
Pasteurization.
For example, at the time, this was a “recipe”
for mice:
“Place a dirty shirt or some rags in an open pot or barrel
containing a few grains of wheat or some wheat bran, and in 21
days, mice will appear. There will be adult males and females
present, and they will be capable of mating and reproducing
more mice.”
Microbes were thought to be the result
of disease and not the cause..........
Theologians also had big problems with
spontaneous generation
Francesco Redi (Italian, 1626-1697)
meat experiment....good example of an
experiment.......
Even with evidence like that,
many still thought microbes were so
simple that they didn't have to arise
from other microbes.
How to prove that simple microbes don’t
arise via spontaneous generation?
hermetically sealed vessels didn’t
allow in the
"vital force" = oxygen
Pasteur’s friend, Professor Balard, came
in and gave him the idea for this:
Also filtered air through sterile cotton = caught lots of microbes
Thus, Pasteur put an end to the idea that
there was some "vital force" in air, and he
was the first to show that some bacteria
don't even need oxygen.
anaerobes (literally (G), without air)
aerobes can use O2 in their metabolism.
More Pasteur accomplishments:
• saved the vinegar industry
• saved the silkworm industry
• the first vaccine for rabies
• tried to improve the quality of French beer
(but he really didn’t like beer……..)
Back to Pasteurization for a minute…
Robert Koch
(1843-1910)
Some things were hard to sterilize especially
if they had touched soil
Koch was a German physician in the late
1800’s.
Tyndall (1820-1893)
Cohn (1828-1898)
In his spare time, he began to study anthrax
a disease of cattle and sheep and sometimes
people.
-endospore containing cells.....
Bacillus (aerobes)
Clostridium (anaerobes).
autoclave and pressure cooker (ca. 1880)
Koch then went and got tons of blood from
healthy cattle and sheep.
None of them had the bacilli in their blood.
He began to experiment with mice, injecting
blood from sick cows into them.
Sure enough…the mice got sick and when he
looked at their blood under the microscope,
he found the bacilli.
He noticed long threads in the blood of cattle
that had died from the disease - they were the
bacilli that other people had announced were
the cause of the disease - but no one had proven
it.
Still, he wasn’t satisfied. He wanted to be
able to prove that the rods, the bacteria, grew
inside the mouse.
He thought and thought…
He finally put some blood
from a sick mouse into the
aqueous humor from an ox’s
eye onto a slide.
Lo and behold - the bacilli began to multiply!!
Koch continued to keep this “culture” of
bacilli growing, every day repeating his
experiment by adding a tiny bit of the
infected drop into a new clean one.
After eight days, he took a drop of this
culture - one that had not been inside a
mouse, and injected it into a fresh, healthy
mouse.
The next day…. The mouse was dead!
He looked at the mouse’s spleen under the
microscope and guess what he saw!
the same bacilli.
Fannie Hesse discovered that agar could be used as
Koch and his postulates:
1) The disease organism must be present
in sick animals and not present in healthy
ones.
2) The organism must be cultivated in pure
culture away from the patient’s body.
3) This culture, when inoculated into a
healthy animal should produce the
characteristic symptoms of the disease.
4) The organism can be re-isolated from
these animals.
MICROBES IN NATURE
a solidifying agent for bacteriological media in 1882.
This greatly accelerated the development of
Microbiology.
Non-medical Micro.
Paul Ehrlich and chemotherapy. Noticed bacteria
picked up certain stains more readily than did
mammalian tissue. Success was with Salvarsan that
killed Trypanosomes and Treponema pallidum.
Early chemo-therapeutic agents often had nasty side
effects. It wasn't until the mid-1900s that very specific
antibiotics were developed (more about that later).
Enrichment culture technique......
use media that is designed to isolate
specific metabolic groups from nature
Sergi Winogradsky (1856-1953)
Winogradsky was the first to describe sulfur
oxidizing bacteria such as Beggiatoa.
These organisms are chemoautotrophs (fix CO2
without photosynthesis).
Martinus Beijerinck (1851-1931)
e.g.
N2-fixing bacteria and many other discoveries.
1922 Kluyver replaced Beijerinck at the University of Delft
and ushered in the modern era of comparative biochemistry.
Kluyver and van Niel proposed that all respiratory reactions
(aerobic and anaerobic) could be summarized using the simple
formula:
AH2 + B -----> A + BH2
For Beggiatoa
SH2 + O2 -----> So + H2O
They also summarized all photosynthetic reactions with:
CO2 + 2 H2A ----> CH2O (cell material) + H2O + 2 A
We will come back to these reactions in a few weeks.