Transcript Plate 4

Plate 4
Germ Theory
Miasma
During the 1800s, the
miasma theory of disease
dominated medical thought
It was believed that
disease could be caused
by the foul smells created
by decomposing bodies,
food, human waste, marsh
gases and general filth.
Road sweeping was one
way to help clean up the
streets and hopefully
prevent the spread of
disease.
http://www.sciencemuseum.org.uk/hommedia.ashx?id=7673&size=Small
The Problem
Wine did not have
consistent flavors
from one year to the
next
Microscopic
examination showed
that yeast and
bacteria were in
spoiled wine and
yeast alone in good
wine
http://wpcontent.answers.com/wikipedia/commons/f/f6/Kombuchacultsm.jpg
Vinegar
The word
"vinegar"
comes from the
Old French vin
aigre, meaning
"sour wine".
http://www.touchofeurope.net/linens/Vinegars.html
Pasteur’s Experiment
Pasteur boiled grape
juice (w/ yeast) plugged
and let cool – no growth
When added just yeast
then grape juice turned
into good wine so he
determined that yeast
was necessary for wine
http://www.icbm.de/~palmikro/mikrobiologischer-garten/pics/hefe_ph.jpg
Pasteur’s Experiment
Bacteria are agents
of change – they
alone sour wine
Acetobacter aceti
bacteria turn alcohol
and sugars into
acetic acid
http://www.vinegarman.com/zoo_vinegar_bacteria1.shtml
Pasteur’s Conclusion
•
Microorganisms
might be agents that
cause disease
•
Pasteurization (rapid
heating and cooling)
retards spoilage by
killing all living cells,
does not kill spores
of bacteria (milk, OJ,
many food products)