Plate 4Germ 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 ProblemWine 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

http://www.vinegarman.com/zoo_vinegar_bacteria1.shtml

Bacteria are agents of change – they alone sour wine

Acetobacter aceti bacteria turn alcohol and sugars into acetic acid

Pasteur’s Experiment

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)