Reference Texts: Page numbers in TFC’s 8th: pp 1- 17, Black’s 6th: 1-10
Ancient Practical Arts:
Birth of civilization between Tigris and Euphrates: grain, yeast for bread, beer, wine.
Bacterial cultures for making cheese. Knew technology, but not science
Significance of microbes?
Prior to 20th century: 30% of world’s inhabitants died of TB
Almost 50% children died fr infect. disease
Today: 50% child mortality due to infectious diseases
CELLS
(recognition depended on new technology of microscope)
Robert Hooke
1665 English, used a compound microscope, noted pores in cork: called cells, slide from Micrographia
Anton van Leeuwenhoek
1673 major improvements in his microscope Looked at “sediments” from his teeth: more ‘animalcules’ in his mouth “moving in the most delightful manner” than in all of Holland. peppercorn infusions. (p. 9) (Leeuwenhoek uses his microscope.)
Matthias Jakob Schleiden and Theodor Schwann 1838-39
(bot and zool.), deduced that all living matter composed of cells. UNIFIED CELL THEORY.
SPONTANEOUS GENERATION
Hippocrates
5th C BC Proposed miasma (foul gas) caused putrefaction. The code of Aesculapius guided early physicians
Aristotle
325 BC thought that life arose spontaneously
van Helmont 1577-1644
formula for mice: dirty rags, wheat bran, place in dark open barrel, 2 weeks – 1 month would have mice. i.e., Maggots arose “spontaneously” from decaying meat.
Francesco Redi
1668 (p 11) Italian, first true scientific experiment, tested spontaneous generation hypothesis: sealed three jars tightly with meat, left three jars unsealed. Open jars produced maggots, sealed did not. But critics thought that fresh air was required. He repeated expt so that air could get in, using gauze to keep out flies, deduced that maggots appeared only when flies preceded.
John T. Needham
1745 heated infusion of chicken broth and corn, poured into covered “clean” flasks. Soon contaminated (turbid: Latin, confused, disordered, crowd). Said could only be due to spontaneous generation
Lazzaro Spallanzani
1765 modified Needham’s experiment: the fluid was sealed in the flasks, and then boiled. noted that they did not show contamination if sterilized in the sealed flask
Laurent Lavoisier
1743-1794 Discovered oxygen in air. Many thought this could be the “vital principle.”
Nicolas Appert
1810 Invented canning. Perfected autoclave: placed food in thick bottles, boiled for 5 hrs, sealed with cork and wax. Used by Napoleon, lent strength to his army.
Rudolf Virchow
1858 German: biogenesis; all cells came from cells: Omnis cellula e cellula.
Louis Pasteur
1861 (p 12) filled long-necked flasks with beef broth. Bent necks of some into S shape, other straight. Reasoned that S trapped airborne contamination. Boiled to sterilize. Deduced that micro organisms ubiquitous, can be destroyed by heating. Blocking access to medium will prevent growth.
ASEPTIC TECHNIQUE
[means “not putrid”] The elimination of microbes, and maintenance of the resulting sterility.
FERMENTATION:
[Ferment means “to rise up”.]
Pasteur
1857 French vintners plagued by spoilage. Current theory was that air acted on grape juice turn to wine. Pasteur found that yeast on surface of grapes performed fermentation. Etymology: fermentum: to cause to rise up, fervere: to boil
Pasteur
1864 Why does wine spoil (sour to vinegar)? Showed due to bacteria, only in presence of air, making acetic acid. Block out oxygen with an air lock, it will not turn to vinegar.
PASTEURIZATION
By heating beer or wine (etc), can kill most bacteria except the thermodermic classic: 63° C (145°F), 30 min now: High Temperature Short Time: HTST: 72° C (163°F), 15 sec
1668 (p 11) Italian, first true scientific experiment, tested spontaneous generation hypothesis: sealed three jars tightly with meat, left three jars unsealed. Open jars produced maggots, sealed did not. But critics thought that fresh air was required. He repeated expt so that air could get in, using gauze to keep out flies, deduced that maggots appeared only when flies preceded.
