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 (microscope 2, microscope 3) 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. |