Brewing for Millenia: Fermentation in History

Brewing for Millenia
Fermentation in History

Throughout human history, bacteria and fungi have been intimately involved with both the success and failure of daily life. Microorganisms cause disease, but they also play a wider role in sustaining life. We know that certain bacteria play a major part in recycling chemical elements as well as compounds. For example, bacteria help return the materials of dead organisms back to the earth, so those materials can be used by living organisms. What's more, without bacterial action, living things would not be able to use certain compounds found in soil, water, and even the atmosphere. Modified versions of these microorganisms are now essential in modern day pharmaceutical production.

ethyl alcohol

Fermentation is one of the oldest ways humans have used microbes. In his book From Caveman to Chemist, Hugh W. Salzberg retells some of the ancient history of fermentation. Since grains, fruits, juices, milk, and other organic liquids ferment naturally, some speculate that fermented drinks and dairy products must have been available not long after early people developed agriculture. The Bible refers to vineyards, wine, and the effects of too much alcohol consumption. Hannah, the mother of the prophet Samuel, was mistakenly admonished by the high priests to “put away thy wine from thee.” Ashurbanipal (668-626 BC), the last great Assyrian emperor, was something of an expert on wines. He compiled a list of what he considered the best wines. In ancient Egypt tax inspectors assessed the quality of the wines. Even poor Egyptians were sometimes buried with jars of beer. In both ancient Egypt and ancient Mesopotamia wines were put into jars at the place of origin in the presence of government officials and sealed with an official seal. In Mesopotamia, brewing was a home industry. The brewers were often women, who carried out the business of selling beer as well. These women-brewers had a relatively privileged position in society during the period of about 4000-2600 BC. The code of law handed down by the Babylonian lawgiver King Hammurabi (reigned 1792-50 BC) included regulations in terms of the sale price of beer and its minimum alcohol content. The brewer-women were also cautioned about allowing political conspiracies to be formulated on their tavern premises.

lactic acid

Fermentation is carried out by both bacteria (prokaryotes) and fungi (eukaryotes) during their metabolism. Both groups of organisms also figure in the world of human disease, as they are both sources of antibiotics, as we'll see throughout this module. Fermentation results in a number of byproducts that have many different uses. As mentioned, the most well-known product of fermentation is ethyl alcohol. This substance is both a beverage as well as a starter molecule for synthesizing other compounds. Since fermentation is carried out in the absence of oxygen, we call it an anaerobic process. It is a method by which organisms such as yeast obtain their energy by converting sugars into other chemical compounds, particularly carbon dioxide and water. Interestingly, our bodies also use this same anaerobic fermentation to obtain energy from sugars when oxygen is in low supply in our blood, such as during vigorous exercise. The products of this process are lactic acid and water rather than the carbon dioxide and water that human metabolism normally produces. In this day and age, pharmaceutical companies utilize the fermentation carried out by microorganisms to produce antibiotics, hormones,and specialized proteins such as antibodies and insulin. This wide range of products is possible because the bacterium or fungus involved in fermentation has been genetically changed to produce a specific substance.

You have the opportunity to explore fermentation as a chemical process through a series of activities linked below. The chemistry, although occurring in a living organism, can be examined outside a yeast or bacterial cell if you are able to extract certain enzymes (known as catalysts in the world of chemistry) from the cells. The fact that enzymes could carry out fermentation outside of a living organism was first shown by Eduard Buchner, a contradiction to the idea of Louis Pasteur that only living things could carry on the fermentation process. Buchner added sugar to juices extracted from yeast cells, even cells that had been killed by heating. Fermentation would begin within an hour. Buchner theorized that the yeast juice contained just one enzyme for converting sugar to carbon dioxide and water. Today we know that yeast cells contain more than a dozen enzymes involved in fermentation.

To experience fermentation for yourself, try the activity Fermentation by Yeast!
For more information, at other Web Sites...

Scientists Awarded Patent for Coal-Purifying Bacteria — news article about one of the newest uses for bacteria, from Brookhaven National Laboratory, 11 December 2001.
The Nobel Prize in Chemistry 1907 — biography and work of Eduard Buchner from the Nobel e-Museum.

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Reference

Morell, Virginia. “The Pyramid Builders,” National Geographic, vol. 200, no. 5, November 2001.

Copyright ©2002 The Chemical Heritage Foundation