Microbial fermentations:

Microbial Fermentations:
Changed The Course Of
Human History
Localized protein deposits inside rod-shape E. coli bacteria(X2000).
by Genentech, Corporate Communication
Christine Case, Ed.D.
Microbiology Professor, Skyline College
When people find out that I'm a microbiologist they frequently ask how I live: "Is your house scrupulously clean? Do you sterilize everything? How do youavoid microbes?" Undaunted by questions concerning my house-cleaning, I enjoy providing examples of the importance of microorganisms in our daily lives and the myriad of foods and drugs that microbes produce. I know that microbiological discoveries have played an important part in the course of human history, contributing to advances in health, nutrition, and use of environmental resources. I wascaptivated and amazed, however, to learn that microbiology was instrumental in the origination of an entire country and that a microbiologist was elected a nation's president.
My training and research experience is in industrial microbiology, where microorganisms are put to work to make a product. Fermentation is an important part of industrial microbiology. Fermentation technology got its originsthe first time someone made wine, was perfected in the 1940's with the production of antibiotics, and is the now the primary method of production in the biotechnology industry.
What Is Fermentation?
Fermentation has always been an important part of our lives: foods can be spoiled by microbial fermentations, foods can be made by microbial fermentations, and muscle cells use fermentation toprovide us with quick responses. Fermentation could be called the staff of life because it gives us the basic food, bread. But how fermentation actually works was not understood until the work of Louis Pasteur in the latter part of the nineteenth century and the research which followed.
Fermentation is the process that produces alcoholic beverages or acidic dairy products. For a cell, fermentationis a way of getting energy without using oxygen. In general, fermentation involves the breaking down of complex organic substances into simpler ones. The microbial or animal cell obtains energy through glycolysis, splitting a sugar molecule and removing electrons from the molecule. The electrons are then passed to an organic molecule such as pyruvic acid. This results in the formation of a wasteproduct that is excreted from the cell. Waste products formed in this way include ethyl alcohol, butyl alcohol, lactic acid, and acetone--the substances vital to our utilization of fermentation.
Lactic Acid Fermentation
During lactic acid fermentation, the electrons released during glycolysis are passed to pyruvic acid to form two molecules of lactic acid. Lactic acid fermentation is carriedout by many bacteria, most notably by the lactic acid bacteria used in the production of yogurt, cheese, sauerkraut, and pickles. Some animal cells such as muscle cells can also use fermentation for a quick burst of energy.
Alcohol Fermentation
Alcohol fermentation also begins with glycolysis to produce two molecules of pyruvic acid, two molecules of ATP, and four electrons. Each pyruvic acidis modified to acetaldehyde and CO2. Two molecules of ethyl alcohol are formed when each acetaldehyde molecule accepts two electrons. Alcohol fermentation is carried out by many bacteria and yeasts .
Fermentation in Industry
In industry, as well as other areas, the uses of fermentation progressed rapidly after Pasteur's discoveries. Between 1900 and 1930, ethyl alcohol and butyl alcohol werethe most important industrial fermentations in the world. But by the 1960s, chemical synthesis of alcohols and other solvents were less expensive and interest in fermentations waned. Questions can be raised about chemical synthesis, however. Chemical manufacture of organic molecules such as alcohols and acetone rely on starting materials made from petroleum. Petroleum is a nonrenewable resource;...