Biotechnology is the use of organisms or their products for the benefit of humans. Biotechnology has long been used in human history. For example, in 1991 archeologists in Italy uncovered a frozen and well-preserved "iceman" in the Italian Alps. Tissue analysis showed him to be 5,300 years old. Studies of his body revealed that he may have used birch fungus that had antihelminthic, or antiparasitic, properties to treat parasitic intestinal infections.
Applied microbiology describes the use and application of current knowledge of microorganisms in various fields including medicine, agriculture, food production, and sanitation of environmental pollutants. Applied microbial biotechnology is as old as human history—for example, yeast has been utilized to make bread since 300 BCE. In 600 BCE, the Chinese used moldy soybeans to treat boils, which represents one of the earliest uses of antibiotics, medicines that destroy or inhibit the growth of microorganisms.
Fermentation is the anaerobic breakdown of a substance, such as glucose by bacteria or yeast, that produces a limited amount of adenosine triphosphate (ATP) for a cell. The advent of agriculture led very quickly to the use of microbes to ferment food and drink. As early as 7000 BCE, fermented drinks such as mead, wine, and beer were being made across the globe. Alcohol was very important for ancient cultures because water was often contaminated with harmful microbes such as the protozoan parasite Giardia or the bacterium Vibrio cholerae. Both organisms are waterborne diseases, with Giardia being found in freshwater lakes and streams and V. cholerae in salt water and brackish (containing a mix of fresh and salt water) water. When these organisms contaminate drinking water, which can occur in areas with poor sanitation or limited ability to treat and purify water, they cause severe diarrhea and fluid loss. The fermentation process killed most of these microbes, producing liquid that was safe to drink. Alcohol was thus vitally important to many cultures and featured heavily in social and religious practices. This remains true today, with many religious rites centering on the consumption of alcohol.Food fermentation using Lactobacillus acidophilus, "lactic acid bacteria” commonly found in yogurt, can prevent the growth of potentially harmful bacteria. L. acidophilus performs the fermentation reaction in the yogurt, converting carbohydrate sugars to lactic acid. The lactic acid decreases the pH of the yogurt, thereby preventing the growth of other species of bacteria that may otherwise spoil the food.
Another important application of microbial biotechnology in history is the leavening of bread. Leavening describes using the yeast organism Saccharomyces cerevisiae or other materials to make bread rise. In yeast leavening, the yeast release carbon dioxide as they grow, resulting in the formation of tiny bubbles and puffing up the dough. While leavening bread imparts no additional nutritional value, it makes the bread easier to eat and allows the bread to act like a sponge, soaking up dishes such as soups and stews. Bread is an important part of meals in many cultures. Many families pass starter cultures down through generations to ensure the family bread continued. A starter culture is a small amount of food containing the microbes necessary to carry out the leavening or fermentation process. It contains a unique strain of Saccharomyces, which causes the bread to have characteristic qualities.