Biotechnology for Fun and Profit

Biotechnology will be defined here as the application of chemical processes that use either biological catalysts or biological raw materials and that occur in vats or tanks of man's design. We can illustrate each component of this definition with the example of home winemaking, in which the biological raw material is sugar and the biological catalyst is yeast. As the fermentation occurs, alcohol is formed as the major product, along with carbon dioxide and more yeast cells. This way of making alcohol dates to ancient times. The Babylonians, for example, were brewing beer as early as 7000 B.C. The original manufacture of wine and beer was done on a small scale, but it did not prove too difficult to make fermented alcohol in large casks and vats and probably our ancestors were thankful for that. The situation was much different in another very old process of biotechnology :.....vinegar manufacture. Here early practitioners were not successful in translating the small-scale process (carried out in shallow wooden tubs) into big tanks in order to make large batches of vinegar. Why not? The basic difference is in the chemical reactions involved. In vinegar manufacture, microorganisms grow on the surface of a liquid where they convert alcohol into vinegar. In the process, they require oxygen, and they generate heat. That reaction causes no problems in shallow vats because the oxygen comes from the air over the liquid, and the cells grow as a film on the liquid surface. Any heat that is released is easily dissipated into the atmosphere. Productivity is not increased in a deeper tank because everything occurs on the surface. An ingenious invention was developed in the early 19th