Effects of Bacterial Growth on the Environment 187 



closely associated with microorganisms and their ability to cause 

 this breakdown of fermentable substances. 



Over one hundred different compounds are produced as the 

 result of microbial fermentation, and these reactions form the basis 

 of some of our large industries today. Yeasts are employed in the 

 manufacture of ethyl alcohol, alcoholic beverages, leavening agents, 

 yeast concentrates, and in the manufacture of glycerol. Bacteria 

 are the biological agents in the preparation of butyl alcohol, acetone 

 and other solvents, lactic acid, and other acids. Molds function in 

 the manufacture of citric, gluconic, and gallic acids, and a host of 

 other miscellaneous products. The chemistry of these reactions is 

 left for discussion in a book designed for more advanced students. 



o 



The word alcohol is derived from two Arabic words, al and 

 kohl, which denote a fine powder used by Oriental women to 

 darken their eyebrows. The methods employed in the manufac- 

 ture of these powders were similar to those used for distilling 

 "spirits." In about the year 1500 the word alcohol was adopted 

 to denote a volatile liquid, and today we think in terms of ethyl 

 alcohol when the word alcohol is mentioned. 



The quantity of pure alcohol used in the United States alone 

 for industrial purposes and the arts and the sciences was estimated 

 to be six hundred and nine million gallons in 1944, as compared 

 with a little less than nineteen million gallons in 1920. The word 

 proof seen on alcohol labels is an old English term meaning 

 strength or quantity of spirit. A one hundred proof spirit contains 

 fifty per cent by volume of alcohol. Such raw materials as molas- 

 ses, sugar beet, sugar cane, and fruit juices are good saccharine 

 materials for producing alcohol. Such starchy substances as pota- 

 toes and cereal grains ( corn, barley, rye, rice, etc. ) also provide 

 large stocks of raw material for biological alcohol production. 

 Molasses is the most common substance used in the manufacture 

 of industrial alcohol in the United States, except during the World 

 Wars when the molasses supply was materially reduced. Sweden 

 and Norway rely upon the fermentation of wood pulp and waste 

 sulfite liquor from wood pulp mills as their source of alcohol. 



