PRODUCTS OF METABOLISM. Ill 



6C 6 H 14 O 6 + H 2 O = 9C 2 H 5 OH+ 4 CH 3 COOH+ ioCO 2 + 8H 2 



Mannit Alcohol Acetic acid 



while the B. ethaceticus makes formic acid instead of hydrogen. 



14 O 6 + H 2 O = 5C 2 H 5 OH+CH 3 COOH+CO 2 +5HCOOH 



Glycerin is decomposed in many ways. It may be oxidized com- 

 pletely or it is fermented into the same products which are derived from 

 sugars. The butyric fermentation of glycerin has already been mentioned. 

 There are also some compounds formed from glycerin which are not 

 found in carbohydrate decomposition. These are the products of partial 

 oxidation, glyceric aldehyde and glyceric acid 



CH 2 OH CH 2 OH CH 2 OH 



I I I 



CHOH CHOH CHOH 



i r i 



CH 2 OH COH COOH 



Glycerin Aldehyde Acid 



The only monovalent alcohol of general occurrence, ethyl alcohol, 

 undergoes only one method of decomposition, namely that of oxidation. 

 This may be incomplete resulting in aldehyde or acetic acid (p. 109) or 

 if the combustion is total, in carbon dioxide and water. The acetic-acid 

 formation is the result of the acetic bacteria. Total combustion is 

 characteristic of molds and Mycodermce. 



ORGANIC ACIDS are valuable food for many microorganisms, in the 

 free form as well as in the form of salts. On acid liquids like fruit juices 

 and jellies, sour milk, sauerkraut, pickle brine, a flora of acidophile organ- 

 isms develops, among which the molds of the Oidium type and the Myco- 

 dermce predominate, while bacteria are found in insignificant numbers. 

 These acidophile organisms destroy organic acids, especially lactic and 

 acetic acid, by total combustion. The oxidation process for lactic acid 

 would be 



For all other acids, the equation is very similar. Some acids are 

 fermented by bacteria by processes more or less similar to sugar fermen- 

 tations. There are so many different possibilities that only a few exam- 

 ples can be mentioned. B. tartar icus decomposes tartaric acid to acetic 

 and succinic acid. The same organism can also ferment succinic acid, 



