230 . PHARMACEUTICAL BACTERIOLOGY 



supposition of an interruption in the development (by the bacteria) of 

 the lactic acid enzyme. It is furthermore demonstrated that very minute 

 doses of mercuric chloride, copper sulphate and other poisons, will cause 

 an increase in the lactic acid forming function while the power of septa- 

 tion and growth of the lactic acid enzyme organisms is very materially 

 decreased. 



B. Oxidizing Ferments 



The oxidizing ferments also known as oxidases cause the oxidation of 

 various organic substances. They appear to act as carriers or trans- 

 mitters of oxygen to the substances undergoing fermentation, though the 

 exact chemical changes involved are not well understood. To this group 

 probably belong a great variety of ferments and fermentation processes, 

 widely distributed in the plant as well as animal kingdoms. Laccase is 

 a ferment concerned in the formation of a lacquer varnish in the lac tree 

 of Asia. Tryosinase found in certain fungi and also in the roots of certain 

 higher plants has the power of oxidizing tryosin which is found in these 

 plants. 



(Enoxidase causes the wine disease known as "casse." The wine 

 loses its red color with the formation of a reddish-brown precipitate. 

 It is highly probable that the multitudinous fermentative changes com- 

 prised under "ripening" processes, "sweating" processes, aroma and 

 flavor formation in wines, tobacco, cheese, etc., are of the oxidizing 

 variety, besides many of the little understood fermentative changes 

 resulting in so-called "diseases" in commercial products as wines, beers, 

 tobacco, cheese, etc. 



C. Alcohol Forming Ferments 



The alcohol forming ferments or zymases or yeast ferments proper 

 are by far the most important from a practical commercial standpoint. 

 Zymases act upon sugars splitting these substances into alcohol and car- 

 bonic acid gas thus acting upon the end products formed by the diastasse. 



Zymases are formed by a great variety of plants and animals, par- 

 ticularly the yeast plants (the Saccharomyces) and Torula species and their 

 varieties. The enzymes of yeast plants may be isolated or separated 

 from the living cells and will continue their fermentative activities 

 independently. 



Alcohol fermentation is by no means a simple process. The degree 

 of alcohol production and of by-product formation varies greatly, depend- 

 ing upon a great variety of factors and influences. To enter into a fuller 

 discussion of the details of the fermentative processes and a description 

 of the organisms involved is not essential. We may however mention 

 the fact that the number of sugar bearing substances capable of under- 



