514 



MICROBIOLOGY OF SPECIAL INDUSTRIES 



characterized commonly as mousey, lactic or turned wines (Pousse and 

 Tourne of the French). 



The disease is due to bacteria. Enormous numbers are readily 

 revealed by the microscope in badly affected wines. There seem to 

 be several or many closely related forms, all short rod-shaped, isolated 

 in the first stages of the disease, but later forming chains or filaments 

 of various lengths. The most noticeable change caused in the com- 

 position of the wine is the decrease of fixed and increase of volatile 

 acidity. The tartaric acid and tartrates are destroyed, and carbonic, 

 acetic, lactic, propionic and other acids formed. 



Fig. 140. — Bacteria of wine diseases. A, bacteria of "turned wine," young wine 

 {After Biohtti); B, bacteria of "turned wine," old wine {After Biolelti); C, mannitic 

 tjacteria {After Maze and Pacottet); D, bacteria of "bitter wine" (After Pacottet). 



Light wines of low acidity are most subject to this disease which 

 may be prevented by measures which increase the acidity and alcohol, 

 by rapid and complete defecation and attenuation of the wine with 

 the proper use of sulphurous acid, and finally by timely filtration and 

 pasteurization. Wines noticeably affected can be used only for dis- 

 tilling; those badly affected are valueless. 



Mannitic Bacteria. — Very sweet grapes of low acidity in hot cUmates 

 are subject during fermentation to a similar trouble characterized by 

 increase of volatile acids and a persistent cloudiness and a vapid 

 sweet-sour taste. The disease is commonly confused with the preceding 

 but^is caused by bacteria of different forms. The form described by 

 Gayon is a very fine short rod which does not unite in filaments. It 

 attacks the sugar, especially the levulose, producing volatile acids and 



