MICROBIOLOGY OF ALCOHOL AND ALCOHOLIC PRODUCTS. 425 



servers have noticed a diplococcus and a sarcina. Kayser and Manceau 

 have recently investigated the subject very thoroughly and described a 

 number of forms which are mostly short rods of from T.JJL to 2 // by .7^ 

 to i.2fi. One large form, 3/* tO4/*X i.6/* to i.y/*, was also noted. They 

 all form chains, usually of considerable length. They all produce an 

 abundant slimy sheath and stain easily with carbol-fuchsin and other 

 aniline dyes and are Gram-positive (Fig. 86) . 



These bacteria attack the sugar but neither the glycerin nor the alcohol 

 and produce mannit, carbon dioxide, lactic and acetic acids and ethyl 

 alcohol. The disease is usually not serious and disappears under the 

 ordinary cellar treatment. Alcohol above thirteen per cent, free tartaric 

 acid, tannin and sulphurous acid in small amounts prevent their 

 growth. 



Propionic and Lactic Bacteria. The most serious and perhaps 

 the commonest disease of wines is characterized by persistent cloudiness, 

 disagreeable odors and flavors, increase of volatile acid and injury to or 

 complete destruction of the color. Wines affected are 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 composition 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. 



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 distilling; 

 thoss badly affected are valueless. 



Mannitic Bacteria. Very sweet grapes of low acidity in hot climates 

 are subject during fermentation to a similar trouble characterized by 

 increase of volatile acidity 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 



