H4 BACTERIA AND THE CARBON DIOXIDE CYCLE 



Other fermentations of monacid alcohols have not been described, but 

 there can be little doubt that such occur. 



Fermentation of higher alcohols (84) has been observed in the casef of 

 a motile bacterium isolated from sheep's dung, Bacillus ethaceticus. A 

 culture of this micro-organism in 60 grm. glycerine formed 



7-52 grammes Ethyl Alcohol, 

 3-88 „ Acetic Acid, 



006 „ Succinic Acid, 



Carbonic Dioxide, 

 Free Hydrogen, 

 Traces of Formic Acid. 



24-19 grm. of glycerine was unchanged. The same bacterium causes similar 

 changes in mannite, but not in its isomer dulcite. The so-called capsule 

 bacillus Pneumococcus of Friedlander ferments mannite also (with the same 

 products), but not dulcite. 



Bacillus ethacetosuccinicus (also isolated from dung) ferments both 

 mannite and dulcite. In cultures eighty-five days old that contained, besides 

 the necessary nutriment, eight grams of fermentable substance, there was 

 formed 



From Dulcite. From Mannite. 

 Ethyl alcohol 

 Formic acid 

 Acetic acid 

 Succinic acid 



co 2 . 



Free H 

 Unfermented residue 



These figures are of some interest, showing that the chief products are 

 alcohol and carbonic dioxide, and proving that the formation of ethyl 

 alcohol is not a monopoly of the Saccharomyces *. 



Glycerine also is capable of fermentation in other ways, butyl alcohol 

 and butyric acid arising among the products (B. orthobutylicus, Chap. XIII). 



As examples of the fermentation of fatty and aromatic acids, given in 

 the form of neutral salts, it may be mentioned that acetic acid is oxidized, 

 by the very organisms that produce it, to C0 2 and H 2 0, and that the 

 dextro-rotatory tartaric acid of wine is converted by various bacteria into 

 formic, acetic, butyric, propionic, lactic, and succinic acids. It is to the 

 activity of such bacteria that the diminution of acidity of wine is due, 

 and probably some of the diseases of wine also. The malic acid in cider is 

 also oxidized by bacteria to acetic, propionic, and butyric acids, carbonic 

 dioxide, and water ; and similar processes are known in the case of citric, 



* B. Fitzianus from hay-infusions also produces ethyl alcohol. 



