EQUATION OF BUTYKIC FERMENTATION. 191 



of. All that can be hoped for is the discovery of more accurately 

 defined equations for each of the various species and their char- 

 acterisation, as e.g. the equation for the fermentation set up by 

 Granulobacter saccharobutyricum, and so on. Nevertheless, even 

 this limitation is not sufficiently strict, as will be evident from 

 what follows. 



L. PERDRIX (I.) examined the fermentative capacity of an 

 anaerobic spore-bearing butyric acid bacterium (closely allied to 

 Botkin's Bacillus butyricus), which he isolated from the water in 

 the Paris mains and named Bacille amylozyme by reason of its 

 property of bringing starch into solution (saccharification). When 

 grown in a meat-broth containing glucose and calcium carbonate, 

 with exclusion of air, this fission fungus produces acetic acid and 

 butyric acid, in addition to hydrogen and carbon dioxide. The 

 mutual ratio of these four fermentation products changes with the 

 increasing age of the culture. In the first three days it can be 

 approximately expressed by the equation 



56C 6 H 12 6 + 42H a O = I56H 2 + ii4CO 2 + 39C 2 H 4 2 + 36C 4 H 8 O 2 , 

 but later on by the equation 



f46C 6 H 12 6 + i8H 2 = U2H 2 + 9 4 C0 2 + I5C 2 H 4 2 + 38C 4 H 8 2 . 



Finally, the transformation becomes simplified, acetic acid 

 being no longer produced, and the sugar then splitting up very 

 nearly as follows 



C 6 H 12 6 = 2H 2 + 2C0 2 + C 4 H 8 O 2 . 



Similar ratios were established for the fermentation of sac- 

 charose and lactose, which is not preceded by inversion. Starch 

 is, as already mentioned, saccharified by the Bacille amylozyme, 

 and is then fermented, amyl alcohol and ethyl alcohol being 

 formed. 



Along with these Schizomycetes must be ranked the Bacillus 

 suaveolens, described by SCLAVO and Gosio (L), which converts 

 starch into dextrin and glucose, and ferments these with excretion 

 of alcohol, aldehyde, formic acid, acetic acid and butyric acid, 

 which then partly unite to form sweet-smelling esters. Butyric 

 acid bacteria that produce aromatic substances as well are im- 

 portant for the ripening of cheese, being essential for the develop- 

 ment of the characteristic odours of the various kinds of cheese. 

 However, in this matter our knowledge is still only in a rudi- 

 mentary state. E. VON FREUDENREICH (I.) separated from milk 

 a Clostridium fwtidum lactis, which develops, in this medium, an 

 odour resembling that of Limburg cheese, and the same observation 

 was made by H. WEIGMANN (L). The Bacillus saccharobutyricus, 

 isolated from so-called " Quargelkase " (small country cheese, a 

 sour soft variety) by V. VON KLECKI (L), and examined by him for 

 its fermentative power, also belongs hereto. 



