404 Action of B. lactis aerogenes on Glucose and Mannitol. 



Further examination has shown that in this case as in that of glucose, both 

 acetylmethylcarbinol and a glycol are produced, but both in much less 

 quantity. The amount of crude glycol actually isolated from the products 

 of fermentation of 50 grammes of mannitol was only 075 gramme. Since, 

 however, the loss in isolating may be roughly taken as about 5 grammes, this 

 is approximately the yield which would be expected if 6 to 7 grammes were 

 formed. The nature of these products and their quantitative estimation, as 

 well as the study of their optical properties, is still under investigation, and 

 search is also being made for these and similar substances among the fermen- 

 tation products of other bacteria. 



General Considerations. 



The production of so large a proportion of 2 : 3-butyleneglycol in these 

 experiments affords clear proof that this substance is derived from the 

 glucose. The interesting question as to the mode of its production from 

 the glucose or mannitol molecule will be best deferred until a more complete 

 examination of the products, and especially of their optical relations, has 

 been made. The close constitutional relation between the glycol and lactic 

 acid, and the readiness with which its oxidation product — diacetyl — passes 

 into an aromatic compound are also points of great interest. It may, 

 however, be noted that the comparison of the fermentation products of 

 B. coli communis and B. lactis aerogenes shows, firstly, that the alcohol 

 produced by the latter organism is slightly greater in amount than that 

 due to the former, and, secondly, that it is at the expense of that part 

 of the molecule which in the B. coli fermentation yields acetic . acid and 

 lactic acid, that the B. lactis aerogenes forms the new products. 



It may further be observed that both these bacteria produce twice as much 

 alcohol from mannitol as from glucose, a fact which tends to confirm the 

 suggestion previously made,* that the formation of alcohol in these reactions 

 is related to the presence of the terminal CH2(OH).CH(OH) group, which 

 occurs twice in the molecule of mannitol and only once in that of glucose. 



A substance of the composition of butyleneglycol has previously been 

 isolated from the product? of fermentation of sugar by yeast,f and was also 

 found in winej and. in brandy. § This substance, boiled at 178° to 179°, 

 yielded a diacetin boiling at 192° to 193°, and was considered to be identical 



* Harden, 'Trans. Chem. Soc.,' 1901, p. 601. 



t Claudon and Morin, ' Compt. Eend.,' 1887, vol. 104, p. 1109 ; Henninger and Sanson, 

 ' Compt. Eend.,' 1888, vol. 106, p. 208. 



\ Henninger, ' Compt. Eend.,' 1882, vol. 95, p. 94. 

 § Morin, ' Compt. Eend.,' 1887, vol. 105, p. 1019. 



