THE BIOLOGICAL ACTIVITIES OF BACTERIA 57 



pure product due to a specific bio-chemical process. The reactions 

 taking place in this phenomenon may be briefly expressed according 

 to the following formulae : 



Lactose Lactic acid 



or 



C G H 12 0, = 2C 3 H 6 3 

 Dextrose Lactic acid 



In the same way lactic acid may be produced by bacteria from 

 levulose. 



Examples of lactic acid formation are furnished by the strepto- 

 coccus lacticus, and B. lactis aerogenes. In the case of the former, 

 the fermentation may indeed proceed 'by the simple chemical process 

 indicated in the formulae, since the action of the bacillus is entirely 

 unaccompanied by the evolution of gas. 



Numerous other bacteria produce large amounts of lactic acid 

 from lactose, possibly by chemical processes less simply formulated. 

 Among these are bacilli of the colon group, B. prodigiosus, B. proteus 

 vulgaris, and many others. Although lactic acid is usually the chief 

 product in the bacterial fermentation of the simpler carbohydrates, 

 acetic, formic, and butyric acids may often be found as by-products 

 in variable amounts. 16 



Oxy doses (Oxydizing Enzymes). The most common example of 

 oxidation by means of bacterial ferments is the production of acetic 

 acid from weak solutions of ethyl alcohol. This process, which is 

 the basis of vinegar production, is universally carried out by bac- 

 terial ferments. While possessed to some extent by a considerable 

 number of microorganisms, acetic acid formation is a function pre- 

 eminently of the bacterial groups described by Hansen, including 

 "Bacterium aceti" and "Bacterium pasteurianum. " To these two 

 original groups, a number of others have since been added. 



The organisms are short, plump bacilli, with a tendency to chain- 

 formation, and occasionally showing characteristically swollen 

 centers and many irregiilar involution forms. In the production 

 of vinegar, as generally practiced by the farmer witli cider or wine, 

 these bacteria accumulate on the surface of the fluid as a pellicle 



Buchner und Meisenheimer, Ber. d.-Deut. chem. Gesellsch., xxxvi, 1903. 



