184 Reduetase, Catalase, Etc. 



conducted for the demonstration of original ferments because of 

 the reactions which they cause. One characteristic is the reduc- 

 ing property of some bacteria and their ability to split up H 2 2 

 into water and molecular oxygen, corresponding to the action of 

 catalase. 



The reducing action of bacteria as indicated by the presence of reductase, has 

 been observed for a long time. Helmholtz in 1843 proved that putrefactive changes 

 which could not be demonstrated by changes of odor could be proved by discoloration 

 of litmus coloring matter. Subsequently this reducing action was confirmed by many 

 authors to be the property of various anaerobic and aerobic organisms. Thus according 

 to Gayon and Dupetit the anaerobes are capable of forming ammonia from nitrates, 

 while the Bacillus prodigiosus, B. anthracis, Spir. finkler and Staphylococcus citreus 

 form nitrites out of nitrates. Others again reduce sulphur to H 2 S (through "Hydro- 

 genase"). 



As an agent for demonstrating the reductase processes some authors, for instance 

 Spina, Cahen, and Wolff, use coloring substances which change into leuco-eompounds, 

 as a result of the reduction, but from renewed contact with the air they become re- 

 oxydized, as for instance tincture of litmus, thionin, methylene blue, indigo blue, neutral 

 red, etc. Others again use metallic salts to render the reduction directly visible (Scheur- 

 len and Klett, Gosio), for instance selenite and tellurite, whose sodium and potassium 

 compounds confer upon the colonies a brick-red or grayish-black tinge, by the reduction 

 or indirectly, the transpiring reductive action is shown through secondary reactions, for 

 instance the formation of nitrites from nitrates, through the addition of iodine starch 

 paste which becomes decolorized by the nitric acid. 



Methylene blue is used at the present time most extensively 

 for the reductase test; that is, the solution recommended by 

 Schardinger consisting of 5 parts of concentrated alcoholic methy- 

 lene blue solution to 195 parts of water is best adapted for the 

 examination of milk. 



The reducing qualities of various bacteria towards methylene 

 blue vary. Thus Jensen established the reduction qualities of a 

 series of milk bacteria, and proved that varieties of colon, staphy- 

 lococci, sarcina, and mould fungi, reduce rapidly, whereas acid 

 streptococci do not decolorize the solution. 



The findings of Koning, who used cultures 24 hours old in his experiments, were 

 the same. Arranged according to length of time, reductions take place as follows: 



Bacillus fluorescens nonliquefaciens, in 8 min. 



Bac. acidi lactici Hueppe, in 12 min. 



Bac. prodigiosus, in 10-15 min. 



Bac. fluorescens liquefaciens, in 13 min. 



Proteus zopfii, in 15 min. 



Bac. coli communis, in 17 min. 



Bac. subtilis, in 30 min. 



Mesentericus, in 60 min. 



Milk bacteria I, in 80 min. 



Streptococci of lactic acid, Oidium lactis and 2 stable atmospheric 



bacteria, not in 90 min. 



Schardinger in 1902 stated that suspensions of the Bacillus acidi laevolactici 

 decolorize in 3 minutes, the Bacillus gasoformans in 3 minutes, the Bacillus lactis 

 pituitosi in 30 minutes, the Bacillus coli in 15 to 20 minutes, etc. 



The ability to reduce methylene blue has also been found in anthrax and tubercle 

 bacilli. 



In the experiments it was proved that although not all bacteria are capable of 

 reducing methylene blue, the power of reduction in some is very strong, while in others 

 it is diminished and in still others it is practically nil. 



Reduction properties appear to be characteristic of the living 



