Bacterial Catalase. 



Antiseptics, such as boracic acid, salicylic acid and formalde- 

 hyde, inhibit or destroy the reduction power of bacteria; the 

 same result is obtained by heating, which destroys the life of 

 the vegetating bacterial cells. 



Milk which has been heated for 10 to 30 minutes at 80 to 100 

 deg. C. shows only the slightest reduction power, which increases 

 again only after the recurrence of bacterial multiplication. 



It should be emphasized that milk, in spite of being spoiled 

 to a marked degree, may have a slow reducing power, as for 

 instance soapy milk, provided this condition is not associated with 

 extensive bacterial contamination with other species of bacteria. 

 Although the bacillus of soapy milk reduces very rapidly, soapy 

 milk in itself is only capable of bringing on this reaction to a 

 very slight degree, which probably is proof that defective flavors 

 may result even when only a very slight bacterial growth has 

 taken place, although the bacterial action is of tremendous 

 importance. 



For the completeness of this chapter it should be mentioned 

 that milk very rich in bacteria, which has been sterilized by heat, 

 reduces also the formalin methylene blue solution as a result of 

 the original bodies in milk, a property which has nothing to do 

 with the Schardinger reaction. 



The formalin methylene blue reducing principle in market 

 milk is also a pre-formed substance, which occurs in milk drawn 

 under sterile conditions (original ferments). 



Bacterial Catalase. 



Similar to the power possessed by body cells and body juices, 

 bacteria have the ability of splitting gaseous oxygen from hydrogen 

 peroxide solutions. This property may be observed in many bac- 

 teria, but it should be mentioned that not all species of bacteria 

 possess it, and that certain bacteria have a specific power in .this 

 direction. 



Koning and Jensen made confirmatory statements to this 

 effect, having found that the acid streptococci of milk do not split 

 H 2 2 . The author's experiments confirm this observation. Jensen 

 made an especially interesting observation, namely, that the bac- 

 terial flora present in milk during the incubation period of souring 

 usually possess strong catalytic properties. 



The following data are taken from a work of Koning, arranged according to the 



catalase figures: 



Species of Bacteria Catalase test Keductase test 



B. prodigiosus 58 15 minutes 



B. proteus zopfii 57 15 minutes 



Milk bacterium 1 55 80 minutes 



B. fluorescens liquefaciens 53 13 minutes 



B. coli communis 39 17 minutes 



B. lact. acid. Hueppe '. 32 12 minutes 



Stable air bacteria II 31 90 minutes 



B. mesentericus 30 60 minutes 



B. fluorescens nonliquef. 29 15 minutes 



