188 Reduetase, Catalase, Etc. 



Stable air bacteria 1 28 90 minutes 



B. subtilis 17 40 minutes 



Milk bacteria II 15 90 minutes 



B. mycoides 11 90 minutes 



Oidium lactis 11 90 minutes 



Str. mastitis longus 90 minutes 



From these figures it may be seen that frequently with a high 

 catalase number a very rapid reduction time may be present. 



Jensen found similar conditions in his investigations; he, 

 however, expresses himself as believing that a parallelism of 

 both factors does not prevail. Arranged according to catalase 

 values expressed in figures, giving the number of c. c. 's of oxygen 

 formed, the relation between catalase and the time of reduction is 



as follows : Catalase Keductase 



B. proteus vulgaris 27 c. c. 7 minutes 



B. proteus zopfii 27 c. c. 5 minutes 



B. prodigiosus 27 c. c. 7 minutes 



Microc candic 27 c. e. 4 minutes 



Microc. A 27 c. c. 3 minutes 



B. coli 18 c. c. 5 minutes 



B. aerogenes 9 c. e. 10 minutes 



B. mycoides 7 c. c. 12 minutes 



B. dentrificans 1 c. c. 10 minutes 



With other bacteria, for instance, butyric acid bacteria, there 

 appears to be no relation between the reduction power and the 

 development of oxygen, whereas with certain lactic acid producers, 

 for instance, the streptococci and cheese bacilli, the inability to 

 develop oxygen coincides with the long time required for reduction. 



In unspoiled milk during the incubation stage of souring and 

 at the beginning of souring at the end of this incubation stage, the 

 bacterial catalase will always have to be considered, but in general 

 the bacterial action in slowly reducing milk is very slight. If in 

 the latter instance high catalase values are obtained then usually 

 the catalase originally present in the milk is responsible for it. 



Koning further showed that catalase increases with the age of milk, and with a 

 rapid angle of incidence. The line of incidence in fresh milk is at first only 

 slightly bent, later more or less so, whereas old milk uniformly shows a rising line. 

 Spindler's recent experiments confirm this statement. From the investigations of 

 Spindler, however, it may be observed that during the time when milk is fresh enough 

 for drinking purposes the fluctuations are only very slight and the catalase value 

 obtained is always greatly dependent on the original catalase value of freshly drawn 

 milk. Faitelowitz indicates that catalase multiplies many fold after keeping fresh milk 

 at room temperature for 24 to 30 hours. 



Through heating to 70 deg. C. the " bacterial catalase" is 

 destroyed, or at least the bacteria are attenuated in their action to 

 such an extent that the oxygen-splitting property becomes almost 

 nil. Chick has already ascertained that this inactivation of the 

 bacterial catalase may be abrogated in a certain time by inoculation 

 of the heated milk with raw milk and Koning states that old 

 pasteurized milk, or milk freshly pasteurized with insufficient heat, 

 splits the H 2 2 . The catalase test is therefore recommended by 

 Kniisel for the examination of pasteurized milk as to its suitability 

 for drinking purposes. 



