Nitrite Bacteria 



303 



fresh soil gave the most brilliant test. Then a series was run 

 as follows: check (synthetic solution), solution plus fresh soil, 

 solution plus sterile soil and solution plus fresh soil. Three- 

 tenths c.c. of nitrite culture was added to the first three. Fresh 

 soil gave best results, sterilized soil not quite as good. Fresh 

 soil wihout the culture gave a slight test after long incubation, 

 showing that the beneficial result was not due to any nitrifying 

 bacteria already in the soil. 



It is evident that there is some substance present, in the bac- 

 teria that grow on nutrient agar, and in the soil itself, that stim- 

 ulates these still impure cultures of the "nitrite" bacteria. It was 

 thought that this substance might be in the nature of a vitamin. 

 In order to test this out, to the synthetic solution, small amounts 

 of the following were added : dried autolised yeast, dried yeast, 

 yeast cake, alfalfa and soil. Two sets were run. One set was 

 sterilized and the other not. It was found that all these sub- 

 stances, sterile or not, stimulated the "nitrite" bacteria. Larger 

 amounts of nitrite were formed in all cases, in a given time, than 

 in check. Since the above substances are rich in vitamin A and 

 B, the writer feels there may be a definite relation between food 

 assessory substances and the "nitrite" organisms. 



149 (2109) 



Some temperature studies on B. acidophilus milk. 



By NICHOLAS KOPELOFF AND PHILIP BEERMAN. 



[From the Department of Bacteriology, Psychiatric Institute, 

 Ward's Island, New York City.] 



Since the beneficial effects of B. acidophilus appear to depend 

 upon a transformation of the intestinal flora, it follows that a 

 mass inoculation is desirable. This means a maximum num- 

 ber of viable organisms per c.c. of pabulum. The usual recom- 

 mendation on commercial preparations of fermented milk is that 

 such milk be kept in a cool place preferably in the ice-box. Con- 

 sequently, the influence of low temperature on the number of 

 viable B. acidophilus in milk seemed worth investigating. 



