JAMES WALTER McLEOD 215 



drawn attention to an apparent exception to the rule that anaerobes are devoid of cata- 

 lase in the propionic acid bacteria. These, however, appear to be microaerophiUc 

 rather tiian strictly anaerobic. The further investigation of their metabolism may 

 throw some fresh light on bacterial respiration. 



OCCURRENCE OF OXIDIZING FERMENTS IN BACTERIA 



Observations on this subject have been scanty. Lehmann and Sano^ claim to have 

 demonstrated tyrosinase in three species of bacteria although they found it absent 

 in the great majority. A brown discoloration in agar media around a colony of mold 

 is not infrequently observed and is probably due to this ferment. Beijerinck^ also 

 found tyrosinase in certain vibrios. Roux-^ observed that B. typhosus produced a green 

 color in extract of artichokes similar to that produced by laccase. The only other ob- 

 servations on the production of direct oxidizing ferments by bacteria that I have been 

 able to find are those of Schultze^ and Kramer^ who studied the immediate effect of 

 smearing bacteria on agar containing a-naphthol and dimethyl-para-phenylene dia- 

 mine. Briefly stated, their results were: no reaction with anaerobes, coccal forms, 

 B. influenzae, protozoa, and dysentery bacilli; a positive reaction with most other 

 bacteria, especially strong with strict aerobes and pigment-forming bacteria. Stapp,^ 

 working with a H2O2 and the benzidin test, found peroxidase reactions in B. colt, 

 Staphylococcus, Sarcina, B. prodigiosus, and B. pyocyaneus. The peroxidase was dis- 

 tinct from catalase in its greater resistance to heat and different sensitivity to iodine 

 and carbon disulphide. He did not find it in streptococcus cultures. In an extremely 

 interesting investigation of Fe containing cell pigments related to hemoglobin Keilin^ 

 found that these were very widely distributed in nature and that their association 

 with a peroxidase reaction was constant. For such pigment he proposed the name 

 "cytochrome," and he found it to be present in yeast and in the aerobic bacterium, 

 B. subtilis, but absent in an anaerobic bacillus, CI. sporogenes. Callow^ has also inves- 

 tigated this subject and found peroxidase in all of a number of bacteria tested, but 

 weak in B. acidl lactici and CI. sporogenes. 



OXIDATIONS PRODUCED BY BACTERIA 



The more the subject of oxidation is studied, the more difficult it becomes to draw 

 any hard-and-fast line between oxidation and reduction. This is true especially of 

 oxidations depending on processes of dehyrogenation and independent of the presence 

 of free oxygen such as have been demonstrated by Wieland' to take place under the 

 influence of a catalyst which may be palladium black or an oxygen-free bacterial 

 powder. The special value of oxygen when taking part in such processes is simply 

 that of taking up the discarded H with which it forms a product, H2O, that does not 



' Lehmann, K. B., and Sano: Arch.f. Hyg., 67, 99. 1908. 



^ Beijerinck, W. M.: Verzamclde Geschriften, 5, i. 



3 Roux, M. G.: Compt. rend. Acad, des sc, 128, 693. 1899. 



"Schultze, W. H.: Centralbl.f. BakterioL, Abt. I, Orig., 56, 544. 1910. 



5 Kramer, G.: ibid., 62, 394. 1912. ' Keilin, D.: Proc. Roy. Soc, B, 98, 312. 1925. 



^ Stapp, C: ibid., 92, 161. 1924. * Callow, A. B.: Biochem. J., 20, 247. 1926. 



»Wieland, H.: Berichted. D. Ch. Gesellsch., 46, 3327. 1913; 54. 2353. 1921. 



