BACTERIOLOGY AND ITS RELATION TO OTHER SCIENCES 107 



Bacterial nutrition. is essentially a biochemical problem, but 

 should make an emphatic appeal to the bacteriologist. It has 

 as yet been but little explored. The impelling need for appro- 

 priate synthetic media in the biometric or quantitative study 

 of physiological activities of bacteria remains today practically 

 unsupplied. We are as yet in the dark regarding the real food 

 requirements of bacteria. 



Until very recently it was a common assumption that prac- 

 tically every sort of organic matter is food for bacteria. Today 

 we are made to realize that the problem of dietetics in bacteri- 

 ology is as real as in animal physiology. Indeed we are 

 observing more and more that the physiology of bacteria and 

 of animal organs is not so very unlike. The processes involved 

 in the pancreatic digestion of protein are in a large measure 

 reproduced by the proteolytic enzymes of organisms of the 

 B. subtilis and Proteus vulgaris types, certainly by the organisms 

 of putrefaction. Bacterial enzymes are able to bring about the 

 rapid cleavage of true proteins with the production of essentially 

 the same decomposition products as those which are formed in 

 ordinary tryptic digestion, namely albumoses, peptones and 

 polypeptides, various amino acids (leucine, tyrosine, etc.) and 

 tryptophane. Certain products are, of course, characteristic 

 of the bacterial cell, as for instance indol, the aromatic oxy- 

 acids, and the ultimate decomposition products, ammonia, 

 hydrogen, methane, carbon dioxide, etc. 



The problems of assimilation of food are essentially the same 

 for the bacterial and animal cell. Foods must be of very simple 

 composition in order that they may be utilized for cell growth. 

 This was demonstrated but a few years ago by Loewi, Abder- 

 halden and others in animal physiology. In the words of Abder- 

 halden, "It is as essential to break down complex nitrogenous 

 food substances into their simple components, before they can 

 be utilized, as it is to reduce the walls of an old church brick 

 by brick before they can be made over into a modern school- 

 house." Recent investigations in our laboratory have impressed 

 most vividly upon us the same fact with reference to bacterial 

 nutrition. 



