70 BACTERIAL METABOLISM 



do the saprophytic types, as Theobald Smith 1 showed long ago. Thus, 

 typhoid bacilli are relatively inert culturally; they form no gas in 

 sugar media, no indol, and do not liquefy gelatin; on the contrary, 

 B. coli and even more strikingly B. proteus are characterized by strik- 

 ing cultural changes; B. coli produces deep-seated changes in protein, 

 resulting in the production of indol; it produces gas from sugar media, 

 but it does not liquefy gelatin. B. proteus behaves much like B. coli 

 in sugar media, but liquefies gelatin as well. These marked changes 

 in the composition of the medium, namely, the production of indol 

 from protein, the production of gas from sugar, and the liquefaction 

 of gelatin, are all phenomena associated with the vegetative or fuel 

 phase of bacteria. 



II. THE NATURE OF BACTERIAL METABOLISM. 



Chemically considered, the anabolic phase of bacterial activity is 

 one characterized by the synthesis of relatively simple substances, 

 chiefly nitrogen-containing, into the complex specific bacterial proto- 

 plasm through a series of synthetic reactions among which reductions 

 and condensations appear to be the more prominent. It is very 

 probable that many of these condensation reactions are hydrogenic 

 in nature; that is, two simpler molecules are united into one molecule 

 of greater complexity through the removal of hydrogen and oxygen 

 from them in the proportions to form water. 



As simple illustrations: the formation of lactose from a molecule 

 each of dextrose and galactose, 



C 6 Hi20 6 + C 6 Hi 2 6 = Ci 2 H 22 On + H 2 

 Dextrose. Galactose. Lactose. 



the formation of a polypeptid, glycyl-glycin, from two molecules of 

 glycocoll, 2 



NH 2 .CH 2 .COOH + H.NH.CH 2 .COOH = NH 2 .CH 2 .CO.NH.CH 2 .COOH + H 2 O 

 Glycocoll. Glycocoll. Glycyl-glycin. 



and the formation of, the glyceride of a fatty acid from glycerin and 

 acetic acid may be cited, 



CH 2 .OH + HOOC.CHs = CH 2 .O.O.CH 3 



CH.OH + HOOC.CHs = CH.O.O.CHs + 3 H 2 O 



I I 



CH 2 .OH + HOOC.CHs CH 2 O.O.CHs 



Glycerin. Acetic acid. Triacetin. 



1 Fermentation Tube, Wilder Quarter Century Book, 1893, p. 219. (See also Kendall, 

 Day and Walker, Jour. Am. Chem. Assn., 1913, xxxv, 1201-1249, for analytical data.) 

 Fischer, Ber. d. deutsch. chem. Gesell., 1906, xxxix, 530. 



