68 METABOLISM 



of its dehydrogenations (LwofF and Lwoff 1937a, b). According to Schlenk and 

 Gingrich (1942) the co-enzyme can be replaced by the nicotinamide riboside, while 

 a mixture of nicotinamide, cZ-ribose and adenyUc acid is inactive. The utiliza- 

 tion of the riboside may thus be considered the limit of adaptability of this organism 

 (Gingrich and Schlenk 1944) in the direction of the synthesis of co-enzyme I. 

 Many bacteria are capable of synthesizing co-enzyme I from simpler substances 

 and can therefore stimulate the growth of the influenza and para-influenza bacilli 

 by reason of their co-enzyme content. For instance, certain lactic-acid bacteria 

 can utilize the purine and pyrimidine bases (Stokstod 1941), and CI. tetani the 

 purine base alone. The conception of nicotinic acid simply as a building block 

 for co-enzyme I in all bacteria has recently been questioned by Saunders, Dorfman 

 and Koser (1941). In a deficient medium, the stimulating effect of co-enzyme I 

 on dysentery bacilli was less than that of the nicotinamide supposed to serve for 

 its synthesis. Co-enzyme I split by hydrolysis, on the other hand, was as active 

 as nicotinamide. It is possible that in this case the nicotinamide may be utilized 

 to form a respiratory hsemochromogen with hajmin. The close relation of nico- 

 tinic acid with glycolysis is illustrated by the action of Salm. paratyphi A and Sh. 

 shigcB on fermentable carbohydrates. According to Kligler and Grossowicz (1940, 

 1941), nicotinic acid is not a growth-promoting substance for these organisms. 

 In its absence there is a slow and partial aerobic glycolysis, and in consequence 

 only a slow protein dissimilation. In its presence good growth occurs and the 

 carbohydrate is rapidly oxidized with the production of COj. In Staph, aureus, 

 nicotinic acid is essential for the oxidation of glucose, which under aerobic con- 

 ditions is converted into pyruvic and lactic acids. The addition of thiamin as 

 well permits the oxidation of the pyruvate ; glycolysis as a whole is more active, 

 and the end products are acetic and lactic and carbonic acids. In the absence 

 of nicotinic acid in a synthetic medium, glucose has an inhibitory effect on growth, 

 perhaps by interfering with the oxidation of the essential amino-acids present 

 (Kligler, Grossowicz and Bergner 1943a, b). 



Just as the influenza bacillus is incapable of synthesizing the co-enzyme needed 

 for its dehydrogenase systems, in the same way it requires a supply of hsemin 

 ready made for incorporation in the enzyme systems concerned with oxygen 

 transport. It has long been known that Hcem. injluenzcB requires hsematin (the 

 X factor, see Chapter 33) and that, grown anaerobically, the organism can dispense 

 with it. Lwoff and Lwoff (1937c) concluded from respiratory studies that the 

 hsematin was needed for the synthesis of cytochrome, cytochrome oxidase, catalase 

 and peroxidases, i.e. it was essential to the completion of the chain of mechanisms 

 transferring hydrogen to atmospheric oxygen. 



Among other accessory growth factors of known composition needed by bacteria 

 we may briefly mention riboflavin for lactobacilli (Snell and Peterson 1940), and strepto- 

 cocci (Mcllwain 1940, Woolley and Hatchings 1940, and Schuman and Farrell 1941) ; 

 lactoflavin for propionobacteria and streptococci (Orla-Jensen, Otte and Snog-Kjaer 

 1936) ; and pimelic acid for C. diphtherice (Mueller 1937) ; ;p-aminobenzoic acid (see 

 p. 162) ; pyridoxin for certain streptococci (Pappenheimer and Hottle 1940, Schuman 

 and Farrell 1941) ; and oleic acid for C. diphtherice (Cohen, Snyder and Mueller 1941) 

 and Erysipelothrix (Hutner 1942). 



It will be seen that the majority of bacterial vitamins are also vitamins for other 

 organisms, including the higher mammals. PimeUc acid is of particular interest, since 

 it has not been recognized as a vitamin in other types of organisms, nor is it a compound 

 that seems likely to play the part of a co-enzyme in bacterial metabolism. Its significance 



