VITAMINS 197 



nous supply of nicotinic acid for growth. Rogosa used the technique 

 of serial passage in a medium devoid of nicotinic acid. It is possible to 

 overlook a vitamin deficiency by failure to observe this precaution. 

 Yeasts found to be deficient for this vitamin include Saccharomyces 

 anamensis 154, S. lactis 131, S. fragilis 15, Zy go saccharomyces lactis (two 

 strains), Torida lactosa 168, T. sphaerica 13, T. cremoris 2, Torulopsis 

 kefyr 149, Mycotorula lactis 130. Strains of Saccharomyces cerevisiae 

 failed to show deficiency for nicotinic acid (Rogosa, 1943; Leonian and 

 Lilly, 1942; Burkholder, 1943). 



Until recently, nicotinic acid deficiency among filamentous fungi iso- 

 lated from nature was unknown. Cantino (1948) has shown that Blasto- 

 cladia pringsheimii is completely deficient for nicotinamide and partially 

 deficient for thiamine and biotin. Some of Cantino's results are pre- 

 sented in Fig. 37. A second filamentous fungus, a strain of Microsporum, 

 audouini, is reported as deficient for nicotinic acid (Area Leao and Cury, 

 1949). Mutants deficient for this vitamin have been developed in 

 Neurospora by Bonner and Beadle (1946) and in Penicillium by Bonner 

 (1946). 



Specificity. In so far as the fungi are concerned, nicotinic acid replaces 

 nicotinic acid amide, but few critical studies in this connection have been 

 made. Various studies have been made of the specificity for bacteria 

 of the compounds related to nicotinic acid. Bovarnick (1943) reported 

 that heating asparagine and glutamic acid together produced a compound 

 which replaced nicotinic acid or its amide for various species of bacteria. 

 This author later showed that this substance was nicotinic acid amide. 

 This is an unsuspected way of adding a vitamin to a basal medium. 



Mode of action. Nicotinic acid amide is a constituent of two or more 

 coenzymes. Codehydrogenase I on hydrolysis yields adenine, nicotinic 

 acid amide, and two molecules of D-ribosephosphoric acid. Codehydro- 

 genase II yields the same products as codehydrogenase I except that three 

 molecules of phosphoric acid, instead of two, are produced. In the 

 literature codehydrogenase I is often referred to as DPN (diphospho- 

 pyridine nucleotide) and codehydrogenase II as TPN (triphosphopyridine 

 nucleotide). These coenzymes in combination with specific proteins 

 form enzyme systems which transfer hydrogen (oxidation-reduction). 

 Apparently the amide of nicotinic acid is reversibly oxidized and reduced 

 in the process. 



One organism. Hemophilus parainfluenzae, requires codehydrogenase 

 I as a growth factor. This organism is unable to form the coenzyme 

 u'hen furnished with the moieties, nicotinic acid amide, adenine, D-ribose, 

 and phosphate. DPN is also known as factor V (Gingrich and Schlenk, 

 1944). Other bacteria are known which require preformed coenzymes 

 as growth factors. While no fungus isolated from nature has yet been 



