NUTRITION OF MICRO-ORGANISMS 



influenced by pantothenic acid was pyruvic acid, but some effect was 

 observed with lactic acid and certain C4 and C5 dicarboxylic acids. 

 Pantothenic acid did not, however, affect the fermentation of glucose, 

 confirming the absence of a correlation between glycolysis and the 

 presence of pantothenic acid noted below. Dorfman et al}^ also 

 found that pantothenic acid stimulated the oxygen uptake of P. 

 morganii in presence of lactic or pyruvic acid. 



Panto yltaurine 



Several of the bacteria that require preformed pantothenic acid 

 have been used to test growth inhibitors that act by antagonising the 

 growth promoting effect of pantothenic acid. The best known of 

 these antagonists is pantoyltaurine, which is derived from pantothenic 

 acid by replacement of the carboxyl group by a sulphonic acid group : 



CH,OH . C(CH3)2 . CHOH . CO . NH . CHj . CH2 . COOH 



Pantothenic acid 



CH2OH . C(CH3)2 . CHOH . CO . NH . CH^ . CHj . SO^U 



Pantoyltaurine « 



This compound was prepared independently by E. E. Snell ^' 

 in the U.S.A., by R. Kuhn, T. Wieland and E. F. Moller ^^ in Germany, 

 and by J. W. Barnett and F. A. Robinson ^^ and H. Mcllwain ^o in 

 this country. 



It inhibits the growth of all organisms that require preformed 

 pantothenic acid, e.g. L. arahinosusy L. pentosus}'^ S. lactis}'' Pro- 

 pionihacterium p'entosaceum}'^ Leuconostoc mesenteroides}'^ Streptohac- 

 terium plantarum}^ Streptococcus haemolyticus,^^ Diplococcus pneu- 

 moniae 2® and exacting strains of C diphtheriae,^^ but not of organisms 

 that synthesise their own pantothenic acid, either completely, such 

 as E. coli, or from added j8-alanine, such as the non-exacting strains 

 of C. diphtheriae. Where inhibition occurred, it could be completely 

 overcome by addition of more pantothenic acid, so that inhibition is 

 of the competitive type, of which other instances are provided by 

 _^-aminobenzoic acid and sulphanilam.ide (page 546) and nicotinic acid 

 and pyridine-^-sulphonic acid (page 291). The amide of pantoyl- 

 taurine, pantoyltauramide,^^' ^^ also inhibited the growth of many of 

 the above organisms, but was less effective than pantoyltaurine ; it 

 appeared to act by the same mechanism as pantoyltaurine. Other 

 inhibitors related to pantothenic acid are discussed on page 397. 



The effects of pantoyl taurine and pantoyltauramide are markedly 

 different with different organisms, although the amount of panto- 

 thenic acid needed for optimal growth of each organism is approxi- 

 mately the same for a number of bacteria. H. Mcllwain ^o calculated 

 the " antibacterial indices " of the two inhibitors, that is the ratio of 



381 



