IX. EFFECTS OF DEFICIENCY 199 



B. IN MICROORGANISMS 

 K. L. R. STOKSTAD 



Tlic distribution of organisms ret^uiring PGA is not as widespread as that 

 of those requiring other growth factors such as biotin, nicotinic acid, or 

 pantothenic acid. The development of PGA-less mutants is much less fre- 

 quent than that of other vitamins re(iuiring mutants. Certain classes of 

 microorganisms, particularly the lactic acid bacteria, have a number of 

 members which require an external source of PGA. Peterson and Peterson,'''^ 

 in a comprehensive review of the vitamin reciuirements of bacteria, list 10 

 bacteria out of a total of 136 as requiring "fohc acid," "eluate factor," 

 "vitamin Be ," or "L. casei factor." 



Although recognition of the need of animals for PGA antedates that of 

 microorganisms, it was the discovery of the latter that provided a rapid 

 assay and hastened the isolation of this vitamin. The nutritive requirements 

 of lactic acid bacteria for PGA were first pointed out by Snell and Peter- 

 son. ^^^ They found that an unidentified factor was required which later 

 proved to be PGA. Later work from this same laboratory showed that 

 other lactic and propionic acids formed bacteria such as Streptococcus 

 faecalis R, Lactobacillus delbruckii, and Propionibacterium pentosaceum 

 also required this factor."^ 



In an investigation of the growth factor reciuirements of a large number 

 of Eiiterococci, Niven and Sherman'^^ found 9 organisms requiring PGA out 

 of a total of 43 studied. Out of 21 strains of Streptococcus lactis, none re- 

 quired PGA.135 



Tetrahymena geleii is unique among the microorganisms in that it has the 

 abiUty to utilize large PGA conjugates which are unavailable to bacteria. 

 The nutrition of the protozoan has been thoroughly investigated by Kidder 

 and associates,"®' '^^ who showed that this organism requires 0.00065 y 

 PGA per milliliter of culture media for half -maximum growth which is 

 about three times that required by S. faecalis R."^ Rhizopterin, also known 

 as the "S. L. R. factor," (N^" formylpteroic acid) which is active for .S. 

 faecalis R but relatively inactive for L. casei was found to be about 0.2 % 

 as active as PGA for T. geleii}^'^ Pteroyltriglutamic acid and petroylhepta- 



"' W. H. Peterson and M. S. Peterson, Bacteriol. Revs. 9, 49 (1945). 



•32 E. E. Snell and W. H. Peterson, /. Bacteriol. 39, 273 (1940). 



•" B. L. Hut chinas, N. Bohonos, and W. II. Peterson, ./. Biol. Chem. 141, 521 (1941). 



''* C. F. Niven, Jr., and J. M. Sherman, J. Bacteriol. 47, 335 (1944). 



'" C. F. Niven, Jr., ./. Bacteriol. 47, 343 (1944). 



"6 G. W. Kidder, Arck. Biochem. 9, 51 (1946). 



'" (J. W. Kidder and R. C. Fuller, III, Science 104, 160 (1946). 



'38 E. L. R. Slokstad, ./. Biol. Chcm. 149, 573 (1943). 



