XIV. NUTRITIONAL VALUE OF FATS 



culture media for these experiments. However, most of the lactic acid 

 bacteria commonly used as assay organisms do not require oleic acid for 

 growth on complete media. This acid becomes essential when biotin is 

 omitted, and its effect is enhanced by Tween 40.^^^ Whitehill, Oleson, 

 and SubbaRow^^^ reported that an essential growth factor present in 

 fish solubles and necessary for the growth of a Lactobacillus isolated from 

 the cecum of a rat was oleic acid. This particular Lactobacillus could be 

 transferred repeatedly on synthetic media, but only in the presence of 

 sodium oleate. The requirement for oleic acid could not be modified by 

 high levels of sodium acetate, biotin, riboflavin, pantothenic acid or by 

 any of the other known factors tested. In the case of a number of lactic 

 acid bacilli, Broquist and SnelP^' reported that the growth-promoting 

 action could not be nullified by an excess of avidin when biotin was absent. 

 Lactobacillus arabinosus did not respond to oleic acid in the presence of 

 egg white (which contains avidin, a substance which combines with bio- 

 tin). Broquist and Snell-^' believe that the inhibitory action of avidin on 

 the growth of L. arabinosus in the presence of oleic acid is due to the ability 

 of avidin to combine with traces of biotin in the cell, which are essential 

 for growth. 



Williams and Fieger^'^ were the first to call attention to the similarity 

 in the stimulating action of oleic acid, of whole rice oil and of biotin on 

 Lactobacillus casei. Although maximum growth (as determined from 

 acid production) could be demonstrated in the presence of lipids, ^^* no 

 synthesis of biotin occurred. ^^^ Of a number of fatty acids tested, lauric, 

 myristic, and linoleic acids strongly inhibited the growth of L. casei, 

 whereas elaidic acid was even more stimulatory than oleic acid.^^^ It 

 would seem, therefore, that the bacteria adapt themselves to either the 

 biotin-free or the biotin-low environment. 



Broquist and SnelP^^ found that, in the absence of biotin, not only are 

 the unsaturated fatty acids required to permit growth of Lactobacillus 

 arabinosus, L. casei, and Streptococcus faecalis, but the dicarboxylic acid, 

 aspartic acid, is also required. On the other hand, Lactobacillus fermenti 

 and Clostridium butyricum require only the unsaturated fatty acids. 



For some time it has been known that there is a fat-soluble and ether- 

 soluble biotin-like component in acid-hydrolyzed plasma capable of 



"2 A. R. Whitehill, J. J. Oleson, and Y. SubbaRow, Arch. Biochem. , 15, 31-37 (1947). 

 "3 H. P. Broquist and E. E. Snell, Arch. Biochem. Biophi/s., 46, 432-442 (1953). 

 "^ V. R. Williams and E. A. Fieger, Ind. Eag. Chein., Anal. Ed., 17, 127-130 (1945). 

 23S V. R. Williams and E. R. Fieger, J. Biol. Chem., 166, 335-343 (194G). 

 "6 H. P. Broquist and E. E. Snell, /. Biol. Chem., 188, 431-444 (1951). 



