FATS AS ESSENTIAL DIETARY COMPONENTS 869 



that unsaturated acids in general, especially linolenic acid, inhibited the 

 oxygen uptake by tubercle bacilli. 



Although Tween 80 promotes the growth of tubercle bacilli, it inhibits 

 small inocula, because of its content of unesterified oleic acid. Bovine 

 serum albumin neutralizes the inhibition by tightly binding the fatty 

 acid ; it also contains a trace of lipase, which releases enough fatty acid to 

 equal the binding capacity of the albumin. Growth from very small 

 inocula (two to three cells) is possible only when hydrolysis of the Tween 

 by this lipase is prevented. ^^^-^^ 



Davis and Dubos'" suggested that the lipolytic activity accounts for 

 the bacteriostatic effect, in a medium containing horse serum and a culture 

 filtrate of Alycohacterium phlei. 



Stanley and Adams^^* found that, of a large number of aliphatic acids 

 which were bactericidal in vitro for Mycobacterium leprae, all the bacteri- 

 cidally effective compounds markedly depressed surface tension, and had a 

 molecular weight of approximately 256 (Cie acids). However, this is not 

 the sole criterion, inasmuch as a-bromopalmitic acid, the total acids of 

 cod liver oil, and some C19 and higher acids were good surface depressors, 

 but were relatively non-effective as bactericides. However, with these 

 exceptions, surface tension paralleled bactericidal effectiveness. 



Spector^^^ observed that the fatty acids of butterfat and of corn oil 

 exerted varying degrees of inhibitory action up on the metabolism of 

 Escherich's intestinal bacillus (Escherichia coli), Lactobacillus casei, and 

 L. arabinosus, depending upon the concentrations employed, and upon the 

 level of the vitamin or amino acid also affecting growth. 



On the other hand, Williams et aL^^*^'^^ found that oleic acid, detoxified 

 with Tween 40, was required for the growth of Lactobacillus bulgaricus. 

 Williams and Fieger^^"^ were able to stimulate the growth of Lactobacillus 

 casei and L. arabinosus by the addition of oleic and linoleic acid to the 

 medium, provided biotin-free bovine serum albumin was also added. 

 Oleic acid is so toxic for the lactic acid bacilli that its growth-promoting 

 action can be observed only wdthin a narrow range of concentrations and 

 pH, and in the absence of biotin.^^^ The addition of Tween 40 greatly 



i2« B. D. Davis and R. J. Dubos, Arch. Biochem., 11, 201-203 (1946). 



1" B. D. Davis and R. J. Dubos, /. Baderiol, 5.5, 11-23 (1948). 



128 W. M. Stanley and R. Adams, /. Am. Chem. Soc, 5/,, 1548-1557 ('n«2). 



•29 H. SixTtor, Arch. Biochem., 11, 167-177 (1946). 



'«" W. L. Williams, E. IIofT-j0rgcnsen, and E. E. Siioll, ./. Biol. Chnii., 177, 933-940 

 (1949). 



1" W. L. Williams, H. P. Broquist, and E. E. Sncll, J. Biol. Chcm., 170, 619-630 

 (1947). 



"2 V. R. Williams and E. A. Fieger, J. Biol. Chem., 177, 739-744 (1949). 



