870 XIV. NUTRITIONAL VALUE OF FATS 



extends the pH range over which the activity of oleic acid is observed. 

 Tween 80, in adequate amounts, has the same effect as does Tween 40 

 with the addition of oleic acid.'^^ 



Kodicek and Worden^^'^ observed that the inhibitory effects of oleic, 

 linoleic, and linolenic acids for Lactohacillus helveticus could be prevented 

 by the addition of several compounds, such as lecithin, cholesterol, calcif- 

 erol, lumisterol, a-tocopherol, a-tocopherol acetate, and sometimes even 

 calcium. The toxicity of oleic acid for Erysipelothrix rhusiopathiae was 

 counteracted bj^ saponin and by bile salts. ^^* The bacteriostatic action of 

 linoleic acid was also noted in the case of other Gram-positive bacteria, 

 such as Streptococcus agalactiae, Micrococcus pyogenes, var. albus, Bacillus 

 anthracis, and Listeria monocytogenes. It was not observed in the case of 

 Gram-negative organisms such as Proteus vulgaris or Escherichia coli. 

 Dubos and Davis ^^^'^^^ reported that growth of the tubercle bacillus 

 {Mycobacterium iubcrculosis) , was stimulated by long-chain fatty acids 

 only if these acids were first esterified or bound in some manner to serum 

 albuinin. This was especially true of oleic acid. 



According to Hedgecock,^" the dietary administration of a mixture of 

 fatty acid esters in proportions simulating those found in coconut oil, 

 and consisting of methyl laurate, methyl myristate, methyl palmitate, 

 methyl stearate, methyl oleate, and methyl linoleate, increased the resist- 

 ance of mice to infection with Mycobacterium tuberculosis. Methyl 

 linoleate alone, and lard alone, did not have this antibacterial effect. 

 The resistance was greatest if the animals had also received rations with 

 20% protein. The increase in resistance may be due to: (1) humoral 

 factors in the immunity reaction of the host, (2) alterations in the biochemi- 

 cal en^^ronment in the tissues of the host which are unfavorable to prolif- 

 eration of the organism, (3) direct inhibition of Mycobacterium tuberculosis 

 by the fatty acids. Hedgecock^^* had previously found that mice on a 

 synthetic diet containing coconut oil were more resistant to tuberculosis 

 than were those which had received olive or linseed oil. Dubos^^* found 

 that dietary peanut oil increased the resistance of mice to the tubercle 

 bacillus, and he attributed this bacteriostatic action to the effect of the 

 oil on the intermediary metabolism. 



The concentration of fatty acids in in vitro studies of microorganisms 



"3 E. Kodicek and A. W. Worden, Biochem. J., 39, 78-85 (1945~i. 



''^ S. H. Hutner, /. BacterioL, 43, 629-640 (1942). 



'^ R. J. Dubos and B. D. Davis, J. Exptl. Med., 83, 409-423 (1946). 



'36 B. D. Davis and R. J. Dubos, J. Exptl. Med., 86, 215-228 (1947). 



'37 L. W. Hedgecock, J. BacterioL, 70, 415-419 (1955). 



'38 R. J. Dubos, J. Exptl. Med., 101, 59-84 ( 1955). 



