FATS AS ESSENTIAL DIETARY COMPONENTS 867 



McKee and co-workors"^ demonstrated that a mixture of fatty aoids 

 could be obtained from the bacteria-free cultures of the ciliated protozoon 

 Tetrahymena geleii. The fatty acids in these lysates consisted of an 

 approximately fifty-fifty mixture of saturated and unsaturated fatty acids, 

 with a fairly high proportion of myristic acid. Partially purified prepara- 

 tions were active in vitro against pneumococci, streptococci, mycobac- 

 teria, and staphylococci, but not against Gram-negative bacilli. Their 

 activity was greatly reduced in the presence of blood or of serum, and 

 could not be demonstrated in mice infected with mycobacteria or pneumo- 

 cocci. Costilow and Speck^-" demonstrated that caprylic (Cs), capric 

 (Cio) and lauric (C12) acids inhibit the growth of Streptococcus lactis, 

 usually present in rancid milk; the degree of inhibition varies directly 

 with the concentration of the acid. It would thus appear that several 

 components of the fatty acid structure are of importance in inhibiting the 

 gro^vth of certain types of bacteria. Properties such as chain length, degree 

 of unsaturation, and the presence of side chains all may affect the al)ility 

 to inhibit bacterial growth. 



Hardwick et al.^~^ observed that volatile and non-volatile fatty acids 

 from commercial peptone inhibited sporulation of aerobic l)acilli in a 

 synthetic medium, in concentrations not inhibitory to growth. The non- 

 volatile fraction was the more active. Saturated fatty acids such as 

 capric, lauric, tridecylic, and myristic acids were especially active in 

 antisporulation. 



By means of a Warburg respirometer, Franke and Schillinger^^- tested 

 a number of acid-fast bacteria, including Mycohacterinm rnbrum, M. 

 phlei ("timothy bacillus"), M. lacticola, M. avium, and also several cocci 

 and bacilli, and parasitic fungi, including Actinomyces chromogenes. They 

 observed inhibition of the growth of these organisms by both saturated 

 and unsaturated fatty acids and dicarboxylic acids. The respiratory 

 activity was found to decrease with the degree of resistance to acid of 

 these acid-fast organisms. It was lowest for tubercle bacilli. The res- 

 piratory inhibition by saturated do to C14 acids and by higher unsaturated 

 acids was related to the number of double bonds. 



According to Drea,'-^ the growth of human tubercle bacilli was inhibited 

 to a notable extent by C12, Ch, and Cie straight-chain acids. The anti- 



1" C. M. McKee, J. D. Butcher, V. Groupg, and M. Moore, Proc. Soc. Expfl. Biol. 

 ilfpd., ^5, 320-332(1947). 



'2» R. N. Costilow and M. L. Speck, /. Dairij Sci., 34, 1104-1110 (1951). 



'21 W. A. Hardwick, B. Guirard, and J. W. Foster, /. Bacteriol., 61, 145-151 (1951). 



'" W. Franke and A. Schillinger, Biochem. Z., 316, 313-334 (1944). 



1" W. F. Drea, J. Bacteriol, 48, 647-553 (1944). 



