MONOUNSATURATED FATTY ACIDS 63 



TABLE 3.2 



Incorporation of Saturated Acids into Long-Chain 

 (Ci6 + Cis) Acids of C. butyricum 



* All the acids were labeled in the carboxyl group. 



Adapted from Bloch et al., Federation Proceedings, 20, 921 (1961). 



These experiments which corroborate previous findings 

 (1, 2) show clearly that permeability factors are not the 

 reason for the inability of saturated fatty acids to substitute 

 for unsaturated fatty acids as promoters of bacterial growth 

 in biotin deficient media. They demonstrate in addition 

 that L. planarum and C. butyricum, just as L. arahinosus, 

 L. casei, and L. delbrueckii, cannot bring about desatura- 

 tion of long-chain fatty acids. 



Of particular significance is the observation (Table 3.2) 

 that in contrast to saturated fatty acids containing 12, 14, 

 16, and 18 carbon atoms, octanoate-l-C^* and decanoate- 

 l-C^^ are incorporated into both the saturated and the 

 monounsaturated fatty acids of C. butyricum (4, 5). As 

 can be expected, acetate also serves as a precursor of both 

 types of fatty acids. The distribution of radioactivity in the 

 hexadecenoicand octadecenoic acids provides the experi- 



