BIOSYNTHESIS OF CYCLOPROPANE FATTY ACIDS 35 



convenience, accuracy, and the amount of material re- 

 quired. However, the fundamental observations which led 

 to recognition of the biosynthetic route to lactobacillic acid 

 were based on the use of reversed phase chromatography on 

 rubber as outlined in this section. 



2. CHEMICAL NATURE OF THE MONOETHENOID 

 FATTY ACIDS IN MICROORGANISMS 



Oleic acid has been reported to be a constituent of the 

 lipids of many microorganisms. Its presence has been in- 

 ferred from the isolation of stearic acid on hydrogenation, 

 and from iodine numbers obtained prior to hydrogenation. 

 Careful structure analyses of the monoethenoid octadecanoic 

 acid from L. arabinosus and L. casei led to its identification 

 as cw-vaccenic acid (m-11-octadecenoic acid) (7, 8). The 

 melting points of r/^-vaccenic acid and oleic acid and a 

 number of their derivatives exhibit a striking similarity 



