46 FATTY ACID METABOLISM IN MICROORGANISMS 



dibasic acids derived from the degradation of trans-9,\0- 

 methyleneoctadecanoic acid (mainly azelaic acid plus sub- 

 eric acid) differ markedly from those resulting from degrada- 

 tion of irfl?75-ll,12-methyleneoctadecanoic acid (undecanedi- 

 oic acid plus sebacic acid). The acids corresponding to each 

 chromatographic peak were isolated and their identity veri- 

 fied by melting point, by mixed melting point with an 

 authentic sample, and by x-ray diffraction measurements. 



The finding that the dibasic acid pattern derived from the 

 degradation of dihydrosterculic acid matches that obtained 

 from ^rflnj-9,10-methyleneoctadecanoic acid; whereas that 

 derived from degradation of lactobacillic acid duplicates 

 essentially that obtained from ^ra775-ll,12-methyleneoctadec- 

 anoic acid establishes the position of the cyclopropane 

 ring in these acids. 



The experiences with this type of degradation (Fig. 2.5), 

 indicate that the major route follows the pathways marked 

 by heavy lines. 



In addition to providing information regarding the ring 

 position, the above mentioned degradative scheme allows 

 the selective removal of the methylene bridge carbon atom 

 from the rest of the carbon chain. Oxidation with hypo- 

 iodite of the total mixture of neutral and acidic products 

 derived from the oxidative degradation yields iodoform. 

 Only two of the many plausible oxidative fragments, namely 

 compounds I and II, can be precursors of this compound. 

 Since the ketone methyl groups of these products originate 

 from the methylene bridge carbon of the original com- 

 pound, the iodoform carbon is likewise derived from this 

 source. The implications of this in the elucidation of the 

 biosynthesis of lactobacillic acid will be discussed in the 

 following section. 



