CHAPTER 



LACTOBACILLIC ACID, 



A NOVEL MICROBIAL METABOLITE 



1. DISCOVERY OF LACTOBACILLIC ACID 



The observation (1-7) that unsaturated fatty acids exert 

 a marked sparing action on the biotin requirements of 

 certain lactic acid organisms prompted initiation of our 

 systematic studies on the chemical nature of bacterial fatty 

 acids. These studies, which led to the discovery of lactoba- 

 cillic acid and to the recognition of cis-va.ccenic acid as an 

 important constituent of bacteria, provided the structural 

 foundation for investigations of fatty acid metabolism in 

 these lower forms of life. 



The chemical nature of the fatty acids of Lactobacillus 

 arahinosus (8, 9), Lactobacillus casei (10), Agrobacterium 

 (Phytomonas) tumefaciens (1 1), and of a group C Streptococ- 

 cus species (12) was determined in detail. The organisms 

 were grown on essentially lipid-free media and fatty acids 

 were isolated in the usual manner. Autoclaving with dilute 

 acid must precede extraction, since some 80% of the fatty 

 acids are present in the bacteria in a "bound" form not 

 soluble in mixtures of acetone and ether. The lipids were 



1 



