cis-9,10-Methylene hexadecanoic acid from the phospholipids of Escherichia coli.

Hofmann and Lucas (1) discovered a saturated cyclopropane compound in Lactobadlus arabinosus which they termed lactobacillic acid. Lactobacillic acid was found to be &s-11,12methylene octadecanoic acid (2). A survey by Hofmann et al. disclosed that lactobacillic acid is present in several lactic acid bacteria (3) but absent in a group C streptococcus (4). Lactobacillic acid was also found to be identical with the previously described “phytomonic acid” of Agrobacterium tumefaciens (5). In an analysis of the methyl esters of the fatty acids of Escherichia coli we found a major constituent which eluted in gasliquid chromatography between the methyl esters of Cl6 and Cl8 fatty acids. This paper describes the characterization of this component as cis-9, lo-methylene hexadecanoic acid, the Cl7 homologue of lactobacillic acid.