THE LIPOIDS OF MICRO-ORGANISMS 381 



The phosphatides of the diphtheria bacilhis, having the 

 iiitro gen-phosphorus ratio of a monoamino-monophospha- 

 tide, on hydrolysis yield aldohexoses, fatty acids, a 

 compound with a high molecular weight and traces of a 

 base. The solid saturated fatty acid was exclusively 

 palmitic acid, and the liquid acids contained a substance, 

 corynin, C50H100O4, m.p. 70° to 71°, containing one 

 carboxyl group and two hydroxyl groups. 



Phytomonas tiunefaciens contains about 2 per cent, 

 of total lipoids when grown on a sjoithetic, glycerol- 

 containing medium and about 6 per cent, when the 

 glycerol is replaced by sucrose. About 70 per cent, of 

 the acetone soluble fat consists of free fatty acids, mainly 

 unsaturated. The phosphatides are lecithin and cephalin 

 in approximately equal quantities. The fatty acids 

 comprise normal saturated and unsaturated Cis and 

 C18 acids as well as liquid saturated branched chain acids 

 of high molecular weight, similar to those in the tubercle 

 bacilli. Among the liquid, saturated fatty acids is crystal- 

 line ph}i:omonic acid, C20H40O2, m.p. 24° C. It is optic- 

 ally inactive and is probably a homologue of tuberculo- 

 stearic acid. It constitutes about 14 per cent, of the 

 total fatty acids. No chloroform soluble wax and no 

 sterols could be isolated. 



The phosphatide of LactohaciUus acidophilus yields 

 glycerophosphoric acid, choline, palmitic, stearic and 

 unsaturated fatty acids, together with a crystalline non- 

 reducing polysaccharide which gives glucose, galactose 

 and fructose on further hydrolysis. 



The yeasts also contain a high proportion of phospha- 

 tides, but their constitution has not been worked out. 



Fat Synthesis. — The mechanism of fat synthesis by 

 micro-organisms has been most extensively studied in the 

 case of the yeast, Endomyces vernalis, which was used as 

 a source of fat in Germany during the 1914-1918 war. 



Haehn and Kinntof , following a suggestion by Magnus 

 Levy that acetaldehyde condensed to give aldol as an 



