240 Harland G. Wood 



This is a most important observation because it indicates the 

 possibihty that formaldehyde per se may be an intermediate. 

 The conversion of added formaldehyde or formate* to a 

 fermentation product is of course not proof that the formal- 

 dehyde or formate is an intermediate. These added com- 

 pounds may be converted to the true intermediate or possibly 

 they may never occur in a normal fermentation. Although 

 formaldehyde has been detected previously in the propionic 

 acid fermentation by use of the fixative dimedon (Wood and 

 Werkman, 1935), in the present case Leaver detected it 

 without the use of a fixative. [1, 3-i*C]-glycerol| was fermented 

 by resting cells in the presence of a pool of 8 x 10* m. unlabelled 

 formaldehyde. After 18 hours the fermentation was stopped 

 and the residual formaldehyde was distilled and determined 

 in an aliquot colorimetrically (Alexander, Landweler and 

 Seligman, 1945). To the 28 /lim. of formaldehyde that 

 remained, unlabelled formaldehvde was added as a carrier 

 and the formaldehyde was isolated as the dimedon derivative. 

 This derivative was recrystallized from alcohol and water to a 

 constant activity of 119 counts/min./mg. C. It was then 

 recrystallized from acetone and water and contained 117 

 counts/min./mg. C. The melting point and mixed melting 

 points were 190°. When corrected for dilution by the carrier 

 formaldehyde, the formaldehyde recovered from the fermen- 

 tation was calculated to contain 720 counts/min./mg. C. The 

 original glycerol contained 808 counts/min./mg. of labelled 

 carbon. It would thus appear that the pool of added for- 

 maldehyde was largely replaced by ^*C -formaldehyde formed 



♦Leaver (1950) found that formate is not fixed in the propionic acid fer- 

 mentation. In the synthesis of serine, Siegel and Lafaye (1950) found that 

 formaldehyde was utilized better than formate by rat liver homogenates and 

 they suggested that formaldehyde is a more direct precursor of the jS-carbon 

 of serine than is formate. Siekevitz and Greenberg (1950) found that rat liver 

 slices do not convert formate to formaldehyde although they do produce 

 formate from the a carbon of glycine. In the synthesis of methyl groups of 

 choline (du Vigneaud, Verly and Wilson, 1950) both formate and formaldehyde 

 are utilized, but Berg (1951) has found that formaldehyde per se probably is 

 not an intermediate in the formation of methyl groups of methionine from 

 formate. 



•{•The [1, 3-^*C]-glycerol was a generous gift from Dr. M. L. Karnovsky. 



