52 FATTY ACID METABOLISM IN MICROORGANISMS 



c.p.m./mmole) and that of the lactobacillic acid fraction 

 (1.25 X 10^ c.p.m./mmole), which corresponds to 82 and 

 92% respectively of that of the added cw-vaccenic acid (spe- 

 cific activity 1.35x10^ c.p.m./mmole), demonstrates con- 

 clusively that lactobacillic acid is indeed formed from 

 m-vaccenic acid. The results show further that there is 

 little degradation or redistribution oi cis-\a.ccemc acid car- 

 boxyl carbon under the conditions employed in these ex- 

 periments. 



In the studies with one-carbon ( jnors methionine-C^^ 

 (2.69 X 107 c.p.m.) or sodium formate-C^* (7.57 X 10^ c.p.m.) 

 were added with 40 mg. of nonlabeled-c/^-vaccenic acid per 

 liter of medium. Cells grown in 3.5 liters of medium were 

 analyzed. In the experiments with cell suspensions, bac- 

 terial cells grown in 1 liter of medium, fortified with 40 

 mg. of nonradioactive cis-\a.ccenic acid, were harvested and 

 washed with 0.85% sodium chloride solution. The bacteria 

 were then suspended in 10 volumes of 0.03M potassium di- 

 hydrogen phosphate (pH 6.8) containing 1% of glucose 

 and sodium formate-C^^ (1.20 X 10^ c.p.m.) and incubated 

 at 37° for 24 hours with occasional shaking, 



Methionine-methyl-C^^ is effectively incorporated into the 

 bacterial cells which contain 3.15 X 10^ c.p.m. or 33.4% of 

 the added radioactivity (Table 2.5). In contrast to the 

 observations with c?Vvaccenic acid, 69.8% of the label is 

 located in the nonlipid fractions, the remaining radioac- 

 tivity being present in the mixed fatty acids (Table 2.5). 

 The bulk of the radioactivity (96.5%) in the mixed fatty 

 acids is located in the lactobacillic acid; the other fatty acids 

 exhibit a very low degree of labeling (Table 2.6). Incorpo- 

 ration of formate carbon into the bacterial cells is low 

 under both sets of experimental conditions. Only 3.5% of 

 the added radioactivity is incorporated into the growing 



