466 Marine Microbiology 



of a large excess of alkali. After reacidification with tartaric acid, 

 the steam distillation of the concentrate yielded a total volatile 

 acid fraction corresponding to 0.55 meq per liter of original cul- 

 ture, i.e., to about 0.1 per cent of the initial hydrocarbon. The 

 steam distillate, concentrated to 10 ml in excess alkali, was chro- 

 matographed on Whatman No. 1 paper with butanol-ammonia. 

 On these chromatograms ( Fig. 1 ) , the presence of enanthic acid, 

 i.e., of the fatty acid conesponding to the initial alkane, is un- 

 equivocal. No caproic acid (Co) is visible, but the presence of 

 other acids belonging to the even series and namely of butyric 

 acid (C4), could suggest a breakdown through an «-oxidation 

 pathway. 



Results Obtained By the Simultaneous Adaptation Method 



Conclusive evidence that the degradation of the fatty acids 

 actually proceeds through a ^-oxidation process has been ob- 

 tained by the method of simultaneous adaptation (10). It was 

 previously observed that the enzymes responsible for the metab- 

 olism of both the alkane and the corresponding fatty acid are 

 adaptative. This was demonstrated by the fact that resting cells 

 grown on glucose only consume O2 in the presence of n-heptane 

 or enanthic acid after a lag phase and that no oxygen consump- 

 tion is observed when chloramphenicol is added. 



The simultaneous adaptations of the resting cells have been 

 determined in the presence of chloramphenicol (50 /'g/ml), 

 in order to supress any secondary adaption on the course of the 

 manometric experiments. The results obtained under these ex- 

 perimental conditions are very significant. From the data re- 

 corded in Table 1, it is clear that the cells grown on n-heptane 

 are simultaneously adapted to the corresponding fatty acid and 

 to the lower acid belonging to the odd series, but not to be 

 corresponding dicarboxylic acid (pimelic) nor to octanoic and 

 hexanoic ( caproic ) acids. Conversely, the cells grown on an even 

 alkane are simultaneously adapted to the coiTesponding and 

 lower acids of the same series, and are not adapted to the acids 

 of the odd series. 



The experiments reported in Table 2 show that the cells 

 grown on n-heptane are adapted to the corresponding mono- 



