Degradation of n-Mcthylhexane by a Pseudomonas 477 



niques (4) as well as by isolation of the fatty acids and their 

 mass-spectrometric identification (2). 



The micro-organism used throughout all our studies was 

 isolated from brackish harbour water and is believed to be closely 

 related to, or identical with Ps. aeruginosa (4). 



Some of the results of the multiple adaptation experiments 

 are presented in Table 1. 



TABLE 1 

 Q02 WITH Various Fatty Acid Substrates of Ps. Cells Grown on 2- 



METHYLHEX.'^NE AND K-HEPTANE 



As expected the figures show a high Qoj for propionic acid 

 oxidation by heptane-grown cells. Slow propionic acid oxidation 

 by 2-methylhexane-grown cells can be explained by the assump- 

 tion that the Co-pathway is followed in 2-methylhexane oxidation, 

 which pathway does not incorporate propionic acid. This conclu- 

 sion is substantiated by a high Q02 for iso-valeric acid, whicli in- 

 deed is an intermediate in the Ce-scheme. 



The two methyl-substituted hexanoic acids are only slowly 

 oxidized by tlie heptane-grown cells, which, of course is not 

 astonishing. The 2-methylhexane-grown cells clearly show pre- 

 ference for the 5-methyl isomer and thus, again the Ce-pathway 

 seems favoured by the micro-organism. 



The oxidation of 2-methylhexanoic acid is, however, not 

 negligible (Qo.. = 80 versus Qo.. = 47 for the heptane-grown 

 cells). A conclusion that the 2-methylhexane molecule is also 

 oxidized at d is, however, not warranted on the basis of multiple 

 adaptation only. 



FATTY-ACID ISOLATION AND IDENTIFICATION 



The conclusions from the multiple adaptation experiments 

 are well supported by the results of fatty acid identification. 



