454 



Marine Microbiology 



2CH3(CH2),4CH3 + 202^ 



2CH3(CH2),4CH20'^0'^H 



2CH3(CH2),4CH20'®H 



8 



H 

 CH3(CH2),4C = 



+H20'^ 



CH3(CH2)|4C^qI6|_^ 



H 



-2H 



r-0 



18 



CH3(CH2)|4CI^ 16 



H 



(O'^ contribution =^ =25%) 



vl8. 



CH3(CH2)|4CH20"'H 

 (50% contribution of O'^J 



Randomization of O'^in acid with O'^ from H^O 



I 



J8 



CH3(CH2),4-C--0'°-(CH2),5CH3 



( of incorporation ^ 75 %) 



Fig. 1. Hypothetical mechanism for bacterial oxidation of 7i-hexadecane 

 and subsequent formation of cetyl palmitate [from Stewart et al. (14)]. 



strated that there appears to be no significant anaerobic oxidation 

 of pure alkanes by Desulfovibrio as evidenced by failure to ob- 

 serve HjS formation in sulfate containing minerals-alkane media. 

 Direct evidence for the participation of gaseous oxygen in 

 alkane oxidations was found by Stewart et al. (14), in a study of 

 the oxidation of n-hexadecane by a gram negative micrococcus 

 characterized by ester excretion when growth at the expense of 

 alkanes. Cetyl palmitate, the ester produced from hexadecane by 

 the organism was isolated after incubation under O^^ enriched 

 atmosphere and was shown to have 75 percent incorporation of 

 atmospheric oxygen. Based upon these findings the mechanism 

 for alkane oxidation and ester formation shown in Figure 1 was 



