460 Marine Microbiology 



results from bacterial alkane oxidation, the olefin resulting from 

 dehydrogenation must be a terminal, or 1-olefin. At this writing 

 no such olefins have been isolated from bacterial oxidations of 

 saturated hydiocarbons. Furthermore, if the 1-olefin is an inter- 

 mediate in alkane oxidation it should be handled l:)y alkane 

 oxidizing microorganisms in the same manner, i.e., oxidation to 

 fatty acids (or methyl ketones or esters). Bruyn (2) isolated 

 hexadecane-diol-1,2 from culture fluids of Candida Upohjtica 

 growing at the expense of 1-hexadecene, but apart from this report 

 little is known concerning microbial utilization of 1-olefins. 

 Stewart et al. (11) isolated esters from Micrococcus strains grow- 

 ing in minerals-olefin media and the esters were shown to have 

 alcohol moieties with a carbon skeleton identical to that of the 

 olefin substrate including an intact double bond (Fig. 4). The 

 findings suggest that olefins are utilized differently by C. 

 lipohjtica and Micrococcus but even more significant is the find- 

 ing that the oxidative attack by bacteria does not apparently occur 

 at the olefinic bond, thus suggesting that the terminal olefin is 

 not an intermediate in the oxidation of long chain alkanes. 



A reasonable reconciliation of these diverse findings based 

 on the activities of different organisms toward various alkanes 

 would seem to be assigning of at least three major pathways to 

 the microbial utilization of alkanes. Long chain alkanes ( C12 - Cis ) 

 are oxidized by the way of 1-alkyl hydroperoxides and the fomia- 

 tion of n-alcohols which in turn are oxidized to /i-fatty acids. Cer- 

 tain short chain length alkanes ( Ca - C, ) produce methyl ketones 

 probably via rearrangement of 1-alkyl free radicals and, finally, 

 intermediate length alkanes ( Cr, - Cio ) are dehydrogenated to the 

 corresponding 1-alkene. Much work remains to be done to es- 

 tablish the pathways more firmly and, considering the metabolic 

 flexibility of microorganisms, it is not unlikely that other meta- 

 bolic sequences for microbial alkane oxidations will be uncovered. 

 Kester and Foster (7), for example, have already demonstrated 

 an intriguing case of bacterial diterminal oxidation of alkanes. 

 Interestingly, later evidence suggests mono-terminal oxidation 

 (hydroperoxidation?) followed by oj-oxidation (Foster, personal 

 communication ) . 



