Mechanisms in the Microbial Oxidation of Alkanes 457 



350 r •RCOOH 



RCHgOOH 



RCH3 



RCH2OH 

 RCHO 



End 



Time (hours) 



Fig. 3. Oxidation of n-dodecane, 1-dodecyl hydroperoxide, and other oxy- 

 genated analogues of dodecane by Micrococcus sp. grown in minerals-dode- 

 cane medium. Each vessel contained 5 /umoles substrate, 0.5 ml. of 0.1 M 

 phosphate buffer (pH 8.0) containing 200 mg. MgS0..7H.O, 1.0 mg. 

 CaCL.2H:0 and 1.0 mg. FeSOf.TH.O per 100 ml. buffer, 10 mg. (dry wt.) 

 of cells. V, = 3.0. Incubation at 30 C. 



factory way has been developed to compare the substrate-water- 

 bacterium interface which may be a real factor in any rate study 

 particularly when the substrates vary in solubility and physical 

 form (solid and liquid). 



Stewart et ah (14) have pointed out that 1-decyl hydro- 

 peroxide is relatively toxic, but our tests witli the series of these 

 materials indicates the toxicity decreases with an increase in the 

 length of the alkyl chain. At low concentrations (5 /-.moles per 

 experimental vessel) non-proliferating cells rapidly oxidized all 

 hydroperoxides tested. The toxicity of the hydroperoxides was 

 high enough to preclude meaningful growth experiments. How- 

 ever, heavy, non-proliferating cell suspensions harvested from 

 alkane-minerals medium and incubated with 400 /-moles of 1-alkyl 

 hydroperoxide (the least toxic of the hydroperoxides) produced 



