Microbial Metabolism of Alicyclic Hydrocarbons: Isolation and Properties of a Cyclohexane-degrading Bacterium

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Abstract
A microorganism which grows on cyclohexane as sole C and energy source was isolated from estuarine mud flats. It was tentatively identified as a Nocardia. The organism, which is auxotrophic for biotin, grows on cyclohexane (supplied as a vapor) with a mean generation time of about 10 h and a YSUB [molar growth yield per mole substrate] of 59.9 g dry wt (mol cyclohexane)-1. Growth on cyclohexane leads to the production of intracytoplasmic membrane structures which are not present after growth on succinate. Growth, respiration and enzyme studies are consistent with the degradation of cyclohexane via cyclohexanol, cyclohexanone, .epsilon.-caprolactone and 6-hydroxycaproate. Extracts of organisms grown on cyclohexane contained cyclohexanol dehydrogenase, cyclohexanone monooxygenase and .epsilon.-caprolactone hydrolase; these enzymes are absent from, or at very low activity in, extracts of organisms grown on succinate.