The metabolism of cyclohexanol by Nocardia globerula CL1

1. Nocardia globerula CL1, isolated by enrichment on cyclohexanol and grown with it as carbon source, oxidized it with a Qo2 of 39μl/h per mg dry wt. and the overall consumption of 2.2μmol of oxygen/mol of substrate. Cyclohexanone, 2-hydroxycyclohexan-1-one dimer and cyclohexane-1,2-dione were oxidized with Qo2 values similar to that for cyclohexanol whereas ∈-caprolactone and 6-hydroxycaproate were oxidized very slowly and adipate not all. 2. Disrupted cell suspensions could not be shown to catalyse the conversion of cyclohexanol into cyclohexanone. 3. A cyclohexanol-induced cyclohexanone oxygenase (specific activity 0.55μmol of NADPH oxidized/min per mg of protein) catalysed the consumption of 1mol of NADPH and 1mol of O2 in the presence of 1mol of cyclohexanone. NADPH oxidation did not occur under anaerobic conditions. The only detected reaction product with 25000g supernatant was 6-hydroxycaproate. 4. Extracts of cyclohexanol-grown cells contained a lactone hydrolase (specific activity 15.6μmol hydrolysed/min per mg of protein), which converted ∈-caprolactone into 6-hydroxycaproate. 5. Incubation of 6-hydroxycaproate with 25000g supernatant in the presence of NAD+ resulted in NAD+ reduction under anaerobic conditions, oxygen consumption under aerobic conditions and the conversion of 6-hydroxycaproate into adipate. 6. Cyclohexanone oxygenase fractions devoid of ∈-caprolactone hydrolase catalysed the stoicheiometric formation of ∈-caprolactone from cyclohexanone in the presence of excess of NADPH. 7. The reaction sequence for the oxidation of cyclohexanone by N. globerula CL1 is: cyclohexanol → cyclohexanone → ∈-caprolactone → 6-hydroxycaproate → adipate. 8. It is suggested that the adipate may be further dissimilated by β-oxidation.