Biotransformation of D-limonene to (+) trans-carveol by toluene-grown Rhodococcus opacus PWD4 cells.
The toluene-degrading strain Rhodococcus opacus PWD4 was found to hydroxylate D-limonene exclusively in the 6-position, yielding enantiomerically pure (+) trans-carveol and traces of (+) carvone. This biotransformation was studied using cells cultivated in chemostat culture with toluene as a carbon and energy source. The maximal specific activity of (+) trans-carveol formation was 14.7 U (g of cells [dry weight])(-1), and the final yield was 94 to 97%. Toluene was found to be a strong competitive inhibitor of the D-limonene conversion. Glucose-grown cells did not form any trans-carveol from D-limonene. These results suggest that one of the enzymes involved in toluene degradation is responsible for this allylic monohydroxylation. Another toluene degrader (Rhodococcus globerulus PWD8) had a lower specific activity but was found to oxidize most of the formed trans-carveol to (+) carvone, allowing for the biocatalytic production of this flavor compound.
Duetz
W A
WA
Institute of Biotechnology, ETH Hönggerberg, HPT, CH 8093, Zürich, Switzerland. duetz@biotech.biol.ethz.ch
Fjällman
A H
AH
Ren
S
S
Jourdat
C
C
Witholt
B
B
D001711:Biotransformation; D003470:Culture Media; D000081005:Cyclohexane Monoterpenes; D053138:Cyclohexenes; D005421:Flavoring Agents / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007536:Isomerism; D000077222:Limonene; D039821:Monoterpenes; D012240:Rhodococcus / Q000254:growth & development* / Q000378:metabolism*; D013045:Species Specificity; D013729:Terpenes / Q000378:metabolism*; D014050:Toluene / Q000378:metabolism*
D003470:Culture Media; D000081005:Cyclohexane Monoterpenes; D053138:Cyclohexenes; D005421:Flavoring Agents; D039821:Monoterpenes; D013729:Terpenes; D014050:Toluene; C006923:carvone; C075856:carveol; D000077222:Limonene; D005947:Glucose