Characterization of new oxidation products of 9H-carbazole and structure related compounds by biphenyl-utilizing bacteria.
9H-Carbazole and its derivatives are useful for versatile pharmacological applications. To obtain different derivatives of 9H-carbazole, 24 isolates of biphenyl-utilizing bacteria have been investigated regarding their ability to produce hydroxylated 9H-carbazole metabolites. Our analyses showed that 9H-carbazole was primarily converted into 9H-carbazol-1-ol (15 strains) and 9H-carbazol-3-ol (9 strains), while carbazol-9-ol was formed as a minor product (12 strains). The formation of 9H-carbazol-3-ol by the spontaneous release from the corresponding dihydrodiols was provided by the first-time detection of 3-hydroxy-1,2,3,9-tetrahydrocarbazol-4-one. The dependence of product yields on different parameters was exemplarily analyzed for Ralstonia sp. SBUG 290. Biphenyl-grown cells showed higher oxidation activities than cells cultivated with organic acids or nutrient broth, while co-cultivation of Ralstonia sp. SBUG 290 with biphenyl and 9H-carbazole led to an enhanced yield of 9H-carbazol-1-ol. The tested bacterial strains were also studied regarding their biotransformation of the two structure-related compounds 9H-fluorene and dibenzothiophene. Twenty-one strains primarily transformed 9H-fluorene into 9H-fluoren-9-ol and fluoren-9-one. Three strains accumulated benzo[c]chromen-6-one as a novel dead-end product during the incubation with 9H-fluorene, 9H-fluoren-9-ol, and fluoren-9-one. Dibenzothiophene has been mainly transformed into the dead-end product dibenzothiophene-5-oxide, while additional metabolites indicated that the transformation followed the so called Kodama pathway.
Institute of Microbiology, Ernst-Moritz-Arndt-University of Greifswald, Friedrich-Ludwig-Jahn-Strasse 15, 17487 Greifswald, Germany. doreen.waldau@uni-greifswald.de
Doreen
D
Waldau
Karen
K
Methling
Annett
A
Mikolasch
Frieder
F
Schauer
D001419:Bacteria / Q000378:metabolism*; D001711:Biotransformation; D002227:Carbazoles / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005449:Fluorenes / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013876:Thiophenes / Q000378:metabolism
D002227:Carbazoles; D005449:Fluorenes; D013876:Thiophenes; C041514:carbazole; C041509:fluorene; C028401:9-fluorenone; C016366:dibenzothiophene