title: Evidence for a novel pathway in the degradation of fluorene by Pseudomonas sp. strain F274.
abstract: A fluorene-utilizing microorganism, identified as a species of Pseudomonas, was isolated from soil severely contaminated from creosote use and was shown to accumulate six major metabolites from fluorene in washed-cell incubations. Five of these products were identified as 9-fluorenol, 9-fluorenone, (+)-1,1a-dihydroxy-1-hydro-9-fluorenone, 8-hydroxy-3,4-benzocoumarin, and phthalic acid. This last compound was also identified in growing cultures supported by fluorene. Fluorene assimilation into cell biomass was estimated to be approximately 50%. The structures of accumulated products indicate that a previously undescribed pathway of fluorene catabolism is employed by Pseudomonas sp. strain F274. This pathway involves oxygenation of fluorene at C-9 to give 9-fluorenol, which is then dehydrogenated to the corresponding ketone, 9-fluorenone. Dioxygenase attack on 9-fluorenone adjacent to the carbonyl group gives an angular diol, 1,1a-dihydroxy-1-hydro-9-fluorenone. Identification of 8-hydroxy-3,4-benzocoumarin and phthalic acid suggests that the five-membered ring of the angular diol is opened first and that the resulting 2'-carboxy derivative of 2,3-dihydroxy-biphenyl is catabolized by reactions analogous to those of biphenyl degradation, leading to the formation of phthalic acid. Cell extracts of fluorene-grown cells possessed high levels of an enzyme characteristic of phthalate catabolism, 4,5-dihydroxyphthalate decarboxylase, together with protocatechuate 4,5-dioxygenase. On the basis of these findings, a pathway of fluorene degradation is proposed to account for its conversion to intermediary metabolites. A range of compounds with structures similar to that of fluorene was acted on by fluorene-grown cells to give products consistent with the initial reactions proposed.
authors.affiliation: Department of Microbiology, University of Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Grifoll
authors.forename: S A
authors.initials: SA
authors.lastname: Selifonov
authors.forename: P J
authors.initials: PJ
authors.lastname: Chapman
mesh_terms: D001673:Biodegradation, Environmental; D002455:Cell Division; D005449:Fluorenes / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D015394:Molecular Structure; D011549:Pseudomonas / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D005449:Fluorenes; C041509:fluorene