title: Recycle use of Sphingomonas sp. CDH-7 cells for continuous degradation of carbazole in the presence of MgCl2.
abstract: Carbazole (CA) is a heterocyclic nitrogen compound contained in the crude petroleum oil and recalcitrant to removal through the refinery processes. For development of the efficient CA-degradation bioprocess, conditions for the recycle use of Sphingomonas sp. CDH-7 resting cells were examined. When the resting cells (O.D.(660) 3.3) were shaken in 50 m M K2HPO4-KH2PO4 buffer (pH 7.0) containing CA 1000 mg/L, CA 880 mg/L was degraded within 3 h, but thereafter the activity decreased markedly. However, the activity was found to be restored to the initial level after the shaking treatment for 3 h in CA-free medium solution or in the buffer containing 20 m M MgCl2. Although the CA-degradation activity of CDH-7 resting cells was lost after 3 h of shaking in the buffer containing 100 m M EDTA, it was restored through the shaking treatment for 3 h in the buffer containing 20 m M MgCl2. When CA was periodically added eight times at a concentration of 100 mg/L (0.599 m M) to the reaction mixture containing the resting cells, CA 778 mg/L (4.66 m M) was continuously degraded within 35 h by the recycle use of resting cells, with the restoration treatment after each CA-degradation reaction by the resting cells.
authors.affiliation: Tsukuba Central 6, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba-shi, Ibaraki 305-8566, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Kohtaro
authors.initials: K
authors.lastname: Kirimura
authors.forename: Takako
authors.initials: T
authors.lastname: Nitta
authors.forename: Kuniki
authors.initials: K
authors.lastname: Kino
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Kurane
authors.forename: Shoji
authors.initials: S
authors.lastname: Usami
mesh_terms: D001673:Biodegradation, Environmental; D002227:Carbazoles / Q000378:metabolism*; D015636:Magnesium Chloride; D020578:Sphingomonas / Q000378:metabolism*; D013997:Time Factors
chemical_list: D002227:Carbazoles; D015636:Magnesium Chloride; C041514:carbazole