Selective and Continuous Degradation of Carbazole Contained in Petroleum Oil by Resting Cells of Sphingomonas sp. CDH-7

Kohtaro Kirimura*, Hiroyuki Nakagawa, Kenji Tsuji, Kazuya Matsuda, Ryuichiro Kurane, Shoji Usami

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


Microbial degradation of carbazole (CA), a model of hard-removal heterocyclic nitrogen compounds contained in petroleum oil, was examined using Sphingomonas sp. CDH-7 isolated from a soil sample by screening for CA-assimilating microorganisms. CDH-7 used CA as a sole source of carbon and nitrogen, and metabolized CA to ammonia via anthranilic acid as an intermediate product. When CDH-7 was cultivated in the medium containing CA at the concentration of 500 mg/l (2.99 mM), CA was completely degraded within 50 h. By the reaction with the resting cells of CDH-7, 500 mg/l of CA was completely degraded within 4 h, with 1.64 mM of ammonia accumulated in the reaction mixture. When CA was added at the concentration of 100 mg/l (0.599 mM) periodically to the reaction mixture ten times, 925 mg/l (5.54 mM) of CA was degraded within 48 h by the resting cells, and 4.50 mM of ammonia was accumulated in the reaction mixture with a 75.1% molar conversion yield based on total CA added. The resting cells could almost completely degrade CA in a two-liquid-phase system which consists of water and organic solvent, even in the presence of 20% (v/v) isooctane, n-hexane, cyclohexane, and kerosene as a model petroleum oil. In the presence of an organic solvent system such as 20% (v/v) p-xylene, toluene, and heptanol, however, CA degradation yields decreased.

Original languageEnglish
Pages (from-to)1563-1568
Number of pages6
JournalBioscience, Biotechnology and Biochemistry
Issue number9
Publication statusPublished - 1999 Jan 1


  • Biodegradation
  • Carbazole
  • Heterocyclic nitrogen compound
  • Resting cell reaction
  • Sphingomonas sp

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry


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