Selective and continuous degradation of carbazole contained in petroleum oil by resting cells of Sphingomonas sp. CDH-7.
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) pxylene, toluene, and heptanol, however, CA degradation yields decreased.
Kirimura
K
K
Department of Applied Chemistry, School of Science and Engineering, Waseda University, Tokyo, Japan.
Nakagawa
H
H
Tsuji
K
K
Matsuda
K
K
Kurane
R
R
Usami
S
S
D001673:Biodegradation, Environmental; D002227:Carbazoles / Q000378:metabolism*; D007700:Kinetics; D010578:Petroleum / Q000378:metabolism*; D012988:Soil Microbiology; D012997:Solvents; D020578:Sphingomonas / Q000302:isolation & purification / Q000378:metabolism*
D002227:Carbazoles; D010578:Petroleum; D012997:Solvents; C041514:carbazole