[Isolation and characterazation of a carbazole-degrading bacterial strain]

A bacterial strain was isolated from soil samples using plate screening techniques. Results indicated this isolated were able to use carbazole as sole source of carbon and energy, simultaneously, including N-Methylcarbazole, 4-Hydroxycarbazole and 2,2'-Biphenol. It was identified as Flavobacterium sp. according to its morphology, and biochemical properties, and 16S rDNA sequence analysis. Utilization of carbazole by the isolates was confirmed by the increase in bacterial biomass and the decrease in substrate concentration in liquid cultures. The optimal pH and temperature for cell growth and carbazole degradation were 7.5 and 30 degrees C, respectively. Resting cells grown in Luria broth also showed activity for decomposing other heterocyclic compounds. In addition, biodegradation of carbazole was carried out with carbazole degrading strain KH-6. The results indicated that 90% of the carbazole could be degraded in the sterilized soil. And strain KH-6 could enhance the degradations of carbazole significantly.