Degradation of quinoline by Rhodococcus sp. QL2 isolated from activated sludge

A novel aerobic gram-positive bacterial strain capable of utilizing quinoline as sole source of carbon, nitrogen and energy was isolated from activated sludge of a coke plant wastewater treatment process. The isolate was identified as Rhodococcus sp. QL2 based on its morphology, physiochemical properties in addition to the results from 16S rDNA sequence analysis. The optimum temperature and the pH for its growth were 35-40 °C and 8.0, respectively. Extra nitrogen sources stimulated the bacterial growth on quinoline. Strain QL2 had strong quinoline degradability, and its degradation kinetics could be described with Haldane's model. Strain QL2 also had a broad range of substrate utilization. Identification of intermediates by GC/MS showed Rhodococcus sp. QL2 degraded quinoline via two pathways simultaneously.