Metabolic pathway analysis of two quinoline-degrading bacterial strains

Two degrading bacterial strains utilizing quinoline as sole carbon source and nitrogen source for growth and supersession were isolated from coking wastewater treatment system. Based on their morphology, physiological and biochemical characters, and sequence analysis of 16S rRNA genes, two bacterial strains were initially identified as Pseudomonas sp.QG6 and Rhodococcus sp.QL2, respectively. Both strains showed good biodegradability for quinoline. They could both degrade completely in 8 h when quinoline initial concentration was 150 mg/L. but in degrading process showed different color change, and on TOC removal efficiency strain QG6 was higher than strain QL2. HPLC analysis showed that the intermediates of quinoline degradation by two strains were different and the polarities of these intermediates were stronger than that of quinoline. GC/MS appraisal results showed that the intermediates of Pseudomonas sp.QG6 had 2-hydroxyquinoline, 8-hydroxycoumarin, and 2, 3-dihydroxyphenylpropionic acid, whereas the intermediates of Rhodococcus sp.QL2 included 2-hydroxyquinoline, 2, 6-dihydroxyquinoline, and 8-hydroxycoumarin. At last, two different metabolic pathways of quinoline degradation were proposed.EI05456-4602