Identification and characterization of quinoline-degrading bacterial strains isolated from the influent pipeline of a bioreactor

Abstract:

[Background] Quinoline is a nitrogen heterocyclic compound with high toxicity, carcinogenicity but low degradability. A lab-scale denitrifying quinoline-degrading bioreactor was developed and in operation for several years. [Objective] To isolate the potential quinoline-degrading bacteria from the influent pipeline of the bioreactor. [Methods] The media with quinoline as sole carbon source were adopted to enrich, screen and purify degrading strains. Phylogenetic analysis was performed through 16S rRNA gene sequencing. The characteristics of quinoline degradation by different strains were investigated under different pH and temperature conditions. [Results] Based on the phylogenetic analysis, four isolates Q1, Q3, Q7 and Q8 were identified as the genera of Sphingobium, Massilia, Rhodococcus and Dyadobacter, respectively. We demonstrated that 50 mg/L quinoline could be removed within 48 h by all of the strains with varied degradation characteristics. The accumulation of 2-hydroxyquinoline was detected during the cultivation of strain Q1, Q3 and Q8. Notably, the genera of Sphingobium, Massilia and Dyadobacter have not been reported yet on quinoline degradation. [Conclusion] The four quinoline-degrading bacteria isolated from the influent pipeline of bioreactor can provide novel strain resources for decontaminating industrial wastewater containing quinoline, which may contribute to further understanding of the mechanism of quinoline biodegradation.