Identification, degradation characteristics, and application of a newly isolated pyridine-degrading Paracidovorax sp. BN6-4

Abstract The Paracidovorax sp. BN6-4 capable of degrading high concentrations of pyridine was isolated from the coking sludge. The removal rate of BN6-4 to 1,000 mg/L pyridine during 48 h was 97.49 ±1.59%. The primary intermediate metabolites of pyridine degradation by strain BN6-4 were identified by gas chromatography-mass spectrometry (GC-MS), including N-Ethylurea, acetamidoacetaldehyde, and N-Hydroxymethylacetamide, etc. Subsequently, two different biodegradation pathways of pyridine were proposed. First, the hydroxylation of pyridine to form the intermediates pyridin-2(1H)-one and 5,6-dihydropyridine-2,5-diol, the former undergoing oxidative ring opening and the latter oxidative ring opening via N-C2 and C2–C3 ring opening to ammonia and carbon dioxide. Furthermore, the organic matter was greatly degraded by the bioremediation of real coking wastewater using BN6-4. This study enriched the microbial resource for pyridine degradation and provided new insights about the biodegradation pathway of pyridine, which is of great significance for the pyridine pollution control and coking wastewater treatment.