Screening, degradation characteristics, and metabolic pathway of an efficient pyridine-degrading bacterial consortium MD1

Abstract:

[Objective] To screen out the bacterial consortium capable of efficiently degrading pyridine and promote the degradation of high-concentration pyridine in wastewater. We screened out a pyridine-degrading bacterial consortium and studied the degradation characteristics and metabolic pathways of the consortium, aiming to provide a theoretical basis and technical support for the microbial degradation and complete mineralization of high-concentration pyridine in wastewater. [Methods] We used pyridine as the only nitrogen source to screen out an efficient pyridine-degrading bacterial consortium MD1 from the aerobic activated sludge and water samples of a pesticide wastewater treatment system. The 16S rRNA high-throughput sequencing was performed to reveal the bacterial species, diversity, and structure of MD1. Single-factor experiments were conducted to study the degradation characteristics of MD1. The metabolites of pyridine degradation by MD1 were initially identified by gas chromatography-mass spectrometry, and the possible degradation pathways of pyridine were deduced. [Results] The degradation rate of MD1 incubated at the optimal conditions of 30 ℃, pH 8.0, and 0.1% NaCl for 72 h reached 98.44%±0.27% when the initial concentration of pyridine was 1 400 mg/L. MD1 was mainly composed of Paracoccus, unclassified_Brucellaceae, and Achromobacter at the genus level. The results of metabolite detection suggested that the possible metabolic pathway of MD1 was pyridine→nicotinic acid→6-hydroxynicotinic acid→2,5-dihydroxypyridine→N-formylmaleamic acid→maleamic acid→maleic acid→CO₂+H₂O. [Conclusion] This study screened out a bacterial consortium MD1 with stable performance in degrading pyridine. The diversity, structure, and pyridine metabolic pathway of MD1 were analyzed, which enriched the resources of pyridine-degrading microorganisms.