Screening, identification and characterization of a pyridine degrading bacterium Paracoccus pantotrophus B21-3

Abstract:

[Background] As a refractory organic pollutant, pyridine is commonly found in wastewater from coking, refining, leather and pharmaceutical industries, causing harm to the environment. [Objective] To treat pyridine contaminated wastewater, bacteria capable of degrading pyridine were screened. [Methods] Pyridine degrading bacteria were isolated from the activated sludge of a wastewater plant in Shijiazhuang by enrichment and selective medium. Bacterium B21-3 was identified by morphological, physiological and biochemical characteristics, (G+C)mol% assay, and 16S rRNA gene phylogenic analysis. The pyridine degradation characteristics were analyzed. [Results] A bacterial strain B21-3 that used pyridine as the sole carbon and energy source was isolated and identified as Paracoccus pantotrophus. The optimal pH and temperature for pyridine degradation were 7.0 and 32 °C, respectively. When the initial concentration of pyridine was 100 mg/L, the degradation percentage of pyridine was 48.50%±0.02%. After acclimation by increasing the initial concentration of pyridine, strain B21-3 tolerated higher concentrations of pyridine and the degradation of pyridine increased significantly. Under the pyridine concentration of 100 mg/L, the degradation percentate of pyridine by domesticated strain B21-3 was 90.26%±1.70%. After the acclimatized strain B21-3 was subcultured on mineral salt plates supplemented with pyridine for 15 generations, the degradation percentage of pyridine was 89.39%±2.03%. [Conclusion] Strain B21-3 had strong pyridine degradation ability with potential for bioremediation of pyridine contaminated wastewater.