Biodegradation of pyridine using aerobic granules in the presence of phenol

Aerobic granules cultivated with 500 mg/L phenol medium effectively degraded pyridine at a concentration of 250-2500 mg/L; maximum degradation rate was 73.0 mg pyridine g/VSS/h at 250 mg/L pyridine concentration. Phenol concentrations of 500-2000 mg/L limited pyridine degradation in a competitive inhibition pattern, as interpreted using Michaelis-Menten kinetics with corresponding parameters V_max, K_m and K_I of 63.7 mg/L h^-1, 827.8 and 1388.9 mg/L, respectively. Fluorescent staining and confocal laser scanning microscopy (CLSM) tests suggested that an active biomass accumulated at the granule outer layer. Denaturing gradient gel electrophoresis (DGGE) fingerprint profile demonstrated that dominating microbial strains exist in phenol and pyridine-degrading aerobic granules.