Degradation of pyrene in soils by extracellular polymeric substances (EPS) extracted from liquid cultures

The extracellular polymeric substances (EPS) isolated from Zoogloea sp. and Aspergillus niger (A. niger) were employed in studies of degradation of pyrene in contaminated soils. The results of the present study showed that pyrene could be degraded in the presence of any one EPS, and the reduction of pyrene increased as the initial concentration of EPS increased. The best degradation was obtained in the presence of Zoogloea sp. EPS 5332.34 mg kg−1 + A. niger EPS 6512.17 mg kg−1, and more than 80% of pyrene was degraded after 35 days, meanwhile, the speedy degraded time was greatly reduced to 14 days from the 21 days required for other EPS combination. To understand the underlying principles of EPS depleting pyrene, the potential factors resulted in this phenomenon were discussed in the latter part, which could provide new insight into the function of EPS in bioremediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soils.