Study Of Bioremediation And Mechanism Of The Combined Pollution Of BaP-Cd In Water Body By Arthrobacter Oxydans

The bioremediation and mechanism of Benzo[a]pyrene (BaP) and Cadmium (Cd), as the target pollutants in PAHs and heavy metals combined pollution, were studied in this paper, including environmental monitoring in pollution place, isolation, indentification and characteristics of BaP-degrading strain, degradation mechanisms of BaP, the interaction mechanism between strain and BaP-Cd, the treatment effect on BaP-Cd combined pollution in water-sediment systems with strain.PAHs and heavy metal monitoring analysis results showed that there was serious BaP-Cd combined pollution in Guangdong Shantou Guiyu. Strain B4 which could tolerateed PAHs and heavy metal combined pollution was isolated from contaminated sediment and identified as Arthrobacter oxydans. The experimental results showed that the concentration of BaP in MSM media was reduced to 0.32 mg.L-1 from the initial concentration of 1.00 mg.L-1 after 5 days of treatment. B4 had degradation ability at BaP concentration ranged from 0.10 to 10.00 mg.L-1, the . degradation rate of BaP reached best within 5 days when pH was 7.0 and the temperature was 30℃, the addition of nutrients could promoted BaP degradation of B4.Research on enzymatic degradation showed that the intracellular and extracellular enzymes secreted by strain B4 both had ability to degrade BaP, the concentration of BaP was reduced to about 0.5 mg.L-1,dioxygenase and glutathione S-transferase (GSTs) may be the key enzyme in degradation of BaP by B4.There was a mineralization process in degradation of BaP, the organic carbon was converted to inorganic carbon continuously during the degradation, BaP had influence on N,P ions transportation between the intracellular and extracellular of B4.UV-Vis, HPLC combined with GC-MS analysis exhibited that the structure of BaP changed with the action of microbe, generating a series of metabolites, such as 4-hydroxy Benzeneethanol, 1-Cyclohexyl-l-butanone, Benzoic acid,4-cyano-, methyl ester, with one benzene rings, through ring-cleavage reactions.B4 could simultaneous degrade and adsorb BaP, Cd in the metabolic process, meanwhile, BaP and Cd mutual influenced their respective residues, owing to changed the strain growth and the corresponding mechanisms. Electron microscopy confirmed that strain B4 could maintain normal growth condition in 1.00mg.L-1 BaP-Cd combined pollution system, thus ensuring their basic capability of degradation and adsorption, pH, H2O2 influenced the treatment effect of BaP-Cd combined pollution by B4.The simulation repair experimental results showed that, the concentration of BaP and Cd in system was respectively reduced to 0.18 mg.L-1 and 0.10 mg.L-1 from the initial concentration of 1.00 mg.L-1 after 15 days of treatment, although influenced by the indigenous microorganisms, the nutrients, shaking or static conditions and the repair time, using B4 to repair BaP-Cd combined pollution in the natural environment was feasible.