Study Of Microbial Degradation Of Chlordane Under Aerobic Condition

Chlordane is one of the persistent organic pollutants which were decided to be controlled globally first by the UNEP due to its physical and chemical stability, recalcitrant degradation under natural conditions and tending to accumulate in organisms. It had been proved that Chlordane may cause cancer, malformation and mutation, so research of elimination of Chlordane in the environments is of great significance to the health and sustainable development of humankind.Chlordane was the research object in this paper. Enterobacter sp.LY402, which had been isolated and proved to be able to degrade PCBs, was researched to biodegrade chloradane under aerobic conditions. The conditions of degradation were also optimized. Furthermore, we also isolated some new bacterium from the samples of pollution point to remove chlordane. The experimental results were followed:(1) LY402 could degrade chlordane in an aerobic environment. The percent of chlordane degradation at 1.0 mg /L was more than 94% after 4 days at 30℃. When exposed to a concentration as high as 10.0 mg/L, LY402 could still degrade 61% of chlordane. There was no obvious difference between cis-chlordane (CC) and trans-chlordane (TC) in the mixture on biotransformation rate. The higher the chlordane initial concentration showed the lower the degradation rate, which indicated that chlordane or intermediate metabolites might be harmful to the micro-organisms. The kinetics of chlordane degradation was evaluated well by pseudo one-order model.(2) The results of optimization of degradation conditions indicated: Temperature, pH could influence the degradation of chlordane by affecting on the growing and enzymatic activity of LY402. A pH range of 5.0-8.0 and a temperature range of 30℃-40℃were most favorable for growth and effective degradation of chlordane.As a good carbon source, both sucrose and sucrose laurate could increase the growing of LY402. However, the degradation of chlordane was inhibited by sucrose lauratenot and not affected by sucrose. (3)Two mixed strains (M-15,M-16) and two single strains (S-2,S-6) , which were isolated from the samples of pollution point, showed a strong ability to remove TC and CC.This paper presented that Enterbacter sp.LY402 could effectively degrade chlordane under aerobic conditions, which might be for reference to solve the complex pollution in the environments. Besides, we got new strains from environment, which might be advantage to study the synergies of different strains to increase the viability and the degradation rate of chlordane in high concentration.