The results of regular determination of DDT content in the sewage sludge of natural wastewater reservoir and of laboratory experiments on degradation and metabolism of DDT by microorganisms indicated that the content of DDT in the sewage sludge of wastewater reservoir was reduced gradually, in which microorganisms played a very important role.Bacillus subtilis isolated from the sewage sludge not only could metabolize DDT to DDD, but also could convert DDD to DDA and DDM. The results of experiments also show...