Identification and Characterization of Brevunmdimonas sp. Strain W-1 for Degradation of DDT

DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl) ethane] resides in soil, bioaccumulate and biomagnify along the food chain and pose risks to ecological components including human beings. Bioremediation is a potential option for the degradation of DDT in soils and slurries. There are very few studies addressing the degradation of DDT by pure cultures. A Gram-negative bacterial strain W-1 was isolated after domestication from DDT contaminated soil, which could utilize DDT as the sole carbon source for growth. This strain was identified as Brevunmdimonas sp. based on morphology, physiological tests, a partial analysis of the 16S rRNA gene and phylogenetic characteristics. The optimal conditions (temperature, pH value, inoculating dose, cultural time and added nutrition) for W-1 to degrade DDT were studied. In a shaky flask containing 10 mg·L-1 DDT, the degrading rate of W-1 on DDT was recorded highest at temperature 30 ℃, pH 8.0. The addition of 10 mg·L-1 glucose or surfactant, i.e., Triton100 or Tween20, to the culture medium increased the bacterial mass and the degradation of DDT. The structural homolog biphenyl and 4-chlorobenzoate (4-CBA) were found to inhibit the growth of bacterial cells and the degradation of DDT. This microbial culture has great potential utility for the bioremediation of waste waster or soil contaminated with DDT and its analogues.